use crate::axes::{Ax, Axis, Operation, Shape, Slice, SliceInfoElemDef, slice_info};
use crate::cache::{ArrayCache, ArrayKeyRef, FrameCache, FrameKeyRef, ReaderKeyRef};
use crate::error::Error;
use crate::metadata::Metadata;
use crate::readers::{Dimensions, DynReader, Frame, Reader};
use crate::stats::MinMax;
#[cfg(feature = "transforms")]
use crate::transforms::Transforms;
use indexmap::IndexMap;
use itertools::{Itertools, iproduct};
use ndarray::{
    Array, Array0, Array1, Array2, ArrayD, Dimension, IntoDimension, Ix0, Ix1, Ix2, Ix5, IxDyn,
    SliceArg, SliceInfoElem, s,
};
use num::traits::ToBytes;
use num::{Bounded, FromPrimitive, ToPrimitive, Zero};
use serde::{Deserialize, Serialize};
use serde_with::serde_as;
use std::any::type_name;
use std::collections::{HashMap, HashSet};
use std::fmt::{Debug, Display, Formatter};
use std::hash::{Hash, Hasher};
use std::iter::Sum;
use std::marker::PhantomData;
use std::ops::{AddAssign, Deref, Div};
use std::path::Path;
use std::sync::Arc;

fn idx_bnd(idx: isize, bnd: isize) -> Result<isize, Error> {
    if idx < -bnd {
        Err(Error::OutOfBounds(idx, bnd))
    } else if idx < 0 {
        Ok(bnd - idx)
    } else if idx < bnd {
        Ok(idx)
    } else {
        Err(Error::OutOfBounds(idx, bnd))
    }
}

fn slc_bnd(idx: isize, bnd: isize) -> Result<isize, Error> {
    if idx < -bnd {
        Err(Error::OutOfBounds(idx, bnd))
    } else if idx < 0 {
        Ok(bnd - idx)
    } else if idx <= bnd {
        Ok(idx)
    } else {
        Err(Error::OutOfBounds(idx, bnd))
    }
}

/// a trait for numeric types that can be used as pixel values
pub trait Number:
    'static
    + Send
    + Sync
    + AddAssign
    + Bounded
    + Clone
    + Div<Self, Output = Self>
    + FromPrimitive
    + PartialOrd
    + Zero
{
}
impl<T> Number for T where
    T: 'static
        + Send
        + Sync
        + AddAssign
        + Bounded
        + Clone
        + Div<Self, Output = Self>
        + FromPrimitive
        + PartialOrd
        + Zero
{
}

/// sliceable view on an image file
#[serde_as]
#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct View<D: Dimension, R: Reader = DynReader> {
    reader: R,
    /// same order as axes
    #[serde_as(as = "Vec<SliceInfoElemDef>")]
    slice: Vec<SliceInfoElem>,
    /// always has all of cztyx with possibly some new axes added
    axes: Vec<Axis>,
    operations: IndexMap<Axis, Operation>,
    dimensionality: PhantomData<D>,
    #[cfg(feature = "transforms")]
    pub(crate) transforms: Transforms,
}

impl<D, R> Hash for View<D, R>
where
    D: Dimension,
    R: Reader,
{
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.reader.hash(state);
        self.slice.hash(state);
        self.axes.hash(state);
        for (ax, op) in self.operations.iter() {
            ax.hash(state);
            op.hash(state);
        }
    }
}

impl<D: Dimension, R: Reader> View<D, R> {
    pub(crate) fn new(reader: R, slice: Vec<SliceInfoElem>, axes: Vec<Axis>) -> Self {
        Self {
            reader,
            slice,
            axes,
            operations: IndexMap::new(),
            dimensionality: PhantomData,
            #[cfg(feature = "transforms")]
            transforms: Transforms::default(),
        }
    }

    #[expect(dead_code)]
    pub(crate) fn new_with_axes(reader: R, axes: Vec<Axis>) -> Result<Self, Error> {
        let mut slice = Vec::new();
        let shape = reader.shape();
        for axis in axes.iter() {
            match axis {
                Axis::C => slice.push(SliceInfoElem::Slice {
                    start: 0,
                    end: Some(shape.c as isize),
                    step: 1,
                }),
                Axis::Z => slice.push(SliceInfoElem::Slice {
                    start: 0,
                    end: Some(shape.z as isize),
                    step: 1,
                }),
                Axis::T => slice.push(SliceInfoElem::Slice {
                    start: 0,
                    end: Some(shape.t as isize),
                    step: 1,
                }),
                Axis::Y => slice.push(SliceInfoElem::Slice {
                    start: 0,
                    end: Some(shape.y as isize),
                    step: 1,
                }),
                Axis::X => slice.push(SliceInfoElem::Slice {
                    start: 0,
                    end: Some(shape.x as isize),
                    step: 1,
                }),
                Axis::New => {
                    slice.push(SliceInfoElem::NewAxis);
                }
            }
        }
        let mut axes = axes.clone();
        for axis in [Axis::C, Axis::Z, Axis::T, Axis::Y, Axis::X] {
            if !axes.contains(&axis) {
                let size = match axis {
                    Axis::C => shape.c,
                    Axis::Z => shape.z,
                    Axis::T => shape.t,
                    Axis::Y => shape.y,
                    Axis::X => shape.x,
                    Axis::New => 1,
                };
                if size > 1 {
                    return Err(Error::OutOfBoundsAxis(format!("{:?}", axis), size));
                }
                slice.push(SliceInfoElem::Index(0));
                axes.push(axis);
            }
        }
        Ok(Self {
            reader,
            slice,
            axes,
            operations: IndexMap::new(),
            dimensionality: PhantomData,
            #[cfg(feature = "transforms")]
            transforms: Transforms::default(),
        })
    }

    /// the file path
    pub fn path(&self) -> &Path {
        self.reader.path()
    }

    /// the series in the file
    pub fn series(&self) -> usize {
        self.reader.series()
    }

    /// set the maximum number of frames the process-wide cache may hold,
    /// evicting the least recently used frames
    pub fn with_cache_capacity(self, capacity: usize) -> Self {
        FrameCache::global().set_capacity(capacity);
        self
    }

    /// the maximum number of frames the process-wide cache may hold
    pub fn cache_capacity(&self) -> usize {
        FrameCache::global().capacity()
    }

    /// set the maximum number of materialized arrays the process-wide cache
    /// may hold, evicting the least recently used arrays
    pub fn with_array_cache_capacity(self, capacity: usize) -> Self {
        ArrayCache::global().set_capacity(capacity);
        self
    }

    /// the maximum number of materialized arrays the process-wide cache may hold
    pub fn array_cache_capacity(&self) -> usize {
        ArrayCache::global().capacity()
    }

    fn with_operations(mut self, operations: IndexMap<Axis, Operation>) -> Self {
        self.operations = operations;
        self
    }

    /// change the dimension into a dynamic dimension
    pub fn into_dyn(self) -> View<IxDyn, R> {
        View {
            reader: self.reader,
            slice: self.slice,
            axes: self.axes,
            operations: self.operations,
            dimensionality: PhantomData,
            #[cfg(feature = "transforms")]
            transforms: Transforms::default(),
        }
    }

    /// change the dimension into a concrete dimension
    pub fn into_dimensionality<D2: Dimension>(self) -> Result<View<D2, R>, Error> {
        if let Some(d) = D2::NDIM {
            if d == self.ndim() {
                Ok(View {
                    reader: self.reader,
                    slice: self.slice,
                    axes: self.axes,
                    operations: self.operations,
                    dimensionality: PhantomData,
                    #[cfg(feature = "transforms")]
                    transforms: self.transforms,
                })
            } else {
                Err(Error::DimensionalityMismatch(d, self.ndim()))
            }
        } else {
            Ok(View {
                reader: self.reader,
                slice: self.slice,
                axes: self.axes,
                operations: self.operations,
                dimensionality: PhantomData,
                #[cfg(feature = "transforms")]
                transforms: self.transforms,
            })
        }
    }

    /// the order of the axes, including axes sliced out
    pub fn get_axes(&self) -> &[Axis] {
        &self.axes
    }

    #[expect(dead_code)]
    pub(crate) fn get_operations(&self) -> &IndexMap<Axis, Operation> {
        &self.operations
    }

    /// the slice defining the view
    pub fn get_slice(&self) -> &[SliceInfoElem] {
        &self.slice
    }

    /// the axes in the view
    pub fn axes(&self) -> Vec<Axis> {
        self.axes
            .iter()
            .zip(self.slice.iter())
            .filter_map(|(ax, s)| {
                if s.is_index() || self.operations.contains_key(ax) {
                    None
                } else {
                    Some(*ax)
                }
            })
            .collect()
    }

    /// remove axes of size 1
    pub fn squeeze(&self) -> Result<View<IxDyn, R>, Error> {
        let view = self.clone().into_dyn();
        let slice: Vec<_> = self
            .shape()
            .into_iter()
            .map(|s| {
                if s == 1 {
                    SliceInfoElem::Index(0)
                } else {
                    SliceInfoElem::Slice {
                        start: 0,
                        end: None,
                        step: 1,
                    }
                }
            })
            .collect();
        view.slice(slice.as_slice())
    }

    pub(crate) fn op_axes(&self) -> Vec<Axis> {
        self.operations.keys().cloned().collect()
    }

    /// the number of dimensions in the view
    pub fn ndim(&self) -> usize {
        if let Some(d) = D::NDIM {
            d
        } else {
            self.shape().len()
        }
    }

    /// the number of pixels in the first dimension
    pub fn len(&self) -> usize {
        self.shape()[0]
    }

    /// whether the view has no pixels in the first dimension
    pub fn is_empty(&self) -> bool {
        self.shape()[0] == 0
    }

    /// the number of pixels in the view
    pub fn size(&self) -> usize {
        self.shape().into_iter().product()
    }

    /// the size of the view along an axis, or `None` if the axis is not present
    pub fn size_ax(&self, ax: Axis) -> Option<usize> {
        self.axes()
            .iter()
            .position(|a| *a == ax)
            .map(|i| self.shape()[i])
    }

    /// the shape of the view
    pub fn shape(&self) -> Shape {
        let mut shape = Shape::new();
        for (ax, s) in self.axes.iter().zip(self.slice.iter()) {
            match s {
                SliceInfoElem::Slice { start, end, step } => {
                    if !self.operations.contains_key(ax) {
                        if let Some(e) = end {
                            shape.order.push(*ax);
                            shape.set_axis(ax, ((e - start).max(0) / step) as usize);
                        } else {
                            panic!("slice has no end")
                        }
                    }
                }
                SliceInfoElem::Index(_) => {}
                SliceInfoElem::NewAxis => {
                    if !self.operations.contains_key(ax) {
                        shape.order.push(*ax);
                    }
                }
            }
        }
        shape
    }

    /// swap two axes
    pub fn swap_axes<A: Ax>(&self, axis0: A, axis1: A) -> Result<Self, Error> {
        let idx0 = axis0.pos_op(&self.axes, &self.slice, &self.op_axes())?;
        let idx1 = axis1.pos_op(&self.axes, &self.slice, &self.op_axes())?;
        let mut slice = self.slice.to_vec();
        slice.swap(idx0, idx1);
        let mut axes = self.axes.clone();
        axes.swap(idx0, idx1);
        Ok(View::new(self.reader.clone(), slice, axes).with_operations(self.operations.clone()))
    }

    /// subset of gives axes will be reordered in given order
    pub fn permute_axes<A: Ax>(&self, axes: &[A]) -> Result<Self, Error> {
        let idx: Vec<usize> = axes
            .iter()
            .map(|a| a.pos_op(&self.axes, &self.slice, &self.op_axes()).unwrap())
            .collect();
        let mut jdx = idx.clone();
        jdx.sort();
        let mut slice = self.slice.to_vec();
        let mut axes = self.axes.clone();
        for (&i, j) in idx.iter().zip(jdx) {
            slice[j] = self.slice[i];
            axes[j] = self.axes[i];
        }
        Ok(View::new(self.reader.clone(), slice, axes).with_operations(self.operations.clone()))
    }

    /// subset of gives axes will be reordered in given order, only axes in axes will be returned
    pub fn permute_axes_dyn<A: Ax>(&self, axes: &[A]) -> Result<View<IxDyn, R>, Error> {
        let idx: Vec<usize> = axes
            .iter()
            .map(|a| a.pos_op(&self.axes, &self.slice, &self.op_axes()).unwrap())
            .collect();
        let mut jdx = idx.clone();
        jdx.sort();
        let mut new_slice = self.slice.to_vec();
        let mut new_axes = self.axes.clone();
        let axes = axes.iter().map(|a| a.n()).collect::<HashSet<_>>();
        for (&i, j) in idx.iter().zip(jdx) {
            new_slice[j] = self.slice[i];
            new_axes[j] = self.axes[i];
        }
        for (ax, s) in new_axes.iter().zip(new_slice.iter_mut()) {
            if let SliceInfoElem::Slice { start, end, step } = s
                && !axes.contains(&ax.n())
            {
                let size = ((end.expect("slice has no end") - *start).max(0) / *step) as usize;
                if size != 1 {
                    return Err(Error::SizeMismatch(ax.to_string(), size));
                }
                *s = SliceInfoElem::Index(*start)
            }
        }

        Ok(View::new(self.reader.clone(), new_slice, new_axes)
            .with_operations(self.operations.clone()))
    }

    /// reverse the order of the axes
    pub fn transpose(&self) -> Result<Self, Error> {
        Ok(View::new(
            self.reader.clone(),
            self.slice.iter().rev().cloned().collect(),
            self.axes.iter().rev().cloned().collect(),
        )
        .with_operations(self.operations.clone()))
    }

    /// reduce an axis with an operation (max, min, sum or mean), returning a view of lower dimensionality
    pub fn operate<A: Ax>(
        &self,
        axis: A,
        operation: Operation,
    ) -> Result<View<D::Smaller, R>, Error> {
        let pos = axis.pos_op(&self.axes, &self.slice, &self.op_axes())?;
        let ax = self.axes[pos];
        let (axes, slice, operations) = if Axis::New == ax {
            let mut axes = self.axes.clone();
            let mut slice = self.slice.clone();
            axes.remove(pos);
            slice.remove(pos);
            (axes, slice, self.operations.clone())
        } else if self.operations.contains_key(&ax) {
            if D::NDIM.is_none() {
                (
                    self.axes.clone(),
                    self.slice.clone(),
                    self.operations.clone(),
                )
            } else {
                return Err(Error::AxisAlreadyOperated(pos, ax.to_string()));
            }
        } else {
            let mut operations = self.operations.clone();
            operations.insert(ax, operation);
            (self.axes.clone(), self.slice.clone(), operations)
        };
        Ok(View::new(self.reader.clone(), slice, axes).with_operations(operations))
    }

    /// maximum along axis
    pub fn max_proj<A: Ax>(&self, axis: A) -> Result<View<D::Smaller, R>, Error> {
        self.operate(axis, Operation::Max)
    }

    /// minimum along axis
    pub fn min_proj<A: Ax>(&self, axis: A) -> Result<View<D::Smaller, R>, Error> {
        self.operate(axis, Operation::Min)
    }

    /// sum along axis
    pub fn sum_proj<A: Ax>(&self, axis: A) -> Result<View<D::Smaller, R>, Error> {
        self.operate(axis, Operation::Sum)
    }

    /// mean along axis
    pub fn mean_proj<A: Ax>(&self, axis: A) -> Result<View<D::Smaller, R>, Error> {
        self.operate(axis, Operation::Mean)
    }

    /// created a new sliced view
    pub fn slice<I>(&self, info: I) -> Result<View<I::OutDim, R>, Error>
    where
        I: SliceArg<D>,
    {
        if self.slice.out_ndim() < info.in_ndim() {
            return Err(Error::NotEnoughFreeDimensions);
        }
        let info = info.as_ref();
        let mut n_idx = 0;
        let mut r_idx = 0;
        let mut new_slice = Vec::new();
        let mut new_axes = Vec::new();
        let reader_slice = self.slice.as_slice();
        while (r_idx < reader_slice.len()) | (n_idx < info.len()) {
            let n = info.get(n_idx);
            let r = reader_slice.get(r_idx);
            let a = self.axes.get(r_idx);
            match a {
                Some(i) if self.operations.contains_key(i) => {
                    new_slice.push(*r.expect("slice should exist for axes under operation"));
                    new_axes.push(*i);
                    r_idx += 1;
                }
                _ => match (n, r) {
                    (
                        Some(SliceInfoElem::Slice {
                            start: info_start,
                            end: info_end,
                            step: info_step,
                        }),
                        Some(SliceInfoElem::Slice { start, end, step }),
                    ) => {
                        let new_start = start + info_start;
                        let end = end.expect("slice has no end");
                        let new_end = if let Some(m) = info_end {
                            end.min(start + info_step * m)
                        } else {
                            end
                        };
                        let new_step = (step * info_step).abs();
                        if new_start > end {
                            return Err(Error::OutOfBounds(*info_start, (end - start) / step));
                        }
                        new_slice.push(SliceInfoElem::Slice {
                            start: new_start,
                            end: Some(new_end),
                            step: new_step,
                        });
                        new_axes.push(*a.expect("axis should exist when slice exists"));
                        n_idx += 1;
                        r_idx += 1;
                    }
                    (
                        Some(SliceInfoElem::Index(k)),
                        Some(SliceInfoElem::Slice { start, end, step }),
                    ) => {
                        let i = if *k < 0 {
                            end.unwrap_or(0) + step.abs() * k
                        } else {
                            start + step.abs() * k
                        };
                        let end = end.expect("slice has no end");
                        if i >= end {
                            return Err(Error::OutOfBounds(i, (end - start) / step));
                        }
                        new_slice.push(SliceInfoElem::Index(i));
                        new_axes.push(*a.expect("axis should exist when slice exists"));
                        n_idx += 1;
                        r_idx += 1;
                    }
                    (Some(SliceInfoElem::Slice { start, .. }), Some(SliceInfoElem::NewAxis)) => {
                        if *start != 0 {
                            return Err(Error::OutOfBounds(*start, 1));
                        }
                        new_slice.push(SliceInfoElem::NewAxis);
                        new_axes.push(Axis::New);
                        n_idx += 1;
                        r_idx += 1;
                    }
                    (Some(SliceInfoElem::Index(k)), Some(SliceInfoElem::NewAxis)) => {
                        if *k != 0 {
                            return Err(Error::OutOfBounds(*k, 1));
                        }
                        n_idx += 1;
                        r_idx += 1;
                    }
                    (Some(SliceInfoElem::NewAxis), Some(SliceInfoElem::NewAxis)) => {
                        new_slice.push(SliceInfoElem::NewAxis);
                        new_slice.push(SliceInfoElem::NewAxis);
                        new_axes.push(Axis::New);
                        new_axes.push(Axis::New);
                        n_idx += 1;
                        r_idx += 1;
                    }
                    (Some(SliceInfoElem::NewAxis), _) => {
                        new_slice.push(SliceInfoElem::NewAxis);
                        new_axes.push(Axis::New);
                        n_idx += 1;
                    }
                    (_, Some(SliceInfoElem::Index(k))) => {
                        new_slice.push(SliceInfoElem::Index(*k));
                        new_axes.push(*a.expect("axis should exist when slice exists"));
                        r_idx += 1;
                    }
                    _ => unreachable!(),
                },
            }
        }
        debug_assert_eq!(r_idx, reader_slice.len());
        while n_idx < info.len() {
            debug_assert!(info[n_idx].is_new_axis());
            new_slice.push(SliceInfoElem::NewAxis);
            new_axes.push(Axis::New);
            n_idx += 1;
        }
        Ok(View::new(self.reader.clone(), new_slice, new_axes)
            .with_operations(self.operations.clone()))
    }

    /// resets axes to cztyx order, with all 5 axes present,
    /// inserts new axes in place of axes under operation (max_proj etc.)
    pub fn reset_axes(&self) -> Result<View<Ix5, R>, Error> {
        let mut axes = Vec::new();
        let mut slice = Vec::new();

        for ax in [Axis::C, Axis::Z, Axis::T, Axis::Y, Axis::X] {
            axes.push(ax);
            let s = self.slice[ax.pos(&self.axes, &self.slice)?];
            match s {
                SliceInfoElem::Slice { .. } => slice.push(s),
                SliceInfoElem::Index(i) => slice.push(SliceInfoElem::Slice {
                    start: i,
                    end: Some(i + 1),
                    step: 1,
                }),
                SliceInfoElem::NewAxis => {
                    panic!("slice should not be NewAxis when axis is one of cztyx")
                }
            }
            if self.operations.contains_key(&ax) {
                axes.push(Axis::New);
                slice.push(SliceInfoElem::NewAxis)
            }
        }
        Ok(View::new(self.reader.clone(), slice, axes).with_operations(self.operations.clone()))
    }

    /// slice, but slice elements are in cztyx order, all cztyx must be given,
    /// but axes not present in view will be ignored, view axes are reordered in cztyx order
    pub fn slice_cztyx<I>(&self, info: I) -> Result<View<I::OutDim, R>, Error>
    where
        I: SliceArg<Ix5>,
    {
        self.reset_axes()?.slice(info)?.into_dimensionality()
    }

    /// the pixel intensity at a given index
    pub fn item_at<T>(&self, index: &[isize]) -> Result<T, Error>
    where
        T: Number,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        let slice: Vec<_> = index.iter().map(|s| SliceInfoElem::Index(*s)).collect();
        let view = self.clone().into_dyn().slice(slice.as_slice())?;
        let arr = view.as_array()?;
        Ok(arr.first().unwrap().clone())
    }

    /// collect the view into an ndarray
    pub fn as_array<T>(&self) -> Result<Array<T, D>, Error>
    where
        T: Number,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        Ok(self.as_array_dyn()?.into_dimensionality()?)
    }

    /// collect the view into a dynamic-dimension ndarray
    pub fn as_array_dyn<T>(&self) -> Result<ArrayD<T>, Error>
    where
        T: Number,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        let key = self.array_key::<T>();
        if let Some(arr) = ArrayCache::global().get(&key) {
            return Ok(arr.as_ref().clone());
        }
        let mut op_xy = IndexMap::new();
        if let Some((&ax, op)) = self.operations.first()
            && ((ax == Axis::X) || (ax == Axis::Y))
        {
            op_xy.insert(ax, op.clone());
            if let Some((&ax2, op2)) = self.operations.get_index(1)
                && ((ax2 == Axis::X) || (ax2 == Axis::Y))
            {
                op_xy.insert(ax2, op2.clone());
            }
        }
        let op_czt = if let Some((&ax, op)) = self.operations.get_index(op_xy.len()) {
            IndexMap::from([(ax, op.clone())])
        } else {
            IndexMap::new()
        };
        let mut shape_out = Vec::new();
        let mut slice = Vec::new();
        let mut ax_out = Vec::new();
        for (s, a) in self.slice.iter().zip(&self.axes) {
            match s {
                SliceInfoElem::Slice { start, end, step } => {
                    let end = end.expect("slice has no end");
                    if !op_xy.contains_key(a) && !op_czt.contains_key(a) {
                        shape_out.push(((end - start).max(0) / step) as usize);
                        slice.push(SliceInfoElem::Slice {
                            start: 0,
                            end: None,
                            step: 1,
                        });
                        ax_out.push(*a);
                    }
                }
                SliceInfoElem::Index(_) => {}
                SliceInfoElem::NewAxis => {
                    shape_out.push(1);
                    slice.push(SliceInfoElem::Index(0));
                    ax_out.push(*a);
                }
            }
        }
        let mut slice_reader = vec![Slice::empty(); 5];
        let mut xy_dim = 0usize;
        let shape_reader = self.reader.shape();
        for (s, &axis) in self.slice.iter().zip(&self.axes) {
            match axis {
                Axis::New => {}
                _ => match s {
                    SliceInfoElem::Slice { start, end, step } => {
                        if let Axis::X | Axis::Y = axis
                            && !op_xy.contains_key(&axis)
                        {
                            xy_dim += 1;
                        }
                        slice_reader[axis as usize] = Slice::new(
                            idx_bnd(*start, shape_reader[axis] as isize)?,
                            slc_bnd(end.unwrap(), shape_reader[axis] as isize)?,
                            *step,
                        );
                    }
                    SliceInfoElem::Index(j) => {
                        slice_reader[axis as usize] = Slice::new(
                            idx_bnd(*j, shape_reader[axis] as isize)?,
                            slc_bnd(*j + 1, shape_reader[axis] as isize)?,
                            1,
                        );
                    }
                    SliceInfoElem::NewAxis => panic!("axis cannot be a new axis"),
                },
            }
        }
        let xy = [
            self.slice[Axis::Y.pos(&self.axes, &self.slice)?],
            self.slice[Axis::X.pos(&self.axes, &self.slice)?],
        ];
        let mut array = if let Some((_, op)) = op_czt.first() {
            match op {
                Operation::Max => {
                    ArrayD::<T>::from_elem(shape_out.into_dimension(), T::min_value())
                }
                Operation::Min => {
                    ArrayD::<T>::from_elem(shape_out.into_dimension(), T::max_value())
                }
                _ => ArrayD::<T>::zeros(shape_out.into_dimension()),
            }
        } else {
            ArrayD::<T>::zeros(shape_out.into_dimension())
        };
        let shape = self.reader.shape();
        let mut axes_out_idx = [None; 5];
        for (i, ax) in ax_out.iter().enumerate() {
            if *ax < Axis::New {
                axes_out_idx[*ax as usize] = Some(i);
            }
        }

        for (c, z, t) in iproduct!(&slice_reader[0], &slice_reader[1], &slice_reader[2]) {
            if let Some(i) = axes_out_idx[0] {
                slice[i] = SliceInfoElem::Index(c)
            };
            if let Some(i) = axes_out_idx[1] {
                slice[i] = SliceInfoElem::Index(z)
            };
            if let Some(i) = axes_out_idx[2] {
                slice[i] = SliceInfoElem::Index(t)
            };
            let frame = self.get_cached_frame(
                (c % shape.c as isize) as usize,
                (z % shape.z as isize) as usize,
                (t % shape.t as isize) as usize,
            )?;

            let arr_frame: Array2<T> = frame.as_ref().try_into()?;
            let arr_frame = match xy_dim {
                0 => {
                    if op_xy.contains_key(&Axis::X) && op_xy.contains_key(&Axis::Y) {
                        let xys = slice_info::<Ix2>(&xy)?;
                        let (&ax0, op0) = op_xy.first().unwrap();
                        let (&ax1, op1) = op_xy.get_index(1).unwrap();
                        let a = arr_frame.slice(xys).to_owned();
                        let b = op0.operate(a, ax0 as usize - 3)?;
                        let c = op1.operate(b.to_owned(), ax1 as usize - 3)?;
                        c.to_owned().into_dyn()
                    } else if op_xy.contains_key(&Axis::X) || op_xy.contains_key(&Axis::Y) {
                        let xys = slice_info::<Ix1>(&xy)?;
                        let (&ax, op) = op_xy.first().unwrap();
                        let a = arr_frame.slice(xys).to_owned();
                        let b = op.operate(a, ax as usize - 3)?;
                        b.to_owned().into_dyn()
                    } else {
                        let xys = slice_info::<Ix0>(&xy)?;
                        arr_frame.slice(xys).to_owned().into_dyn()
                    }
                }
                1 => {
                    if op_xy.contains_key(&Axis::X) || op_xy.contains_key(&Axis::Y) {
                        let xys = slice_info::<Ix2>(&xy)?;
                        let (&ax, op) = op_xy.first().unwrap();
                        let a = arr_frame.slice(xys).to_owned();
                        let b = op.operate(a, ax as usize - 3)?;
                        b.to_owned().into_dyn()
                    } else {
                        let xys = slice_info::<Ix1>(&xy)?;
                        arr_frame.slice(xys).to_owned().into_dyn()
                    }
                }
                2 => {
                    let xys = slice_info::<Ix2>(&xy)?;
                    if axes_out_idx[4] < axes_out_idx[3] {
                        arr_frame.t().slice(xys).to_owned().into_dyn()
                    } else {
                        arr_frame.slice(xys).to_owned().into_dyn()
                    }
                }
                _ => {
                    unreachable!("xy cannot be 3d or more");
                }
            };
            if let Some((_, op)) = op_czt.first() {
                match op {
                    Operation::Max => {
                        array
                            .slice_mut(slice.as_slice())
                            .zip_mut_with(&arr_frame, |x, y| {
                                *x = if *x >= *y { x.clone() } else { y.clone() }
                            });
                    }
                    Operation::Min => {
                        array
                            .slice_mut(slice.as_slice())
                            .zip_mut_with(&arr_frame, |x, y| {
                                *x = if *x < *y { x.clone() } else { y.clone() }
                            });
                    }
                    Operation::Sum => {
                        array
                            .slice_mut(slice.as_slice())
                            .zip_mut_with(&arr_frame, |x, y| *x += y.clone());
                    }
                    Operation::Mean => {
                        array
                            .slice_mut(slice.as_slice())
                            .zip_mut_with(&arr_frame, |x, y| *x += y.clone());
                    }
                }
            } else {
                array.slice_mut(slice.as_slice()).assign(&arr_frame)
            }
        }
        let mut out = Some(array);
        let mut ax_out: HashMap<Axis, usize> = ax_out
            .into_iter()
            .enumerate()
            .map(|(i, a)| (a, i))
            .collect();
        for (ax, op) in self.operations.iter().skip(op_xy.len() + op_czt.len()) {
            if let Some(idx) = ax_out.remove(ax) {
                for i in ax_out.values_mut() {
                    if *i > idx {
                        *i -= 1;
                    }
                }
                let arr = out.take().unwrap();
                let a = op.operate(arr, idx)?;
                let _ = out.insert(a);
            }
        }
        let n = if let Some((&ax, op)) = op_czt.first()
            && *op == Operation::Mean
        {
            self.axes
                .iter()
                .zip(self.slice.iter())
                .find(|(a, _)| **a == ax)
                .and_then(|(_, s)| match s {
                    SliceInfoElem::Slice { start, end, step } => {
                        end.map(|e| (((e - start).max(0) / step) as usize).max(1))
                    }
                    _ => Some(1),
                })
                .unwrap_or(1)
        } else {
            1
        };
        let array = if n == 1 {
            out.take().unwrap()
        } else {
            let m = T::from_usize(n).unwrap_or_else(|| T::zero());
            out.take().unwrap().mapv(|x| x / m.clone())
        };
        ArrayCache::global().insert(key.to_owned(), array.clone());
        Ok(array)
    }

    /// turn the view into a 1d array
    pub fn flatten<T>(&self) -> Result<Array1<T>, Error>
    where
        T: Number,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        Ok(Array1::from_iter(self.as_array()?.iter().cloned()))
    }

    /// turn the data into a byte vector
    pub fn to_bytes<T>(&self) -> Result<Vec<u8>, Error>
    where
        T: Number + ToBytesVec,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        Ok(self
            .as_array()?
            .iter()
            .flat_map(|i| i.to_bytes_vec())
            .collect())
    }

    fn frame_key(&self, c: usize, z: usize, t: usize) -> FrameKeyRef<'_> {
        FrameKeyRef {
            reader: ReaderKeyRef {
                name: self.reader.reader_name(),
                path: self.reader.path(),
                series: self.reader.series(),
                position: self.reader.position(),
            },
            c,
            z,
            t,
        }
    }

    fn array_key<T: 'static>(&self) -> ArrayKeyRef<'_> {
        ArrayKeyRef {
            reader: ReaderKeyRef {
                name: self.reader.reader_name(),
                path: self.reader.path(),
                series: self.reader.series(),
                position: self.reader.position(),
            },
            dtype: type_name::<T>(),
            slice: &self.slice,
            axes: &self.axes,
            operations: &self.operations,
        }
    }

    fn get_cached_frame(&self, c: usize, z: usize, t: usize) -> Result<Arc<Frame>, Error> {
        let key = self.frame_key(c, z, t);
        if let Some(frame) = FrameCache::global().get(&key) {
            return Ok(frame);
        }
        let frame = Arc::new(self.reader.get_frame(c, z, t)?);
        FrameCache::global().insert(key.to_owned(), frame.clone());
        Ok(frame)
    }

    /// retrieve a single frame at czt, sliced accordingly
    pub fn get_frame<T, N>(&self, c: N, z: N, t: N) -> Result<Array2<T>, Error>
    where
        T: Number,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
        N: Display + ToPrimitive,
    {
        let c = c
            .to_isize()
            .ok_or_else(|| Error::Cast(c.to_string(), "isize".to_string()))?;
        let z = z
            .to_isize()
            .ok_or_else(|| Error::Cast(z.to_string(), "isize".to_string()))?;
        let t = t
            .to_isize()
            .ok_or_else(|| Error::Cast(t.to_string(), "isize".to_string()))?;
        self.slice_cztyx(s![c, z, t, .., ..])?.as_array()
    }

    fn get_stat<T>(&self, operation: Operation) -> Result<T, Error>
    where
        T: Number + Sum,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        let arr: ArrayD<T> = self.as_array_dyn()?;
        Ok(match operation {
            Operation::Max => arr
                .flatten()
                .into_iter()
                .reduce(|a, b| if a > b { a } else { b })
                .unwrap_or_else(|| T::min_value()),
            Operation::Min => arr
                .flatten()
                .into_iter()
                .reduce(|a, b| if a < b { a } else { b })
                .unwrap_or_else(|| T::max_value()),
            Operation::Sum => arr.flatten().into_iter().sum(),
            Operation::Mean => {
                arr.flatten().into_iter().sum::<T>()
                    / T::from_usize(arr.len()).ok_or_else(|| {
                        Error::Cast(arr.len().to_string(), type_name::<T>().to_string())
                    })?
            }
        })
    }

    /// maximum intensity
    pub fn max<T>(&self) -> Result<T, Error>
    where
        T: Number + Sum,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        self.get_stat(Operation::Max)
    }

    /// minimum intensity
    pub fn min<T>(&self) -> Result<T, Error>
    where
        T: Number + Sum,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        self.get_stat(Operation::Min)
    }

    /// sum intensity
    pub fn sum<T>(&self) -> Result<T, Error>
    where
        T: Number + Sum,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        self.get_stat(Operation::Sum)
    }

    /// mean intensity
    pub fn mean<T>(&self) -> Result<T, Error>
    where
        T: Number + Sum,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        self.get_stat(Operation::Mean)
    }

    /// gives a helpful summary of the recorded experiment
    pub fn summary(&self) -> Result<String, Error> {
        let mut s = "".to_string();
        s.push_str(&format!("path/filename: {}\n", self.path().display()));
        s.push_str(&format!("series/pos:    {}\n", self.series()));
        s.push_str(&format!("reader:        {}\n", self.reader_name()));
        s.push_str(&format!("dtype:         {:?}\n", self.pixel_type()));
        let axes = self
            .axes()
            .into_iter()
            .map(|ax| format!("{}", ax))
            .join("")
            .to_lowercase();
        let shape = self
            .shape()
            .into_iter()
            .map(|s| format!("{}", s))
            .join(" x ");
        let space = " ".repeat(6usize.saturating_sub(axes.len()));
        s.push_str(&format!("shape ({}):{}{}\n", axes, space, shape));
        s.push_str(&self.metadata()?.summary()?);
        Ok(s)
    }
}

impl<D: Dimension, R: Reader> Deref for View<D, R> {
    type Target = R;

    fn deref(&self) -> &Self::Target {
        &self.reader
    }
}

impl<T, D, R> TryFrom<View<D, R>> for Array<T, D>
where
    T: Number,
    D: Dimension,
    R: Reader,
    ArrayD<T>: MinMax<Output = ArrayD<T>>,
    Array1<T>: MinMax<Output = Array0<T>>,
    Array2<T>: MinMax<Output = Array1<T>>,
{
    type Error = Error;

    fn try_from(view: View<D, R>) -> Result<Self, Self::Error> {
        view.as_array()
    }
}

impl<T, D, R> TryFrom<&View<D, R>> for Array<T, D>
where
    T: Number,
    D: Dimension,
    R: Reader,
    ArrayD<T>: MinMax<Output = ArrayD<T>>,
    Array1<T>: MinMax<Output = Array0<T>>,
    Array2<T>: MinMax<Output = Array1<T>>,
{
    type Error = Error;

    fn try_from(view: &View<D, R>) -> Result<Self, Self::Error> {
        view.as_array()
    }
}

/// trait to define a function to retrieve the only item in a 0d array
pub trait Item {
    /// the single item in the 0d array, cast to `T`
    fn item<T>(&self) -> Result<T, Error>
    where
        T: Number,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>;
}

impl<R: Reader> View<Ix5, R> {
    /// create a view on the image at `path`, parsing series and position from the file name
    pub fn from_path<P>(path: P) -> Result<Self, Error>
    where
        P: AsRef<Path>,
    {
        let (path, dimensions) = Dimensions::parse_path(path)?;
        Ok(R::new(path, dimensions.s.unwrap_or(0), dimensions.p.unwrap_or(0))?.view())
    }
}

impl<R: Reader> Item for View<Ix0, R> {
    fn item<T>(&self) -> Result<T, Error>
    where
        T: Number,
        ArrayD<T>: MinMax<Output = ArrayD<T>>,
        Array1<T>: MinMax<Output = Array0<T>>,
        Array2<T>: MinMax<Output = Array1<T>>,
    {
        Ok(self.as_array()?.first().ok_or(Error::EmptyView)?.clone())
    }
}

impl<D: Dimension, R: Reader> Display for View<D, R> {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        if let Ok(summary) = self.summary() {
            write!(f, "{}", summary)
        } else {
            write!(f, "{}", self.path().display())
        }
    }
}

/// trait to convert numbers to bytes
pub trait ToBytesVec {
    /// the number as a vector of bytes in native endianness
    fn to_bytes_vec(&self) -> Vec<u8>;
}

macro_rules! to_bytes_vec_impl {
    ($($t:ty $(,)?)*) => {
        $(
            impl ToBytesVec for $t {

                #[inline]
                fn to_bytes_vec(&self) -> Vec<u8> {
                    self.to_ne_bytes().to_vec()
                }
            }
        )*
    };
}

to_bytes_vec_impl!(
    u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize, f32, f64
);

#[cfg(test)]
mod tests {
    use crate::axes::{Axis, Operation};
    use crate::cache::{ArrayCache, ArrayKey, ArrayKeyRef, FrameCache, ReaderKey, ReaderKeyRef};
    use crate::error::Error;
    use crate::readers::{DynReader, Frame, Reader};
    use crate::stats::MinMax;
    use crate::view::Item;
    use indexmap::IndexMap;
    use ndarray::{Array, Array4, Array5, NewAxis};
    use ndarray::{Array2, ArrayD, IxDyn, SliceInfoElem, s};
    use std::path::{Path, PathBuf};
    use std::sync::Arc;

    fn open(file: &str) -> Result<DynReader, Error> {
        let path = std::env::current_dir()?
            .join("tests")
            .join("files")
            .join(file);
        DynReader::new(&path, 0, 0)
    }

    #[test]
    fn view() -> Result<(), Error> {
        let file = "tiffseq/YTL1841B2-2-1_1hr_DMSO_galinduction_1";
        let reader = open(file)?;
        let view = reader.view();
        println!("view: {:?}", view);
        let a = view.slice(s![0, 5, 0, .., ..])?;
        println!("a: {:?}", a);
        let b = reader.get_frame(0, 5, 0)?;
        let c: Array2<isize> = a.try_into()?;
        println!("c {:?}", c);
        let d: Array2<isize> = b.try_into()?;
        println!("d {:?}", d);
        assert_eq!(c, d);
        Ok(())
    }

    #[test]
    fn view_shape() -> Result<(), Error> {
        let file = "tiffseq/YTL1841B2-2-1_1hr_DMSO_galinduction_1";
        let reader = open(file)?;
        let view = reader.view();
        let a = view.slice(s![0, ..5, 0, .., 100..200])?;
        let shape = a.shape();
        assert_eq!(shape.to_vec(), vec![5, 1024, 100]);
        Ok(())
    }

    #[test]
    fn view_new_axis() -> Result<(), Error> {
        let file = "tiffseq/YTL1841B2-2-1_1hr_DMSO_galinduction_1";
        let reader = open(file)?;
        let view = reader.view();
        let a = Array5::<u8>::zeros((1, 9, 1, 1024, 1024));
        let a = a.slice(s![0, ..5, 0, NewAxis, 100..200, ..]);
        let v = view.slice(s![0, ..5, 0, NewAxis, 100..200, ..])?;
        assert_eq!(v.shape().to_vec(), a.shape());
        let a = a.slice(s![NewAxis, .., .., NewAxis, .., .., NewAxis]);
        let v = v.slice(s![NewAxis, .., .., NewAxis, .., .., NewAxis])?;
        assert_eq!(v.shape().to_vec(), a.shape());
        Ok(())
    }

    #[test]
    fn view_permute_axes() -> Result<(), Error> {
        let file = "tiffseq/YTL1841B2-2-1_1hr_DMSO_galinduction_1";
        let reader = open(file)?;
        let view = reader.view();
        let s = view.shape();
        let mut a = Array5::<u8>::zeros((s[0], s[1], s[2], s[3], s[4]));
        assert_eq!(view.shape().to_vec(), a.shape());
        let b: Array5<usize> = view.clone().try_into()?;
        assert_eq!(b.shape(), a.shape());

        let view = view.swap_axes(Axis::C, Axis::Z)?;
        a.swap_axes(0, 1);
        assert_eq!(view.shape().to_vec(), a.shape());
        let b: Array5<usize> = view.clone().try_into()?;
        assert_eq!(b.shape(), a.shape());
        let view = view.permute_axes(&[Axis::X, Axis::Z, Axis::Y])?;
        let a = a.permuted_axes([4, 1, 2, 0, 3]);
        assert_eq!(view.shape().to_vec(), a.shape());
        let b: Array5<usize> = view.clone().try_into()?;
        assert_eq!(b.shape(), a.shape());
        Ok(())
    }

    macro_rules! test_max {
        ($($name:ident: $b:expr $(,)?)*) => {
            $(
                #[test]
                fn $name() -> Result<(), Error> {
                    let file = "tiffseq/YTL1841B2-2-1_1hr_DMSO_galinduction_1";
                    let reader = open(file)?;
                    let view = reader.view();
                    let array: Array5<usize> = view.clone().try_into()?;
                    let view = view.max_proj($b)?;
                    let a: Array4<usize> = view.clone().try_into()?;
                    let b = array.max($b)?;
                    assert_eq!(a.shape(), b.shape());
                    assert_eq!(a, b);
                    Ok(())
                }
            )*
        };
    }

    test_max! {
        max_c: 0
        max_z: 1
        max_t: 2
        max_y: 3
        max_x: 4
    }

    macro_rules! test_index {
        ($($name:ident: $b:expr $(,)?)*) => {
            $(
                #[test]
                fn $name() -> Result<(), Error> {
                    let file = "tiffseq/YTL1841B2-2-1_1hr_DMSO_galinduction_1";
                    let reader = open(file)?;
                    let view = reader.view();
                    let v4: Array<usize, _> = view.slice($b)?.try_into()?;
                    let a5: Array5<usize> = reader.view().try_into()?;
                    let a4 = a5.slice($b).to_owned();
                    assert_eq!(a4, v4);
                    Ok(())
                }
            )*
        };
    }

    test_index! {
        index_0: s![.., .., .., .., ..]
        index_1: s![0, .., .., .., ..]
        index_2: s![.., 0, .., .., ..]
        index_3: s![.., .., 0, .., ..]
        index_4: s![.., .., .., 0, ..]
        index_5: s![.., .., .., .., 0]
        index_6: s![0, 0, .., .., ..]
        index_7: s![0, .., 0, .., ..]
        index_8: s![0, .., .., 0, ..]
        index_9: s![0, .., .., .., 0]
        index_a: s![.., 0, 0, .., ..]
        index_b: s![.., 0, .., 0, ..]
        index_c: s![.., 0, .., .., 0]
        index_d: s![.., .., 0, 0, ..]
        index_e: s![.., .., 0, .., 0]
        index_f: s![.., .., .., 0, 0]
        index_g: s![0, 0, 0, .., ..]
        index_h: s![0, 0, .., 0, ..]
        index_i: s![0, 0, .., .., 0]
        index_j: s![0, .., 0, 0, ..]
        index_k: s![0, .., 0, .., 0]
        index_l: s![0, .., .., 0, 0]
        index_m: s![0, 0, 0, 0, ..]
        index_n: s![0, 0, 0, .., 0]
        index_o: s![0, 0, .., 0, 0]
        index_p: s![0, .., 0, 0, 0]
        index_q: s![.., 0, 0, 0, 0]
        index_r: s![0, 0, 0, 0, 0]
    }

    #[test]
    fn dyn_view() -> Result<(), Error> {
        let file = "tiffseq/YTL1841B2-2-1_1hr_DMSO_galinduction_1";
        let reader = open(file)?;
        let a = reader.view().into_dyn();
        let b = a.max_proj(1)?;
        let c = b.slice(s![0, 0, .., ..])?;
        let d = c.as_array::<usize>()?;
        assert_eq!(d.shape(), [1024, 1024]);
        Ok(())
    }

    #[test]
    fn item() -> Result<(), Error> {
        let file = "czi/1xp53-01-AP1.czi";
        let reader = open(file)?;
        let view = reader.view();
        let a = view.slice(s![.., 0, 0, 0, 0])?;
        let b = a.slice(s![0])?;
        let item = b.item::<usize>()?;
        assert_eq!(item, 2);
        Ok(())
    }

    #[test]
    fn slice_cztyx() -> Result<(), Error> {
        let file = "czi/1xp53-01-AP1.czi";
        let reader = open(file)?;
        let view = reader.view().max_proj(Axis::Z)?.into_dyn();
        println!("view.axes: {:?}", view.get_axes());
        println!("view.slice: {:?}", view.get_slice());
        let r = view.reset_axes()?;
        println!("r.axes: {:?}", r.get_axes());
        println!("r.slice: {:?}", r.get_slice());
        let a = view.slice_cztyx(s![0, 0, 0, .., ..])?;
        println!("a.axes: {:?}", a.get_axes());
        println!("a.slice: {:?}", a.get_slice());
        assert_eq!(a.axes(), [Axis::Y, Axis::X]);
        Ok(())
    }

    #[test]
    fn reset_axes() -> Result<(), Error> {
        let file = "czi/1xp53-01-AP1.czi";
        let reader = open(file)?;
        let view = reader.view().max_proj(Axis::Z)?;
        let view = view.reset_axes()?;
        assert_eq!(view.axes(), [Axis::C, Axis::New, Axis::T, Axis::Y, Axis::X]);
        let a = view.as_array::<f64>()?;
        assert_eq!(a.ndim(), 5);
        Ok(())
    }

    #[test]
    fn reset_axes2() -> Result<(), Error> {
        let file = "czi/Experiment-2029.czi";
        let reader = open(file)?;
        let view = reader.view().squeeze()?;
        let a = view.reset_axes()?;
        assert_eq!(a.axes(), [Axis::C, Axis::Z, Axis::T, Axis::Y, Axis::X]);
        Ok(())
    }

    #[test]
    fn reset_axes3() -> Result<(), Error> {
        let file = "czi/Experiment-2029.czi";
        let reader = open(file)?;
        let view4 = reader.view().squeeze()?;
        let view = view4.max_proj(Axis::Z)?.into_dyn();
        let slice = view.slice_cztyx(s![0, .., .., .., ..])?.into_dyn();
        let a = slice.as_array::<u16>()?;
        assert_eq!(slice.shape().to_vec(), [1, 10, 1280, 1280]);
        assert_eq!(a.shape(), [1, 10, 1280, 1280]);
        let r = slice.reset_axes()?;
        let b = r.as_array::<u16>()?;
        assert_eq!(r.shape().to_vec(), [1, 1, 10, 1280, 1280]);
        assert_eq!(b.shape(), [1, 1, 10, 1280, 1280]);
        let q = slice.max_proj(Axis::C)?.max_proj(Axis::T)?;
        let c = q.as_array::<f64>()?;
        assert_eq!(q.shape().to_vec(), [1, 1280, 1280]);
        assert_eq!(c.shape().to_vec(), [1, 1280, 1280]);
        let p = q.reset_axes()?;
        let d = p.as_array::<u16>()?;
        println!("axes: {:?}", p.get_axes());
        println!("operations: {:?}", p.get_operations());
        println!("slice: {:?}", p.get_slice());
        assert_eq!(p.shape().to_vec(), [1, 1, 1, 1280, 1280]);
        assert_eq!(d.shape(), [1, 1, 1, 1280, 1280]);
        Ok(())
    }

    #[test]
    fn max() -> Result<(), Error> {
        let file = "czi/Experiment-2029.czi";
        let reader = open(file)?;
        let view = reader.view();
        let m = view.max_proj(Axis::T)?;
        let a = m.as_array::<u16>()?;
        assert_eq!(m.shape().to_vec(), [2, 1, 1280, 1280]);
        assert_eq!(a.shape(), [2, 1, 1280, 1280]);
        let mc = view.max_proj(Axis::C)?;
        let a = mc.as_array::<u16>()?;
        assert_eq!(mc.shape().to_vec(), [1, 10, 1280, 1280]);
        assert_eq!(a.shape(), [1, 10, 1280, 1280]);
        let mz = mc.max_proj(Axis::Z)?;
        let a = mz.as_array::<u16>()?;
        assert_eq!(mz.shape().to_vec(), [10, 1280, 1280]);
        assert_eq!(a.shape(), [10, 1280, 1280]);
        let mt = mz.max_proj(Axis::T)?;
        let a = mt.as_array::<u16>()?;
        assert_eq!(mt.shape().to_vec(), [1280, 1280]);
        assert_eq!(a.shape(), [1280, 1280]);
        Ok(())
    }

    #[test]
    fn frame_cache() -> Result<(), Error> {
        let cache = FrameCache::new(2);
        let key = |c: usize, z: usize, t: usize| {
            (
                ReaderKey {
                    name: "test".to_string(),
                    path: PathBuf::from("test.tif"),
                    series: 0,
                    position: 0,
                },
                c,
                z,
                t,
            )
        };
        cache.insert(
            key(0, 0, 0),
            Arc::new(Frame::from(Array2::from_elem((2, 2), 1u16))),
        );
        cache.insert(
            key(0, 0, 1),
            Arc::new(Frame::from(Array2::from_elem((2, 2), 2u16))),
        );
        assert!(cache.get(&key(0, 0, 0)).is_some());
        cache.insert(
            key(0, 0, 2),
            Arc::new(Frame::from(Array2::from_elem((2, 2), 3u16))),
        );
        assert!(cache.get(&key(0, 0, 0)).is_some());
        assert!(cache.get(&key(0, 0, 1)).is_none());
        assert!(cache.get(&key(0, 0, 2)).is_some());
        assert_eq!(cache.len(), 2);
        Ok(())
    }

    #[test]
    fn array_cache() -> Result<(), Error> {
        let cache = ArrayCache::new(2);
        let key = |dtype: &'static str, index: isize, axes: &[Axis]| ArrayKey {
            reader: ReaderKey {
                name: "test".to_string(),
                path: PathBuf::from("test.tif"),
                series: 0,
                position: 0,
            },
            dtype,
            slice: vec![SliceInfoElem::Index(index)],
            axes: axes.to_vec(),
            operations: vec![],
        };
        let k0 = key("u16", 0, &[Axis::T]);
        let k1 = key("u16", 1, &[Axis::T]);
        cache.insert(k0.clone(), ArrayD::<u16>::zeros(IxDyn(&[2, 2])));
        cache.insert(k1.clone(), ArrayD::<u16>::zeros(IxDyn(&[2, 2])));
        assert!(cache.get::<u16, _>(&k0).is_some());
        cache.insert(
            key("u16", 2, &[Axis::T]),
            ArrayD::<u16>::zeros(IxDyn(&[2, 2])),
        );
        assert!(cache.get::<u16, _>(&k0).is_some());
        assert!(cache.get::<u16, _>(&k1).is_none());
        assert_eq!(cache.len(), 2);
        let ops: IndexMap<Axis, Operation> = IndexMap::new();
        let borrowed = ArrayKeyRef {
            reader: ReaderKeyRef {
                name: "test",
                path: Path::new("test.tif"),
                series: 0,
                position: 0,
            },
            dtype: "u16",
            slice: &[SliceInfoElem::Index(0)],
            axes: &[Axis::T],
            operations: &ops,
        };
        assert!(cache.get::<f64, _>(&borrowed).is_none());
        assert!(cache.get::<u16, _>(&borrowed).is_some());
        Ok(())
    }

    #[test]
    fn as_array_caches_frames() -> Result<(), Error> {
        let file = "tiffseq/YTL1841B2-2-1_1hr_DMSO_galinduction_1";
        let reader = open(file)?;
        let view = reader.view();
        let shape = view.shape();
        let (c, z, t) = (shape[0] - 1, shape[1] - 1, shape[2] - 1);
        let cache = FrameCache::global();
        let a: Array5<usize> = view.clone().try_into()?;
        assert!(cache.get(&view.frame_key(c, z, t)).is_some());
        let b: Array5<usize> = view.clone().try_into()?;
        assert_eq!(a, b);
        // a fresh reader on the same file shares the same cache key
        let view2 = open(file)?.view();
        assert_eq!(view.frame_key(c, z, t), view2.frame_key(c, z, t));
        let c2: Array5<usize> = view2.clone().try_into()?;
        assert_eq!(a, c2);
        Ok(())
    }
}