exr 0.7.1

//! Read and write all supported aspects of an exr image, including deep data and multiresolution levels.
//! Use `exr::image::simple` if you do not need deep data or resolution levels.

use smallvec::SmallVec;
use half::f16;
use crate::io::*;
use crate::meta::*;
use crate::meta::attributes::*;
use crate::error::{Result, UnitResult, Error};
use crate::math::*;
use std::io::{Seek, BufReader, BufWriter};
use crate::image::{LineRefMut, LineRef, OnWriteProgress, OnReadProgress, WriteOptions, ReadOptions};

// TODO dry this module with image::full?



/// An exr image.
///
/// Supports all possible exr image features.
/// An exr image may contain multiple layers.
/// All meta data is encoded in this image,
/// including custom attributes.
#[derive(Clone, PartialEq, Debug)]
pub struct Image {

    /// All layers contained in the image file
    pub layers: Layers,

    /// Attributes that apply to the whole image file.
    /// These attributes appear in each layer of the file.
    /// Excludes technical meta data.
    pub attributes: ImageAttributes,
}

/// List of layers in an image.
pub type Layers = SmallVec<[Layer; 3]>;


/// A single layer of an exr image.
/// Contains meta data and actual pixel information of the channels.
#[derive(Clone, PartialEq, Debug)]
pub struct Layer {

    /// List of channels in this layer.
    /// Contains the actual pixel data of the image.
    pub channels: Channels,

    /// Attributes that apply to this layer. Excludes technical meta data.
    /// May still contain attributes that should be considered global for an image file.
    pub attributes: LayerAttributes,

    /// The rectangle that positions this layer
    /// within the global infinite 2D space of the file.
    pub data_size: Vec2<usize>,

    /// In what order the tiles of this header occur in the file.
    /// Does not change any actual image orientation.
    pub line_order: LineOrder,

    /// How the pixel data of all channels in this layer is compressed. May be `Compression::Uncompressed`.
    pub compression: Compression,

    /// If this is some pair of numbers, the image is divided into tiles of that size.
    /// If this is none, the image is divided into scan line blocks, depending on the compression method.
    pub tiles: Option<Vec2<usize>>,

}


/// List of channels in a Layer
// TODO API use sorted set by name instead??
pub type Channels = SmallVec<[Channel; 5]>;


/// Contains an arbitrary list of pixel data.
/// Each channel can have a different pixel type,
/// either f16, f32, or u32.
#[derive(Clone, Debug, PartialEq)]
pub struct Channel {

    /// One of "R", "G", or "B" most of the time.
    pub name: Text,

    /// The actual pixel data. Contains a flattened vector of samples.
    /// The vector contains each row, one after another.
    /// The number of pixels depends on the resolution of the layer
    /// and the sampling rate of this channel.
    ///
    /// Thus, a specific pixel value can be found at the index
    /// `samples[(y_index / sampling_y) * width + (x_index / sampling_x)]`.
    pub samples: Samples,

    /// Are the samples in this channel in linear color space?
    pub is_linear: bool,

    /// How many of the samples are skipped compared to the other channels in this layer.
    ///
    /// Can be used for chroma subsampling for manual lossy data compression.
    /// Values other than 1 are allowed only in flat, scan-line based images.
    /// If an image is deep or tiled, x and y sampling rates for all of its channels must be 1.
    pub sampling: Vec2<usize>,
}

/// Actual pixel data in a channel. Is either one of f16, f32, or u32.
// TODO not require vec storage but also on-the-fly generation
#[derive(Clone, PartialEq)]
pub enum Samples {

    /// The representation of 16-bit floating-point numbers is analogous to IEEE 754,
    /// but with 5 exponent bits and 10 bits for the fraction.
    ///
    /// Currently this crate is using the `half` crate, which is an implementation of the IEEE 754-2008 standard, meeting that requirement.
    F16(Vec<f16>),

    /// 32-bit float samples.
    F32(Vec<f32>),

    /// 32-bit unsigned int samples.
    /// Used for segmentation of layers.
    U32(Vec<u32>),
}


/*#[derive(Clone, PartialEq)] TODO
pub enum Samples {
    F16(SampleStorage<f16>),
    F32(SampleStorage<f32>),
    U32(SampleStorage<u32>),
}

pub trait SampleStorage<T> {
    fn sample(position: Vec2, resolution: Vec2) -> T,
    fn allocate() ???
}

impl SampleStorage<f16> for Vec<f16> { }
impl SampleStorage<f16> for Fn(Vec2) -> Iterator<Item=f16> { }*/




/*#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub struct ChannelSampler<'t, T: 't> {
    samples: &'t [T],
    subsampled_size: Vec2<usize>,
    subsampling_factor: Vec2<usize>,
}

impl<'t, T> ChannelSampler<'t, T> {
    pub fn sample(&self, pixel: Vec2<usize>) -> &'t T {
        let local_index = pixel / self.subsampling_factor;
        debug_assert!(local_index.0 < self.subsampled_size.0, "invalid x coordinate");
        debug_assert!(local_index.1 < self.subsampled_size.1, "invalid y coordinate");
        &self.samples[local_index.1 * self.subsampled_size.0 + local_index.0]
    }
}*/



impl Image {

    /// Create an image that is to be written to a file.
    ///
    /// Consider using `Image::new_from_layers` for creating an image with multiple layers.
    /// Use the raw `Image { .. }` constructor for even more complex cases.
    pub fn new_from_single_layer(layer: Layer) -> Self {
        Self {
            attributes: ImageAttributes {
                display_window: layer.data_window(),
                pixel_aspect: 1.0,
                list: Vec::new()
            },

            layers: smallvec![ layer ],
        }
    }

    /// Create an image that is to be written to a file.
    /// Define the `display_window` to describe the area
    /// within the infinite 2D space that should be visible.
    ///
    /// Consider using `Image::new_from_single_layer` for simpler cases.
    /// Use the raw `Image { .. }` constructor for more complex cases.
    pub fn new_from_layers(layers: Layers, display_window: IntRect) -> Self {
        Self {
            layers,
            attributes: ImageAttributes {
                display_window,
                pixel_aspect: 1.0,
                list: Vec::new()
            }
        }
    }


    /// Read the exr image from a file.
    /// Use `read_from_unbuffered` instead, if you do not have a file.
    /// Returns an empty image in case only deep data exists in the file.
    #[must_use]
    pub fn read_from_file(path: impl AsRef<std::path::Path>, options: ReadOptions<impl OnReadProgress>) -> Result<Self> {
        Self::read_from_unbuffered(std::fs::File::open(path)?, options)
    }

    /// Buffer the reader and then read the exr image from it.
    /// Use `read_from_buffered` instead, if your reader is an in-memory reader.
    /// Use `read_from_file` instead, if you have a file path.
    ///
    ///
    /// _Note: If you encounter a reader that is not send or not seek,
    /// open an issue on the github repository._
    #[must_use]
    pub fn read_from_unbuffered(unbuffered: impl Read + Send + Seek, options: ReadOptions<impl OnReadProgress>) -> Result<Self> { // TODO not need be seek nor send
        Self::read_from_buffered(BufReader::new(unbuffered), options)
    }

    /// Read the exr image from a reader.
    /// Use `read_from_file` instead, if you have a file path.
    /// Use `read_from_unbuffered` instead, if this is not an in-memory reader.
    ///
    ///
    /// _Note: If you encounter a reader that is not send or not seek,
    /// open an issue on the github repository._
    #[must_use]
    pub fn read_from_buffered(read: impl Read + Send + Seek, options: ReadOptions<impl OnReadProgress>) -> Result<Self> { // TODO not need be seek nor send
        let mut image: Image = crate::image::read_filtered_lines_from_buffered(
            read,
            Image::allocate,

            |_image, header, tile_index| {
                !header.deep && tile_index.location.is_largest_resolution_level()
            },

            |image, _meta, line| Image::insert_line(image, line),

            options

        )?;

        {   // remove channels that had no data (deep data is not loaded)
            for layer in &mut image.layers {
                layer.channels.retain(|channel| channel.samples.len() > 0);
            }

            // remove parts that had only deep channels
            image.layers.retain(|layer| layer.channels.len() > 0);
        }

        Ok(image)
    }

    /// Write the exr image to a file.
    /// Use `write_to_unbuffered` instead if you do not have a file.
    /// If an error occurs, attempts to delete the partially written file.
    #[must_use]
    pub fn write_to_file(&self, path: impl AsRef<std::path::Path>, options: WriteOptions<impl OnWriteProgress>) -> UnitResult {
        crate::io::attempt_delete_file_on_write_error(path, |write|
            self.write_to_unbuffered(write, options)

        )
    }

    /// Buffer the writer and then write the exr image to it.
    /// Use `read_from_buffered` instead, if your reader is an in-memory writer.
    /// Use `read_from_file` instead, if you have a file path.
    /// If your writer cannot seek, you can write to an in-memory vector of bytes first, using `write_to_buffered`.
    #[must_use]
    pub fn write_to_unbuffered(&self, unbuffered: impl Write + Seek, options: WriteOptions<impl OnWriteProgress>) -> UnitResult {
        self.write_to_buffered(BufWriter::new(unbuffered), options)
    }

    /// Write the exr image to a writer.
    /// Use `read_from_file` instead, if you have a file path.
    /// Use `read_from_unbuffered` instead, if this is not an in-memory writer.
    /// If your writer cannot seek, you can write to an in-memory vector of bytes first.
    #[must_use]
    pub fn write_to_buffered(&self, write: impl Write + Seek, options: WriteOptions<impl OnWriteProgress>) -> UnitResult {
        crate::image::write_all_lines_to_buffered(
            write,  self.infer_meta_data(),
            |_meta, line_mut| {
                self.extract_line(line_mut);
                Ok(()) // TODO abort also on line but not only chunk
            },
            options
        )
    }
}


impl Layer {

    /// Create a new layer with all required fields.
    /// Uses scan line blocks, and no custom attributes.
    /// Use `Layer::with_compression` or `Layer::with_block_format`
    /// to further configure the file.
    ///
    /// Infers the display window from the data size.
    /// Note that for all layers of a file, the display window must be the same.
    ///
    /// Panics if anything is invalid or missing.
    /// Will sort channels to correct order if necessary.
    pub fn new(name: Text, data_size: Vec2<usize>, mut channels: Channels) -> Self {
        assert!(!channels.is_empty(), "at least one channel is required");

        assert!(
            channels.iter().all(|chan|
                chan.samples.len() / (chan.sampling.0 * chan.sampling.1) == data_size.area()

            ),
            "channel data size must conform to data window size (scaled by channel sampling)"
        );

        channels.sort_by_key(|chan| chan.name.clone()); // TODO why clone?!

        Layer {
            channels,
            data_size,
            compression: Compression::Uncompressed,

            tiles: None,
            line_order: LineOrder::Unspecified, // non-parallel write will set this to increasing if possible

            attributes: LayerAttributes {
                name: Some(name),
                data_position: Vec2(0, 0),
                screen_window_center: Vec2(0.0, 0.0),
                screen_window_width: 1.0,
                list: Vec::new(),
            }
        }
    }

    /// Specify how the image is split into blocks in the file.
    /// See `Image::tiles` and `Image::line_order` for more information.
    pub fn with_block_format(self, tiles: Option<Vec2<usize>>, line_order: LineOrder) -> Self {
        Self { tiles, line_order, .. self }
    }

    /// Set the compression of this layer.
    pub fn with_compression(self, compression: Compression) -> Self {
        Self { compression, .. self }
    }

    /// The rectangle describing the bounding box of this layer
    /// within the infinite global 2D space of the file.
    pub fn data_window(&self) -> IntRect {
        IntRect::new(self.attributes.data_position, self.data_size)
    }
}


impl Channel {

    /// Create a Channel from name and samples.
    /// Set `is_linear` if the color space of the samples values is linear.
    /// Panics if anything is invalid or missing.
    pub fn new(name: Text, is_linear: bool, samples: Samples) -> Self {
        Self { name, samples, is_linear, sampling: Vec2(1, 1) }
    }

    /// Create a Channel from name and samples.
    /// Use this if the color space of the samples values is linear, otherwise, use `Channel::new`.
    /// Panics if anything is invalid or missing.
    pub fn new_linear(name: Text, samples: Samples) -> Self {
        Self::new(name, true, samples)
    }
}

impl Samples {

    /// Number of samples in this vector.
    pub fn len(&self) -> usize {
        match self {
            Samples::F16(vec) => vec.len(),
            Samples::F32(vec) => vec.len(),
            Samples::U32(vec) => vec.len(),
        }
    }
}



impl Image {

    /// Allocate an image ready to be filled with pixel data.
    pub fn allocate(headers: &[Header]) -> Result<Self> {
        let shared_attributes = &headers.iter()
            // pick the header with the most attributes
            // (all headers should have the same shared attributes anyways)
            .max_by_key(|header| header.shared_attributes.list.len())
            .expect("no headers found").shared_attributes;

        let headers : Result<_> = headers.iter()
            .map(Layer::allocate).collect();

        Ok(Image {
            layers: headers?,
            attributes: shared_attributes.clone(),
        })
    }

    /// Insert one line of pixel data into this image.
    /// Returns an error for invalid index or line contents.
    pub fn insert_line(&mut self, line: LineRef<'_>) -> UnitResult {
        debug_assert_ne!(line.location.sample_count, 0, "line width calculation bug");

        let layer = self.layers.get_mut(line.location.layer)
            .ok_or(Error::invalid("chunk part index"))?;

        layer.insert_line(line)
    }

    /// Read one line of pixel data from this channel.
    /// Panics for an invalid index or write error.
    pub fn extract_line(&self, line: LineRefMut<'_>) {
        debug_assert_ne!(line.location.sample_count, 0, "line width calculation bug");

        let layer = self.layers.get(line.location.layer)
            .expect("invalid part index");

        layer.extract_line(line)
    }

    /// Create the meta data that describes this image.
    pub fn infer_meta_data(&self) -> MetaData {
        let headers: Headers = self.layers.iter()
            .map(|layer| layer.infer_header(&self.attributes))
            .collect();

        MetaData::new(headers)
    }
}


impl Layer {

    /// Allocate an layer ready to be filled with pixel data.
    pub fn allocate(header: &Header) -> Result<Self> {
        Ok(Layer {
            data_size: header.data_size,
            attributes: header.own_attributes.clone(),
            channels: header.channels.list.iter().map(|channel| Channel::allocate(header, channel)).collect(),
            compression: header.compression,
            line_order: header.line_order,

            tiles: match header.blocks {
                Blocks::ScanLines => None,
                Blocks::Tiles(tiles) => Some(tiles.tile_size),
            }
        })
    }


    // TODO no insert or extract, only `get(line_index) -> Line<'_ mut>`?

    /// Insert one line of pixel data into this layer.
    /// Returns an error for invalid index or line contents.
    pub fn insert_line(&mut self, line: LineRef<'_>) -> UnitResult {
        debug_assert!(line.location.position.0 + line.location.sample_count <= self.data_size.0, "line index calculation bug");
        debug_assert!(line.location.position.1 < self.data_size.1, "line index calculation bug");

        self.channels.get_mut(line.location.channel)
            .expect("invalid channel index")
            .insert_line(line, self.data_size)
    }

    /// Read one line of pixel data from this layer.
    /// Panics for an invalid index or write error.
    pub fn extract_line(&self, line: LineRefMut<'_>) {
        debug_assert!(line.location.position.0 + line.location.sample_count <= self.data_size.0, "line index calculation bug");
        debug_assert!(line.location.position.1 < self.data_size.1, "line index calculation bug");

        self.channels.get(line.location.channel)
            .expect("invalid channel index")
            .extract_line(line, self.data_size)
    }

    /// Create the meta data that describes this layer.
    pub fn infer_header(&self, shared_attributes: &ImageAttributes) -> Header {
        let blocks = match self.tiles {
            Some(tiles) => Blocks::Tiles(TileDescription {
                tile_size: tiles,
                level_mode: LevelMode::Singular,
                rounding_mode: RoundingMode::Down
            }),

            None => Blocks::ScanLines,
        };

        let channels = self.channels.iter()
            .map(Channel::infer_channel_attribute).collect();

        let chunk_count = compute_chunk_count(
            self.compression, self.data_size, blocks
        );

        Header {
            chunk_count,

            data_size: self.data_size,
            compression: self.compression,
            channels: ChannelList::new(channels),
            line_order: self.line_order,

            own_attributes: self.attributes.clone(), // TODO no clone?
            shared_attributes: shared_attributes.clone(),

            blocks,

            deep_data_version: None,
            max_samples_per_pixel: None,
            deep: false,
        }
    }
}

impl Channel {

    /// Allocate a channel ready to be filled with pixel data.
    pub fn allocate(header: &Header, channel: &crate::meta::attributes::Channel) -> Self {
        // do not allocate for deep data
        let size = if header.deep { Vec2(0, 0) } else {
            header.data_size / channel.sampling
        };

        Channel {
            name: channel.name.clone(), is_linear: channel.is_linear, sampling: channel.sampling,
            samples: Samples::allocate(size, channel.pixel_type)
        }
    }

    /// Insert one line of pixel data into this channel.
    pub fn insert_line(&mut self, line: LineRef<'_>, resolution: Vec2<usize>) -> UnitResult {
        assert_eq!(line.location.level, Vec2(0,0), "line index calculation bug");
        self.samples.insert_line(resolution / self.sampling, line)
    }

    /// Read one line of pixel data from this channel.
    /// Panics for an invalid index or write error.
    pub fn extract_line(&self, line: LineRefMut<'_>, resolution: Vec2<usize>) {
        debug_assert_eq!(line.location.level, Vec2(0,0), "line index calculation bug");
        self.samples.extract_line(line, resolution / self.sampling)
    }

    /// Create the meta data that describes this channel.
    pub fn infer_channel_attribute(&self) -> attributes::Channel {
        attributes::Channel {
            pixel_type: match self.samples {
                Samples::F16(_) => PixelType::F16,
                Samples::F32(_) => PixelType::F32,
                Samples::U32(_) => PixelType::U32,
            },

            name: self.name.clone(),
            is_linear: self.is_linear,
            sampling: self.sampling,
        }
    }
}


impl Samples {

    /// Allocate a sample block ready to be filled with pixel data.
    pub fn allocate(resolution: Vec2<usize>, pixel_type: PixelType) -> Self {
        let count = resolution.area();

        match pixel_type {
            PixelType::F16 => Samples::F16(vec![ f16::ZERO; count ] ),
            PixelType::F32 => Samples::F32(vec![ 0.0; count ] ),
            PixelType::U32 => Samples::U32(vec![ 0; count ] ),
        }
    }

    /// Insert one line of pixel data into this sample block.
    pub fn insert_line(&mut self, resolution: Vec2<usize>, line: LineRef<'_>) -> UnitResult {
        debug_assert_ne!(line.location.sample_count, 0, "line index calculation bug");

        if line.location.position.0 + line.location.sample_count > resolution.0 {
            return Err(Error::invalid("data block x coordinate"))
        }

        if line.location.position.1 > resolution.1 {
            return Err(Error::invalid("data block y coordinate"))
        }

        debug_assert_ne!(resolution.0, 0, "sample size bug");
        debug_assert_ne!(line.location.sample_count, 0, "line index calculation bug");

        let start_index = line.location.position.1 * resolution.0 + line.location.position.0;
        let end_index = start_index + line.location.sample_count;

        match self {
            Samples::F16(samples) => line.read_samples_into_slice(&mut samples[start_index .. end_index]),
            Samples::F32(samples) => line.read_samples_into_slice(&mut samples[start_index .. end_index]),
            Samples::U32(samples) => line.read_samples_into_slice(&mut samples[start_index .. end_index]),
        }
    }

    /// Read one line of pixel data from this sample block.
    /// Panics for an invalid index or write error.
    pub fn extract_line(&self, line: LineRefMut<'_>, resolution: Vec2<usize>) {
        let index = line.location;

        debug_assert!(index.position.0 + index.sample_count <= resolution.0, "line index calculation bug");
        debug_assert!(index.position.1 < resolution.1, "line index calculation bug");
        debug_assert_ne!(index.sample_count, 0, "line index bug");

        debug_assert_ne!(resolution.0, 0, "sample size but");
        debug_assert_ne!(index.sample_count, 0, "line index bug");

        let start_index = index.position.1 * resolution.0 + index.position.0;
        let end_index = start_index + index.sample_count;

        match &self {
            Samples::F16(samples) =>
                line.write_samples_from_slice(&samples[start_index .. end_index])
                .expect("writing line bytes failed"),

            Samples::F32(samples) =>
                line.write_samples_from_slice(&samples[start_index .. end_index])
                .expect("writing line bytes failed"),

            Samples::U32(samples) =>
                line.write_samples_from_slice(&samples[start_index .. end_index])
                .expect("writing line bytes failed"),
        }
    }
}

impl std::fmt::Debug for Samples {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Samples::F16(vec) => write!(formatter, "[f16; {}]", vec.len()),
            Samples::F32(vec) => write!(formatter, "[f32; {}]", vec.len()),
            Samples::U32(vec) => write!(formatter, "[u32; {}]", vec.len()),
        }
    }
}