// Copyright (c) 2017 The vulkano developers
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or http://opensource.org/licenses/MIT>,
// at your option. All files in the project carrying such
// notice may not be copied, modified, or distributed except
// according to those terms.

use std::error;
use std::fmt;

use VulkanObject;
use device::Device;
use format::FormatTy;
use format::PossibleCompressedFormatDesc;
use image::ImageAccess;
use image::ImageDimensions;

/// Checks whether a copy image command is valid.
///
/// Note that this doesn't check whether `layer_count` is equal to 0. TODO: change that?
///
/// # Panic
///
/// - Panics if the source or the destination was not created with `device`.
///
pub fn check_copy_image<S, D>(device: &Device, source: &S, source_offset: [i32; 3],
                              source_base_array_layer: u32, source_mip_level: u32,
                              destination: &D, destination_offset: [i32; 3],
                              destination_base_array_layer: u32, destination_mip_level: u32,
                              extent: [u32; 3], layer_count: u32)
                              -> Result<(), CheckCopyImageError>
    where S: ?Sized + ImageAccess,
          D: ?Sized + ImageAccess
{
    let source_inner = source.inner();
    let destination_inner = destination.inner();

    assert_eq!(source_inner.image.device().internal_object(),
               device.internal_object());
    assert_eq!(destination_inner.image.device().internal_object(),
               device.internal_object());

    if !source_inner.image.usage_transfer_source() {
        return Err(CheckCopyImageError::MissingTransferSourceUsage);
    }

    if !destination_inner.image.usage_transfer_destination() {
        return Err(CheckCopyImageError::MissingTransferDestinationUsage);
    }

    if source.samples() != destination.samples() {
        return Err(CheckCopyImageError::SampleCountMismatch);
    }

    let source_format_ty = source.format().ty();
    let destination_format_ty = destination.format().ty();

    if source_format_ty.is_depth_and_or_stencil() {
        if source.format() != destination.format() {
            return Err(CheckCopyImageError::DepthStencilFormatMismatch);
        }
    }

    // TODO: The correct check here is that the uncompressed element size of the source is
    // equal to the compressed element size of the destination.  However, format doesn't
    // currently expose this information, so to be safe, we simply disallow compressed formats.
    if source.format().is_compressed() || destination.format().is_compressed() ||
            (source.format().size() != destination.format().size()) {
        return Err(CheckCopyImageError::SizeIncompatibleFormatsTypes {
                       source_format_ty: source.format().ty(),
                       destination_format_ty: destination.format().ty(),
                   });
    }

    let source_dimensions = match source
        .dimensions()
        .mipmap_dimensions(source_mip_level) {
        Some(d) => d,
        None => return Err(CheckCopyImageError::SourceCoordinatesOutOfRange),
    };

    let destination_dimensions = match destination
        .dimensions()
        .mipmap_dimensions(destination_mip_level) {
        Some(d) => d,
        None => return Err(CheckCopyImageError::DestinationCoordinatesOutOfRange),
    };

    if source_base_array_layer + layer_count > source_dimensions.array_layers() {
        return Err(CheckCopyImageError::SourceCoordinatesOutOfRange);
    }

    if destination_base_array_layer + layer_count > destination_dimensions.array_layers() {
        return Err(CheckCopyImageError::DestinationCoordinatesOutOfRange);
    }

    if source_offset[0] < 0 ||
            source_offset[0] as u32 + extent[0] > source_dimensions.width() {
        return Err(CheckCopyImageError::SourceCoordinatesOutOfRange);
    }

    if source_offset[1] < 0 ||
            source_offset[1] as u32 + extent[1] > source_dimensions.height() {
        return Err(CheckCopyImageError::SourceCoordinatesOutOfRange);
    }

    if source_offset[2] < 0 ||
            source_offset[2] as u32 + extent[2] > source_dimensions.depth() {
        return Err(CheckCopyImageError::SourceCoordinatesOutOfRange);
    }

    if destination_offset[0] < 0 ||
            destination_offset[0] as u32 + extent[0] > destination_dimensions.width() {
        return Err(CheckCopyImageError::DestinationCoordinatesOutOfRange);
    }

    if destination_offset[1] < 0 ||
            destination_offset[1] as u32 + extent[1] > destination_dimensions.height() {
        return Err(CheckCopyImageError::DestinationCoordinatesOutOfRange);
    }

    if destination_offset[2] < 0 ||
            destination_offset[2] as u32 + extent[2] > destination_dimensions.depth() {
        return Err(CheckCopyImageError::DestinationCoordinatesOutOfRange);
    }

    match source_dimensions {
        ImageDimensions::Dim1d { .. } => {
            if source_offset[1] != 0 || extent[1] != 1 {
                return Err(CheckCopyImageError::IncompatibleRangeForImageType);
            }
            if source_offset[2] != 0 || extent[2] != 1 {
                return Err(CheckCopyImageError::IncompatibleRangeForImageType);
            }
        },
        ImageDimensions::Dim2d { .. } => {
            if source_offset[2] != 0 || extent[2] != 1 {
                return Err(CheckCopyImageError::IncompatibleRangeForImageType);
            }
        },
        ImageDimensions::Dim3d { .. } => {},
    }

    match destination_dimensions {
        ImageDimensions::Dim1d { .. } => {
            if destination_offset[1] != 0 || extent[1] != 1 {
                return Err(CheckCopyImageError::IncompatibleRangeForImageType);
            }
            if destination_offset[2] != 0 || extent[2] != 1 {
                return Err(CheckCopyImageError::IncompatibleRangeForImageType);
            }
        },
        ImageDimensions::Dim2d { .. } => {
            if destination_offset[2] != 0 || extent[2] != 1 {
                return Err(CheckCopyImageError::IncompatibleRangeForImageType);
            }
        },
        ImageDimensions::Dim3d { .. } => {},
    }

    Ok(())
}

/// Error that can happen from `check_copy_image`.
#[derive(Debug, Copy, Clone)]
pub enum CheckCopyImageError {
    /// The source is missing the transfer source usage.
    MissingTransferSourceUsage,
    /// The destination is missing the transfer destination usage.
    MissingTransferDestinationUsage,
    /// The number of samples in the source and destination do not match.
    SampleCountMismatch,
    /// The format of the source and destination must be equal when copying depth/stencil images.
    DepthStencilFormatMismatch,
    /// The types of the source format and the destination format aren't size-compatible.
    SizeIncompatibleFormatsTypes {
        source_format_ty: FormatTy,
        destination_format_ty: FormatTy,
    },
    /// The offsets, array layers and/or mipmap levels are out of range in the source image.
    SourceCoordinatesOutOfRange,
    /// The offsets, array layers and/or mipmap levels are out of range in the destination image.
    DestinationCoordinatesOutOfRange,
    /// The offsets or extent are incompatible with the image type.
    IncompatibleRangeForImageType,
}

impl error::Error for CheckCopyImageError {
    #[inline]
    fn description(&self) -> &str {
        match *self {
            CheckCopyImageError::MissingTransferSourceUsage => {
                "the source is missing the transfer source usage"
            },
            CheckCopyImageError::MissingTransferDestinationUsage => {
                "the destination is missing the transfer destination usage"
            },
            CheckCopyImageError::SampleCountMismatch => {
                "the number of samples in the source and destination do not match"
            }
            CheckCopyImageError::DepthStencilFormatMismatch => {
                "the format of the source and destination must be equal when copying \
                 depth/stencil images"
            },
            CheckCopyImageError::SizeIncompatibleFormatsTypes { .. } => {
                "the types of the source format and the destination format aren't size-compatible"
            },
            CheckCopyImageError::SourceCoordinatesOutOfRange => {
                "the offsets, array layers and/or mipmap levels are out of range in the source \
                 image"
            },
            CheckCopyImageError::DestinationCoordinatesOutOfRange => {
                "the offsets, array layers and/or mipmap levels are out of range in the \
                 destination image"
            },
            CheckCopyImageError::IncompatibleRangeForImageType => {
                "the offsets or extent are incompatible with the image type"
            },
        }
    }
}

impl fmt::Display for CheckCopyImageError {
    #[inline]
    fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        write!(fmt, "{}", error::Error::description(self))
    }
}