/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

use std::borrow::Cow;
use std::cell::Cell;
use std::collections::HashSet;

use dom_struct::dom_struct;
use webgpu::wgpu::command as wgpu_com;
use webgpu::{self, wgt, WebGPU, WebGPURequest};

use crate::dom::bindings::cell::DomRefCell;
use crate::dom::bindings::codegen::Bindings::WebGPUBinding::{
    GPUCommandBufferDescriptor, GPUCommandEncoderMethods, GPUComputePassDescriptor, GPUExtent3D,
    GPUImageCopyBuffer, GPUImageCopyTexture, GPURenderPassDescriptor, GPUSize64,
};
use crate::dom::bindings::codegen::UnionTypes::DoubleSequenceOrGPUColorDict;
use crate::dom::bindings::num::Finite;
use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
use crate::dom::bindings::root::{Dom, DomRoot};
use crate::dom::bindings::str::USVString;
use crate::dom::globalscope::GlobalScope;
use crate::dom::gpubuffer::GPUBuffer;
use crate::dom::gpucommandbuffer::GPUCommandBuffer;
use crate::dom::gpucomputepassencoder::GPUComputePassEncoder;
use crate::dom::gpuconvert::{
    convert_ic_buffer, convert_ic_texture, convert_load_op, convert_store_op,
    convert_texture_size_to_dict, convert_texture_size_to_wgt,
};
use crate::dom::gpudevice::GPUDevice;
use crate::dom::gpurenderpassencoder::GPURenderPassEncoder;

// TODO(sagudev): this is different now
// https://gpuweb.github.io/gpuweb/#enumdef-encoder-state
#[derive(MallocSizeOf, PartialEq)]
pub enum GPUCommandEncoderState {
    Open,
    EncodingRenderPass,
    EncodingComputePass,
    Closed,
}

#[dom_struct]
pub struct GPUCommandEncoder {
    reflector_: Reflector,
    #[ignore_malloc_size_of = "defined in webgpu"]
    #[no_trace]
    channel: WebGPU,
    label: DomRefCell<USVString>,
    #[no_trace]
    encoder: webgpu::WebGPUCommandEncoder,
    buffers: DomRefCell<HashSet<DomRoot<GPUBuffer>>>,
    state: DomRefCell<GPUCommandEncoderState>,
    device: Dom<GPUDevice>,
    valid: Cell<bool>,
}

impl GPUCommandEncoder {
    pub fn new_inherited(
        channel: WebGPU,
        device: &GPUDevice,
        encoder: webgpu::WebGPUCommandEncoder,
        label: USVString,
    ) -> Self {
        Self {
            channel,
            reflector_: Reflector::new(),
            label: DomRefCell::new(label),
            device: Dom::from_ref(device),
            encoder,
            buffers: DomRefCell::new(HashSet::new()),
            state: DomRefCell::new(GPUCommandEncoderState::Open),
            valid: Cell::new(true),
        }
    }

    pub fn new(
        global: &GlobalScope,
        channel: WebGPU,
        device: &GPUDevice,
        encoder: webgpu::WebGPUCommandEncoder,
        label: USVString,
    ) -> DomRoot<Self> {
        reflect_dom_object(
            Box::new(GPUCommandEncoder::new_inherited(
                channel, device, encoder, label,
            )),
            global,
        )
    }
}

impl GPUCommandEncoder {
    pub fn id(&self) -> webgpu::WebGPUCommandEncoder {
        self.encoder
    }

    pub fn set_state(&self, set: GPUCommandEncoderState, expect: GPUCommandEncoderState) {
        if *self.state.borrow() == expect {
            *self.state.borrow_mut() = set;
        } else {
            self.valid.set(false);
            *self.state.borrow_mut() = GPUCommandEncoderState::Closed;
        }
    }
}

impl GPUCommandEncoderMethods for GPUCommandEncoder {
    /// <https://gpuweb.github.io/gpuweb/#dom-gpuobjectbase-label>
    fn Label(&self) -> USVString {
        self.label.borrow().clone()
    }

    /// <https://gpuweb.github.io/gpuweb/#dom-gpuobjectbase-label>
    fn SetLabel(&self, value: USVString) {
        *self.label.borrow_mut() = value;
    }

    /// <https://gpuweb.github.io/gpuweb/#dom-gpucommandencoder-begincomputepass>
    fn BeginComputePass(
        &self,
        descriptor: &GPUComputePassDescriptor,
    ) -> DomRoot<GPUComputePassEncoder> {
        self.set_state(
            GPUCommandEncoderState::EncodingComputePass,
            GPUCommandEncoderState::Open,
        );

        let compute_pass = if !self.valid.get() {
            None
        } else {
            Some(wgpu_com::ComputePass::new(
                self.encoder.0,
                &wgpu_com::ComputePassDescriptor {
                    label: descriptor
                        .parent
                        .label
                        .as_ref()
                        .map(|l| Cow::Borrowed(&**l)),
                    timestamp_writes: None,
                },
            ))
        };

        GPUComputePassEncoder::new(
            &self.global(),
            self.channel.clone(),
            self,
            compute_pass,
            descriptor.parent.label.clone().unwrap_or_default(),
        )
    }

    /// <https://gpuweb.github.io/gpuweb/#dom-gpucommandencoder-beginrenderpass>
    fn BeginRenderPass(
        &self,
        descriptor: &GPURenderPassDescriptor,
    ) -> DomRoot<GPURenderPassEncoder> {
        self.set_state(
            GPUCommandEncoderState::EncodingRenderPass,
            GPUCommandEncoderState::Open,
        );

        let render_pass = if !self.valid.get() {
            None
        } else {
            let depth_stencil = descriptor.depthStencilAttachment.as_ref().map(|depth| {
                wgpu_com::RenderPassDepthStencilAttachment {
                    depth: wgpu_com::PassChannel {
                        load_op: convert_load_op(depth.depthLoadOp),
                        store_op: convert_store_op(depth.depthStoreOp),
                        clear_value: *depth.depthClearValue.unwrap_or_default(),
                        read_only: depth.depthReadOnly,
                    },
                    stencil: wgpu_com::PassChannel {
                        load_op: convert_load_op(depth.stencilLoadOp),
                        store_op: convert_store_op(depth.stencilStoreOp),
                        clear_value: depth.stencilClearValue,
                        read_only: depth.stencilReadOnly,
                    },
                    view: depth.view.id().0,
                }
            });

            let desc = wgpu_com::RenderPassDescriptor {
                color_attachments: Cow::Owned(
                    descriptor
                        .colorAttachments
                        .iter()
                        .map(|color| {
                            let channel = wgpu_com::PassChannel {
                                load_op: convert_load_op(Some(color.loadOp)),
                                store_op: convert_store_op(Some(color.storeOp)),
                                clear_value: if let Some(clear_val) = &color.clearValue {
                                    match clear_val {
                                        DoubleSequenceOrGPUColorDict::DoubleSequence(s) => {
                                            let mut w = s.clone();
                                            if w.len() < 3 {
                                                w.resize(3, Finite::wrap(0.0f64));
                                            }
                                            w.resize(4, Finite::wrap(1.0f64));
                                            wgt::Color {
                                                r: *w[0],
                                                g: *w[1],
                                                b: *w[2],
                                                a: *w[3],
                                            }
                                        },
                                        DoubleSequenceOrGPUColorDict::GPUColorDict(d) => {
                                            wgt::Color {
                                                r: *d.r,
                                                g: *d.g,
                                                b: *d.b,
                                                a: *d.a,
                                            }
                                        },
                                    }
                                } else {
                                    wgt::Color::TRANSPARENT
                                },
                                read_only: false,
                            };
                            Some(wgpu_com::RenderPassColorAttachment {
                                resolve_target: color.resolveTarget.as_ref().map(|t| t.id().0),
                                channel,
                                view: color.view.id().0,
                            })
                        })
                        .collect::<Vec<_>>(),
                ),
                depth_stencil_attachment: depth_stencil.as_ref(),
                label: descriptor
                    .parent
                    .label
                    .as_ref()
                    .map(|l| Cow::Borrowed(&**l)),
                timestamp_writes: None,
                occlusion_query_set: None,
            };
            Some(wgpu_com::RenderPass::new(self.encoder.0, &desc))
        };

        GPURenderPassEncoder::new(
            &self.global(),
            self.channel.clone(),
            render_pass,
            self,
            descriptor.parent.label.clone().unwrap_or_default(),
        )
    }

    /// <https://gpuweb.github.io/gpuweb/#dom-gpucommandencoder-copybuffertobuffer>
    fn CopyBufferToBuffer(
        &self,
        source: &GPUBuffer,
        source_offset: GPUSize64,
        destination: &GPUBuffer,
        destination_offset: GPUSize64,
        size: GPUSize64,
    ) {
        if !(*self.state.borrow() == GPUCommandEncoderState::Open) {
            self.valid.set(false);
            return;
        }

        self.buffers.borrow_mut().insert(DomRoot::from_ref(source));
        self.buffers
            .borrow_mut()
            .insert(DomRoot::from_ref(destination));
        self.channel
            .0
            .send((
                None,
                WebGPURequest::CopyBufferToBuffer {
                    command_encoder_id: self.encoder.0,
                    source_id: source.id().0,
                    source_offset,
                    destination_id: destination.id().0,
                    destination_offset,
                    size,
                },
            ))
            .expect("Failed to send CopyBufferToBuffer");
    }

    /// <https://gpuweb.github.io/gpuweb/#dom-gpucommandencoder-copybuffertotexture>
    fn CopyBufferToTexture(
        &self,
        source: &GPUImageCopyBuffer,
        destination: &GPUImageCopyTexture,
        copy_size: GPUExtent3D,
    ) {
        if !(*self.state.borrow() == GPUCommandEncoderState::Open) {
            self.valid.set(false);
            return;
        }

        self.buffers
            .borrow_mut()
            .insert(DomRoot::from_ref(&*source.buffer));

        self.channel
            .0
            .send((
                None,
                WebGPURequest::CopyBufferToTexture {
                    command_encoder_id: self.encoder.0,
                    source: convert_ic_buffer(source),
                    destination: convert_ic_texture(destination),
                    copy_size: convert_texture_size_to_wgt(&convert_texture_size_to_dict(
                        &copy_size,
                    )),
                },
            ))
            .expect("Failed to send CopyBufferToTexture");
    }

    /// <https://gpuweb.github.io/gpuweb/#dom-gpucommandencoder-copybuffertotexture>
    fn CopyTextureToBuffer(
        &self,
        source: &GPUImageCopyTexture,
        destination: &GPUImageCopyBuffer,
        copy_size: GPUExtent3D,
    ) {
        if !(*self.state.borrow() == GPUCommandEncoderState::Open) {
            self.valid.set(false);
            return;
        }

        self.buffers
            .borrow_mut()
            .insert(DomRoot::from_ref(&*destination.buffer));

        self.channel
            .0
            .send((
                None,
                WebGPURequest::CopyTextureToBuffer {
                    command_encoder_id: self.encoder.0,
                    source: convert_ic_texture(source),
                    destination: convert_ic_buffer(destination),
                    copy_size: convert_texture_size_to_wgt(&convert_texture_size_to_dict(
                        &copy_size,
                    )),
                },
            ))
            .expect("Failed to send CopyTextureToBuffer");
    }

    /// <https://gpuweb.github.io/gpuweb/#GPUCommandEncoder-copyTextureToTexture>
    fn CopyTextureToTexture(
        &self,
        source: &GPUImageCopyTexture,
        destination: &GPUImageCopyTexture,
        copy_size: GPUExtent3D,
    ) {
        if !(*self.state.borrow() == GPUCommandEncoderState::Open) {
            self.valid.set(false);
            return;
        }

        self.channel
            .0
            .send((
                None,
                WebGPURequest::CopyTextureToTexture {
                    command_encoder_id: self.encoder.0,
                    source: convert_ic_texture(source),
                    destination: convert_ic_texture(destination),
                    copy_size: convert_texture_size_to_wgt(&convert_texture_size_to_dict(
                        &copy_size,
                    )),
                },
            ))
            .expect("Failed to send CopyTextureToTexture");
    }

    /// <https://gpuweb.github.io/gpuweb/#dom-gpucommandencoder-finish>
    fn Finish(&self, descriptor: &GPUCommandBufferDescriptor) -> DomRoot<GPUCommandBuffer> {
        self.channel
            .0
            .send((
                self.device.use_current_scope(),
                WebGPURequest::CommandEncoderFinish {
                    command_encoder_id: self.encoder.0,
                    device_id: self.device.id().0,
                    is_error: !self.valid.get(),
                    // TODO(zakorgy): We should use `_descriptor` here after it's not empty
                    // and the underlying wgpu-core struct is serializable
                },
            ))
            .expect("Failed to send Finish");

        *self.state.borrow_mut() = GPUCommandEncoderState::Closed;
        let buffer = webgpu::WebGPUCommandBuffer(self.encoder.0);
        GPUCommandBuffer::new(
            &self.global(),
            self.channel.clone(),
            buffer,
            self.buffers.borrow_mut().drain().collect(),
            descriptor.parent.label.clone().unwrap_or_default(),
        )
    }
}