/* 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 http://mozilla.org/MPL/2.0/. */

mod bind;
mod bundle;
mod clear;
mod compute;
mod draw;
mod query;
mod render;
mod transfer;

pub use self::bundle::*;
pub use self::compute::*;
pub use self::draw::*;
pub use self::query::*;
pub use self::render::*;
pub use self::transfer::*;

use crate::{
    hub::{Global, GlobalIdentityHandlerFactory, HalApi, Storage, Token},
    id,
    memory_init_tracker::MemoryInitTrackerAction,
    resource::{Buffer, Texture},
    track::{BufferState, ResourceTracker, TextureState, TrackerSet},
    Label, Stored,
};

use hal::CommandEncoder as _;
use smallvec::SmallVec;
use thiserror::Error;

const PUSH_CONSTANT_CLEAR_ARRAY: &[u32] = &[0_u32; 64];

#[derive(Debug)]
enum CommandEncoderStatus {
    Recording,
    Finished,
    Error,
}

struct CommandEncoder<A: hal::Api> {
    raw: A::CommandEncoder,
    list: Vec<A::CommandBuffer>,
    is_open: bool,
    label: Option<String>,
}

//TODO: handle errors better
impl<A: hal::Api> CommandEncoder<A> {
    fn close(&mut self) {
        if self.is_open {
            self.is_open = false;
            let cmd_buf = unsafe { self.raw.end_encoding().unwrap() };
            self.list.push(cmd_buf);
        }
    }

    fn open(&mut self) -> &mut A::CommandEncoder {
        if !self.is_open {
            self.is_open = true;
            let label = self.label.as_deref();
            unsafe { self.raw.begin_encoding(label).unwrap() };
        }
        &mut self.raw
    }
}

pub struct BackedCommands<A: hal::Api> {
    pub(crate) encoder: A::CommandEncoder,
    pub(crate) list: Vec<A::CommandBuffer>,
    pub(crate) trackers: TrackerSet,
}

pub struct CommandBuffer<A: hal::Api> {
    encoder: CommandEncoder<A>,
    status: CommandEncoderStatus,
    pub(crate) device_id: Stored<id::DeviceId>,
    pub(crate) trackers: TrackerSet,
    pub(crate) used_swap_chains: SmallVec<[Stored<id::SwapChainId>; 1]>,
    pub(crate) buffer_memory_init_actions: Vec<MemoryInitTrackerAction<id::BufferId>>,
    limits: wgt::Limits,
    downlevel: wgt::DownlevelCapabilities,
    support_fill_buffer_texture: bool,
    #[cfg(feature = "trace")]
    pub(crate) commands: Option<Vec<crate::device::trace::Command>>,
}

impl<A: HalApi> CommandBuffer<A> {
    pub(crate) fn new(
        encoder: A::CommandEncoder,
        device_id: Stored<id::DeviceId>,
        limits: wgt::Limits,
        downlevel: wgt::DownlevelCapabilities,
        features: wgt::Features,
        #[cfg(feature = "trace")] enable_tracing: bool,
        label: &Label,
    ) -> Self {
        CommandBuffer {
            encoder: CommandEncoder {
                raw: encoder,
                is_open: false,
                list: Vec::new(),
                label: crate::LabelHelpers::borrow_option(label).map(|s| s.to_string()),
            },
            status: CommandEncoderStatus::Recording,
            device_id,
            trackers: TrackerSet::new(A::VARIANT),
            used_swap_chains: Default::default(),
            buffer_memory_init_actions: Default::default(),
            limits,
            downlevel,
            support_fill_buffer_texture: features.contains(wgt::Features::CLEAR_COMMANDS),
            #[cfg(feature = "trace")]
            commands: if enable_tracing {
                Some(Vec::new())
            } else {
                None
            },
        }
    }

    pub(crate) fn insert_barriers(
        raw: &mut A::CommandEncoder,
        base: &mut TrackerSet,
        head_buffers: &ResourceTracker<BufferState>,
        head_textures: &ResourceTracker<TextureState>,
        buffer_guard: &Storage<Buffer<A>, id::BufferId>,
        texture_guard: &Storage<Texture<A>, id::TextureId>,
    ) {
        profiling::scope!("insert_barriers");
        debug_assert_eq!(A::VARIANT, base.backend());

        let buffer_barriers = base.buffers.merge_replace(head_buffers).map(|pending| {
            let buf = &buffer_guard[pending.id];
            pending.into_hal(buf)
        });
        let texture_barriers = base.textures.merge_replace(head_textures).map(|pending| {
            let tex = &texture_guard[pending.id];
            pending.into_hal(tex)
        });

        unsafe {
            raw.transition_buffers(buffer_barriers);
            raw.transition_textures(texture_barriers);
        }
    }
}

impl<A: hal::Api> CommandBuffer<A> {
    fn get_encoder_mut(
        storage: &mut Storage<Self, id::CommandEncoderId>,
        id: id::CommandEncoderId,
    ) -> Result<&mut Self, CommandEncoderError> {
        match storage.get_mut(id) {
            Ok(cmd_buf) => match cmd_buf.status {
                CommandEncoderStatus::Recording => Ok(cmd_buf),
                CommandEncoderStatus::Finished => Err(CommandEncoderError::NotRecording),
                CommandEncoderStatus::Error => Err(CommandEncoderError::Invalid),
            },
            Err(_) => Err(CommandEncoderError::Invalid),
        }
    }

    pub fn is_finished(&self) -> bool {
        match self.status {
            CommandEncoderStatus::Finished => true,
            _ => false,
        }
    }

    pub(crate) fn into_baked(self) -> BackedCommands<A> {
        BackedCommands {
            encoder: self.encoder.raw,
            list: self.encoder.list,
            trackers: self.trackers,
        }
    }
}

impl<A: hal::Api> crate::hub::Resource for CommandBuffer<A> {
    const TYPE: &'static str = "CommandBuffer";

    fn life_guard(&self) -> &crate::LifeGuard {
        unreachable!()
    }

    fn label(&self) -> &str {
        self.encoder.label.as_ref().map_or("", |s| s.as_str())
    }
}

#[derive(Copy, Clone, Debug)]
pub struct BasePassRef<'a, C> {
    pub label: Option<&'a str>,
    pub commands: &'a [C],
    pub dynamic_offsets: &'a [wgt::DynamicOffset],
    pub string_data: &'a [u8],
    pub push_constant_data: &'a [u32],
}

#[doc(hidden)]
#[derive(Debug)]
#[cfg_attr(
    any(feature = "serial-pass", feature = "trace"),
    derive(serde::Serialize)
)]
#[cfg_attr(
    any(feature = "serial-pass", feature = "replay"),
    derive(serde::Deserialize)
)]
pub struct BasePass<C> {
    pub label: Option<String>,
    pub commands: Vec<C>,
    pub dynamic_offsets: Vec<wgt::DynamicOffset>,
    pub string_data: Vec<u8>,
    pub push_constant_data: Vec<u32>,
}

impl<C: Clone> BasePass<C> {
    fn new(label: &Label) -> Self {
        Self {
            label: label.as_ref().map(|cow| cow.to_string()),
            commands: Vec::new(),
            dynamic_offsets: Vec::new(),
            string_data: Vec::new(),
            push_constant_data: Vec::new(),
        }
    }

    #[cfg(feature = "trace")]
    fn from_ref(base: BasePassRef<C>) -> Self {
        Self {
            label: base.label.map(str::to_string),
            commands: base.commands.to_vec(),
            dynamic_offsets: base.dynamic_offsets.to_vec(),
            string_data: base.string_data.to_vec(),
            push_constant_data: base.push_constant_data.to_vec(),
        }
    }

    pub fn as_ref(&self) -> BasePassRef<C> {
        BasePassRef {
            label: self.label.as_deref(),
            commands: &self.commands,
            dynamic_offsets: &self.dynamic_offsets,
            string_data: &self.string_data,
            push_constant_data: &self.push_constant_data,
        }
    }
}

#[derive(Clone, Debug, Error)]
pub enum CommandEncoderError {
    #[error("command encoder is invalid")]
    Invalid,
    #[error("command encoder must be active")]
    NotRecording,
}

impl<G: GlobalIdentityHandlerFactory> Global<G> {
    pub fn command_encoder_finish<A: HalApi>(
        &self,
        encoder_id: id::CommandEncoderId,
        _desc: &wgt::CommandBufferDescriptor<Label>,
    ) -> (id::CommandBufferId, Option<CommandEncoderError>) {
        profiling::scope!("finish", "CommandEncoder");

        let hub = A::hub(self);
        let mut token = Token::root();
        let (mut cmd_buf_guard, _) = hub.command_buffers.write(&mut token);

        let error = match CommandBuffer::get_encoder_mut(&mut *cmd_buf_guard, encoder_id) {
            Ok(cmd_buf) => {
                cmd_buf.encoder.close();
                cmd_buf.status = CommandEncoderStatus::Finished;
                //Note: if we want to stop tracking the swapchain texture view,
                // this is the place to do it.
                log::trace!("Command buffer {:?} {:#?}", encoder_id, cmd_buf.trackers);
                None
            }
            Err(e) => Some(e),
        };

        (encoder_id, error)
    }

    pub fn command_encoder_push_debug_group<A: HalApi>(
        &self,
        encoder_id: id::CommandEncoderId,
        label: &str,
    ) -> Result<(), CommandEncoderError> {
        profiling::scope!("push_debug_group", "CommandEncoder");

        let hub = A::hub(self);
        let mut token = Token::root();

        let (mut cmd_buf_guard, _) = hub.command_buffers.write(&mut token);
        let cmd_buf = CommandBuffer::get_encoder_mut(&mut *cmd_buf_guard, encoder_id)?;
        let cmd_buf_raw = cmd_buf.encoder.open();

        unsafe {
            cmd_buf_raw.begin_debug_marker(label);
        }
        Ok(())
    }

    pub fn command_encoder_insert_debug_marker<A: HalApi>(
        &self,
        encoder_id: id::CommandEncoderId,
        label: &str,
    ) -> Result<(), CommandEncoderError> {
        profiling::scope!("insert_debug_marker", "CommandEncoder");

        let hub = A::hub(self);
        let mut token = Token::root();

        let (mut cmd_buf_guard, _) = hub.command_buffers.write(&mut token);
        let cmd_buf = CommandBuffer::get_encoder_mut(&mut *cmd_buf_guard, encoder_id)?;
        let cmd_buf_raw = cmd_buf.encoder.open();

        unsafe {
            cmd_buf_raw.insert_debug_marker(label);
        }
        Ok(())
    }

    pub fn command_encoder_pop_debug_group<A: HalApi>(
        &self,
        encoder_id: id::CommandEncoderId,
    ) -> Result<(), CommandEncoderError> {
        profiling::scope!("pop_debug_marker", "CommandEncoder");

        let hub = A::hub(self);
        let mut token = Token::root();

        let (mut cmd_buf_guard, _) = hub.command_buffers.write(&mut token);
        let cmd_buf = CommandBuffer::get_encoder_mut(&mut *cmd_buf_guard, encoder_id)?;
        let cmd_buf_raw = cmd_buf.encoder.open();

        unsafe {
            cmd_buf_raw.end_debug_marker();
        }
        Ok(())
    }
}

fn push_constant_clear<PushFn>(offset: u32, size_bytes: u32, mut push_fn: PushFn)
where
    PushFn: FnMut(u32, &[u32]),
{
    let mut count_words = 0_u32;
    let size_words = size_bytes / wgt::PUSH_CONSTANT_ALIGNMENT;
    while count_words < size_words {
        let count_bytes = count_words * wgt::PUSH_CONSTANT_ALIGNMENT;
        let size_to_write_words =
            (size_words - count_words).min(PUSH_CONSTANT_CLEAR_ARRAY.len() as u32);

        push_fn(
            offset + count_bytes,
            &PUSH_CONSTANT_CLEAR_ARRAY[0..size_to_write_words as usize],
        );

        count_words += size_to_write_words;
    }
}

#[derive(Debug)]
struct StateChange<T> {
    last_state: Option<T>,
}

impl<T: Copy + PartialEq> StateChange<T> {
    fn new() -> Self {
        Self { last_state: None }
    }
    fn set_and_check_redundant(&mut self, new_state: T) -> bool {
        let already_set = self.last_state == Some(new_state);
        self.last_state = Some(new_state);
        already_set
    }
    fn is_unset(&self) -> bool {
        self.last_state.is_none()
    }
    fn reset(&mut self) {
        self.last_state = None;
    }
}

trait MapPassErr<T, O> {
    fn map_pass_err(self, scope: PassErrorScope) -> Result<T, O>;
}

#[derive(Clone, Copy, Debug, Error)]
pub enum PassErrorScope {
    #[error("In a bundle parameter")]
    Bundle,
    #[error("In a pass parameter")]
    Pass(id::CommandEncoderId),
    #[error("In a set_bind_group command")]
    SetBindGroup(id::BindGroupId),
    #[error("In a set_pipeline command")]
    SetPipelineRender(id::RenderPipelineId),
    #[error("In a set_pipeline command")]
    SetPipelineCompute(id::ComputePipelineId),
    #[error("In a set_push_constant command")]
    SetPushConstant,
    #[error("In a set_vertex_buffer command")]
    SetVertexBuffer(id::BufferId),
    #[error("In a set_index_buffer command")]
    SetIndexBuffer(id::BufferId),
    #[error("In a set_viewport command")]
    SetViewport,
    #[error("In a set_scissor_rect command")]
    SetScissorRect,
    #[error("In a draw command, indexed:{indexed} indirect:{indirect}")]
    Draw {
        indexed: bool,
        indirect: bool,
        pipeline: Option<id::RenderPipelineId>,
    },
    #[error("While resetting queries after the renderpass was ran")]
    QueryReset,
    #[error("In a write_timestamp command")]
    WriteTimestamp,
    #[error("In a begin_pipeline_statistics_query command")]
    BeginPipelineStatisticsQuery,
    #[error("In a end_pipeline_statistics_query command")]
    EndPipelineStatisticsQuery,
    #[error("In a execute_bundle command")]
    ExecuteBundle,
    #[error("In a dispatch command, indirect:{indirect}")]
    Dispatch {
        indirect: bool,
        pipeline: Option<id::ComputePipelineId>,
    },
    #[error("In a pop_debug_group command")]
    PopDebugGroup,
}