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

use std::slice;
use std::sync::Arc;

pub(crate) use self::clear::clear_texture;
pub use self::{
    bundle::*, clear::ClearError, compute::*, draw::*, query::*, render::*, transfer::*,
};

use self::memory_init::CommandBufferTextureMemoryActions;

use crate::device::{Device, DeviceError};
use crate::error::{ErrorFormatter, PrettyError};
use crate::hub::Hub;
use crate::id::CommandBufferId;
use crate::snatch::SnatchGuard;

use crate::init_tracker::BufferInitTrackerAction;
use crate::resource::{Resource, ResourceInfo, ResourceType};
use crate::track::{Tracker, UsageScope};
use crate::{api_log, global::Global, hal_api::HalApi, id, resource_log, Label};

use hal::CommandEncoder as _;
use parking_lot::Mutex;
use thiserror::Error;

#[cfg(feature = "trace")]
use crate::device::trace::Command as TraceCommand;

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

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

pub(crate) struct CommandEncoder<A: HalApi> {
    raw: A::CommandEncoder,
    list: Vec<A::CommandBuffer>,
    is_open: bool,
    label: Option<String>,
}

//TODO: handle errors better
impl<A: HalApi> CommandEncoder<A> {
    /// Closes the live encoder
    fn close_and_swap(&mut self) -> Result<(), DeviceError> {
        if self.is_open {
            self.is_open = false;
            let new = unsafe { self.raw.end_encoding()? };
            self.list.insert(self.list.len() - 1, new);
        }

        Ok(())
    }

    fn close(&mut self) -> Result<(), DeviceError> {
        if self.is_open {
            self.is_open = false;
            let cmd_buf = unsafe { self.raw.end_encoding()? };
            self.list.push(cmd_buf);
        }

        Ok(())
    }

    pub(crate) fn discard(&mut self) {
        if self.is_open {
            self.is_open = false;
            unsafe { self.raw.discard_encoding() };
        }
    }

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

        Ok(&mut self.raw)
    }

    fn open_pass(&mut self, label: Option<&str>) -> Result<(), DeviceError> {
        self.is_open = true;
        unsafe { self.raw.begin_encoding(label)? };

        Ok(())
    }
}

pub struct BakedCommands<A: HalApi> {
    pub(crate) encoder: A::CommandEncoder,
    pub(crate) list: Vec<A::CommandBuffer>,
    pub(crate) trackers: Tracker<A>,
    buffer_memory_init_actions: Vec<BufferInitTrackerAction<A>>,
    texture_memory_actions: CommandBufferTextureMemoryActions<A>,
}

pub(crate) struct DestroyedBufferError(pub id::BufferId);
pub(crate) struct DestroyedTextureError(pub id::TextureId);

pub struct CommandBufferMutable<A: HalApi> {
    pub(crate) encoder: CommandEncoder<A>,
    status: CommandEncoderStatus,
    pub(crate) trackers: Tracker<A>,
    buffer_memory_init_actions: Vec<BufferInitTrackerAction<A>>,
    texture_memory_actions: CommandBufferTextureMemoryActions<A>,
    pub(crate) pending_query_resets: QueryResetMap<A>,
    #[cfg(feature = "trace")]
    pub(crate) commands: Option<Vec<TraceCommand>>,
}

impl<A: HalApi> CommandBufferMutable<A> {
    pub(crate) fn open_encoder_and_tracker(
        &mut self,
    ) -> Result<(&mut A::CommandEncoder, &mut Tracker<A>), DeviceError> {
        let encoder = self.encoder.open()?;
        let tracker = &mut self.trackers;

        Ok((encoder, tracker))
    }
}

pub struct CommandBuffer<A: HalApi> {
    pub(crate) device: Arc<Device<A>>,
    limits: wgt::Limits,
    support_clear_texture: bool,
    pub(crate) info: ResourceInfo<CommandBuffer<A>>,
    pub(crate) data: Mutex<Option<CommandBufferMutable<A>>>,
}

impl<A: HalApi> Drop for CommandBuffer<A> {
    fn drop(&mut self) {
        if self.data.lock().is_none() {
            return;
        }
        resource_log!("resource::CommandBuffer::drop {:?}", self.info.label());
        let mut baked = self.extract_baked_commands();
        unsafe {
            baked.encoder.reset_all(baked.list.into_iter());
        }
        unsafe {
            use hal::Device;
            self.device.raw().destroy_command_encoder(baked.encoder);
        }
    }
}

impl<A: HalApi> CommandBuffer<A> {
    pub(crate) fn new(
        encoder: A::CommandEncoder,
        device: &Arc<Device<A>>,
        #[cfg(feature = "trace")] enable_tracing: bool,
        label: Option<String>,
    ) -> Self {
        CommandBuffer {
            device: device.clone(),
            limits: device.limits.clone(),
            support_clear_texture: device.features.contains(wgt::Features::CLEAR_TEXTURE),
            info: ResourceInfo::new(
                label
                    .as_ref()
                    .unwrap_or(&String::from("<CommandBuffer>"))
                    .as_str(),
                None,
            ),
            data: Mutex::new(Some(CommandBufferMutable {
                encoder: CommandEncoder {
                    raw: encoder,
                    is_open: false,
                    list: Vec::new(),
                    label,
                },
                status: CommandEncoderStatus::Recording,
                trackers: Tracker::new(),
                buffer_memory_init_actions: Default::default(),
                texture_memory_actions: Default::default(),
                pending_query_resets: QueryResetMap::new(),
                #[cfg(feature = "trace")]
                commands: if enable_tracing {
                    Some(Vec::new())
                } else {
                    None
                },
            })),
        }
    }

    pub(crate) fn insert_barriers_from_tracker(
        raw: &mut A::CommandEncoder,
        base: &mut Tracker<A>,
        head: &Tracker<A>,
        snatch_guard: &SnatchGuard,
    ) {
        profiling::scope!("insert_barriers");

        base.buffers.set_from_tracker(&head.buffers);
        base.textures.set_from_tracker(&head.textures);

        Self::drain_barriers(raw, base, snatch_guard);
    }

    pub(crate) fn insert_barriers_from_scope(
        raw: &mut A::CommandEncoder,
        base: &mut Tracker<A>,
        head: &UsageScope<A>,
        snatch_guard: &SnatchGuard,
    ) {
        profiling::scope!("insert_barriers");

        base.buffers.set_from_usage_scope(&head.buffers);
        base.textures.set_from_usage_scope(&head.textures);

        Self::drain_barriers(raw, base, snatch_guard);
    }

    pub(crate) fn drain_barriers(
        raw: &mut A::CommandEncoder,
        base: &mut Tracker<A>,
        snatch_guard: &SnatchGuard,
    ) {
        profiling::scope!("drain_barriers");

        let buffer_barriers = base.buffers.drain_transitions(snatch_guard);
        let (transitions, textures) = base.textures.drain_transitions(snatch_guard);
        let texture_barriers = transitions
            .into_iter()
            .enumerate()
            .map(|(i, p)| p.into_hal(textures[i].unwrap().raw().unwrap()));

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

impl<A: HalApi> CommandBuffer<A> {
    fn get_encoder(
        hub: &Hub<A>,
        id: id::CommandEncoderId,
    ) -> Result<Arc<Self>, CommandEncoderError> {
        let storage = hub.command_buffers.read();
        match storage.get(id.transmute()) {
            Ok(cmd_buf) => match cmd_buf.data.lock().as_ref().unwrap().status {
                CommandEncoderStatus::Recording => Ok(cmd_buf.clone()),
                CommandEncoderStatus::Finished => Err(CommandEncoderError::NotRecording),
                CommandEncoderStatus::Error => Err(CommandEncoderError::Invalid),
            },
            Err(_) => Err(CommandEncoderError::Invalid),
        }
    }

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

    pub(crate) fn extract_baked_commands(&mut self) -> BakedCommands<A> {
        log::trace!(
            "Extracting BakedCommands from CommandBuffer {:?}",
            self.info.label()
        );
        let data = self.data.lock().take().unwrap();
        BakedCommands {
            encoder: data.encoder.raw,
            list: data.encoder.list,
            trackers: data.trackers,
            buffer_memory_init_actions: data.buffer_memory_init_actions,
            texture_memory_actions: data.texture_memory_actions,
        }
    }

    pub(crate) fn from_arc_into_baked(self: Arc<Self>) -> BakedCommands<A> {
        if let Some(mut command_buffer) = Arc::into_inner(self) {
            command_buffer.extract_baked_commands()
        } else {
            panic!("CommandBuffer cannot be destroyed because is still in use");
        }
    }
}

impl<A: HalApi> Resource for CommandBuffer<A> {
    const TYPE: ResourceType = "CommandBuffer";

    type Marker = crate::id::markers::CommandBuffer;

    fn as_info(&self) -> &ResourceInfo<Self> {
        &self.info
    }

    fn as_info_mut(&mut self) -> &mut ResourceInfo<Self> {
        &mut self.info
    }

    fn label(&self) -> String {
        let str = match self.data.lock().as_ref().unwrap().encoder.label.as_ref() {
            Some(label) => label.clone(),
            _ => String::new(),
        };
        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],
}

/// A stream of commands for a render pass or compute pass.
///
/// This also contains side tables referred to by certain commands,
/// like dynamic offsets for [`SetBindGroup`] or string data for
/// [`InsertDebugMarker`].
///
/// Render passes use `BasePass<RenderCommand>`, whereas compute
/// passes use `BasePass<ComputeCommand>`.
///
/// [`SetBindGroup`]: RenderCommand::SetBindGroup
/// [`InsertDebugMarker`]: RenderCommand::InsertDebugMarker
#[doc(hidden)]
#[derive(Debug)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct BasePass<C> {
    pub label: Option<String>,

    /// The stream of commands.
    pub commands: Vec<C>,

    /// Dynamic offsets consumed by [`SetBindGroup`] commands in `commands`.
    ///
    /// Each successive `SetBindGroup` consumes the next
    /// [`num_dynamic_offsets`] values from this list.
    pub dynamic_offsets: Vec<wgt::DynamicOffset>,

    /// Strings used by debug instructions.
    ///
    /// Each successive [`PushDebugGroup`] or [`InsertDebugMarker`]
    /// instruction consumes the next `len` bytes from this vector.
    pub string_data: Vec<u8>,

    /// Data used by `SetPushConstant` instructions.
    ///
    /// See the documentation for [`RenderCommand::SetPushConstant`]
    /// and [`ComputeCommand::SetPushConstant`] for details.
    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)]
#[non_exhaustive]
pub enum CommandEncoderError {
    #[error("Command encoder is invalid")]
    Invalid,
    #[error("Command encoder must be active")]
    NotRecording,
    #[error(transparent)]
    Device(#[from] DeviceError),
}

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

        let hub = A::hub(self);

        let error = match hub.command_buffers.get(encoder_id.transmute()) {
            Ok(cmd_buf) => {
                let mut cmd_buf_data = cmd_buf.data.lock();
                let cmd_buf_data = cmd_buf_data.as_mut().unwrap();
                match cmd_buf_data.status {
                    CommandEncoderStatus::Recording => {
                        if let Err(e) = cmd_buf_data.encoder.close() {
                            Some(e.into())
                        } else {
                            cmd_buf_data.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);
                            None
                        }
                    }
                    CommandEncoderStatus::Finished => Some(CommandEncoderError::NotRecording),
                    CommandEncoderStatus::Error => {
                        cmd_buf_data.encoder.discard();
                        Some(CommandEncoderError::Invalid)
                    }
                }
            }
            Err(_) => Some(CommandEncoderError::Invalid),
        };

        (encoder_id.transmute(), error)
    }

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

        let hub = A::hub(self);

        let cmd_buf = CommandBuffer::get_encoder(hub, encoder_id)?;
        let mut cmd_buf_data = cmd_buf.data.lock();
        let cmd_buf_data = cmd_buf_data.as_mut().unwrap();
        #[cfg(feature = "trace")]
        if let Some(ref mut list) = cmd_buf_data.commands {
            list.push(TraceCommand::PushDebugGroup(label.to_string()));
        }

        let cmd_buf_raw = cmd_buf_data.encoder.open()?;
        if !self
            .instance
            .flags
            .contains(wgt::InstanceFlags::DISCARD_HAL_LABELS)
        {
            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!("CommandEncoder::insert_debug_marker");
        api_log!("CommandEncoder::insert_debug_marker {label}");

        let hub = A::hub(self);

        let cmd_buf = CommandBuffer::get_encoder(hub, encoder_id)?;
        let mut cmd_buf_data = cmd_buf.data.lock();
        let cmd_buf_data = cmd_buf_data.as_mut().unwrap();

        #[cfg(feature = "trace")]
        if let Some(ref mut list) = cmd_buf_data.commands {
            list.push(TraceCommand::InsertDebugMarker(label.to_string()));
        }

        if !self
            .instance
            .flags
            .contains(wgt::InstanceFlags::DISCARD_HAL_LABELS)
        {
            let cmd_buf_raw = cmd_buf_data.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!("CommandEncoder::pop_debug_marker");
        api_log!("CommandEncoder::pop_debug_group");

        let hub = A::hub(self);

        let cmd_buf = CommandBuffer::get_encoder(hub, encoder_id)?;
        let mut cmd_buf_data = cmd_buf.data.lock();
        let cmd_buf_data = cmd_buf_data.as_mut().unwrap();

        #[cfg(feature = "trace")]
        if let Some(ref mut list) = cmd_buf_data.commands {
            list.push(TraceCommand::PopDebugGroup);
        }

        let cmd_buf_raw = cmd_buf_data.encoder.open()?;
        if !self
            .instance
            .flags
            .contains(wgt::InstanceFlags::DISCARD_HAL_LABELS)
        {
            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, Copy, Clone)]
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 reset(&mut self) {
        self.last_state = None;
    }
}

impl<T: Copy + PartialEq> Default for StateChange<T> {
    fn default() -> Self {
        Self::new()
    }
}

#[derive(Debug)]
struct BindGroupStateChange {
    last_states: [StateChange<id::BindGroupId>; hal::MAX_BIND_GROUPS],
}

impl BindGroupStateChange {
    fn new() -> Self {
        Self {
            last_states: [StateChange::new(); hal::MAX_BIND_GROUPS],
        }
    }

    unsafe fn set_and_check_redundant(
        &mut self,
        bind_group_id: id::BindGroupId,
        index: u32,
        dynamic_offsets: &mut Vec<u32>,
        offsets: *const wgt::DynamicOffset,
        offset_length: usize,
    ) -> bool {
        // For now never deduplicate bind groups with dynamic offsets.
        if offset_length == 0 {
            // If this get returns None, that means we're well over the limit,
            // so let the call through to get a proper error
            if let Some(current_bind_group) = self.last_states.get_mut(index as usize) {
                // Bail out if we're binding the same bind group.
                if current_bind_group.set_and_check_redundant(bind_group_id) {
                    return true;
                }
            }
        } else {
            // We intentionally remove the memory of this bind group if we have dynamic offsets,
            // such that if you try to bind this bind group later with _no_ dynamic offsets it
            // tries to bind it again and gives a proper validation error.
            if let Some(current_bind_group) = self.last_states.get_mut(index as usize) {
                current_bind_group.reset();
            }
            dynamic_offsets
                .extend_from_slice(unsafe { slice::from_raw_parts(offsets, offset_length) });
        }
        false
    }
    fn reset(&mut self) {
        self.last_states = [StateChange::new(); hal::MAX_BIND_GROUPS];
    }
}

impl Default for BindGroupStateChange {
    fn default() -> Self {
        Self::new()
    }
}

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_occlusion_query command")]
    BeginOcclusionQuery,
    #[error("In a end_occlusion_query command")]
    EndOcclusionQuery,
    #[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,
}

impl PrettyError for PassErrorScope {
    fn fmt_pretty(&self, fmt: &mut ErrorFormatter) {
        // This error is not in the error chain, only notes are needed
        match *self {
            Self::Pass(id) => {
                fmt.command_buffer_label(&id.transmute());
            }
            Self::SetBindGroup(id) => {
                fmt.bind_group_label(&id);
            }
            Self::SetPipelineRender(id) => {
                fmt.render_pipeline_label(&id);
            }
            Self::SetPipelineCompute(id) => {
                fmt.compute_pipeline_label(&id);
            }
            Self::SetVertexBuffer(id) => {
                fmt.buffer_label(&id);
            }
            Self::SetIndexBuffer(id) => {
                fmt.buffer_label(&id);
            }
            Self::Draw {
                pipeline: Some(id), ..
            } => {
                fmt.render_pipeline_label(&id);
            }
            Self::Dispatch {
                pipeline: Some(id), ..
            } => {
                fmt.compute_pipeline_label(&id);
            }
            _ => {}
        }
    }
}