// Copyright 2023 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include "common/logging/log.h"
#include "video_core/renderer_opengl/gl_state.h"
#include "video_core/renderer_opengl/gl_texture_mailbox.h"

namespace OpenGL {

OGLTextureMailbox::OGLTextureMailbox(bool has_debug_tool_) : has_debug_tool{has_debug_tool_} {
    for (auto& frame : swap_chain) {
        free_queue.push(&frame);
    }
}

OGLTextureMailbox::~OGLTextureMailbox() {
    // Lock the mutex and clear out the present and free_queues and notify any people who are
    // blocked to prevent deadlock on shutdown
    std::scoped_lock lock(swap_chain_lock);
    free_queue = {};
    present_queue.clear();
    present_cv.notify_all();
    free_cv.notify_all();
}

void OGLTextureMailbox::ReloadPresentFrame(Frontend::Frame* frame, u32 height, u32 width) {
    frame->present.Release();
    frame->present.Create();
    GLint previous_draw_fbo{};
    glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &previous_draw_fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, frame->present.handle);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,
                              frame->color.handle);
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
        LOG_CRITICAL(Render_OpenGL, "Failed to recreate present FBO!");
    }
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, previous_draw_fbo);
    frame->color_reloaded = false;
}

void OGLTextureMailbox::ReloadRenderFrame(Frontend::Frame* frame, u32 width, u32 height) {
    OpenGLState prev_state = OpenGLState::GetCurState();
    OpenGLState state = OpenGLState::GetCurState();

    // Recreate the color texture attachment
    frame->color.Release();
    frame->color.Create();
    state.renderbuffer = frame->color.handle;
    state.Apply();
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, width, height);

    // Recreate the FBO for the render target
    frame->render.Release();
    frame->render.Create();
    state.draw.read_framebuffer = frame->render.handle;
    state.draw.draw_framebuffer = frame->render.handle;
    state.Apply();
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,
                              frame->color.handle);
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
        LOG_CRITICAL(Render_OpenGL, "Failed to recreate render FBO!");
    }
    prev_state.Apply();
    frame->width = width;
    frame->height = height;
    frame->color_reloaded = true;
}

Frontend::Frame* OGLTextureMailbox::GetRenderFrame() {
    std::unique_lock lock{swap_chain_lock};

    // If theres no free frames, we will reuse the oldest render frame
    if (free_queue.empty()) {
        auto frame = present_queue.back();
        present_queue.pop_back();
        return frame;
    }

    Frontend::Frame* frame = free_queue.front();
    free_queue.pop();
    return frame;
}

void OGLTextureMailbox::ReleaseRenderFrame(Frontend::Frame* frame) {
    std::unique_lock lock{swap_chain_lock};
    present_queue.push_front(frame);
    present_cv.notify_one();

    DebugNotifyNextFrame();
}

void OGLTextureMailbox::LoadPresentFrame() {
    // Free the previous frame and add it back to the free queue
    if (previous_frame) {
        free_queue.push(previous_frame);
        free_cv.notify_one();
    }

    // The newest entries are pushed to the front of the queue
    Frontend::Frame* frame = present_queue.front();
    present_queue.pop_front();
    // Remove all old entries from the present queue and move them back to the free_queue
    for (auto f : present_queue) {
        free_queue.push(f);
    }
    present_queue.clear();
    previous_frame = frame;
}

Frontend::Frame* OGLTextureMailbox::TryGetPresentFrame(int timeout_ms) {
    DebugWaitForNextFrame();

    std::unique_lock lock{swap_chain_lock};
    // Wait for new entries in the present_queue
    present_cv.wait_for(lock, std::chrono::milliseconds(timeout_ms),
                        [&] { return !present_queue.empty(); });
    if (present_queue.empty()) {
        // Timed out waiting for a frame to draw so return the previous frame
        return previous_frame;
    }

    LoadPresentFrame();
    return previous_frame;
}

void OGLTextureMailbox::DebugNotifyNextFrame() {
    if (!has_debug_tool) {
        return;
    }
    frame_for_debug++;
    std::scoped_lock lock{debug_synch_mutex};
    debug_synch_condition.notify_one();
}

void OGLTextureMailbox::DebugWaitForNextFrame() {
    if (!has_debug_tool) {
        return;
    }
    const int last_frame = frame_for_debug;
    std::unique_lock lock{debug_synch_mutex};
    debug_synch_condition.wait(lock, [this, last_frame] { return frame_for_debug > last_frame; });
}

Frontend::Frame* OGLVideoDumpingMailbox::GetRenderFrame() {
    std::unique_lock lock{swap_chain_lock};

    // If theres no free frames, we will wait until one shows up
    if (free_queue.empty()) {
        free_cv.wait(lock, [&] { return (!free_queue.empty() || quit); });
        if (quit) {
            throw OGLTextureMailboxException("VideoDumpingMailbox quitting");
        }

        if (free_queue.empty()) {
            LOG_CRITICAL(Render_OpenGL, "Could not get free frame");
            return nullptr;
        }
    }

    Frontend::Frame* frame = free_queue.front();
    free_queue.pop();
    return frame;
}

void OGLVideoDumpingMailbox::LoadPresentFrame() {
    // Free the previous frame and add it back to the free queue
    if (previous_frame) {
        free_queue.push(previous_frame);
        free_cv.notify_one();
    }

    Frontend::Frame* frame = present_queue.back();
    present_queue.pop_back();
    previous_frame = frame;

    // Do not remove entries from the present_queue, as video dumping would require
    // that we preserve all frames
}

Frontend::Frame* OGLVideoDumpingMailbox::TryGetPresentFrame(int timeout_ms) {
    std::unique_lock lock{swap_chain_lock};
    // Wait for new entries in the present_queue
    present_cv.wait_for(lock, std::chrono::milliseconds(timeout_ms),
                        [&] { return !present_queue.empty(); });
    if (present_queue.empty()) {
        // Timed out waiting for a frame
        return nullptr;
    }

    LoadPresentFrame();
    return previous_frame;
}

} // namespace OpenGL