#include "Explicit_Frame_Flow.h"
#include "../../architecture/Render_Time.h"
#include "../../architecture/Update_Completion.h"

namespace renderive {

namespace {
struct Explicit_Render_Surface_Handle final : Render_Frame_Surface_Handle {
    explicit Explicit_Render_Surface_Handle(std::shared_ptr<Render_Output> output) : output(std::move(output)) {}
    std::shared_ptr<Render_Output> output;
};

struct Explicit_Present_Surface_Handle final {
    explicit Explicit_Present_Surface_Handle(std::shared_ptr<Render_Output> output) : output_value(std::move(output)) {}

    [[nodiscard]] Render_Output* output() const {
        return output_value.get();
    }

    std::shared_ptr<Render_Output> output_value;
};

Explicit_Render_Surface_Handle* explicit_handle(Render_Frame_Surface& surface) {
    return static_cast<Explicit_Render_Surface_Handle*>(surface.handle.get());
}
} // namespace

Explicit_Frame_Flow::Explicit_Frame_Flow()
    : pending_requests(memory_resource(Memory_Domain::Update_Completion)) {}

Render_Ticket Explicit_Frame_Flow::request_render() {
    auto state = make_update_state();
    {
        std::lock_guard<std::mutex> lock(request_mutex);
        pending_requests.push_back(state);
    }
    manual_request_pending.store(true, std::memory_order_release);
    return Render_Ticket(std::move(state));
}

void Explicit_Frame_Flow::attach(Frame_Flow_Host& host_value) {
    host = &host_value;
}

Frame_Flow_Runtime_Snapshot Explicit_Frame_Flow::runtime_snapshot(std::uint64_t now_ns, bool destroying) const {
    return {
        destroying,
        manual_request_pending.load(std::memory_order_acquire),
        render_job_active.load(std::memory_order_acquire),
        frame_ready.load(std::memory_order_acquire),
        present_active.load(std::memory_order_acquire),
        now_ns
    };
}

void Explicit_Frame_Flow::advance_edit_version() {
    edit_version.fetch_add(1, std::memory_order_acq_rel);
}

void Explicit_Frame_Flow::cancel_all_update_states() {
    {
        std::lock_guard<std::mutex> lock(request_mutex);
        for (auto& state : pending_requests) {
            if (state)
                state->complete_all(std::make_error_code(std::errc::operation_canceled), Update_Outcome::Cancelled);
        }
        pending_requests.clear();
    }
    std::shared_ptr<Render_Output> output;
    {
        std::lock_guard<std::mutex> lock(surface_mutex);
        output = std::move(present_surface);
    }
    if (output)
        cancel_update_states(output->presented_update_states);
}

Render_Frame_Surface Explicit_Frame_Flow::begin_render_frame() {
    if (render_job_active.exchange(true, std::memory_order_acq_rel))
        return {};
    auto output = std::make_shared<Render_Output>();
    auto handle = std::make_unique<Explicit_Render_Surface_Handle>(output);
    auto* output_pointer = output.get();
    std::uint64_t input_version = edit_version.load(std::memory_order_acquire);
    return Render_Frame_Surface(output_pointer, input_version, std::move(handle));
}

void Explicit_Frame_Flow::cancel_render_frame(Render_Frame_Surface&& surface) {
    (void)surface;
    render_job_active.store(false, std::memory_order_release);
}

void Explicit_Frame_Flow::discard_render_frame(Render_Frame_Surface&& surface) {
    (void)surface;
    render_job_active.store(false, std::memory_order_release);
}

Render_Surface_Publish_Result Explicit_Frame_Flow::publish_rendered_frame(Render_Frame_Surface&& surface, std::uint64_t now_ns) {
    Render_Surface_Publish_Result result;
    auto* handle = explicit_handle(surface);
    if (!handle || !handle->output) {
        render_job_active.store(false, std::memory_order_release);
        return result;
    }
    if (handle->output->metadata) {
        handle->output->metadata->transition_12_ns = now_ns;
        handle->output->metadata->ready_queue_wait_ns = now_ns > handle->output->metadata->render_end_ns ? now_ns - handle->output->metadata->render_end_ns : 0;
        handle->output->metadata->update_request_id = ++next_present_request_id;
        handle->output->metadata->update_request_time_ns = now_ns;
        result.update_request_id = handle->output->metadata->update_request_id;
        result.update_request_time = now_ns;
    }
    std::shared_ptr<Render_Output> output = std::move(handle->output);
    Size size = output ? output->image.size() : Size{};
    {
        std::lock_guard<std::mutex> lock(surface_mutex);
        present_surface = output;
    }
    frame_ready.store(true, std::memory_order_release);
    paint_request_pending.store(true, std::memory_order_release);
    render_job_active.store(false, std::memory_order_release);
    result.dirty_rect = Rect{0, 0, size.width, size.height};
    result.request_present = true;
    return result;
}

Render_Surface_Publish_Result Explicit_Frame_Flow::request_present(std::uint64_t now_ns) {
    Render_Surface_Publish_Result result;
    std::shared_ptr<Render_Output> output;
    {
        std::lock_guard<std::mutex> lock(surface_mutex);
        output = present_surface;
    }
    if (!output)
        return result;
    if (output->metadata) {
        output->metadata->update_request_id = ++next_present_request_id;
        output->metadata->update_request_time_ns = now_ns;
        result.update_request_id = output->metadata->update_request_id;
        result.update_request_time = now_ns;
    }
    paint_request_pending.store(true, std::memory_order_release);
    Size size = output->image.size();
    result.dirty_rect = Rect{0, 0, size.width, size.height};
    result.request_present = true;
    return result;
}

Present_Surface_Lease Explicit_Frame_Flow::begin_present(std::uint64_t now_ns, std::shared_ptr<Frame_Lifecycle_Record>& returned_frame_record) {
    returned_frame_record.reset();
    std::shared_ptr<Render_Output> output;
    {
        std::lock_guard<std::mutex> lock(surface_mutex);
        output = present_surface;
    }
    if (!output || present_active.exchange(true, std::memory_order_acq_rel))
        return {};
    bool is_new = frame_ready.exchange(false, std::memory_order_acq_rel);
    bool pending = paint_request_pending.exchange(false, std::memory_order_acq_rel);
    if (is_new && output->metadata) {
        output->metadata->transition_23_ns = now_ns;
        output->metadata->present_queue_wait_ns = now_ns > output->metadata->transition_12_ns ? now_ns - output->metadata->transition_12_ns : 0;
    }
    return Present_Surface_Lease_Access::from_handle<Explicit_Present_Surface_Handle>(
        is_new,
        pending,
        std::move(output));
}

std::shared_ptr<Frame_Lifecycle_Record> Explicit_Frame_Flow::end_present(Present_Surface_Lease&& surface, std::uint64_t paint_begin_ns, std::uint64_t paint_end_ns) {
    std::shared_ptr<Frame_Lifecycle_Record> record;
    Render_Output* output = Present_Surface_Lease_Access::output(surface);
    if (output && surface.new_frame()) {
        record = output->metadata;
        if (record) {
            record->paint_begin_ns = paint_begin_ns;
            record->paint_end_ns = paint_end_ns;
            record->outcome = Frame_Outcome::Presented;
        }
        complete_update_states(output->presented_update_states, Update_Stage::Presented);
    }
    Present_Surface_Lease_Access::reset(surface);
    present_active.store(false, std::memory_order_release);
    return record;
}

void Explicit_Frame_Flow::activate_view(std::uint64_t now_ns) {
    view_active_state.store(true, std::memory_order_release);
    evaluate(now_ns);
}

void Explicit_Frame_Flow::deactivate_view() {
    view_active_state.store(false, std::memory_order_release);
}

bool Explicit_Frame_Flow::view_active() const {
    return view_active_state.load(std::memory_order_acquire);
}

void Explicit_Frame_Flow::notify_model_dirty(std::uint64_t now_ns) {
    evaluate(now_ns);
}

void Explicit_Frame_Flow::notify_viewport_changed(Size, std::uint64_t now_ns) {
    evaluate(now_ns);
}

void Explicit_Frame_Flow::notify_render_finished(Frame_Lifecycle_Record&, std::uint64_t now_ns) {
    evaluate(now_ns);
}

void Explicit_Frame_Flow::notify_paint_finished(std::uint64_t now_ns) {
    evaluate(now_ns);
}

void Explicit_Frame_Flow::notify_frame_returned(Frame_Lifecycle_Record&, std::uint64_t now_ns) {
    evaluate(now_ns);
}

void Explicit_Frame_Flow::notify_timer_fired(std::uint64_t now_ns) {
    evaluate(now_ns);
}

void Explicit_Frame_Flow::drain_frame_update_states(std::pmr::vector<std::shared_ptr<Update_State>>& output) {
    std::lock_guard<std::mutex> lock(request_mutex);
    for (auto& state : pending_requests)
        output.push_back(std::move(state));
    pending_requests.clear();
    manual_request_pending.store(false, std::memory_order_release);
}

Explicit_Diagnostics Explicit_Frame_Flow::explicit_diagnostics() const {
    std::lock_guard<std::mutex> lock(request_mutex);
    return Explicit_Diagnostics{
        view_active_state.load(std::memory_order_acquire),
        static_cast<std::uint64_t>(pending_requests.size())
    };
}

Flow_Diagnostics Explicit_Frame_Flow::diagnostics() const {
    Explicit_Diagnostics typed = explicit_diagnostics();
    return Flow_Diagnostics{
        Common_Flow_Diagnostics{typed.active},
        typed
    };
}

void Explicit_Frame_Flow::shutdown() {
    host = nullptr;
    cancel_all_update_states();
    view_active_state.store(false, std::memory_order_release);
    manual_request_pending.store(false, std::memory_order_release);
    render_job_active.store(false, std::memory_order_release);
    frame_ready.store(false, std::memory_order_release);
    present_active.store(false, std::memory_order_release);
    paint_request_pending.store(false, std::memory_order_release);
}

void Explicit_Frame_Flow::evaluate(std::uint64_t now_ns) {
    if (!host)
        return;
    Frame_Flow_Runtime_Snapshot runtime = host->runtime_snapshot(now_ns);
    if (runtime.destroying)
        return;
    if (runtime.middle_has_new_frame && !runtime.paint_active)
        host->request_paint_from_middle();
    if (!manual_request_pending.load(std::memory_order_acquire))
        return;
    if (runtime.render_job_active)
        return;
    if (host->try_render_once())
        manual_request_pending.store(false, std::memory_order_release);
}

} // namespace renderive