#include "stream_bridge.h"
#include <deque>
#include <mutex>
#include <algorithm>

extern "C" {
#include "../../../lib/debug_config.h"
#include "../../../lib/mem.h"
#include "../../../lib/u_async.h"
#include "../../../src/utun_instance.h"
#include "../../../src/stream/stream.h"
#include "../../../src/stream/stream_member.h"
}

namespace {
struct Viewer { uint64_t id = 0, group = 0, source = 0, epoch = 0; };
struct Bridge {
    std::mutex lock;
    UTUN_INSTANCE* inst = nullptr;
    posted_task* pending = nullptr;
    uint64_t watch = 0;
    bool watchPending = false, opening = false, stopping = false, overflow = false;
    Viewer viewer, requested;
    STREAM_HANDLE* handle = nullptr;
    stream_media_receiver* receiver = nullptr;
    std::deque<StreamRecord> output;
    size_t bytes = 0;
} bridge;

void process(void*);

/* Вызывается под lock; резервирование делает отказ команды наблюдаемым до изменения состояния. */
bool schedule() {
    if (!bridge.inst || !uasync_is_running(bridge.inst->ua)) {
        DEBUG_WARN(DEBUG_CATEGORY_STREAM, "desktop stream command rejected: core unavailable"); return false;
    }
    if (bridge.pending) return true;
    auto* task = static_cast<posted_task*>(u_calloc(1, sizeof(posted_task)));
    if (!task) { DEBUG_ERROR(DEBUG_CATEGORY_STREAM, "desktop stream task allocation failed"); return false; }
    task->callback = process; bridge.pending = task;
    uasync_post_reserved(bridge.inst->ua, task);
    return true;
}

/* Управляющие записи не теряются при media pressure; старые readers не накапливают очередь. */
void output(StreamRecord record) {
    if (bridge.output.size() >= 256 || bridge.bytes + static_cast<size_t>(record.data.size()) > 4u * 1024u * 1024u) {
        DEBUG_WARN(DEBUG_CATEGORY_STREAM, "desktop stream RX pressure id=%llu records=%zu bytes=%zu; wait KEY",
                   (unsigned long long)record.id, bridge.output.size(), bridge.bytes);
        bridge.output.clear(); bridge.bytes = 0; bridge.overflow = true;
        bridge.output.push_back({record.id, 0, StreamRecordKind::Gap});
        if (record.kind == StreamRecordKind::Video || record.kind == StreamRecordKind::Audio) return;
    }
    bridge.bytes += static_cast<size_t>(record.data.size()); bridge.output.push_back(std::move(record));
}

/* Только uasync под lock; снимает собственное владение подпиской, не транспорт других владельцев. */
void closeViewer(StreamRecordKind kind, int reason) {
    if (bridge.viewer.id) output({bridge.viewer.id, 0, kind, {}, 0, reason});
    if (bridge.handle) stream_close(bridge.handle);
    stream_media_receiver_destroy(bridge.receiver);
    DEBUG_INFO(DEBUG_CATEGORY_STREAM, "desktop viewer released id=%llu reason=%d",
               (unsigned long long)bridge.viewer.id, reason);
    bridge.handle = nullptr; bridge.receiver = nullptr; bridge.viewer = {}; bridge.overflow = false;
}

void mediaFrame(void*, const stream_media_format* format, const stream_media_video* video, const stream_media_audio* audio) {
    if (bridge.overflow) return;
    StreamRecord record; record.id = bridge.viewer.id; record.format = *format;
    if (video) {
        record.kind = StreamRecordKind::Video; record.pts = video->pts_us; record.flags = video->flags;
        record.data = QByteArray(reinterpret_cast<const char*>(video->data), static_cast<int>(video->length));
    } else {
        record.kind = StreamRecordKind::Audio; record.pts = audio->pts_us;
        record.data = QByteArray(reinterpret_cast<const char*>(audio->data), static_cast<int>(audio->length));
    }
    output(std::move(record));
}

/* Scratch receiver/stream не покидает callback; decoder получает собственные копии. */
void mediaEvent(UTUN_INSTANCE* inst, const stream_event* event, void*) {
    std::lock_guard<std::mutex> guard(bridge.lock);
    if (inst != bridge.inst || !bridge.handle || event->descriptor.group_id != bridge.viewer.group
        || event->descriptor.source_node_id != bridge.viewer.source || event->descriptor.source_epoch != bridge.viewer.epoch) return;
    if (event->type == STREAM_EVENT_DATA) {
        int result = stream_media_receiver_feed(bridge.receiver, event->data, event->length);
        if (result != STREAM_OK) {
            DEBUG_ERROR(DEBUG_CATEGORY_STREAM, "desktop viewer media rejected result=%d", result);
            closeViewer(StreamRecordKind::Closed, STREAM_CLOSE_FAILED);
        } else if (bridge.overflow) {
            stream_media_receiver_gap(bridge.receiver); bridge.overflow = false;
        }
    } else if (event->type == STREAM_EVENT_GAP) {
        stream_media_receiver_gap(bridge.receiver); output({bridge.viewer.id, 0, StreamRecordKind::Gap});
    } else if (event->type == STREAM_EVENT_END || !stream_handle_active(bridge.handle)) {
        closeViewer(event->type == STREAM_EVENT_END ? StreamRecordKind::End : StreamRecordKind::Closed, event->reason);
    }
}

/* Сериализованный actor: старый owner закрывается перед открытием нового выбранного источника. */
void process(void*) {
    std::lock_guard<std::mutex> guard(bridge.lock);
    bridge.pending = nullptr;
    if (!bridge.inst) return;
    if (bridge.watchPending) {
        bridge.watchPending = false;
        if (stream_watch_sources(bridge.inst, bridge.watch) != STREAM_OK)
            DEBUG_ERROR(DEBUG_CATEGORY_STREAM, "desktop stream source watch failed group=%llx", (unsigned long long)bridge.watch);
    }
    if (bridge.stopping || bridge.opening) {
        if (bridge.viewer.id) closeViewer(StreamRecordKind::Closed, STREAM_CLOSE_STOPPED);
        bridge.stopping = false;
    }
    if (!bridge.opening) return;
    bridge.opening = false; bridge.viewer = bridge.requested; bridge.requested = {};
    stream_member_state member{};
    int reason = STREAM_CLOSE_FAILED;
    int result = stream_member_load(bridge.inst, bridge.viewer.group, bridge.viewer.source, &member, nullptr);
    if (result == STREAM_OK && (!member.published || member.source.source_epoch != bridge.viewer.epoch)) {
        DEBUG_WARN(DEBUG_CATEGORY_STREAM, "desktop selected source changed source=%llx expected=%llx actual=%llx",
                   (unsigned long long)bridge.viewer.source, (unsigned long long)bridge.viewer.epoch,
                   (unsigned long long)(member.published ? member.source.source_epoch : 0));
        result = STREAM_ERR_CONFLICT; reason = STREAM_CLOSE_SOURCE_CHANGED;
    }
    if (result == STREAM_OK) result = stream_subscribe_open(bridge.inst, bridge.viewer.group, bridge.viewer.source, &bridge.handle);
    stream_info info{};
    if (result == STREAM_OK) result = stream_get_info(bridge.handle, &info);
    if (result == STREAM_OK && info.descriptor.source_epoch != bridge.viewer.epoch) {
        DEBUG_WARN(DEBUG_CATEGORY_STREAM, "desktop reader encountered stale local epoch");
        result = STREAM_ERR_CONFLICT; reason = STREAM_CLOSE_SOURCE_CHANGED;
    }
    if (result == STREAM_OK) result = stream_media_receiver_create(&bridge.receiver, mediaFrame, nullptr);
    if (result != STREAM_OK) {
        DEBUG_ERROR(DEBUG_CATEGORY_STREAM, "desktop viewer open failed id=%llu group=%llx source=%llx result=%d",
                   (unsigned long long)bridge.viewer.id, (unsigned long long)bridge.viewer.group,
                   (unsigned long long)bridge.viewer.source, result);
        closeViewer(StreamRecordKind::Closed, reason); return;
    }
    output({bridge.viewer.id, 0, StreamRecordKind::Opened});
    DEBUG_INFO(DEBUG_CATEGORY_STREAM, "desktop viewer opened id=%llu group=%llx source=%llx epoch=%llx",
               (unsigned long long)bridge.viewer.id, (unsigned long long)bridge.viewer.group,
               (unsigned long long)bridge.viewer.source, (unsigned long long)bridge.viewer.epoch);
}
}

bool gui_stream_attach(UTUN_INSTANCE* inst) {
    std::lock_guard<std::mutex> guard(bridge.lock);
    if (!inst || !inst->stream || bridge.inst) {
        DEBUG_ERROR(DEBUG_CATEGORY_STREAM, "desktop stream attach rejected"); return false;
    }
    bridge.inst = inst; bridge.output.clear(); bridge.bytes = 0;
    stream_set_event_callback(inst, mediaEvent, nullptr);
    DEBUG_INFO(DEBUG_CATEGORY_STREAM, "desktop stream bridge attached"); return true;
}

void gui_stream_detach(UTUN_INSTANCE* inst) {
    std::lock_guard<std::mutex> guard(bridge.lock);
    if (!inst || bridge.inst != inst) return;
    if (bridge.pending) uasync_cancel_post(inst->ua, bridge.pending);
    stream_watch_sources(inst, 0);
    bridge.pending = nullptr; stream_set_event_callback(inst, nullptr, nullptr);
    if (bridge.viewer.id) closeViewer(StreamRecordKind::Closed, STREAM_CLOSE_SERVICE);
    if (bridge.opening) output({bridge.requested.id, 0, StreamRecordKind::Closed, {}, 0, STREAM_CLOSE_SERVICE});
    bridge.inst = nullptr; bridge.requested = {}; bridge.opening = bridge.stopping = bridge.watchPending = false;
    DEBUG_INFO(DEBUG_CATEGORY_STREAM, "desktop stream bridge detached");
}

bool gui_stream_watch(uint64_t group) {
    std::lock_guard<std::mutex> guard(bridge.lock);
    if (!schedule()) return false;
    bridge.watch = group; bridge.watchPending = true; return true;
}

bool gui_stream_open(uint64_t id, uint64_t group, uint64_t source, uint64_t epoch) {
    std::lock_guard<std::mutex> guard(bridge.lock);
    if (!id || !group || !source || !epoch) { DEBUG_ERROR(DEBUG_CATEGORY_STREAM, "desktop viewer invalid identity"); return false; }
    if (!schedule()) return false;
    if (bridge.opening) output({bridge.requested.id, 0, StreamRecordKind::Closed, {}, 0, STREAM_CLOSE_STOPPED});
    bridge.requested = {id, group, source, epoch}; bridge.opening = true; return true;
}

void gui_stream_stop(uint64_t id) {
    std::lock_guard<std::mutex> guard(bridge.lock);
    if (bridge.opening && bridge.requested.id == id) {
        bridge.opening = false; bridge.requested = {}; output({id, 0, StreamRecordKind::Closed, {}, 0, STREAM_CLOSE_STOPPED});
    }
    if (bridge.viewer.id == id && schedule()) bridge.stopping = true;
    for (auto i = bridge.output.begin(); i != bridge.output.end();) {
        if (i->id == id) { bridge.bytes -= static_cast<size_t>(i->data.size()); i = bridge.output.erase(i); }
        else ++i;
    }
}

bool gui_stream_pull(uint64_t id, StreamRecord& record) {
    std::lock_guard<std::mutex> guard(bridge.lock);
    auto i = std::find_if(bridge.output.begin(), bridge.output.end(), [id](const StreamRecord& r) { return r.id == id; });
    if (i == bridge.output.end()) return false;
    bridge.bytes -= static_cast<size_t>(i->data.size()); record = std::move(*i); bridge.output.erase(i); return true;
}

bool gui_stream_ready() { std::lock_guard<std::mutex> guard(bridge.lock); return bridge.inst != nullptr; }