#include "player.h"

#include <limits.h>
#include <stdint.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct DecoderThreadArgs {
    Player *player;
    const Channel *channel;
} DecoderThreadArgs;

static void player_set_error(Player *player, const char *message) {
    if (!player || !player->error_mutex) {
        return;
    }

    SDL_LockMutex(player->error_mutex);
    snprintf(player->last_error, sizeof(player->last_error), "%s", message ? message : "Unknown playback error");
    SDL_UnlockMutex(player->error_mutex);
}

static int should_stop(Player *player) {
    return player ? SDL_AtomicGet(&player->stop_requested) : 1;
}

static int decode_thread_main(void *userdata) {
    DecoderThreadArgs *args = (DecoderThreadArgs *) userdata;
    Player *player = args->player;
    const Channel *channel = args->channel;
    AVFormatContext *format_context = NULL;
    AVCodecContext *codec_context = NULL;
    AVPacket *packet = NULL;
    AVFrame *decoded_frame = NULL;
    struct SwsContext *sws_context = NULL;
    const AVCodec *codec = NULL;
    int video_stream_index = -1;
    int rc = -1;
    int rgb_stride = 0;
    double seek_seconds = 0.0;
    AVRational time_base;
    Uint64 wall_base_ms = 0;
    int first_frame = 1;

    free(args);

    if (avformat_open_input(&format_context, channel->file_path, NULL, NULL) < 0) {
        player_set_error(player, "Unable to open media file");
        return -1;
    }

    if (avformat_find_stream_info(format_context, NULL) < 0) {
        player_set_error(player, "Unable to read stream metadata");
        goto cleanup;
    }

    for (unsigned int i = 0; i < format_context->nb_streams; ++i) {
        if (format_context->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_stream_index = (int) i;
            break;
        }
    }

    if (video_stream_index < 0) {
        player_set_error(player, "No video stream found");
        goto cleanup;
    }

    codec = avcodec_find_decoder(format_context->streams[video_stream_index]->codecpar->codec_id);
    if (!codec) {
        player_set_error(player, "Unsupported video codec");
        goto cleanup;
    }

    codec_context = avcodec_alloc_context3(codec);
    if (!codec_context) {
        player_set_error(player, "Unable to allocate codec context");
        goto cleanup;
    }

    if (avcodec_parameters_to_context(codec_context, format_context->streams[video_stream_index]->codecpar) < 0 ||
        avcodec_open2(codec_context, codec, NULL) < 0) {
        player_set_error(player, "Unable to initialize decoder");
        goto cleanup;
    }

    decoded_frame = av_frame_alloc();
    packet = av_packet_alloc();
    if (!decoded_frame || !packet) {
        player_set_error(player, "Unable to allocate FFmpeg frame buffers");
        goto cleanup;
    }

    rgb_stride = codec_context->width * 4;
    time_base = format_context->streams[video_stream_index]->time_base;
    sws_context = sws_getContext(codec_context->width,
                                 codec_context->height,
                                 codec_context->pix_fmt,
                                 codec_context->width,
                                 codec_context->height,
                                 AV_PIX_FMT_RGBA,
                                 SWS_BILINEAR,
                                 NULL,
                                 NULL,
                                 NULL);
    if (!sws_context) {
        player_set_error(player, "Unable to initialize scaler");
        goto cleanup;
    }

    seek_seconds = channel_live_position(channel, player->app_start_time, time(NULL));
    if (channel->duration_seconds > 0.0) {
        int64_t seek_target = (int64_t) (seek_seconds / av_q2d(time_base));
        avformat_seek_file(format_context, video_stream_index, INT64_MIN, seek_target, INT64_MAX, 0);
        avcodec_flush_buffers(codec_context);
    }

    while (!should_stop(player)) {
        if (av_read_frame(format_context, packet) < 0) {
            if (channel->duration_seconds > 0.0) {
                seek_seconds = 0.0;
                wall_base_ms = SDL_GetTicks64();
                avformat_seek_file(format_context, video_stream_index, INT64_MIN, 0, INT64_MAX, 0);
                avcodec_flush_buffers(codec_context);
                continue;
            }
            break;
        }

        if (packet->stream_index != video_stream_index) {
            av_packet_unref(packet);
            continue;
        }

        if (avcodec_send_packet(codec_context, packet) < 0) {
            av_packet_unref(packet);
            continue;
        }
        av_packet_unref(packet);

        while (!should_stop(player)) {
            double frame_seconds;
            int delay_ms;
            int receive = avcodec_receive_frame(codec_context, decoded_frame);
            if (receive == AVERROR(EAGAIN) || receive == AVERROR_EOF) {
                break;
            }
            if (receive < 0) {
                player_set_error(player, "Video decode failed");
                goto cleanup;
            }

            frame_seconds = decoded_frame->best_effort_timestamp == AV_NOPTS_VALUE
                ? seek_seconds
                : decoded_frame->best_effort_timestamp * av_q2d(time_base);

            if (first_frame) {
                wall_base_ms = SDL_GetTicks64();
                first_frame = 0;
            }

            delay_ms = (int) (((frame_seconds - seek_seconds) * 1000.0) - (double) (SDL_GetTicks64() - wall_base_ms));
            if (delay_ms > 1 && delay_ms < 250) {
                SDL_Delay((Uint32) delay_ms);
            }

            {
                FrameData frame = {0};
                uint8_t *dest_data[4] = {0};
                int dest_linesize[4] = {0};

                frame.width = codec_context->width;
                frame.height = codec_context->height;
                frame.stride = rgb_stride;
                frame.pts_seconds = frame_seconds;
                frame.pixels = malloc((size_t) frame.stride * (size_t) frame.height);
                if (!frame.pixels) {
                    player_set_error(player, "Unable to allocate frame buffer");
                    goto cleanup;
                }

                dest_data[0] = frame.pixels;
                dest_linesize[0] = frame.stride;
                sws_scale(sws_context,
                          (const uint8_t *const *) decoded_frame->data,
                          decoded_frame->linesize,
                          0,
                          codec_context->height,
                          dest_data,
                          dest_linesize);
                frame_queue_push(&player->frame_queue, &frame);
            }
        }
    }

    rc = 0;

cleanup:
    if (packet) {
        av_packet_free(&packet);
    }
    if (decoded_frame) {
        av_frame_free(&decoded_frame);
    }
    if (codec_context) {
        avcodec_free_context(&codec_context);
    }
    if (format_context) {
        avformat_close_input(&format_context);
    }
    if (sws_context) {
        sws_freeContext(sws_context);
    }
    return rc;
}

static void player_stop_thread(Player *player) {
    if (!player || !player->thread) {
        return;
    }

    SDL_AtomicSet(&player->stop_requested, 1);
    SDL_WaitThread(player->thread, NULL);
    player->thread = NULL;
}

int player_init(Player *player, const ChannelList *channels, time_t app_start_time) {
    if (!player || !channels) {
        return -1;
    }

    memset(player, 0, sizeof(*player));
    player->channels = channels;
    player->current_index = -1;
    player->app_start_time = app_start_time;
    player->error_mutex = SDL_CreateMutex();
    if (!player->error_mutex) {
        return -1;
    }

    if (frame_queue_init(&player->frame_queue) != 0) {
        SDL_DestroyMutex(player->error_mutex);
        memset(player, 0, sizeof(*player));
        return -1;
    }

    return 0;
}

void player_destroy(Player *player) {
    if (!player) {
        return;
    }

    player_stop_thread(player);
    frame_queue_destroy(&player->frame_queue);
    if (player->error_mutex) {
        SDL_DestroyMutex(player->error_mutex);
    }
    memset(player, 0, sizeof(*player));
}

int player_tune(Player *player, int channel_index) {
    DecoderThreadArgs *args;

    if (!player || !player->channels || channel_index < 0 || channel_index >= player->channels->count) {
        return -1;
    }

    player_stop_thread(player);
    frame_queue_clear(&player->frame_queue);
    SDL_AtomicSet(&player->stop_requested, 0);
    player->current_index = channel_index;
    player->tuning_blackout_until = SDL_GetTicks() + 200;
    player_set_error(player, "");

    args = malloc(sizeof(*args));
    if (!args) {
        player_set_error(player, "Unable to allocate thread args");
        return -1;
    }

    args->player = player;
    args->channel = &player->channels->items[channel_index];
    player->thread = SDL_CreateThread(decode_thread_main, "decoder", args);
    if (!player->thread) {
        free(args);
        player_set_error(player, "Unable to start decoder thread");
        return -1;
    }

    return 0;
}

int player_consume_latest_frame(Player *player, FrameData *out) {
    if (!player || !out) {
        return 0;
    }

    return frame_queue_pop_latest(&player->frame_queue, out);
}

double player_live_position(const Player *player, time_t now) {
    if (!player || !player->channels || player->current_index < 0 || player->current_index >= player->channels->count) {
        return 0.0;
    }

    return channel_live_position(&player->channels->items[player->current_index], player->app_start_time, now);
}

int player_is_in_blackout(const Player *player) {
    return player && SDL_GetTicks() < player->tuning_blackout_until;
}

void player_get_error(Player *player, char *buffer, size_t buffer_size) {
    if (!player || !buffer || buffer_size == 0) {
        return;
    }

    SDL_LockMutex(player->error_mutex);
    snprintf(buffer, buffer_size, "%s", player->last_error);
    SDL_UnlockMutex(player->error_mutex);
}