/*
 * Copyright (c) 2013 Nicolas George
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libavutil/avassert.h"
#include "avfilter.h"
#include "bufferqueue.h"
#include "framesync.h"
#include "internal.h"

#define OFFSET(member) offsetof(FFFrameSync, member)

static const char *framesync_name(void *ptr)
{
    return "framesync";
}

static const AVClass framesync_class = {
    .version                   = LIBAVUTIL_VERSION_INT,
    .class_name                = "framesync",
    .item_name                 = framesync_name,
    .category                  = AV_CLASS_CATEGORY_FILTER,
    .option                    = NULL,
    .parent_log_context_offset = OFFSET(parent),
};

enum {
    STATE_BOF,
    STATE_RUN,
    STATE_EOF,
};

void ff_framesync_init(FFFrameSync *fs, void *parent, unsigned nb_in)
{
    fs->class  = &framesync_class;
    fs->parent = parent;
    fs->nb_in  = nb_in;
}

static void framesync_sync_level_update(FFFrameSync *fs)
{
    unsigned i, level = 0;

    for (i = 0; i < fs->nb_in; i++)
        if (fs->in[i].state != STATE_EOF)
            level = FFMAX(level, fs->in[i].sync);
    av_assert0(level <= fs->sync_level);
    if (level < fs->sync_level)
        av_log(fs, AV_LOG_VERBOSE, "Sync level %u\n", level);
    if (level)
        fs->sync_level = level;
    else
        fs->eof = 1;
}

int ff_framesync_configure(FFFrameSync *fs)
{
    unsigned i;
    int64_t gcd, lcm;

    if (!fs->time_base.num) {
        for (i = 0; i < fs->nb_in; i++) {
            if (fs->in[i].sync) {
                if (fs->time_base.num) {
                    gcd = av_gcd(fs->time_base.den, fs->in[i].time_base.den);
                    lcm = (fs->time_base.den / gcd) * fs->in[i].time_base.den;
                    if (lcm < AV_TIME_BASE / 2) {
                        fs->time_base.den = lcm;
                        fs->time_base.num = av_gcd(fs->time_base.num,
                                                   fs->in[i].time_base.num);
                    } else {
                        fs->time_base.num = 1;
                        fs->time_base.den = AV_TIME_BASE;
                        break;
                    }
                } else {
                    fs->time_base = fs->in[i].time_base;
                }
            }
        }
        if (!fs->time_base.num) {
            av_log(fs, AV_LOG_ERROR, "Impossible to set time base\n");
            return AVERROR(EINVAL);
        }
        av_log(fs, AV_LOG_VERBOSE, "Selected %d/%d time base\n",
               fs->time_base.num, fs->time_base.den);
    }

    for (i = 0; i < fs->nb_in; i++)
        fs->in[i].pts = fs->in[i].pts_next = AV_NOPTS_VALUE;
    fs->sync_level = UINT_MAX;
    framesync_sync_level_update(fs);

    return 0;
}

static void framesync_advance(FFFrameSync *fs)
{
    int latest;
    unsigned i;
    int64_t pts;

    if (fs->eof)
        return;
    while (!fs->frame_ready) {
        latest = -1;
        for (i = 0; i < fs->nb_in; i++) {
            if (!fs->in[i].have_next) {
                if (latest < 0 || fs->in[i].pts < fs->in[latest].pts)
                    latest = i;
            }
        }
        if (latest >= 0) {
            fs->in_request = latest;
            break;
        }

        pts = fs->in[0].pts_next;
        for (i = 1; i < fs->nb_in; i++)
            if (fs->in[i].pts_next < pts)
                pts = fs->in[i].pts_next;
        if (pts == INT64_MAX) {
            fs->eof = 1;
            break;
        }
        for (i = 0; i < fs->nb_in; i++) {
            if (fs->in[i].pts_next == pts ||
                (fs->in[i].before == EXT_INFINITY &&
                 fs->in[i].state == STATE_BOF)) {
                av_frame_free(&fs->in[i].frame);
                fs->in[i].frame      = fs->in[i].frame_next;
                fs->in[i].pts        = fs->in[i].pts_next;
                fs->in[i].frame_next = NULL;
                fs->in[i].pts_next   = AV_NOPTS_VALUE;
                fs->in[i].have_next  = 0;
                fs->in[i].state      = fs->in[i].frame ? STATE_RUN : STATE_EOF;
                if (fs->in[i].sync == fs->sync_level && fs->in[i].frame)
                    fs->frame_ready = 1;
                if (fs->in[i].state == STATE_EOF &&
                    fs->in[i].after == EXT_STOP)
                    fs->eof = 1;
            }
        }
        if (fs->eof)
            fs->frame_ready = 0;
        if (fs->frame_ready)
            for (i = 0; i < fs->nb_in; i++)
                if ((fs->in[i].state == STATE_BOF &&
                     fs->in[i].before == EXT_STOP))
                    fs->frame_ready = 0;
        fs->pts = pts;
    }
}

static int64_t framesync_pts_extrapolate(FFFrameSync *fs, unsigned in,
                                         int64_t pts)
{
    /* Possible enhancement: use the link's frame rate */
    return pts + 1;
}

static void framesync_inject_frame(FFFrameSync *fs, unsigned in, AVFrame *frame)
{
    int64_t pts;

    av_assert0(!fs->in[in].have_next);
    if (frame) {
        pts = av_rescale_q(frame->pts, fs->in[in].time_base, fs->time_base);
        frame->pts = pts;
    } else {
        pts = fs->in[in].state != STATE_RUN || fs->in[in].after == EXT_INFINITY
            ? INT64_MAX : framesync_pts_extrapolate(fs, in, fs->in[in].pts);
        fs->in[in].sync = 0;
        framesync_sync_level_update(fs);
    }
    fs->in[in].frame_next = frame;
    fs->in[in].pts_next   = pts;
    fs->in[in].have_next  = 1;
}

int ff_framesync_add_frame(FFFrameSync *fs, unsigned in, AVFrame *frame)
{
    av_assert1(in < fs->nb_in);
    if (!fs->in[in].have_next)
        framesync_inject_frame(fs, in, frame);
    else
        ff_bufqueue_add(fs, &fs->in[in].queue, frame);
    return 0;
}

void ff_framesync_next(FFFrameSync *fs)
{
    unsigned i;

    av_assert0(!fs->frame_ready);
    for (i = 0; i < fs->nb_in; i++)
        if (!fs->in[i].have_next && fs->in[i].queue.available)
            framesync_inject_frame(fs, i, ff_bufqueue_get(&fs->in[i].queue));
    fs->frame_ready = 0;
    framesync_advance(fs);
}

void ff_framesync_drop(FFFrameSync *fs)
{
    fs->frame_ready = 0;
}

int ff_framesync_get_frame(FFFrameSync *fs, unsigned in, AVFrame **rframe,
                           unsigned get)
{
    AVFrame *frame;
    unsigned need_copy = 0, i;
    int64_t pts_next;
    int ret;

    if (!fs->in[in].frame) {
        *rframe = NULL;
        return 0;
    }
    frame = fs->in[in].frame;
    if (get) {
        /* Find out if we need to copy the frame: is there another sync
           stream, and do we know if its current frame will outlast this one? */
        pts_next = fs->in[in].have_next ? fs->in[in].pts_next : INT64_MAX;
        for (i = 0; i < fs->nb_in && !need_copy; i++)
            if (i != in && fs->in[i].sync &&
                (!fs->in[i].have_next || fs->in[i].pts_next < pts_next))
                need_copy = 1;
        if (need_copy) {
            if (!(frame = av_frame_clone(frame)))
                return AVERROR(ENOMEM);
            if ((ret = av_frame_make_writable(frame)) < 0) {
                av_frame_free(&frame);
                return ret;
            }
        } else {
            fs->in[in].frame = NULL;
        }
        fs->frame_ready = 0;
    }
    *rframe = frame;
    return 0;
}

void ff_framesync_uninit(FFFrameSync *fs)
{
    unsigned i;

    for (i = 0; i < fs->nb_in; i++) {
        av_frame_free(&fs->in[i].frame);
        av_frame_free(&fs->in[i].frame_next);
        ff_bufqueue_discard_all(&fs->in[i].queue);
    }
}

int ff_framesync_process_frame(FFFrameSync *fs, unsigned all)
{
    int ret, count = 0;

    av_assert0(fs->on_event);
    while (1) {
        ff_framesync_next(fs);
        if (fs->eof || !fs->frame_ready)
            break;
        if ((ret = fs->on_event(fs)) < 0)
            return ret;
        ff_framesync_drop(fs);
        count++;
        if (!all)
            break;
    }
    if (!count && fs->eof)
        return AVERROR_EOF;
    return count;
}

int ff_framesync_filter_frame(FFFrameSync *fs, AVFilterLink *inlink,
                              AVFrame *in)
{
    int ret;

    if ((ret = ff_framesync_process_frame(fs, 1)) < 0)
        return ret;
    if ((ret = ff_framesync_add_frame(fs, FF_INLINK_IDX(inlink), in)) < 0)
        return ret;
    if ((ret = ff_framesync_process_frame(fs, 0)) < 0)
        return ret;
    return 0;
}

int ff_framesync_request_frame(FFFrameSync *fs, AVFilterLink *outlink)
{
    AVFilterContext *ctx = outlink->src;
    int input, ret;

    if ((ret = ff_framesync_process_frame(fs, 0)) < 0)
        return ret;
    if (ret > 0)
        return 0;
    if (fs->eof)
        return AVERROR_EOF;
    outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
    input = fs->in_request;
    ret = ff_request_frame(ctx->inputs[input]);
    if (ret == AVERROR_EOF) {
        if ((ret = ff_framesync_add_frame(fs, input, NULL)) < 0)
            return ret;
        if ((ret = ff_framesync_process_frame(fs, 0)) < 0)
            return ret;
        ret = 0;
    }
    return ret;
}