/*
 * This file is part of MPlayer.
 *
 * MPlayer is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * MPlayer 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with MPlayer; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

// Initial draft of my new cache system...
// Note it runs in 2 processes (using fork()), but doesn't require locking!!
// TODO: seeking, data consistency checking

#define READ_SLEEP_TIME 10
// These defines are used to reduce the cost of many successive
// seeks (e.g. when a file has no index) by spinning quickly at first.
#define INITIAL_FILL_USLEEP_TIME 1000
#define INITIAL_FILL_USLEEP_COUNT 10
#define FILL_USLEEP_TIME 50000
#define PREFILL_SLEEP_TIME 200
#define CONTROL_SLEEP_TIME 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>

#include <libavutil/common.h>

#include "config.h"

#include "osdep/shmem.h"
#include "osdep/timer.h"

#include "core/mp_msg.h"

#include "stream.h"
#include "core/mp_common.h"

// Note: (cache_vars_t*)(cache->priv)->cache == cache
typedef struct {
    stream_t *cache;    // wrapper stream, used by demuxer etc.
    stream_t *stream;   // "real" stream, used to read from the source media
    unsigned int cache_pid;
    // constats:
    unsigned char *buffer;    // base pointer of the allocated buffer memory
    int64_t buffer_size; // size of the allocated buffer memory
    int sector_size; // size of a single sector (2048/2324)
    int64_t back_size; // we should keep back_size amount of old bytes for backward seek
    int64_t fill_limit; // we should fill buffer only if space>=fill_limit
    int64_t seek_limit; // keep filling cache if distance is less that seek limit
    pid_t ppid; // parent PID to detect killed parent
    // filler's pointers:
    int eof;
    int64_t min_filepos; // buffer contain only a part of the file, from min-max pos
    int64_t max_filepos;
    int64_t offset;    // filepos <-> bufferpos  offset value (filepos of the buffer's first byte)
    // reader's pointers:
    int64_t read_filepos;
    // commands/locking:
//  int seek_lock;   // 1 if we will seek/reset buffer, 2 if we are ready for cmd
//  int fifo_flag;  // 1 if we should use FIFO to notice cache about buffer reads.
// callback
    volatile int control;
    volatile uint64_t control_uint_arg;
    volatile double control_double_arg;
    volatile struct stream_lang_req control_lang_arg;
    volatile struct stream_dvd_info_req control_dvd_info_arg;
    volatile int control_res;
    volatile double stream_time_length;
    volatile double stream_time_pos;
    volatile double stream_start_time;
    volatile int idle;
} cache_vars_t;

static void cache_wakeup(stream_t *stream)
{
    cache_vars_t *s = stream->priv;
    // signal process to wake up immediately
    kill(s->cache_pid, SIGUSR1);
}

// Runs in the forked process
static void cache_flush(cache_vars_t *s)
{
    s->offset = s->min_filepos = s->max_filepos = s->read_filepos; // drop cache content :(
}

// Runs in the main process
static int cache_read(cache_vars_t *s, unsigned char *buf, int size)
{
    int total = 0;
    int sleep_count = 0;
    int64_t last_max = s->max_filepos;
    while (size > 0) {
        int64_t pos, newb, len;

        //printf("CACHE2_READ: 0x%X <= 0x%X <= 0x%X  \n",s->min_filepos,s->read_filepos,s->max_filepos);

        if (s->read_filepos >= s->max_filepos || s->read_filepos <
            s->min_filepos) {
            // eof?
            if (s->eof)
                break;
            if (s->max_filepos == last_max) {
                if (sleep_count++ == 10)
                    mp_msg(MSGT_CACHE, MSGL_WARN, "Cache empty, consider "
                           "increasing -cache and/or -cache-min. "
                           "[performance issue]\n");
            } else {
                last_max = s->max_filepos;
                sleep_count = 0;
            }
            // waiting for buffer fill...
            if (stream_check_interrupt(READ_SLEEP_TIME)) {
                s->eof = 1;
                break;
            }
            continue; // try again...
        }
        sleep_count = 0;

        newb = s->max_filepos - s->read_filepos; // new bytes in the buffer

//    printf("*** newb: %d bytes ***\n",newb);

        pos = s->read_filepos - s->offset;
        if (pos < 0)
            pos += s->buffer_size;
        else if (pos >= s->buffer_size)
            pos -= s->buffer_size;

        if (newb > s->buffer_size - pos)
            newb = s->buffer_size - pos;                 // handle wrap...
        if (newb > size)
            newb = size;

        // check:
        if (s->read_filepos < s->min_filepos)
            mp_msg(MSGT_CACHE, MSGL_ERR,
                   "Ehh. s->read_filepos<s->min_filepos !!! Report bug...\n");

        // len=write(mem,newb)
        //printf("Buffer read: %d bytes\n",newb);
        memcpy(buf, &s->buffer[pos], newb);
        buf += newb;
        len = newb;
        // ...

        s->read_filepos += len;
        size -= len;
        total += len;

    }
    return total;
}

// Runs in the forked process
static int cache_fill(cache_vars_t *s)
{
    int64_t back, back2, newb, space, len, pos;
    int64_t read = s->read_filepos;
    int read_chunk;
    int wraparound_copy = 0;

    if (read < s->min_filepos || read > s->max_filepos) {
        // seek...
        mp_msg(MSGT_CACHE, MSGL_DBG2,
               "Out of boundaries... seeking to 0x%" PRIX64 "  \n", read);
        // drop cache contents only if seeking backward or too much fwd.
        // This is also done for on-disk files, since it loses the backseek cache.
        // That in turn can cause major bandwidth increase and performance
        // issues with e.g. mov or badly interleaved files
        if (read < s->min_filepos || read >= s->max_filepos + s->seek_limit) {
            cache_flush(s);
            if (s->stream->eof)
                stream_reset(s->stream);
            stream_seek_unbuffered(s->stream, read);
            mp_msg(MSGT_CACHE, MSGL_DBG2, "Seek done. new pos: 0x%" PRIX64 "  \n",
                   (int64_t)stream_tell(s->stream));
        }
    }

    // calc number of back-bytes:
    back = read - s->min_filepos;
    if (back < 0)
        back = 0;    // strange...
    if (back > s->back_size)
        back = s->back_size;

    // calc number of new bytes:
    newb = s->max_filepos - read;
    if (newb < 0)
        newb = 0;    // strange...

    // calc free buffer space:
    space = s->buffer_size - (newb + back);

    // calc bufferpos:
    pos = s->max_filepos - s->offset;
    if (pos >= s->buffer_size)
        pos -= s->buffer_size;                 // wrap-around

    if (space < s->fill_limit) {
//    printf("Buffer is full (%d bytes free, limit: %d)\n",space,s->fill_limit);
        return 0; // no fill...
    }

//  printf("### read=0x%X  back=%d  newb=%d  space=%d  pos=%d\n",read,back,newb,space,pos);

    // try to avoid wrap-around. If not possible due to sector size
    // do an extra copy.
    if (space > s->buffer_size - pos) {
        if (s->buffer_size - pos >= s->sector_size)
            space = s->buffer_size - pos;
        else {
            space = s->sector_size;
            wraparound_copy = 1;
        }
    }

    // limit one-time block size
    read_chunk = s->stream->read_chunk;
    if (!read_chunk)
        read_chunk = 4 * s->sector_size;
    space = FFMIN(space, read_chunk);

#if 1
    // back+newb+space <= buffer_size
    back2 = s->buffer_size - (space + newb); // max back size
    if (s->min_filepos < (read - back2))
        s->min_filepos = read - back2;
#else
    s->min_filepos = read - back; // avoid seeking-back to temp area...
#endif

    if (wraparound_copy) {
        int to_copy;
        len = stream_read_unbuffered(s->stream, s->stream->buffer, space);
        to_copy = FFMIN(len, s->buffer_size - pos);
        memcpy(s->buffer + pos, s->stream->buffer, to_copy);
        memcpy(s->buffer, s->stream->buffer + to_copy, len - to_copy);
    } else
        len = stream_read_unbuffered(s->stream, &s->buffer[pos], space);
    s->eof = !len;

    s->max_filepos += len;
    if (pos + len >= s->buffer_size)
        s->offset += s->buffer_size; // wrap...

    return len;

}

// Runs in the forked process
static int cache_execute_control(cache_vars_t *s)
{
    double double_res;
    unsigned uint_res;
    uint64_t uint64_res;
    int needs_flush = 0;
    static double last;
    int quit = s->control == -2;
    uint64_t old_pos = s->stream->pos;
    int old_eof = s->stream->eof;
    if (quit || !s->stream->control) {
        s->stream_time_length = 0;
        s->stream_time_pos = MP_NOPTS_VALUE;
        s->control_res = STREAM_UNSUPPORTED;
        s->control = -1;
        return !quit;
    }
    if (mp_time_sec() - last > 0.099) {
        double len, pos;
        if (s->stream->control(s->stream, STREAM_CTRL_GET_TIME_LENGTH,
                               &len) == STREAM_OK)
            s->stream_time_length = len;
        else
            s->stream_time_length = 0;
        if (s->stream->control(s->stream, STREAM_CTRL_GET_CURRENT_TIME,
                               &pos) == STREAM_OK)
            s->stream_time_pos = pos;
        else
            s->stream_time_pos = MP_NOPTS_VALUE;
        if (s->stream->control(s->stream, STREAM_CTRL_GET_START_TIME,
                               &pos) == STREAM_OK)
            s->stream_start_time = pos;
        else
            s->stream_start_time = MP_NOPTS_VALUE;
        // if parent PID changed, main process was killed -> exit
        if (s->ppid != getppid()) {
            mp_msg(MSGT_CACHE, MSGL_WARN,
                   "Parent process disappeared, exiting cache process.\n");
            return 0;
        }
        last = mp_time_sec();
    }
    if (s->control == -1)
        return 1;
    switch (s->control) {
    case STREAM_CTRL_SEEK_TO_TIME:
        needs_flush = 1;
    case STREAM_CTRL_GET_CURRENT_TIME:
    case STREAM_CTRL_GET_ASPECT_RATIO:
    case STREAM_CTRL_GET_START_TIME:
    case STREAM_CTRL_GET_CHAPTER_TIME:
        double_res = s->control_double_arg;
        s->control_res = s->stream->control(s->stream, s->control, &double_res);
        s->control_double_arg = double_res;
        break;
    case STREAM_CTRL_SEEK_TO_CHAPTER:
    case STREAM_CTRL_SET_ANGLE:
        needs_flush = 1;
        uint_res = s->control_uint_arg;
    case STREAM_CTRL_GET_NUM_TITLES:
    case STREAM_CTRL_GET_NUM_CHAPTERS:
    case STREAM_CTRL_GET_CURRENT_TITLE:
    case STREAM_CTRL_GET_CURRENT_CHAPTER:
    case STREAM_CTRL_GET_NUM_ANGLES:
    case STREAM_CTRL_GET_ANGLE:
        s->control_res = s->stream->control(s->stream, s->control, &uint_res);
        s->control_uint_arg = uint_res;
        break;
    case STREAM_CTRL_GET_SIZE:
        s->control_res = s->stream->control(s->stream, s->control, &uint64_res);
        s->control_uint_arg = uint64_res;
        break;
    case STREAM_CTRL_GET_LANG:
        s->control_res = s->stream->control(s->stream, s->control,
                                            (void *)&s->control_lang_arg);
        break;
    case STREAM_CTRL_GET_DVD_INFO:
        s->control_res = s->stream->control(s->stream, s->control,
                                            (void *)&s->control_dvd_info_arg);
        break;
    case STREAM_CTRL_MANAGES_TIMELINE:
        s->control_res = s->stream->control(s->stream, s->control, NULL);
        break;
    default:
        s->control_res = STREAM_UNSUPPORTED;
        break;
    }
    if (s->control_res == STREAM_OK && needs_flush) {
        s->read_filepos = s->stream->pos;
        s->eof = s->stream->eof;
        cache_flush(s);
    } else if (needs_flush &&
               (old_pos != s->stream->pos || old_eof != s->stream->eof))
        mp_msg(
            MSGT_STREAM, MSGL_ERR,
            "STREAM_CTRL changed stream pos but returned error, this is not allowed!\n");
    s->control = -1;
    return 1;
}

static void *shared_alloc(int64_t size)
{
    return shmem_alloc(size);
}

static void shared_free(void *ptr, int64_t size)
{
    shmem_free(ptr, size);
}

static cache_vars_t *cache_init(int64_t size, int sector)
{
    int64_t num;
    cache_vars_t *s = shared_alloc(sizeof(cache_vars_t));
    if (s == NULL)
        return NULL;

    memset(s, 0, sizeof(cache_vars_t));
    num = size / sector;
    if (num < 32)
        num = 32;
    //64kb min_size
    s->buffer_size = num * sector;
    s->sector_size = sector;
    s->buffer = shared_alloc(s->buffer_size);

    if (s->buffer == NULL) {
        shared_free(s, sizeof(cache_vars_t));
        return NULL;
    }

    s->fill_limit = 8 * sector;
    s->back_size = s->buffer_size / 2;
    s->ppid = getpid();
    return s;
}

static void cache_uninit(stream_t *s)
{
    cache_vars_t *c = s->priv;
    if (c->cache_pid) {
        kill(c->cache_pid, SIGKILL);
        waitpid(c->cache_pid, NULL, 0);
        c->cache_pid = 0;
    }
    if (!c)
        return;
    shared_free(c->buffer, c->buffer_size);
    c->buffer = NULL;
    c->stream = NULL;
    shared_free(c, sizeof(cache_vars_t));
    s->priv = NULL;
}

static void exit_sighandler(int x)
{
    // close stream
    exit(0);
}

static void dummy_sighandler(int x)
{
}

/**
 * Main loop of the cache process or thread.
 */
static void cache_mainloop(cache_vars_t *s)
{
    int sleep_count = 0;
    struct sigaction sa = {
        .sa_handler = SIG_IGN
    };
    sigaction(SIGUSR1, &sa, NULL);
    do {
        if (!cache_fill(s)) {
            s->idle = 1;
            // Let signal wake us up, we cannot leave this
            // enabled since we do not handle EINTR in most places.
            // This might need extra code to work on BSD.
            sa.sa_handler = dummy_sighandler;
            sigaction(SIGUSR1, &sa, NULL);
            if (sleep_count < INITIAL_FILL_USLEEP_COUNT) {
                sleep_count++;
                mp_sleep_us(INITIAL_FILL_USLEEP_TIME);
            } else
                mp_sleep_us(FILL_USLEEP_TIME);  // idle
            sa.sa_handler = SIG_IGN;
            sigaction(SIGUSR1, &sa, NULL);
        } else {
            sleep_count = 0;
            s->idle = 0;
        }
    } while (cache_execute_control(s));
}

static int cache_fill_buffer(struct stream *stream, char *buffer, int max_len)
{
    cache_vars_t *c = stream->priv;
    assert(c->cache_pid);

    if (stream->pos != c->read_filepos)
        mp_msg(MSGT_CACHE, MSGL_ERR,
               "!!! read_filepos differs!!! report this bug...\n");

    return cache_read(c, buffer, max_len);
}

static int cache_seek(stream_t *stream, int64_t pos)
{
    cache_vars_t *s = stream->priv;
    int64_t newpos;
    assert(s->cache_pid);

//  s->seek_lock=1;

    mp_msg(MSGT_CACHE, MSGL_DBG2, "CACHE2_SEEK: 0x%" PRIX64 " <= 0x%" PRIX64
           " (0x%" PRIX64 ") <= 0x%" PRIX64 "  \n",
           s->min_filepos, pos, s->read_filepos, s->max_filepos);

    newpos = pos / s->sector_size;
    newpos *= s->sector_size;                        // align
    stream->pos = s->read_filepos = newpos;
    s->eof = 0; // !!!!!!!
    cache_wakeup(stream);
    return 1;
}

static int cache_control(stream_t *stream, int cmd, void *arg)
{
    int sleep_count = 0;
    int pos_change = 0;
    cache_vars_t *s = stream->priv;
    switch (cmd) {
    case STREAM_CTRL_GET_CACHE_SIZE:
        *(int64_t *)arg = s->buffer_size;
        return STREAM_OK;
    case STREAM_CTRL_GET_CACHE_FILL:
        *(int64_t *)arg = s->max_filepos - s->read_filepos;
        return STREAM_OK;
    case STREAM_CTRL_GET_CACHE_IDLE:
        *(int *)arg = s->idle;
        return STREAM_OK;
    case STREAM_CTRL_SEEK_TO_TIME:
        s->control_double_arg = *(double *)arg;
        s->control = cmd;
        pos_change = 1;
        break;
    case STREAM_CTRL_SEEK_TO_CHAPTER:
    case STREAM_CTRL_SET_ANGLE:
        s->control_uint_arg = *(unsigned *)arg;
        s->control = cmd;
        pos_change = 1;
        break;
    // the core might call these every frame, so cache them...
    case STREAM_CTRL_GET_TIME_LENGTH:
        *(double *)arg = s->stream_time_length;
        return s->stream_time_length ? STREAM_OK : STREAM_UNSUPPORTED;
    case STREAM_CTRL_GET_CURRENT_TIME:
        *(double *)arg = s->stream_time_pos;
        return s->stream_time_pos !=
               MP_NOPTS_VALUE ? STREAM_OK : STREAM_UNSUPPORTED;
    case STREAM_CTRL_GET_START_TIME:
        *(double *)arg = s->stream_start_time;
        return s->stream_start_time !=
               MP_NOPTS_VALUE ? STREAM_OK : STREAM_UNSUPPORTED;
    case STREAM_CTRL_GET_CHAPTER_TIME:
        s->control_double_arg = *(double *)arg;
        s->control = cmd;
        break;
    case STREAM_CTRL_GET_LANG:
        s->control_lang_arg = *(struct stream_lang_req *)arg;
    case STREAM_CTRL_GET_DVD_INFO:
        s->control_dvd_info_arg = *(struct stream_dvd_info_req *)arg;
    case STREAM_CTRL_GET_NUM_TITLES:
    case STREAM_CTRL_GET_NUM_CHAPTERS:
    case STREAM_CTRL_GET_CURRENT_TITLE:
    case STREAM_CTRL_GET_CURRENT_CHAPTER:
    case STREAM_CTRL_GET_ASPECT_RATIO:
    case STREAM_CTRL_GET_NUM_ANGLES:
    case STREAM_CTRL_GET_ANGLE:
    case STREAM_CTRL_GET_SIZE:
    case STREAM_CTRL_MANAGES_TIMELINE:
    case -2:
        s->control = cmd;
        break;
    default:
        return STREAM_UNSUPPORTED;
    }
    cache_wakeup(stream);
    while (s->control != -1) {
        if (sleep_count++ == 1000)
            mp_msg(MSGT_CACHE, MSGL_WARN,
                   "Cache not responding! [performance issue]\n");
        if (stream_check_interrupt(CONTROL_SLEEP_TIME)) {
            s->eof = 1;
            return STREAM_UNSUPPORTED;
        }
    }
    if (s->control_res != STREAM_OK)
        return s->control_res;
    // We cannot do this on failure, since this would cause the
    // stream position to jump when e.g. STREAM_CTRL_SEEK_TO_TIME
    // is unsupported - but in that case we need the old value
    // to do the fallback seek.
    // This unfortunately can lead to slightly different behaviour
    // with and without cache if the protocol changes pos even
    // when an error happened.
    if (pos_change) {
        stream->pos = s->read_filepos;
        stream->eof = s->eof;
    }
    switch (cmd) {
    case STREAM_CTRL_GET_TIME_LENGTH:
    case STREAM_CTRL_GET_CURRENT_TIME:
    case STREAM_CTRL_GET_ASPECT_RATIO:
    case STREAM_CTRL_GET_START_TIME:
    case STREAM_CTRL_GET_CHAPTER_TIME:
        *(double *)arg = s->control_double_arg;
        break;
    case STREAM_CTRL_GET_NUM_TITLES:
    case STREAM_CTRL_GET_NUM_CHAPTERS:
    case STREAM_CTRL_GET_CURRENT_TITLE:
    case STREAM_CTRL_GET_CURRENT_CHAPTER:
    case STREAM_CTRL_GET_NUM_ANGLES:
    case STREAM_CTRL_GET_ANGLE:
        *(unsigned *)arg = s->control_uint_arg;
        break;
    case STREAM_CTRL_GET_SIZE:
        *(uint64_t *)arg = s->control_uint_arg;
        break;
    case STREAM_CTRL_GET_LANG:
        *(struct stream_lang_req *)arg = s->control_lang_arg;
        break;
    case STREAM_CTRL_GET_DVD_INFO:
        *(struct stream_dvd_info_req *)arg = s->control_dvd_info_arg;
        break;
    case STREAM_CTRL_MANAGES_TIMELINE:
        break;
    }
    return s->control_res;
}

// return 1 on success, 0 if the function was interrupted and -1 on error, or
// if the cache is disabled
int stream_cache_init(stream_t *cache, stream_t *stream, int64_t size,
                      int64_t min, int64_t seek_limit)
{
    if (size < 0)
        size = stream->cache_size * 1024;
    if (!size)
        return -1;
    mp_tmsg(MSGT_NETWORK, MSGL_INFO, "Cache size set to %" PRId64 " KiB\n",
            size / 1024);

    int ss = stream->sector_size ? stream->sector_size : STREAM_BUFFER_SIZE;
    cache_vars_t *s;

    if (size > SIZE_MAX) {
        mp_msg(MSGT_CACHE, MSGL_FATAL,
               "Cache size larger than max. allocation size\n");
        return -1;
    }

    s = cache_init(size, ss);
    if (s == NULL)
        return -1;
    cache->priv = s;
    s->cache = cache;
    s->stream = stream; // callback
    s->seek_limit = seek_limit;

    cache->seek = cache_seek;
    cache->fill_buffer = cache_fill_buffer;
    cache->control = cache_control;
    cache->close = cache_uninit;

    //make sure that we won't wait from cache_fill
    //more data than it is allowed to fill
    if (s->seek_limit > s->buffer_size - s->fill_limit)
        s->seek_limit = s->buffer_size - s->fill_limit;
    if (min > s->buffer_size - s->fill_limit)
        min = s->buffer_size - s->fill_limit;
    // to make sure we wait for the cache process/thread to be active
    // before continuing
    if (min <= 0)
        min = 1;

    pid_t child_pid = fork();
    if (child_pid) {
        if (child_pid == (pid_t)-1)
            child_pid = 0;
        if (!child_pid) {
            mp_msg(MSGT_CACHE, MSGL_ERR,
                   "Starting cache process/thread failed: %s.\n",
                   strerror(errno));
            return -1;
        }
        s->cache_pid = child_pid;
        // wait until cache is filled at least prefill_init %
        mp_msg(MSGT_CACHE, MSGL_V, "CACHE_PRE_INIT: %" PRId64 " [%" PRId64 "] "
               "%" PRId64 "  pre:%" PRId64 "  eof:%d  \n",
               s->min_filepos, s->read_filepos, s->max_filepos, min, s->eof);
        while (s->read_filepos < s->min_filepos ||
               s->max_filepos - s->read_filepos < min)
        {
            mp_tmsg(MSGT_CACHE, MSGL_STATUS, "\rCache fill: %5.2f%% "
                    "(%" PRId64 " bytes)   ",
                    100.0 * (float)(s->max_filepos - s->read_filepos) /
                        (float)(s->buffer_size),
                    s->max_filepos - s->read_filepos);
            if (s->eof)
                break;    // file is smaller than prefill size
            if (stream_check_interrupt(PREFILL_SLEEP_TIME))
                return 0;
        }
        mp_msg(MSGT_CACHE, MSGL_STATUS, "\n");
        return 1; // parent exits
    }

    signal(SIGTERM, exit_sighandler); // kill
    cache_mainloop(s);
    // make sure forked code never leaves this function
    exit(0);
}