/*
 * This file is part of mpv.
 *
 * mpv 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.
 *
 * mpv 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 mpv.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <strings.h>

#include "common/common.h"
#include "options/options.h"
#include "common/msg.h"
#include "common/playlist.h"
#include "options/path.h"
#include "stream/stream.h"
#include "demux.h"

#define PROBE_SIZE (8 * 1024)

static bool check_mimetype(struct stream *s, const char *const *list)
{
    if (s->mime_type) {
        for (int n = 0; list && list[n]; n++) {
            if (strcmp(s->mime_type, list[n]) == 0)
                return true;
        }
    }
    return false;
}

struct pl_parser {
    struct mp_log *log;
    struct stream *s;
    char buffer[8 * 1024];
    int utf16;
    struct playlist *pl;
    bool error;
    bool probing;
    bool force;
    enum demux_check check_level;
    struct stream *real_stream;
};

static char *pl_get_line0(struct pl_parser *p)
{
    char *res = stream_read_line(p->s, p->buffer, sizeof(p->buffer), p->utf16);
    if (res) {
        int len = strlen(res);
        if (len > 0 && res[len - 1] == '\n')
            res[len - 1] = '\0';
    } else {
        p->error |= !p->s->eof;
    }
    return res;
}

static bstr pl_get_line(struct pl_parser *p)
{
    return bstr0(pl_get_line0(p));
}

static void pl_add(struct pl_parser *p, bstr entry)
{
    char *s = bstrto0(NULL, entry);
    playlist_add_file(p->pl, s);
    talloc_free(s);
}

static bool pl_eof(struct pl_parser *p)
{
    return p->error || p->s->eof;
}

static bool maybe_text(bstr d)
{
    for (int n = 0; n < d.len; n++) {
        unsigned char c = d.start[n];
        if (c < 32 && c != '\n' && c != '\r' && c != '\t')
            return false;
    }
    return true;
}

static int parse_m3u(struct pl_parser *p)
{
    bstr line = bstr_strip(pl_get_line(p));
    if (p->probing && !bstr_equals0(line, "#EXTM3U")) {
        // Last resort: if the file extension is m3u, it might be headerless.
        if (p->check_level == DEMUX_CHECK_UNSAFE) {
            char *ext = mp_splitext(p->real_stream->url, NULL);
            bstr data = stream_peek(p->real_stream, PROBE_SIZE);
            if (ext && !strcmp(ext, "m3u") && data.len > 10 && maybe_text(data))
                goto ok;
        }
        return -1;
    }
ok:
    if (p->probing)
        return 0;
    while (line.len || !pl_eof(p)) {
        if (line.len > 0 && !bstr_startswith0(line, "#"))
            pl_add(p, line);
        line = bstr_strip(pl_get_line(p));
    }
    return 0;
}

static int parse_ref_init(struct pl_parser *p)
{
    bstr line = bstr_strip(pl_get_line(p));
    if (!bstr_equals0(line, "[Reference]"))
        return -1;

    // ASF http streaming redirection - this is needed because ffmpeg http://
    // and mmsh:// can not automatically switch automatically between each
    // others. Both protocols use http - MMSH requires special http headers
    // to "activate" it, and will in other cases return this playlist.
    static const char *const mmsh_types[] = {"audio/x-ms-wax",
        "audio/x-ms-wma", "video/x-ms-asf", "video/x-ms-afs", "video/x-ms-wmv",
        "video/x-ms-wma", "application/x-mms-framed",
        "application/vnd.ms.wms-hdr.asfv1", NULL};
    bstr burl = bstr0(p->s->url);
    if (bstr_eatstart0(&burl, "http://") && check_mimetype(p->s, mmsh_types)) {
        MP_INFO(p, "Redirecting to mmsh://\n");
        playlist_add_file(p->pl, talloc_asprintf(p, "mmsh://%.*s", BSTR_P(burl)));
        return 0;
    }

    while (!pl_eof(p)) {
        line = bstr_strip(pl_get_line(p));
        if (bstr_case_startswith(line, bstr0("Ref"))) {
            bstr_split_tok(line, "=", &(bstr){0}, &line);
            if (line.len)
                pl_add(p, line);
        }
    }
    return 0;
}

static int parse_mov_rtsptext(struct pl_parser *p)
{
    bstr line = pl_get_line(p);
    if (!bstr_eatstart(&line, bstr0("RTSPtext")))
        return -1;
    if (p->probing)
        return 0;
    line = bstr_strip(line);
    do {
        if (bstr_case_startswith(line, bstr0("rtsp://"))) {
            pl_add(p, line);
            return 0;
        }
    } while (!pl_eof(p) && (line = bstr_strip(pl_get_line(p))).len);
    return -1;
}

static int parse_pls(struct pl_parser *p)
{
    bstr line = {0};
    while (!line.len && !pl_eof(p))
        line = bstr_strip(pl_get_line(p));
    if (bstrcasecmp0(line, "[playlist]") != 0)
        return -1;
    if (p->probing)
        return 0;
    while (!pl_eof(p)) {
        line = bstr_strip(pl_get_line(p));
        bstr key, value;
        if (bstr_split_tok(line, "=", &key, &value) &&
            bstr_case_startswith(key, bstr0("File")))
        {
            value = bstr_strip(value);
            if (bstr_startswith0(value, "\"") && bstr_endswith0(value, "\""))
                value = bstr_splice(value, 1, -1);
            pl_add(p, value);
        }
    }
    return 0;
}

static int parse_txt(struct pl_parser *p)
{
    if (!p->force)
        return -1;
    if (p->probing)
        return 0;
    MP_WARN(p, "Reading plaintext playlist.\n");
    while (!pl_eof(p)) {
        bstr line = bstr_strip(pl_get_line(p));
        if (line.len == 0)
            continue;
        pl_add(p, line);
    }
    return 0;
}

#define MIME_TYPES(...) \
    .mime_types = (const char*const[]){__VA_ARGS__, NULL}

struct pl_format {
    const char *name;
    int (*parse)(struct pl_parser *p);
    const char *const *mime_types;
};

static const struct pl_format formats[] = {
    {"m3u", parse_m3u,
     MIME_TYPES("audio/mpegurl", "audio/x-mpegurl", "application/x-mpegurl")},
    {"ini", parse_ref_init},
    {"mov", parse_mov_rtsptext},
    {"pls", parse_pls,
     MIME_TYPES("audio/x-scpls")},
    {"txt", parse_txt},
};

static const struct pl_format *probe_pl(struct pl_parser *p)
{
    int64_t start = stream_tell(p->s);
    for (int n = 0; n < MP_ARRAY_SIZE(formats); n++) {
        const struct pl_format *fmt = &formats[n];
        stream_seek(p->s, start);
        if (check_mimetype(p->s, fmt->mime_types)) {
            MP_VERBOSE(p, "forcing format by mime-type.\n");
            p->force = true;
            return fmt;
        }
        if (fmt->parse(p) >= 0)
            return fmt;
    }
    return NULL;
}

static int open_file(struct demuxer *demuxer, enum demux_check check)
{
    bool force = check < DEMUX_CHECK_UNSAFE || check == DEMUX_CHECK_REQUEST;

    struct pl_parser *p = talloc_zero(NULL, struct pl_parser);
    p->log = demuxer->log;
    p->pl = talloc_zero(p, struct playlist);
    p->real_stream = demuxer->stream;

    bstr probe_buf = stream_peek(demuxer->stream, PROBE_SIZE);
    p->s = open_memory_stream(probe_buf.start, probe_buf.len);
    p->s->mime_type = demuxer->stream->mime_type;
    p->utf16 = stream_skip_bom(p->s);
    p->force = force;
    p->check_level = check;
    p->probing = true;
    const struct pl_format *fmt = probe_pl(p);
    free_stream(p->s);
    playlist_clear(p->pl);
    if (!fmt) {
        talloc_free(p);
        return -1;
    }

    p->probing = false;
    p->error = false;
    p->s = demuxer->stream;
    p->utf16 = stream_skip_bom(p->s);
    bool ok = fmt->parse(p) >= 0 && !p->error;
    if (ok)
        playlist_add_base_path(p->pl, mp_dirname(demuxer->filename));
    demuxer->playlist = talloc_steal(demuxer, p->pl);
    demuxer->filetype = fmt->name;
    talloc_free(p);
    return ok ? 0 : -1;
}

const struct demuxer_desc demuxer_desc_playlist = {
    .name = "playlist",
    .desc = "Playlist file",
    .open = open_file,
};