/*

 * 3GPP TS 26.245 Timed Text decoder

 * Copyright (c) 2012  Philip Langdale <philipl@overt.org>

 *

 * 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 "avcodec.h"

#include "ass.h"

#include "libavutil/opt.h"

#include "libavutil/avstring.h"

#include "libavutil/common.h"

#include "libavutil/bprint.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/mem.h"

#include "bytestream.h"

#include "codec_internal.h"

#define STYLE_FLAG_BOLD         (1<<0)

#define STYLE_FLAG_ITALIC       (1<<1)

#define STYLE_FLAG_UNDERLINE    (1<<2)

#define BOX_SIZE_INITIAL    40

#define STYL_BOX   (1<<0)

#define HLIT_BOX   (1<<1)

#define HCLR_BOX   (1<<2)

#define TWRP_BOX   (1<<3)

#define BOTTOM_LEFT     1

#define BOTTOM_CENTER   2

#define BOTTOM_RIGHT    3

#define MIDDLE_LEFT     4

#define MIDDLE_CENTER   5

#define MIDDLE_RIGHT    6

#define TOP_LEFT        7

#define TOP_CENTER      8

#define TOP_RIGHT       9

#define RGB_TO_BGR(c) (((c) & 0xff) << 16 | ((c) & 0xff00) | (((c) >> 16) & 0xff))

typedef struct {

    uint16_t font_id;

    char *font;

} FontRecord;

typedef struct {

    uint16_t start;

    uint16_t end;

    uint8_t flags;

    uint8_t bold;

    uint8_t italic;

    uint8_t underline;

    int color;

    uint8_t alpha;

    uint8_t fontsize;

    uint16_t font_id;

} StyleBox;

typedef struct {

    StyleBox style;

    const char *font;

    int back_color;

    uint8_t back_alpha;

    int alignment;

} MovTextDefault;

typedef struct {

    uint16_t hlit_start;

    uint16_t hlit_end;

} HighlightBox;

typedef struct {

   uint8_t hlit_color[4];

} HilightcolorBox;

typedef struct {

    uint8_t wrap_flag;

} TextWrapBox;

typedef struct {

    AVClass *class;

    StyleBox *s;

    HighlightBox h;

    HilightcolorBox c;

    FontRecord *ftab;

    TextWrapBox w;

    MovTextDefault d;

    uint8_t box_flags;

    uint16_t style_entries, ftab_entries;

    int readorder;

    int frame_width;

    int frame_height;

} MovTextContext;

typedef struct {

    uint32_t type;

    unsigned base_size;

    int (*decode)(const uint8_t *tsmb, MovTextContext *m, uint64_t size);

} Box;

static void mov_text_cleanup(MovTextContext *m)

{

    if (m->box_flags & STYL_BOX) {

        av_freep(&m->s);

        m->style_entries = 0;

    }

}

static void mov_text_cleanup_ftab(MovTextContext *m)

{

    for (unsigned i = 0; i < m->ftab_entries; i++)

        av_freep(&m->ftab[i].font);

    av_freep(&m->ftab);

    m->ftab_entries = 0;

}

static void mov_text_parse_style_record(StyleBox *style, const uint8_t **ptr)

{

    // fontID

    style->font_id   = bytestream_get_be16(ptr);

    // face-style-flags

    style->flags     = bytestream_get_byte(ptr);

    style->bold      = !!(style->flags & STYLE_FLAG_BOLD);

    style->italic    = !!(style->flags & STYLE_FLAG_ITALIC);

    style->underline = !!(style->flags & STYLE_FLAG_UNDERLINE);

    // fontsize

    style->fontsize  = bytestream_get_byte(ptr);

    // Primary color

    style->color     = bytestream_get_be24(ptr);

    style->color     = RGB_TO_BGR(style->color);

    style->alpha     = bytestream_get_byte(ptr);

}

static int mov_text_tx3g(AVCodecContext *avctx, MovTextContext *m)

{

    const uint8_t *tx3g_ptr = avctx->extradata;

    int i, j = -1, font_length, remaining = avctx->extradata_size - BOX_SIZE_INITIAL;

    int8_t v_align, h_align;

    unsigned ftab_entries;

    m->ftab_entries = 0;

    if (remaining < 0)

        return -1;

    // Display Flags

    tx3g_ptr += 4;

    // Alignment

    h_align = bytestream_get_byte(&tx3g_ptr);

    v_align = bytestream_get_byte(&tx3g_ptr);

    if (h_align == 0) {

        if (v_align == 0)

            m->d.alignment = TOP_LEFT;

        if (v_align == 1)

            m->d.alignment = MIDDLE_LEFT;

        if (v_align == -1)

            m->d.alignment = BOTTOM_LEFT;

    }

    if (h_align == 1) {

        if (v_align == 0)

            m->d.alignment = TOP_CENTER;

        if (v_align == 1)

            m->d.alignment = MIDDLE_CENTER;

        if (v_align == -1)

            m->d.alignment = BOTTOM_CENTER;

    }

    if (h_align == -1) {

        if (v_align == 0)

            m->d.alignment = TOP_RIGHT;

        if (v_align == 1)

            m->d.alignment = MIDDLE_RIGHT;

        if (v_align == -1)

            m->d.alignment = BOTTOM_RIGHT;

    }

    // Background Color

    m->d.back_color = bytestream_get_be24(&tx3g_ptr);

    m->d.back_color = RGB_TO_BGR(m->d.back_color);

    m->d.back_alpha = bytestream_get_byte(&tx3g_ptr);

    // BoxRecord

    tx3g_ptr += 8;

    // StyleRecord

    tx3g_ptr += 4;

    mov_text_parse_style_record(&m->d.style, &tx3g_ptr);

    // FontRecord

    // FontRecord Size

    tx3g_ptr += 4;

    // ftab

    tx3g_ptr += 4;

    // In case of broken header, init default font

    m->d.font = ASS_DEFAULT_FONT;

    ftab_entries = bytestream_get_be16(&tx3g_ptr);

    if (!ftab_entries)

        return 0;

    remaining   -= 3 * ftab_entries;

    if (remaining < 0)

        return AVERROR_INVALIDDATA;

    m->ftab = av_calloc(ftab_entries, sizeof(*m->ftab));

    if (!m->ftab)

        return AVERROR(ENOMEM);

    m->ftab_entries = ftab_entries;

    for (i = 0; i < m->ftab_entries; i++) {

        m->ftab[i].font_id = bytestream_get_be16(&tx3g_ptr);

        if (m->ftab[i].font_id == m->d.style.font_id)

            j = i;

        font_length = bytestream_get_byte(&tx3g_ptr);

        remaining  -= font_length;

        if (remaining < 0) {

            mov_text_cleanup_ftab(m);

            return -1;

        }

        m->ftab[i].font = av_malloc(font_length + 1);

        if (!m->ftab[i].font) {

            mov_text_cleanup_ftab(m);

            return AVERROR(ENOMEM);

        }

        bytestream_get_buffer(&tx3g_ptr, m->ftab[i].font, font_length);

        m->ftab[i].font[font_length] = '\0';

    }

    if (j >= 0)

        m->d.font = m->ftab[j].font;

    return 0;

}

static int decode_twrp(const uint8_t *tsmb, MovTextContext *m, uint64_t size)

{

    m->box_flags |= TWRP_BOX;

    m->w.wrap_flag = bytestream_get_byte(&tsmb);

    return 0;

}

static int decode_hlit(const uint8_t *tsmb, MovTextContext *m, uint64_t size)

{

    m->box_flags |= HLIT_BOX;

    m->h.hlit_start = bytestream_get_be16(&tsmb);

    m->h.hlit_end   = bytestream_get_be16(&tsmb);

    return 0;

}

static int decode_hclr(const uint8_t *tsmb, MovTextContext *m, uint64_t size)

{

    m->box_flags |= HCLR_BOX;

    bytestream_get_buffer(&tsmb, m->c.hlit_color, 4);

    return 0;

}

static int styles_equivalent(const StyleBox *a, const StyleBox *b)

{

#define CMP(field) ((a)->field == (b)->field)

    return CMP(bold)  && CMP(italic)   && CMP(underline) && CMP(color) &&

           CMP(alpha) && CMP(fontsize) && CMP(font_id);

#undef CMP

}

static int decode_styl(const uint8_t *tsmb, MovTextContext *m, uint64_t size)

{

    int i;

    int style_entries = bytestream_get_be16(&tsmb);

    StyleBox *tmp;

    // A single style record is of length 12 bytes.

    if (2 + style_entries * 12 > size)

        return -1;

    tmp = av_realloc_array(m->s, style_entries, sizeof(*m->s));

    if (!tmp)

        return AVERROR(ENOMEM);

    m->s             = tmp;

    m->style_entries = style_entries;

    m->box_flags |= STYL_BOX;

    for(i = 0; i < m->style_entries; i++) {

        StyleBox *style = &m->s[i];

        style->start = bytestream_get_be16(&tsmb);

        style->end   = bytestream_get_be16(&tsmb);

        if (style->end < style->start ||

            (i && style->start < m->s[i - 1].end)) {

            mov_text_cleanup(m);

            return AVERROR_INVALIDDATA;

        }

        if (style->start == style->end) {

            /* Skip this style as it applies to no character */

            tsmb += 8;

            m->style_entries--;

            i--;

            continue;

        }

        mov_text_parse_style_record(style, &tsmb);

        if (styles_equivalent(style, &m->d.style)) {

            /* Skip this style as it is equivalent to the default style */

            m->style_entries--;

            i--;

            continue;

        } else if (i && style->start == style[-1].end &&

                   styles_equivalent(style, &style[-1])) {

            /* Merge the two adjacent styles */

            style[-1].end = style->end;

            m->style_entries--;

            i--;

            continue;

        }

    }

    return 0;

}

static const Box box_types[] = {

    { MKBETAG('s','t','y','l'), 2, decode_styl },

    { MKBETAG('h','l','i','t'), 4, decode_hlit },

    { MKBETAG('h','c','l','r'), 4, decode_hclr },

    { MKBETAG('t','w','r','p'), 1, decode_twrp }

};

const static size_t box_count = FF_ARRAY_ELEMS(box_types);

// Return byte length of the UTF-8 sequence starting at text[0]. 0 on error.

static int get_utf8_length_at(const char *text, const char *text_end)

{

    const char *start = text;

    int err = 0;

    uint32_t c;

    GET_UTF8(c, text < text_end ? (uint8_t)*text++ : (err = 1, 0), goto error;);

    if (err)

        goto error;

    return text - start;

error:

    return 0;

}

static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end,

                       AVCodecContext *avctx)

{

    MovTextContext *m = avctx->priv_data;

    const StyleBox *const default_style = &m->d.style;

    int i = 0;

    int text_pos = 0;

    int entry = 0;

    int color = default_style->color;

    if (text < text_end && m->box_flags & TWRP_BOX) {

        if (m->w.wrap_flag == 1) {

            av_bprintf(buf, "{\\q1}"); /* End of line wrap */

        } else {

            av_bprintf(buf, "{\\q2}"); /* No wrap */

        }

    }

    while (text < text_end) {

        int len;

        if ((m->box_flags & STYL_BOX) && entry < m->style_entries) {

            const StyleBox *style = &m->s[entry];

            if (text_pos == style->end) {

                av_bprintf(buf, "{\\r}");

                color = default_style->color;

                entry++;

                style++;

            }

            if (entry < m->style_entries && text_pos == style->start) {

                if (style->bold ^ default_style->bold)

                    av_bprintf(buf, "{\\b%d}", style->bold);

                if (style->italic ^ default_style->italic)

                    av_bprintf(buf, "{\\i%d}", style->italic);

                if (style->underline ^ default_style->underline)

                    av_bprintf(buf, "{\\u%d}", style->underline);

                if (style->fontsize != default_style->fontsize)

                    av_bprintf(buf, "{\\fs%d}", style->fontsize);

                if (style->font_id != default_style->font_id)

                    for (i = 0; i < m->ftab_entries; i++) {

                        if (style->font_id == m->ftab[i].font_id)

                            av_bprintf(buf, "{\\fn%s}", m->ftab[i].font);

                    }

                if (default_style->color != style->color) {

                    color = style->color;

                    av_bprintf(buf, "{\\1c&H%X&}", color);

                }

                if (default_style->alpha != style->alpha)

                    av_bprintf(buf, "{\\1a&H%02X&}", 255 - style->alpha);

            }

        }

        if (m->box_flags & HLIT_BOX) {

            if (text_pos == m->h.hlit_start) {

                /* If hclr box is present, set the secondary color to the color

                 * specified. Otherwise, set primary color to white and secondary

                 * color to black. These colors will come from TextSampleModifier

                 * boxes in future and inverse video technique for highlight will

                 * be implemented.

                 */

                if (m->box_flags & HCLR_BOX) {

                    av_bprintf(buf, "{\\2c&H%02x%02x%02x&}", m->c.hlit_color[2],

                                m->c.hlit_color[1], m->c.hlit_color[0]);

                } else {

                    av_bprintf(buf, "{\\1c&H000000&}{\\2c&HFFFFFF&}");

                }

            }

            if (text_pos == m->h.hlit_end) {

                if (m->box_flags & HCLR_BOX) {

                    av_bprintf(buf, "{\\2c&H%X&}", default_style->color);

                } else {

                    av_bprintf(buf, "{\\1c&H%X&}{\\2c&H%X&}",

                               color, default_style->color);

                }

            }

        }

        len = get_utf8_length_at(text, text_end);

        if (len < 1) {

            av_log(avctx, AV_LOG_ERROR, "invalid UTF-8 byte in subtitle\n");

            len = 1;

        }

        switch (*text) {

        case '\r':

            break;

        case '\n':

            av_bprintf(buf, "\\N");

            break;

        default:

            av_bprint_append_data(buf, text, len);

            break;

        }

        text += len;

        text_pos++;

    }

    return 0;

}

static av_cold int mov_text_init(AVCodecContext *avctx) {

    /*

     * TODO: Handle the default text style.

     * NB: Most players ignore styles completely, with the result that

     * it's very common to find files where the default style is broken

     * and respecting it results in a worse experience than ignoring it.

     */

    int ret;

    MovTextContext *m = avctx->priv_data;

    ret = mov_text_tx3g(avctx, m);

    if (ret == 0) {

        const StyleBox *const default_style = &m->d.style;

        if (!m->frame_width || !m->frame_height) {

            m->frame_width = ASS_DEFAULT_PLAYRESX;

            m->frame_height = ASS_DEFAULT_PLAYRESY;

        }

        return ff_ass_subtitle_header_full(avctx,

                    m->frame_width, m->frame_height,

                    m->d.font, default_style->fontsize,

                    (255U - default_style->alpha) << 24 | default_style->color,

                    (255U - default_style->alpha) << 24 | default_style->color,

                    (255U - m->d.back_alpha) << 24 | m->d.back_color,

                    (255U - m->d.back_alpha) << 24 | m->d.back_color,

                    default_style->bold, default_style->italic, default_style->underline,

                    ASS_DEFAULT_BORDERSTYLE, m->d.alignment);

    } else

        return ff_ass_subtitle_header_default(avctx);

}

static int mov_text_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,

                                 int *got_sub_ptr, const AVPacket *avpkt)

{

    MovTextContext *m = avctx->priv_data;

    int ret;

    AVBPrint buf;

    const char *ptr = avpkt->data, *end;

    int text_length;

    size_t i;

    if (!ptr || avpkt->size < 2)

        return AVERROR_INVALIDDATA;

    /*

     * A packet of size two with value zero is an empty subtitle

     * used to mark the end of the previous non-empty subtitle.

     * We can just drop them here as we have duration information

     * already. If the value is non-zero, then it's technically a

     * bad packet.

     */

    if (avpkt->size == 2)

        return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;

    /*

     * The first two bytes of the packet are the length of the text string

     * In complex cases, there are style descriptors appended to the string

     * so we can't just assume the packet size is the string size.

     */

    text_length = AV_RB16(ptr);

    end = ptr + FFMIN(2 + text_length, avpkt->size);

    ptr += 2;

    mov_text_cleanup(m);

    m->style_entries = 0;

    m->box_flags = 0;

    // Note that the spec recommends lines be no longer than 2048 characters.

    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);

    if (text_length + 2 < avpkt->size) {

        const uint8_t *tsmb = end;

        const uint8_t *const tsmb_end = avpkt->data + avpkt->size;

        // A box is a minimum of 8 bytes.

        while (tsmb_end - tsmb >= 8) {

            uint64_t tsmb_size = bytestream_get_be32(&tsmb);

            uint32_t tsmb_type = bytestream_get_be32(&tsmb);

            int size_var, ret_tsmb;

            if (tsmb_size == 1) {

                if (tsmb_end - tsmb < 8)

                    break;

                tsmb_size = bytestream_get_be64(&tsmb);

                size_var = 16;

            } else

                size_var = 8;

            //size_var is equal to 8 or 16 depending on the size of box

            if (tsmb_size < size_var) {

                av_log(avctx, AV_LOG_ERROR, "tsmb_size invalid\n");

                return AVERROR_INVALIDDATA;

            }

            tsmb_size -= size_var;

            if (tsmb_end - tsmb < tsmb_size)

                break;

            for (i = 0; i < box_count; i++) {

                if (tsmb_type == box_types[i].type) {

                    if (tsmb_size < box_types[i].base_size)

                        break;

                    ret_tsmb = box_types[i].decode(tsmb, m, tsmb_size);

                    if (ret_tsmb == -1)

                        break;

                }

            }

            tsmb += tsmb_size;

        }

        text_to_ass(&buf, ptr, end, avctx);

        mov_text_cleanup(m);

    } else

        text_to_ass(&buf, ptr, end, avctx);

    ret = ff_ass_add_rect(sub, buf.str, m->readorder++, 0, NULL, NULL);

    av_bprint_finalize(&buf, NULL);

    if (ret < 0)

        return ret;

    *got_sub_ptr = sub->num_rects > 0;

    return avpkt->size;

}

static av_cold int mov_text_decode_close(AVCodecContext *avctx)

{

    MovTextContext *m = avctx->priv_data;

    mov_text_cleanup_ftab(m);

    mov_text_cleanup(m);

    return 0;

}

static av_cold void mov_text_flush(AVCodecContext *avctx)

{

    MovTextContext *m = avctx->priv_data;

    if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))

        m->readorder = 0;

}

#define OFFSET(x) offsetof(MovTextContext, x)

#define FLAGS AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_SUBTITLE_PARAM

static const AVOption options[] = {

    { "width", "Frame width, usually video width", OFFSET(frame_width), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },

    { "height", "Frame height, usually video height", OFFSET(frame_height), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },

    { NULL },

};

static const AVClass mov_text_decoder_class = {

    .class_name = "MOV text decoder",

    .item_name  = av_default_item_name,

    .option     = options,

    .version    = LIBAVUTIL_VERSION_INT,

};

const FFCodec ff_movtext_decoder = {

    .p.name       = "mov_text",

    CODEC_LONG_NAME("3GPP Timed Text subtitle"),

    .p.type       = AVMEDIA_TYPE_SUBTITLE,

    .p.id         = AV_CODEC_ID_MOV_TEXT,

    .priv_data_size = sizeof(MovTextContext),

    .p.priv_class = &mov_text_decoder_class,

    .init         = mov_text_init,

    FF_CODEC_DECODE_SUB_CB(mov_text_decode_frame),

    .close        = mov_text_decode_close,

    .flush        = mov_text_flush,

};