/*
  * WebVTT subtitle encoder
  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
  * Copyright (c) 2014  Aman Gupta <ffmpeg@tmm1.net>
  *
  * 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 <stdarg.h>
 #include "avcodec.h"
 #include "libavutil/avstring.h"
 #include "libavutil/bprint.h"
 #include "ass_split.h"
 #include "ass.h"
 
 #define WEBVTT_STACK_SIZE 64
 typedef struct {
     AVCodecContext *avctx;
     ASSSplitContext *ass_ctx;
     AVBPrint buffer;
     unsigned timestamp_end;
     int count;
     char stack[WEBVTT_STACK_SIZE];
     int stack_ptr;
 } WebVTTContext;
 
 #ifdef __GNUC__
 __attribute__ ((__format__ (__printf__, 2, 3)))
 #endif
 static void webvtt_print(WebVTTContext *s, const char *str, ...)
 {
     va_list vargs;
     va_start(vargs, str);
     av_vbprintf(&s->buffer, str, vargs);
     va_end(vargs);
 }
 
 static int webvtt_stack_push(WebVTTContext *s, const char c)
 {
     if (s->stack_ptr >= WEBVTT_STACK_SIZE)

         return -1;

     s->stack[s->stack_ptr++] = c;
     return 0;
 }
 
 static char webvtt_stack_pop(WebVTTContext *s)
 {
     if (s->stack_ptr <= 0)
         return 0;
     return s->stack[--s->stack_ptr];
 }
 
 static int webvtt_stack_find(WebVTTContext *s, const char c)
 {
     int i;
     for (i = s->stack_ptr-1; i >= 0; i--)
         if (s->stack[i] == c)
             break;
     return i;
 }
 
 static void webvtt_close_tag(WebVTTContext *s, char tag)
 {
     webvtt_print(s, "</%c>", tag);
 }
 
 static void webvtt_stack_push_pop(WebVTTContext *s, const char c, int close)
 {
     if (close) {
         int i = c ? webvtt_stack_find(s, c) : 0;
         if (i < 0)
             return;
         while (s->stack_ptr != i)
             webvtt_close_tag(s, webvtt_stack_pop(s));
     } else if (webvtt_stack_push(s, c) < 0)
         av_log(s->avctx, AV_LOG_ERROR, "tag stack overflow\n");
 }
 
 static void webvtt_style_apply(WebVTTContext *s, const char *style)
 {
     ASSStyle *st = ff_ass_style_get(s->ass_ctx, style);
     if (st) {
         if (st->bold != ASS_DEFAULT_BOLD) {
             webvtt_print(s, "<b>");
             webvtt_stack_push(s, 'b');
         }
         if (st->italic != ASS_DEFAULT_ITALIC) {
             webvtt_print(s, "<i>");
             webvtt_stack_push(s, 'i');
         }
         if (st->underline != ASS_DEFAULT_UNDERLINE) {
             webvtt_print(s, "<u>");
             webvtt_stack_push(s, 'u');
         }
     }
 }
 
 static void webvtt_text_cb(void *priv, const char *text, int len)
 {
     WebVTTContext *s = priv;
     av_bprint_append_data(&s->buffer, text, len);
 }
 
 static void webvtt_new_line_cb(void *priv, int forced)
 {
     webvtt_print(priv, "\n");
 }
 
 static void webvtt_style_cb(void *priv, char style, int close)
 {
     if (style == 's') // strikethrough unsupported
         return;
 
     webvtt_stack_push_pop(priv, style, close);
     if (!close)
         webvtt_print(priv, "<%c>", style);
 }
 
 static void webvtt_cancel_overrides_cb(void *priv, const char *style)
 {
     webvtt_stack_push_pop(priv, 0, 1);
     webvtt_style_apply(priv, style);
 }
 
 static void webvtt_end_cb(void *priv)
 {
     webvtt_stack_push_pop(priv, 0, 1);
 }
 
 static const ASSCodesCallbacks webvtt_callbacks = {
     .text             = webvtt_text_cb,
     .new_line         = webvtt_new_line_cb,
     .style            = webvtt_style_cb,
     .color            = NULL,
     .font_name        = NULL,
     .font_size        = NULL,
     .alignment        = NULL,
     .cancel_overrides = webvtt_cancel_overrides_cb,
     .move             = NULL,
     .end              = webvtt_end_cb,
 };
 
 static int webvtt_encode_frame(AVCodecContext *avctx,
                                unsigned char *buf, int bufsize, const AVSubtitle *sub)
 {
     WebVTTContext *s = avctx->priv_data;
     ASSDialog *dialog;

     int i;

 
     av_bprint_clear(&s->buffer);
 
     for (i=0; i<sub->num_rects; i++) {

         const char *ass = sub->rects[i]->ass;
 

         if (sub->rects[i]->type != SUBTITLE_ASS) {
             av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");

             return AVERROR(EINVAL);

         }
 

 #if FF_API_ASS_TIMING

         if (!strncmp(ass, "Dialogue: ", 10)) {

             int num;

             dialog = ff_ass_split_dialog(s->ass_ctx, ass, 0, &num);
             // TODO reindent

         for (; dialog && num--; dialog++) {
             webvtt_style_apply(s, dialog->style);
             ff_ass_split_override_codes(&webvtt_callbacks, s, dialog->text);
         }

         } else {

 #endif

             dialog = ff_ass_split_dialog2(s->ass_ctx, ass);
             if (!dialog)
                 return AVERROR(ENOMEM);
             webvtt_style_apply(s, dialog->style);
             ff_ass_split_override_codes(&webvtt_callbacks, s, dialog->text);
             ff_ass_free_dialog(&dialog);

 #if FF_API_ASS_TIMING

         }

 #endif

     }
 
     if (!av_bprint_is_complete(&s->buffer))
         return AVERROR(ENOMEM);
     if (!s->buffer.len)
         return 0;
 
     if (s->buffer.len > bufsize) {
         av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");

         return AVERROR_BUFFER_TOO_SMALL;

     }
     memcpy(buf, s->buffer.str, s->buffer.len);
 
     return s->buffer.len;
 }
 
 static int webvtt_encode_close(AVCodecContext *avctx)
 {
     WebVTTContext *s = avctx->priv_data;
     ff_ass_split_free(s->ass_ctx);
     av_bprint_finalize(&s->buffer, NULL);
     return 0;
 }
 
 static av_cold int webvtt_encode_init(AVCodecContext *avctx)
 {
     WebVTTContext *s = avctx->priv_data;
     s->avctx = avctx;
     s->ass_ctx = ff_ass_split(avctx->subtitle_header);
     av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
     return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
 }
 
 AVCodec ff_webvtt_encoder = {
     .name           = "webvtt",
     .long_name      = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
     .type           = AVMEDIA_TYPE_SUBTITLE,
     .id             = AV_CODEC_ID_WEBVTT,
     .priv_data_size = sizeof(WebVTTContext),
     .init           = webvtt_encode_init,
     .encode_sub     = webvtt_encode_frame,
     .close          = webvtt_encode_close,
 };