feat(stats): add v1 immersion stats dashboard (#19)

src/core/services/subtitle-cue-parser.ts

@@ -0,0 +1,191 @@
+export interface SubtitleCue {
+  startTime: number;
+  endTime: number;
+  text: string;
+}
+
+const SRT_TIMING_PATTERN =
+  /^\s*(?:(\d{1,2}):)?(\d{2}):(\d{2})[,.](\d{1,3})\s*-->\s*(?:(\d{1,2}):)?(\d{2}):(\d{2})[,.](\d{1,3})/;
+
+function parseTimestamp(
+  hours: string | undefined,
+  minutes: string,
+  seconds: string,
+  millis: string,
+): number {
+  return (
+    Number(hours || 0) * 3600 +
+    Number(minutes) * 60 +
+    Number(seconds) +
+    Number(millis.padEnd(3, '0')) / 1000
+  );
+}
+
+export function parseSrtCues(content: string): SubtitleCue[] {
+  const cues: SubtitleCue[] = [];
+  const lines = content.split(/\r?\n/);
+  let i = 0;
+
+  while (i < lines.length) {
+    const line = lines[i]!;
+    const timingMatch = SRT_TIMING_PATTERN.exec(line);
+    if (!timingMatch) {
+      i += 1;
+      continue;
+    }
+
+    const startTime = parseTimestamp(
+      timingMatch[1],
+      timingMatch[2]!,
+      timingMatch[3]!,
+      timingMatch[4]!,
+    );
+    const endTime = parseTimestamp(
+      timingMatch[5],
+      timingMatch[6]!,
+      timingMatch[7]!,
+      timingMatch[8]!,
+    );
+
+    i += 1;
+    const textLines: string[] = [];
+    while (i < lines.length && lines[i]!.trim() !== '') {
+      textLines.push(lines[i]!);
+      i += 1;
+    }
+
+    const text = textLines.join('\n').trim();
+    if (text) {
+      cues.push({ startTime, endTime, text });
+    }
+  }
+
+  return cues;
+}
+
+const ASS_OVERRIDE_TAG_PATTERN = /\{[^}]*\}/g;
+
+const ASS_TIMING_PATTERN = /^(\d+):(\d{2}):(\d{2})\.(\d{1,2})$/;
+const ASS_FORMAT_PREFIX = 'Format:';
+const ASS_DIALOGUE_PREFIX = 'Dialogue:';
+
+function parseAssTimestamp(raw: string): number | null {
+  const match = ASS_TIMING_PATTERN.exec(raw.trim());
+  if (!match) {
+    return null;
+  }
+  const hours = Number(match[1]);
+  const minutes = Number(match[2]);
+  const seconds = Number(match[3]);
+  const centiseconds = Number(match[4]!.padEnd(2, '0'));
+  return hours * 3600 + minutes * 60 + seconds + centiseconds / 100;
+}
+
+export function parseAssCues(content: string): SubtitleCue[] {
+  const cues: SubtitleCue[] = [];
+  const lines = content.split(/\r?\n/);
+  let inEventsSection = false;
+  let startFieldIndex = -1;
+  let endFieldIndex = -1;
+  let textFieldIndex = -1;
+
+  for (const line of lines) {
+    const trimmed = line.trim();
+
+    if (trimmed.startsWith('[') && trimmed.endsWith(']')) {
+      inEventsSection = trimmed.toLowerCase() === '[events]';
+      if (!inEventsSection) {
+        startFieldIndex = -1;
+        endFieldIndex = -1;
+        textFieldIndex = -1;
+      }
+      continue;
+    }
+
+    if (!inEventsSection) {
+      continue;
+    }
+
+    if (trimmed.startsWith(ASS_FORMAT_PREFIX)) {
+      const formatFields = trimmed
+        .slice(ASS_FORMAT_PREFIX.length)
+        .split(',')
+        .map((field) => field.trim().toLowerCase());
+      startFieldIndex = formatFields.indexOf('start');
+      endFieldIndex = formatFields.indexOf('end');
+      textFieldIndex = formatFields.indexOf('text');
+      continue;
+    }
+
+    if (!trimmed.startsWith(ASS_DIALOGUE_PREFIX)) {
+      continue;
+    }
+
+    if (startFieldIndex < 0 || endFieldIndex < 0 || textFieldIndex < 0) {
+      continue;
+    }
+
+    const fields = trimmed.slice(ASS_DIALOGUE_PREFIX.length).split(',');
+    if (
+      startFieldIndex >= fields.length ||
+      endFieldIndex >= fields.length ||
+      textFieldIndex >= fields.length
+    ) {
+      continue;
+    }
+
+    const startTime = parseAssTimestamp(fields[startFieldIndex]!);
+    const endTime = parseAssTimestamp(fields[endFieldIndex]!);
+    if (startTime === null || endTime === null) {
+      continue;
+    }
+
+    const rawText = fields
+      .slice(textFieldIndex)
+      .join(',')
+      .replace(ASS_OVERRIDE_TAG_PATTERN, '')
+      .trim();
+    if (rawText) {
+      cues.push({ startTime, endTime, text: rawText });
+    }
+  }
+
+  return cues;
+}
+
+function detectSubtitleFormat(source: string): 'srt' | 'vtt' | 'ass' | 'ssa' | null {
+  const [normalizedSource = source] =
+    (() => {
+      try {
+        return /^[a-z]+:\/\//i.test(source) ? new URL(source).pathname : source;
+      } catch {
+        return source;
+      }
+    })().split(/[?#]/, 1)[0] ?? '';
+  const ext = normalizedSource.split('.').pop()?.toLowerCase() ?? '';
+  if (ext === 'srt') return 'srt';
+  if (ext === 'vtt') return 'vtt';
+  if (ext === 'ass' || ext === 'ssa') return 'ass';
+  return null;
+}
+
+export function parseSubtitleCues(content: string, filename: string): SubtitleCue[] {
+  const format = detectSubtitleFormat(filename);
+  let cues: SubtitleCue[];
+
+  switch (format) {
+    case 'srt':
+    case 'vtt':
+      cues = parseSrtCues(content);
+      break;
+    case 'ass':
+    case 'ssa':
+      cues = parseAssCues(content);
+      break;
+    default:
+      return [];
+  }
+
+  cues.sort((a, b) => a.startTime - b.startTime);
+  return cues;
+}