#!/usr/bin/env python3
"""Convert TMPlayer subtitles (HH:MM:SS:text, '|' = line break) to SRT.

TMPlayer stores only a start time per line, so end times are inferred:
each cue ends when the next one starts (minus a small gap), or earlier if
its text is short enough to be read sooner.

    python3 tmp2srt.py input/film.txt [output.srt]
"""
import re
import sys
from pathlib import Path

# A separator after the timestamp is optional in the wild: some lines use
# ':', some a bare space, some nothing at all.
LINE_RE = re.compile(r"^\s*(\d{1,2}):(\d{2}):(\d{2}):?\s*(.*)$")

CPS = 16.0          # reading speed used to size a cue when there is room
MIN_DUR = 1.2       # s
MAX_DUR = 7.0       # s
GAP = 0.08          # s left between consecutive cues


def _fmt(t: float) -> str:
    ms = int(round(t * 1000))
    h, ms = divmod(ms, 3600000)
    m, ms = divmod(ms, 60000)
    s, ms = divmod(ms, 1000)
    return f"{h:02d}:{m:02d}:{s:02d},{ms:03d}"


def parse(path: Path):
    cues, skipped = [], []
    for n, raw in enumerate(path.read_text(encoding="utf-8-sig").splitlines(), 1):
        if not raw.strip():
            continue
        m = LINE_RE.match(raw)
        if not m:
            skipped.append((n, raw))
            continue
        h, mi, s, text = m.groups()
        text = text.replace("|", "\n").strip()
        if not text:
            continue
        cues.append((int(h) * 3600 + int(mi) * 60 + int(s), text))
    cues.sort(key=lambda c: c[0])
    return cues, skipped


def to_srt(cues) -> str:
    out = []
    for i, (start, text) in enumerate(cues):
        wanted = len(text.replace("\n", " ")) / CPS
        end = start + max(MIN_DUR, min(MAX_DUR, wanted))
        if i + 1 < len(cues):
            end = min(end, cues[i + 1][0] - GAP)
        if end <= start:                      # cues closer together than MIN_DUR
            end = (cues[i + 1][0] if i + 1 < len(cues) else start + MIN_DUR) - 0.01
        if end <= start:
            end = start + 0.1
        out.append(f"{i + 1}\n{_fmt(start)} --> {_fmt(end)}\n{text}\n")
    return "\n".join(out)


def main():
    if len(sys.argv) < 2:
        sys.exit(__doc__)
    src = Path(sys.argv[1])
    dst = Path(sys.argv[2]) if len(sys.argv) > 2 else src.with_suffix(".srt")
    cues, skipped = parse(src)
    dst.write_text(to_srt(cues), encoding="utf-8")
    print(f"{src} -> {dst}: {len(cues)} cues")
    for n, raw in skipped:
        print(f"  skipped line {n}: {raw[:70]!r}")


if __name__ == "__main__":
    main()