#!/usr/bin/env python3
"""Write the burned-in captions as an SRT on the *edited* timeline.

The clip drops a span in the middle, so a cue anchored to source seconds has to
be shifted by however much was cut before it. A cue that straddles a cut is an
error, not something to silently trim: it means CUES and KEEP disagree.
"""
import sys
from cues import CUES, KEEP


def to_out(t):
    acc = 0.0
    for a, b in KEEP:
        if a <= t <= b:
            return acc + (t - a)
        acc += b - a
    return None


def ts(t):
    h, rem = divmod(t, 3600)
    m, s = divmod(rem, 60)
    return f"{int(h):02d}:{int(m):02d}:{s:06.3f}".replace(".", ",")


def main(out_path):
    lines = []
    for i, (a, b, text) in enumerate(CUES, 1):
        oa, ob = to_out(a), to_out(b)
        if oa is None or ob is None:
            sys.exit(f"cue {i} ({a}-{b}) falls outside KEEP: {text!r}")
        if ob <= oa:
            sys.exit(f"cue {i} is inverted after mapping: {oa} -> {ob}")
        lines.append(f"{i}\n{ts(oa)} --> {ts(ob)}\n{text}\n")
    for (a1, b1, _), (a2, _, _) in zip(CUES, CUES[1:]):
        if a2 < b1:
            sys.exit(f"cues overlap at {a2}")
    open(out_path, "w").write("\n".join(lines) + "\n")
    print(f"{len(CUES)} cues -> {out_path}")
    print("edited duration:", round(sum(b - a for a, b in KEEP), 2), "s")


if __name__ == "__main__":
    main(sys.argv[1])