# License: GNU AGPL v3: http://www.gnu.org/licenses/
# This file is part of `delarte` (https://git.afpy.org/fcode/delarte.git)

"""Provide WebVTT to SRT subtitles conversion."""

import re

from .error import WebVTTError

RE_CUE_START = r"^((?:\d\d:)\d\d:\d\d)\.(\d\d\d) --> ((?:\d\d:)\d\d:\d\d)\.(\d\d\d)"
RE_STYLED_CUE = r"^<c\.(\w+)\.bg_(?:\w+)>(.*)</c>$"


def convert(input, output):
    """Convert input ArteTV's WebVTT string data and write it on output file."""
    # This is a very (very) simple implementation based on what has actually
    # been seen on ArteTV and is not at all a generic WebVTT solution.

    blocks = []
    block = []

    for line in input.splitlines():
        if not line and block:
            blocks.append(block)
            block = []
        else:
            block.append(line)
    if block:
        blocks.append(block)
        block = []

    if not blocks:
        raise WebVTTError("INVALID_DATA")

    header = blocks.pop(0)
    if not (len(header) == 1 and header[0].startswith("WEBVTT")):
        raise WebVTTError("INVALID_HEADER")

    counter = 1
    for block in blocks:
        if m := re.match(RE_CUE_START, block.pop(0)):
            print(f"{counter}", file=output)
            print(f"{m[1]},{m[2]} --> {m[3]},{m[4]}", file=output)
            for line in block:
                if m := re.match(RE_STYLED_CUE, line):
                    print(f'<font color="{m[1]}">{m[2]}</font>', file=output)
                else:
                    print(line, file=output)
            print("", file=output)
            counter += 1

    if counter == 1:
        raise WebVTTError("EMPTY_DATA")