import re
import math


def leading_zeros(value, digits=2):
    value = "000000" + str(value)
    return value[-digits:]


def convert_time(raw_time):
    if int(raw_time) == 0:
        return "{}:{}:{},{}".format(0, 0, 0, 0)

    ms = '000'
    if len(raw_time) > 4:
        ms = leading_zeros(int(raw_time[:-4]) % 1000, 3)
    time_in_seconds = int(raw_time[:-7]) if len(raw_time) > 7 else 0
    second = leading_zeros(time_in_seconds % 60)
    minute = leading_zeros(int(math.floor(time_in_seconds / 60)) % 60)
    hour = leading_zeros(int(math.floor(time_in_seconds / 3600)))
    return "{}:{}:{},{}".format(hour, minute, second, ms)


def to_srt(text):
    def append_subs(start, end, prev_content, format_time):
        subs.append({
            "start_time": convert_time(start) if format_time else start,
            "end_time": convert_time(end) if format_time else end,
            "content": u"\n".join(prev_content),
        })

    begin_re = re.compile(u"\s*<p begin=")
    sub_lines = (l for l in text.split("\n") if re.search(begin_re, l))
    subs = []
    prev_time = {"start": 0, "end": 0}
    prev_content = []
    start = end = ''
    start_re = re.compile(u'begin\="([0-9:\.]*)')
    end_re = re.compile(u'end\="([0-9:\.]*)')
    # this regex was sometimes too strict. I hope the new one is never too lax
    # content_re = re.compile(u'xml\:id\=\"subtitle[0-9]+\">(.*)</p>')
    content_re = re.compile(u'\">(.*)</p>')
    alt_content_re = re.compile(u'<span style=\"[a-zA-Z0-9_]+\">(.*?)</span>')
    br_re = re.compile(u'(<br\s*\/?>)+')
    fmt_t = True
    for s in sub_lines:
        content = []
        alt_content = re.search(alt_content_re, s)
        while (alt_content):  # background text may have additional styling.
            # background may also contain several `<span> </span>` groups
            s = s.replace(alt_content.group(0), alt_content.group(1))
            alt_content = re.search(alt_content_re, s)
        content = re.search(content_re, s).group(1)

        br_tags = re.search(br_re, content)
        if br_tags:
            content = u"\n".join(content.split(br_tags.group()))

        prev_start = prev_time["start"]
        start = re.search(start_re, s).group(1)
        end = re.search(end_re, s).group(1)
        if len(start.split(":")) > 1:
            fmt_t = False
            start = start.replace(".", ",")
            end = end.replace(".", ",")
        if (prev_start == start and prev_time["end"] == end) or not prev_start:
            # Fix for multiple lines starting at the same time
            prev_time = {"start": start, "end": end}
            prev_content.append(content)
            continue
        append_subs(prev_time["start"], prev_time["end"], prev_content, fmt_t)
        prev_time = {"start": start, "end": end}
        prev_content = [content]
    append_subs(start, end, prev_content, fmt_t)

    lines = (u"{}\n{} --> {}\n{}\n".format(
        s + 1, subs[s]["start_time"], subs[s]["end_time"], subs[s]["content"])
        for s in range(len(subs)))
    return u"\n".join(lines)