import json
import os
import re
import sys
import zlib
from typing import Callable, Optional, TextIO

system_encoding = sys.getdefaultencoding()

if system_encoding != "utf-8":

    def make_safe(string):
        # replaces any character not representable using the system default encoding with an '?',
        # avoiding UnicodeEncodeError (https://github.com/openai/whisper/discussions/729).
        return string.encode(system_encoding, errors="replace").decode(system_encoding)

else:

    def make_safe(string):
        # utf-8 can encode any Unicode code point, so no need to do the round-trip encoding
        return string


def exact_div(x, y):
    assert x % y == 0
    return x // y


def str2bool(string):
    str2val = {"True": True, "False": False}
    if string in str2val:
        return str2val[string]
    else:
        raise ValueError(f"Expected one of {set(str2val.keys())}, got {string}")


def optional_int(string):
    return None if string == "None" else int(string)


def optional_float(string):
    return None if string == "None" else float(string)


def compression_ratio(text) -> float:
    text_bytes = text.encode("utf-8")
    return len(text_bytes) / len(zlib.compress(text_bytes))


def format_timestamp(
    seconds: float, always_include_hours: bool = False, decimal_marker: str = "."
):
    assert seconds >= 0, "non-negative timestamp expected"
    milliseconds = round(seconds * 1000.0)

    hours = milliseconds // 3_600_000
    milliseconds -= hours * 3_600_000

    minutes = milliseconds // 60_000
    milliseconds -= minutes * 60_000

    seconds = milliseconds // 1_000
    milliseconds -= seconds * 1_000

    hours_marker = f"{hours:02d}:" if always_include_hours or hours > 0 else ""
    return (
        f"{hours_marker}{minutes:02d}:{seconds:02d}{decimal_marker}{milliseconds:03d}"
    )


class ResultWriter:
    extension: str

    def __init__(self, output_dir: str):
        self.output_dir = output_dir

    def __call__(self, result: dict, audio_path: str, options: dict):
        audio_basename = os.path.basename(audio_path)
        audio_basename = os.path.splitext(audio_basename)[0]
        output_path = os.path.join(
            self.output_dir, audio_basename + "." + self.extension
        )

        with open(output_path, "w", encoding="utf-8") as f:
            self.write_result(result, file=f, options=options)

    def write_result(self, result: dict, file: TextIO, options: dict):
        raise NotImplementedError


class WriteTXT(ResultWriter):
    extension: str = "txt"

    def write_result(self, result: dict, file: TextIO, options: dict):
        for segment in result["segments"]:
            print(segment["text"].strip(), file=file, flush=True)


class SubtitlesWriter(ResultWriter):
    always_include_hours: bool
    decimal_marker: str

    def iterate_result(self, result: dict, options: dict):
        raw_max_line_width: Optional[int] = options["max_line_width"]
        max_line_count: Optional[int] = options["max_line_count"]
        highlight_words: bool = options["highlight_words"]
        max_line_width = 1000 if raw_max_line_width is None else raw_max_line_width
        preserve_segments = max_line_count is None or raw_max_line_width is None

        def iterate_subtitles():
            line_len = 0
            line_count = 1
            # the next subtitle to yield (a list of word timings with whitespace)
            subtitle: list[dict] = []
            last = result["segments"][0]["words"][0]["start"]
            for segment in result["segments"]:
                for i, original_timing in enumerate(segment["words"]):
                    timing = original_timing.copy()
                    long_pause = not preserve_segments and timing["start"] - last > 3.0
                    has_room = line_len + len(timing["word"]) <= max_line_width
                    seg_break = i == 0 and len(subtitle) > 0 and preserve_segments
                    if line_len > 0 and has_room and not long_pause and not seg_break:
                        # line continuation
                        line_len += len(timing["word"])
                    else:
                        # new line
                        timing["word"] = timing["word"].strip()
                        if (
                            len(subtitle) > 0
                            and max_line_count is not None
                            and (long_pause or line_count >= max_line_count)
                            or seg_break
                        ):
                            # subtitle break
                            yield subtitle
                            subtitle = []
                            line_count = 1
                        elif line_len > 0:
                            # line break
                            line_count += 1
                            timing["word"] = "\n" + timing["word"]
                        line_len = len(timing["word"].strip())
                    subtitle.append(timing)
                    last = timing["start"]
            if len(subtitle) > 0:
                yield subtitle

        if "words" in result["segments"][0]:
            for subtitle in iterate_subtitles():
                subtitle_start = self.format_timestamp(subtitle[0]["start"])
                subtitle_end = self.format_timestamp(subtitle[-1]["end"])
                subtitle_text = "".join([word["word"] for word in subtitle])
                if highlight_words:
                    last = subtitle_start
                    all_words = [timing["word"] for timing in subtitle]
                    for i, this_word in enumerate(subtitle):
                        start = self.format_timestamp(this_word["start"])
                        end = self.format_timestamp(this_word["end"])
                        if last != start:
                            yield last, start, subtitle_text

                        yield start, end, "".join(
                            [
                                re.sub(r"^(\s*)(.*)$", r"\1<u>\2</u>", word)
                                if j == i
                                else word
                                for j, word in enumerate(all_words)
                            ]
                        )
                        last = end
                else:
                    yield subtitle_start, subtitle_end, subtitle_text
        else:
            for segment in result["segments"]:
                segment_start = self.format_timestamp(segment["start"])
                segment_end = self.format_timestamp(segment["end"])
                segment_text = segment["text"].strip().replace("-->", "->")
                yield segment_start, segment_end, segment_text

    def format_timestamp(self, seconds: float):
        return format_timestamp(
            seconds=seconds,
            always_include_hours=self.always_include_hours,
            decimal_marker=self.decimal_marker,
        )


class WriteVTT(SubtitlesWriter):
    extension: str = "vtt"
    always_include_hours: bool = False
    decimal_marker: str = "."

    def write_result(self, result: dict, file: TextIO, options: dict):
        print("WEBVTT\n", file=file)
        for start, end, text in self.iterate_result(result, options):
            print(f"{start} --> {end}\n{text}\n", file=file, flush=True)


class WriteSRT(SubtitlesWriter):
    extension: str = "srt"
    always_include_hours: bool = True
    decimal_marker: str = ","

    def write_result(self, result: dict, file: TextIO, options: dict):
        for i, (start, end, text) in enumerate(
            self.iterate_result(result, options), start=1
        ):
            print(f"{i}\n{start} --> {end}\n{text}\n", file=file, flush=True)


class WriteTSV(ResultWriter):
    """
    Write a transcript to a file in TSV (tab-separated values) format containing lines like:
    <start time in integer milliseconds>\t<end time in integer milliseconds>\t<transcript text>

    Using integer milliseconds as start and end times means there's no chance of interference from
    an environment setting a language encoding that causes the decimal in a floating point number
    to appear as a comma; also is faster and more efficient to parse & store, e.g., in C++.
    """

    extension: str = "tsv"

    def write_result(self, result: dict, file: TextIO, options: dict):
        print("start", "end", "text", sep="\t", file=file)
        for segment in result["segments"]:
            print(round(1000 * segment["start"]), file=file, end="\t")
            print(round(1000 * segment["end"]), file=file, end="\t")
            print(segment["text"].strip().replace("\t", " "), file=file, flush=True)


class WriteJSON(ResultWriter):
    extension: str = "json"

    def write_result(self, result: dict, file: TextIO, options: dict):
        json.dump(result, file)


def get_writer(
    output_format: str, output_dir: str
) -> Callable[[dict, TextIO, dict], None]:
    writers = {
        "txt": WriteTXT,
        "vtt": WriteVTT,
        "srt": WriteSRT,
        "tsv": WriteTSV,
        "json": WriteJSON,
    }

    if output_format == "all":
        all_writers = [writer(output_dir) for writer in writers.values()]

        def write_all(result: dict, file: TextIO, options: dict):
            for writer in all_writers:
                writer(result, file, options)

        return write_all

    return writers[output_format](output_dir)