#!/usr/bin/env python3
"""Run MaterialSub dependency and font checks before a long download."""

from __future__ import annotations

import argparse
import json
import shutil
import sys
from typing import Any, Sequence

import burn_subtitles as burn


def assess(*, font: str, allow_missing_font: bool, youtube: bool) -> tuple[int, dict[str, Any]]:
    if sys.version_info < (3, 10):
        return 2, {
            "complete": False,
            "stage": "dependency_required",
            "error": "Python 3.10 or newer is required",
        }
    yt_dlp = shutil.which("yt-dlp")
    if not yt_dlp:
        return 2, {
            "complete": False,
            "stage": "dependency_required",
            "error": "yt-dlp was not found in PATH",
        }
    try:
        ffmpeg, ffprobe = burn._required_executables()
        burn._require_libass_subtitles_filter(ffmpeg)
    except burn.BurnError as exc:
        return 2, {
            "complete": False,
            "stage": "dependency_required",
            "error": str(exc),
        }

    warnings: list[str] = []
    if youtube and not shutil.which("deno"):
        warnings.append(
            "Deno was not found; current yt-dlp may expose fewer YouTube formats"
        )
    installed = burn._font_installed(font)
    if installed is False and not allow_missing_font:
        return 3, {
            "complete": False,
            "stage": "font_decision_required",
            "font": font,
            "font_installed": False,
            "substitution_allowed": False,
            "instruction": (
                "Install the requested font, or rerun preflight and the final burn "
                "with --allow-missing-font to accept libass substitution"
            ),
            "warnings": warnings,
        }
    if installed is False:
        warnings.append(f"Font {font!r} is missing; libass substitution was accepted")
    elif installed is None:
        warnings.append(f"Could not verify whether font {font!r} is installed")
    return 0, {
        "complete": True,
        "stage": "preflight_complete",
        "font": font,
        "font_installed": installed,
        "substitution_allowed": bool(installed is False and allow_missing_font),
        "executables": {
            "yt_dlp": yt_dlp,
            "ffmpeg": ffmpeg,
            "ffprobe": ffprobe,
        },
        "warnings": warnings,
    }


def _parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(description="Check MaterialSub dependencies before downloading.")
    parser.add_argument("--font", default="MiSans")
    parser.add_argument("--allow-missing-font", action="store_true")
    parser.add_argument("--youtube", action="store_true")
    return parser


def main(argv: Sequence[str] | None = None) -> int:
    args = _parser().parse_args(argv)
    font = args.font.strip()
    if not font:
        print(json.dumps({"complete": False, "error": "font cannot be empty"}))
        return 2
    exit_code, result = assess(
        font=font,
        allow_missing_font=args.allow_missing_font,
        youtube=args.youtube,
    )
    print(json.dumps(result, ensure_ascii=False, sort_keys=True))
    return exit_code


if __name__ == "__main__":
    raise SystemExit(main())