#!/usr/bin/env cached-nix-shell
#!nix-shell -i python3 -p python3 ffmpeg-full
from subprocess import run
import mimetypes
import os.path
import re
import sys


def lavfi_escape(parameter):
    return (
        parameter.replace("'", "\\'")
        .replace(":", "\:")
        .replace("\\'", "\\\\\\'")
        .replace("[", "\[")
        .replace("]", "\]")
        .replace(",", "\,")
    )


infile = sys.argv[1]
try:
    timeout = sys.argv[2]
except IndexError:
    timeout = 1800
# the system default font
# if the font name does not include this but the resulting fqn does, it is treated as missing
default_font = "Roboto"

res = run(
    [
        "ffmpeg",
        "-hide_banner",
        "-t",
        str(timeout),
        "-f",
        "lavfi",
        "-i",
        "nullsrc=16x16",
        "-filter:v",
        f"subtitles={lavfi_escape(infile)}",
        "-f",
        "null",
        "-",
    ],
    capture_output=True,
)

if res.returncode != 0:
    print("ffmpeg failed")
    print(f"stdout: {res.stdout.decode('utf-8')}")
    print(f"stderr: {res.stderr.decode('utf-8')}")
    sys.exit(1)

if res.stdout != b"":
    print(f"Got Stdout: {res.stdout.decode('utf-8')}")

substitutions = []
fonts = []

for line in res.stderr.decode("utf-8").splitlines():
    substitution = re.match(
        "^\[Parsed_subtitles_0 @ 0x[0-9a-f]*\] Glyph .* not found, selecting one more font for \((.*), ([0-9]{1,3}), ([0-9]{1,3})\)",
        line,
    )
    fontselect = re.match(
        "^\[Parsed_subtitles_0 @ 0x[0-9a-f]*\] fontselect: \((.*), ([0-9]{1,3}), ([0-9]{1,3})\) -> (.*), ([0-9]*), (.*)",
        line,
    )
    if substitution is not None:
        substitutions.append(
            (
                substitution.group(1),
                int(substitution.group(2)),
                int(substitution.group(3)),
            )
        )
    if fontselect is not None:
        font = {
            "name": fontselect.group(1),
            "weight": int(fontselect.group(2)),
            "italic": int(fontselect.group(3)),
            "path": fontselect.group(4),
            #'?': fontselect.group(5),
            "fqn": fontselect.group(6),
        }
        if font["name"] == "":
            continue

        if (font["name"], font["weight"], font["italic"]) in substitutions:
            print(
                f"Font {font['name']} lacks glyph support which lead to the substitution by {font['fqn']}, not including substitution font"
            )
            continue

        if default_font in font["fqn"] and not default_font in font["name"]:
            print(
                f"Font {font['name']} could not be found (based on {font['fqn']} looking like the default font)"
            )
            sys.exit(1)

        fonts.append(font)

command = ["mkvmerge", "-q", "-o", f"{os.path.splitext(infile)[0]}.mks", infile]

for font in fonts:
    command.extend(
        [
            "--attachment-mime-type",
            mimetypes.guess_type(font["path"])[0] or "font/sfnt",
            "--attach-file",
            font["path"],
        ]
    )

run(command, check=True)