#!/usr/bin/env python3

import argparse
import os
import re
import subprocess
from pathlib import Path, PurePath


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--destdir", default="/", type=Path)
    ap.add_argument("--confdir", type=PurePath)
    ap.add_argument("--statedir", type=PurePath)
    ap.add_argument("--bindir", type=PurePath)
    ap.add_argument("--datadir", type=PurePath)
    ap.add_argument("--unitdir", type=PurePath)
    ap.add_argument("--sysusersdir", type=PurePath)
    ap.add_argument("--is-systemd", action="store_true", default=None)
    ap.add_argument("--no-run", action="store_true")
    ap.add_argument("prefix", choices=["home", "system", "usr", "usr/local"])

    vals = ap.parse_args()

    if not vals.destdir.is_absolute():
        raise ValueError(f"destdir={destdir} must be absolute")

    if vals.is_systemd is None:
        vals.is_systemd = "systemd" in str(Path("/sbin/init").resolve())

    conf = vars(vals)
    for key, val in list(conf.items()):
        if val is None:
            del conf[key]

    if vals.prefix == "home":
        user = os.env["USER"]
        confdir = conf.setdefault("confdir", PurePath(f"home/{user}/.config/jwebmail"))
        statedir = conf.setdefault(
            "statedir", PurePath(f"home/{user}/.local/state/jwebmail")
        )
        bindir = conf.setdefault("bindir", PurePath(f"home/{user}/.local/bin"))
        datadir = conf.setdefault(
            "datadir", PurePath(f"home/{user}/.local/share/jwebmail")
        )
        unitdir = conf.setdefault(
            "unitdir", PurePath(f"home/{user}/.config/systemd/user")
        )
        sysusersdir = None

        (vals.destdir / confdir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / statedir).mkdir(0o700, exist_ok=True)
        (vals.destdir / datadir).mkdir(0o755, exist_ok=True)
    elif vals.prefix == "system":
        confdir = conf.setdefault("confdir", PurePath("etc/jwebmail"))
        statedir = conf.setdefault("statedir", PurePath("var/jwebmail"))
        bindir = conf.setdefault("bindir", PurePath("usr/bin"))
        datadir = conf.setdefault("datadir", PurePath("usr/share/jwebmail"))
        unitdir = conf.setdefault("unitdir", PurePath("etc/systemd/system"))
        sysusersdir = conf.setdefault("sysusersdir", PurePath("etc/sysusers.d"))

        (vals.destdir / confdir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / statedir.parent).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / statedir).mkdir(0o750, exist_ok=True)
        (vals.destdir / datadir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / unitdir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / sysusersdir).mkdir(0o755, exist_ok=True, parents=True)
    elif vals.prefix == "usr":
        confdir = conf.setdefault("confdir", PurePath("etc/jwebmail"))
        statedir = conf.setdefault("statedir", PurePath("var/lib/jwebmail"))
        bindir = conf.setdefault("bindir", PurePath("usr/bin"))
        datadir = conf.setdefault("datadir", PurePath("usr/share/jwebmail"))
        unitdir = conf.setdefault("unitdir", PurePath("usr/lib/systemd/system"))
        sysusersdir = conf.setdefault("sysusersdir", PurePath("usr/lib/sysusers.d"))

        (vals.destdir / confdir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / statedir.parent).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / statedir).mkdir(0o750, exist_ok=True)
        (vals.destdir / datadir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / unitdir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / sysusersdir).mkdir(0o755, exist_ok=True, parents=True)
    elif vals.prefix == "usr/local":
        confdir = conf.setdefault("confdir", PurePath("usr/local/etc/jwebmail"))
        statedir = conf.setdefault("statedir", PurePath("var/local/lib/jwebmail"))
        bindir = conf.setdefault("bindir", PurePath("usr/local/bin"))
        datadir = conf.setdefault("datadir", PurePath("usr/local/share/jwebmail"))
        unitdir = conf.setdefault("unitdir", PurePath("usr/local/lib/systemd/system"))
        sysusersdir = conf.setdefault(
            "sysusersdir", PurePath("usr/local/lib/sysusers.d")
        )

        (vals.destdir / confdir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / statedir.parent).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / statedir).mkdir(0o750, exist_ok=True)
        (vals.destdir / datadir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / unitdir).mkdir(0o755, exist_ok=True, parents=True)
        (vals.destdir / sysusersdir).mkdir(0o755, exist_ok=True, parents=True)
    else:
        raise ValueError(
            "first arg <prefix> must be one of `home`, `system`, `usr` or `usr/local`"
        )

    try:
        if vals.is_systemd:
            install_service_unit(
                "script/jwebmail.service.in",
                vals.destdir / unitdir,
                str(vals.destdir / confdir),
                str(vals.destdir / bindir),
                vals.no_run,
            )

        if vals.is_systemd and vals.prefix != "home":
            install_jwebmail_user(
                "script/jwebmail.conf.in",
                vals.destdir / sysusersdir,
                str(vals.destdir / statedir),
                vals.no_run,
            )
    except subprocess.CalledProcessError:
        os.exit("A command failed to execute. Is systemd installed? Try running with `--no-run`.")


def substitute_file(in_file, out_path, variables):
    in_file_content = open(in_file).read()
    out_file_content = re.sub(
        r"@(\w+)@", lambda match: variables[match[1]], in_file_content, flags=re.ASCII
    )
    open(out_path / Path(in_file).name.removesuffix(".in"), mode="w").write(
        out_file_content
    )


def install_jwebmail_user(in_file, out_path, statedir, no_run):
    substitute_file(
        in_file,
        out_path,
        dict(STATEDIR=statedir),
    )
    if not no_run:
        subprocess.run("systemd-sysusers", check=True)


def install_service_unit(in_file, out_path, confdir, bindir):
    substitute_file(
        in_file,
        out_path,
        dict(CONFDIR=confdir, BINDIR=bindir),
    )
    if not no_run:
        subprocess.run(["systemctl", "daemon-reload"], check=True)


if __name__ == "__main__":
    main()