"""Reading and updating patchbay.conf (shared with patchbayd, see config.c)."""

import os
import tempfile

DEFAULTS = {
    "role": "client",
    "database": "/etc/patchbay/patchbay.db",
    "rundir": "/run/patchbay",
    "webbind": "0.0.0.0",
    "webport": "8443",
    "tlscert": "/etc/patchbay/tls.crt",
    "tlskey": "/etc/patchbay/tls.key",
    "sessionhours": "12",
    "sysopuser": "admin",
    "sysopemail": "",
    "sysoppassword": "",
    "mailhost": "",
    "mailport": "587",
    "mailsecurity": "starttls",
    "mailuser": "",
    "mailpassword": "",
    "mailfrom": "",
}

# Canonical spelling used when a key has to be appended to the file.
CANONICAL = {
    "sysoppassword": "SysopPassword",
    "sysopemail": "SysopEmail",
    "mailhost": "MailHost",
    "mailport": "MailPort",
    "mailsecurity": "MailSecurity",
    "mailuser": "MailUser",
    "mailpassword": "MailPassword",
    "mailfrom": "MailFrom",
}


def _parse_line(line):
    s = line.strip()
    if not s or s[0] in "#;[" or "=" not in s:
        return None
    key, val = s.split("=", 1)
    val = val.strip()
    if len(val) >= 2 and val[0] == '"' and val[-1] == '"':
        val = val[1:-1]
    return key.strip().lower(), val


class Config:
    """Keys are case-insensitive and stored lower-case."""

    def __init__(self, path):
        self.path = path
        self.values = dict(DEFAULTS)
        with open(path, encoding="utf-8") as f:
            for line in f:
                kv = _parse_line(line)
                if kv:
                    self.values[kv[0]] = kv[1]

    def get(self, key, default=None):
        return self.values.get(key.lower(), default)

    def getint(self, key, default=0):
        try:
            return int(self.get(key, default))
        except (TypeError, ValueError):
            return default

    def update(self, changes):
        """Rewrites the given keys in place, keeping comments and order."""
        changes = {k.lower(): v for k, v in changes.items()}
        for v in changes.values():
            if "\n" in str(v) or "\r" in str(v):
                raise ValueError("newline in config value")
        with open(self.path, encoding="utf-8") as f:
            lines = f.readlines()

        done = set()
        out = []
        for line in lines:
            kv = _parse_line(line)
            if kv and kv[0] in changes:
                if kv[0] in done:
                    continue  # drop duplicates of a rewritten key
                key_text = line.split("=", 1)[0].strip()
                out.append(f"{key_text} = {self._quote(changes[kv[0]])}\n")
                done.add(kv[0])
            else:
                out.append(line)
        missing = [k for k in changes if k not in done]
        if missing:
            if out and not out[-1].endswith("\n"):
                out[-1] += "\n"
            for k in missing:
                out.append(f"{CANONICAL.get(k, k)} = {self._quote(changes[k])}\n")

        st = os.stat(self.path)
        fd, tmp = tempfile.mkstemp(dir=os.path.dirname(self.path) or ".", prefix=".patchbay.conf.")
        try:
            with os.fdopen(fd, "w", encoding="utf-8") as f:
                f.writelines(out)
            os.chmod(tmp, st.st_mode & 0o777)
            try:
                os.chown(tmp, st.st_uid, st.st_gid)
            except PermissionError:
                pass
            os.replace(tmp, self.path)
        except BaseException:
            if os.path.exists(tmp):
                os.unlink(tmp)
            raise
        self.values.update({k: str(v) for k, v in changes.items()})

    @staticmethod
    def _quote(v):
        v = str(v)
        return f'"{v}"' if v != v.strip() else v