from contextlib import closing

from flask import current_app, g
from flask_login import UserMixin, current_user

from .model.read_mails import QMailAuthuser

EXPIRATION_SEC = 60 * 60 * 25


class JWebmailUser(UserMixin):
    def __init__(self, mail_addr, password):
        self.id = mail_addr
        self.password = password


class RedisTimeoutSession:
    def __init__(self, username, passwd, timeout, port=6379):
        import redis

        self.timeout = timeout
        self.conn = redis.Redis(
            host="localhost",
            port=port,
            decode_responses=True,
            protocol=3,
            username=username,
            password=passwd,
        )

    def set(self, key, value):
        self.conn.setex(f"jwm:user:{key}", self.timeout, value)

    def get(self, key):
        return self.conn.getex(f"jwm:user:{key}", self.timeout)

    def close(self):
        self.conn.close()


class MysqlTimeoutSession:
    def __init__(self, username, passwd, timeout, database="jwebmaildb1", port=3306):
        import mysql.connector

        self.timeout = timeout
        self.conn = mysql.connector.connect(
            host="localhost",
            port=port,
            username=username,
            password=passwd,
            database=database,
        )

    def set(self, key, value):
        with closing(self.conn.cursor()) as cur:
            cur.execute(
                "REPLACE INTO session VALUES (%s, %s, now() + INTERVAL %s SECOND)",
                [key, value, self.timeout],
            )
            self.conn.commit()

    def get(self, key):
        with closing(self.conn.cursor()) as cur:
            cur.execute("DELETE FROM session WHERE timeout < now()")
            cur.execute(
                "UPDATE session SET timeout = now() + INTERVAL %s SECOND WHERE user = %s",
                [self.timeout, key],
            )
            cur.execute("SELECT password FROM session WHERE user = %s", [key])
            row = cur.fetchone()
            self.conn.commit()

            return None if row is None else row[0]

    def close(self):
        self.conn.close()


class SqliteTimeoutSession:
    def __init__(self, _username, _passwd, timeout, database):
        import sqlite3

        self.timeout = timeout

        self.conn = sqlite3.connect(database, isolation_level="IMMEDIATE")
        cur = self.conn.cursor()
        cur.execute(
            "CREATE TABLE IF NOT EXISTS session (user text PRIMARY KEY, password text, timeout integer NOT NULL) STRICT"
        )
        cur.execute("CREATE INDEX IF NOT EXISTS timeout_idx ON session (timeout)")

    def set(self, key, value):
        with closing(self.conn.cursor()) as cur:
            cur.execute(
                "REPLACE INTO session VALUES (?, ?, unixepoch('now', format('%d seconds', ?)))",
                [key, value, self.timeout],
            )
            self.conn.commit()

    def get(self, key):
        with closing(self.conn.cursor()) as cur:
            cur.execute("DELETE FROM session WHERE timeout < unixepoch()")
            cur.execute(
                "UPDATE session SET timeout = unixepoch('now', format('%d seconds', ?)) WHERE user = ? RETURNING password",
                [self.timeout, key],
            )
            row = cur.fetchone()
            self.conn.commit()

            return None if row is None else row[0]

    def close(self):
        self.conn.close()


def select_timeout_session():
    session_type = current_app.config["JWEBMAIL"]["READ_MAILS"]["SESSION_TYPE"]

    user = "jwebmail"
    passwd = current_app.config["JWEBMAIL"]["READ_MAILS"]["SESSION_STORE_PASSWD"]
    args = dict()
    db_name = current_app.config["JWEBMAIL"]["READ_MAILS"].get("SESSION_STORE_DB_NAME")
    if db_name:
        args["database"] = db_name

    if session_type == "REDIS":
        return RedisTimeoutSession(user, passwd, EXPIRATION_SEC)
    elif session_type == "MYSQL":
        return MysqlTimeoutSession(user, passwd, EXPIRATION_SEC, **args)
    elif session_type == "SQLITE":
        args.setdefault("database", "/var/local/lib/jwebmail/jwebmail.sqlite3")
        return SqliteTimeoutSession(user, passwd, EXPIRATION_SEC, **args)
    else:
        raise ValueError(f"unknown session_type {session_type!r}")


def build_qma(username, password):
    authenticator = current_app.config["JWEBMAIL"]["READ_MAILS"]["AUTHENTICATOR"]
    backend = current_app.config["JWEBMAIL"]["READ_MAILS"]["BACKEND"]
    mailbox = current_app.config["JWEBMAIL"]["READ_MAILS"]["MAILBOX"]
    mailbox_user = current_app.config["JWEBMAIL"]["READ_MAILS"]["MAILBOX_USER"]

    return QMailAuthuser(
        username, password, backend, mailbox, mailbox_user, authenticator
    )


def login(username, password):
    return build_qma(username, password).verify_user()


def add_user(user: JWebmailUser):
    r = select_timeout_session()
    r.set(user.get_id(), user.password)
    r.close()


def load_user(username: str) -> JWebmailUser:
    r = select_timeout_session()
    passwd = r.get(username)
    r.close()
    if passwd is None:
        return None
    return JWebmailUser(username, passwd)


def get_read_mails_logged_in():
    if "read_mails" in g:
        return g.read_mails

    qma = build_qma(current_user.get_id(), current_user.password)
    g.read_mails = qma
    return qma