//
//  rhimportd
//
//  The Radio Helsinki Rivendell Import Daemon
//
//
//  Copyright (C) 2015 Christian Pointner <equinox@helsinki.at>
//
//  This file is part of rhimportd.
//
//  rhimportd is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  any later version.
//
//  rhimportd is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with rhimportd. If not, see <http://www.gnu.org/licenses/>.
//

package rhimport

import (
	"database/sql"
	"fmt"
	_ "github.com/go-sql-driver/mysql"
)

type getPasswordResult struct {
	password string
	err      error
}

type getPasswordRequest struct {
	username string
	cached   bool
	response chan getPasswordResult
}

type RDDB struct {
	dbh               *sql.DB
	password_cache    map[string]string
	getPasswordChan   chan getPasswordRequest
	dbGetPasswordStmt *sql.Stmt
	quit              chan bool
	done              chan bool
}

func (self *RDDB) init(conf *Config) (err error) {
	dsn := fmt.Sprintf("%s:%s@tcp(%s:3306)/%s", conf.db_user, conf.db_passwd, conf.db_host, conf.db_db)
	if self.dbh, err = sql.Open("mysql", dsn); err != nil {
		return
	}
	if self.dbGetPasswordStmt, err = self.dbh.Prepare("select PASSWORD from USERS where LOGIN_NAME = ?"); err != nil {
		return
	}

	return
}

func (self *RDDB) getPassword(username string, cached bool) (pwd string, err error) {

	if cached {
		pwd = self.password_cache[username]
	}

	if pwd == "" {
		err = self.dbGetPasswordStmt.QueryRow(username).Scan(&pwd)
		if err != nil {
			if err == sql.ErrNoRows {
				err = fmt.Errorf("user '%s' not known by rivendell", username)
			}
			return
		}
		self.password_cache[username] = pwd
	}

	return
}

func (self *RDDB) dispatchRequests() {
	defer func() { self.done <- true }()
	for {
		select {
		case <-self.quit:
			return
		case req := <-self.getPasswordChan:
			if req.cached {
				rhdl.Println("RDDB: got getPassword request for", req.username, "(cached)")
			} else {
				rhdl.Println("RDDB: got getPassword request for", req.username, "(not cached)")
			}
			pwd, err := self.getPassword(req.username, req.cached)
			req.response <- getPasswordResult{pwd, err}
		}
	}
}

func (self *RDDB) Cleanup() {
	self.quit <- true
	<-self.done
	close(self.quit)
	close(self.done)
	close(self.getPasswordChan)
	if self.dbh != nil {
		self.dbh.Close()
	}
	if self.dbGetPasswordStmt != nil {
		self.dbGetPasswordStmt.Close()
	}
}

func NewRDDB(conf *Config) (db *RDDB, err error) {
	db = new(RDDB)

	db.quit = make(chan bool)
	db.done = make(chan bool)
	db.password_cache = make(map[string]string)
	db.getPasswordChan = make(chan getPasswordRequest)

	if err = db.init(conf); err != nil {
		return
	}

	go db.dispatchRequests()
	return
}