package adlin

import (
	"database/sql"
	_ "github.com/go-sql-driver/mysql"
	"log"
	"os"
	"time"
)

var db *sql.DB

func DSNGenerator() string {
	db_user := "adlin"
	db_password := "adlin"
	db_host := ""
	db_db := "adlin"

	if v, exists := os.LookupEnv("MYSQL_HOST"); exists {
		db_host = v
	}
	if v, exists := os.LookupEnv("MYSQL_PASSWORD"); exists {
		db_password = v
	} else if v, exists := os.LookupEnv("MYSQL_ROOT_PASSWORD"); exists {
		db_user = "root"
		db_password = v
	}
	if v, exists := os.LookupEnv("MYSQL_USER"); exists {
		db_user = v
	}
	if v, exists := os.LookupEnv("MYSQL_DATABASE"); exists {
		db_db = v
	}

	return db_user + ":" + db_password + "@" + db_host + "/" + db_db
}

func DBInit(dsn string) (err error) {
	if db, err = sql.Open("mysql", dsn+"?parseTime=true&foreign_key_checks=1"); err != nil {
		return
	}

	_, err = db.Exec(`SET SESSION sql_mode = 'STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';`)
	for i := 0; err != nil && i < 5; i += 1 {
		if _, err = db.Exec(`SET SESSION sql_mode = 'STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';`); err != nil && i <= 5 {
			log.Println("An error occurs when trying to connect to DB, will retry in 2 seconds: ", err)
			time.Sleep(2 * time.Second)
		}
	}

	return
}

func DBCreate() (err error) {
	if _, err = db.Exec(`
CREATE TABLE IF NOT EXISTS students(
  id_student INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
  login VARCHAR(255) NOT NULL UNIQUE,
  time TIMESTAMP NOT NULL,
  associatedDomain VARCHAR(255) UNIQUE,
  delegatedDomain VARCHAR(255) UNIQUE
) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
`); err != nil {
		return
	}
	if _, err = db.Exec(`
CREATE TABLE IF NOT EXISTS student_keys(
  id_key INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
  id_student INTEGER NOT NULL,
  sshkey TEXT,
  time TIMESTAMP NOT NULL,
  FOREIGN KEY(id_student) REFERENCES students(id_student)
) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
`); err != nil {
		return
	}
	if _, err := db.Exec(`
CREATE TABLE IF NOT EXISTS student_login(
  id_student INTEGER NOT NULL,
  ip VARCHAR(255) NOT NULL,
  mac VARCHAR(255) NOT NULL,
  time TIMESTAMP NOT NULL,
  FOREIGN KEY(id_student) REFERENCES students(id_student)
) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
`); err != nil {
		return err
	}
	if _, err := db.Exec(`
CREATE TABLE IF NOT EXISTS student_challenges(
  id_st INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
  id_student INTEGER NOT NULL,
  challenge INTEGER NOT NULL,
  time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  value VARCHAR(255) NOT NULL,
  CONSTRAINT token_found UNIQUE (id_student,challenge),
  FOREIGN KEY(id_student) REFERENCES students(id_student)
) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
`); err != nil {
		return err
	}
	if _, err := db.Exec(`
CREATE TABLE IF NOT EXISTS student_challenge_errors(
  id_st INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
  id_student INTEGER NOT NULL,
  challenge INTEGER NOT NULL,
  time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  error VARCHAR(255) NOT NULL,
  CONSTRAINT token_found UNIQUE (id_student,challenge),
  FOREIGN KEY(id_student) REFERENCES students(id_student)
) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
`); err != nil {
		return err
	}
	if _, err := db.Exec(`
CREATE TABLE IF NOT EXISTS student_pong(
  id_student INTEGER NOT NULL,
  last TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  count INTEGER UNSIGNED DEFAULT 1,
  state BOOLEAN NOT NULL DEFAULT 0,
  CONSTRAINT one_pong UNIQUE (id_student,state),
  FOREIGN KEY(id_student) REFERENCES students(id_student)
) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
`); err != nil {
		return err
	}
	if _, err := db.Exec(`
CREATE TABLE IF NOT EXISTS student_sessions(
  id_session BLOB(255) NOT NULL,
  id_student INTEGER,
  time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  FOREIGN KEY(id_student) REFERENCES students(id_student)
) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
`); err != nil {
		return err
	}
	if _, err := db.Exec(`
CREATE TABLE IF NOT EXISTS student_tunnel_tokens(
  token BLOB(255) NOT NULL,
  token_text CHAR(10) NOT NULL,
  id_student INTEGER NOT NULL,
  time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  pubkey BLOB(50) DEFAULT NULL,
  suffixip INTEGER NOT NULL,
  version INTEGER NOT NULL,
  FOREIGN KEY(id_student) REFERENCES students(id_student)
) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
`); err != nil {
		return err
	}
	return
}

func DBClose() error {
	return db.Close()
}

func DBPrepare(query string) (*sql.Stmt, error) {
	return db.Prepare(query)
}

func DBQuery(query string, args ...interface{}) (*sql.Rows, error) {
	return db.Query(query, args...)
}

func DBExec(query string, args ...interface{}) (sql.Result, error) {
	return db.Exec(query, args...)
}

func DBQueryRow(query string, args ...interface{}) *sql.Row {
	return db.QueryRow(query, args...)
}