package main

import (
	"database/sql"
	"fmt"

	"g.arns.lt/zordsdavini/abcex"
	_ "github.com/mattn/go-sqlite3"
)

var migrations = []string{}

func connectDB() (*sql.DB, error) {
	db, err := sql.Open("sqlite3", "./main.db")
	if err != nil {
		return db, err
	}

	err = checkPreinstall(db)
	if err != nil {
		return db, err
	}

	return db, nil
}

func checkPreinstall(db *sql.DB) error {
	sqlStmt := `
        CREATE TABLE IF NOT EXISTS Urls (id INTEGER NOT NULL PRIMARY KEY, url TEXT NOT NULL, short_url TEXT NULL);
        CREATE UNIQUE INDEX IF NOT EXISTS url_idx ON Urls (short_url);

        CREATE TABLE IF NOT EXISTS Stats (id INTEGER NOT NULL PRIMARY KEY, name TEXT NOT NULL, count INT, comment TEXT);
        CREATE UNIQUE INDEX IF NOT EXISTS stats_idx ON Stats (name);
        INSERT OR IGNORE INTO Stats (name, count) VALUES ('last_migration', 0);
	`
	_, err := db.Exec(sqlStmt)
	if err != nil {
		return err
	}

	err = runMigrations(db)
	if err != nil {
		return err
	}

	return nil
}

func runMigrations(db *sql.DB) error {
	lastMigration, err := getStatsCounter(db, "last_migration")
	if err != nil {
		return err
	}

	for i := lastMigration; i < len(migrations); i++ {
		sqlStmt := migrations[i]
		_, err := db.Exec(sqlStmt)
		if err != nil {
			return err
		}

		db.Exec("UPDATE Stats SET count=count+1 WHERE name='last_migration';")
	}

	return nil
}

func getStatsCounter(db *sql.DB, name string) (int, error) {
	stmt, err := db.Prepare("SELECT count FROM Stats WHERE name = ?")
	if err != nil {
		return 0, err
	}
	defer stmt.Close()

	var count int
	err = stmt.QueryRow(name).Scan(&count)
	if err != nil {
		return 0, nil
	}

	return count, nil
}

func getStatsComment(db *sql.DB, name string) (string, error) {
	stmt, err := db.Prepare("SELECT comment FROM Stats WHERE name = ?")
	if err != nil {
		return "", err
	}
	defer stmt.Close()

	var comment string
	err = stmt.QueryRow(name).Scan(&comment)
	if err != nil {
		return "", nil
	}

	return comment, nil
}

func getShortUrl(db *sql.DB, url string) string {
	if len(url) == 0 {
		return ""
	}

	fmt.Println(url)
	res, err := db.Exec(
		"INSERT INTO Urls (url) VALUES (?);",
		url,
	)
	if err != nil {
		return ""
	}

	lid, err := res.LastInsertId()
	if err != nil {
		return ""
	}

	shortUrl := abcex.Encode(lid)
	fmt.Println(lid, shortUrl)

	db.Exec(
		"UPDATE Urls SET short_url=? WHERE id=?",
		shortUrl,
		lid,
	)

	return shortUrl
}

func getRedirectUrl(db *sql.DB, shortUrl string) string {
	stmt, err := db.Prepare("SELECT url FROM Urls WHERE short_url = ?")
	if err != nil {
		return ""
	}
	defer stmt.Close()

	var url string
	err = stmt.QueryRow(shortUrl).Scan(&url)
	if err != nil {
		return ""
	}

	return url
}