package main

import (
	"database/sql"
	"fmt"
	"log"

	_ "github.com/mattn/go-sqlite3"
)

var db *sql.DB

type Album struct {
	ID     int64
	Title  string
	Artist string
	Price  float32
}
type Test_counter struct {
	ID      int64
	Counter int64
}

func main() {
	var err error
	db, err = sql.Open("sqlite3", "./db.sqlite3")
	if err != nil {
		log.Fatal(err)
	}
	pErr := db.Ping()
	if pErr != nil {
		log.Fatal(pErr)
	}
	fmt.Println("Connected!")

	count, err := counterIncrement()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println("You are visitor #", count)

	albums, err := albumsByArtist("John Coltrane")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("Albums found: %v\n", albums)
}

func counterIncrement() (int64, error) {
	_, err := db.Exec("UPDATE `test_counter` SET `counter` = `counter`+1 WHERE `id` = 0")
	if err != nil {
		return 0, fmt.Errorf("counterIncrement: %v", err)
	}

	var count int64
	row := db.QueryRow("SELECT counter FROM test_counter WHERE id = 0")
	if err := row.Scan(&count); err != nil {
		if err == sql.ErrNoRows {
			return count, fmt.Errorf("counterIncrement: NO COUNTER")
		}
		return count, fmt.Errorf("counterIncrement: %v", err)
	}
	return count, nil
}

func albumsByArtist(name string) ([]Album, error) {
	var albums []Album

	rows, err := db.Query("SELECT * FROM album WHERE artist = ?", name)
	if err != nil {
		return nil, fmt.Errorf("albumbsByArtist %q: %v", name, err)
	}
	defer rows.Close()
	for rows.Next() {
		var alb Album
		if err := rows.Scan(&alb.ID, &alb.Title, &alb.Artist, &alb.Price); err != nil {
			return nil, fmt.Errorf("albumbsByArtist %q: %v", name, err)
		}
		albums = append(albums, alb)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("albumbsByArtist %q: %v", name, err)
	}
	return albums, nil
}