package database

import (
	"fmt"
	"log"
	"os"
	"path"
	"time"

	"git.phc.dm.unipi.it/phc/website/util"
	"github.com/jmoiron/sqlx"
	_ "github.com/mattn/go-sqlite3"
)

type migration struct {
	Timestamp string
	Filename  string
}

type sqliteDB struct {
	*sqlx.DB
}

func (db *sqliteDB) Migrate(migrationFolder string) error {
	log.Printf(`Creating migrations table`)
	if _, err := db.Exec(`CREATE TABLE IF NOT EXISTS migrations(timestamp TEXT, filename TEXT)`); err != nil {
		return err
	}

	log.Printf(`Loading applied migrations`)
	appliedMigrations := []migration{}
	if err := db.Select(&appliedMigrations, `SELECT * FROM migrations`); err != nil {
		return err
	}

	entries, err := os.ReadDir(migrationFolder)
	if err != nil {
		return err
	}

	for i, entry := range entries {
		if entry.IsDir() {
			return fmt.Errorf("no dirs in migrations folder")
		}

		if i < len(appliedMigrations) {
			if appliedMigrations[i].Filename != entry.Name() {
				return fmt.Errorf("misapplied migration %q with %q", appliedMigrations[i].Filename, entry.Name())
			}

			log.Printf("Found applied migration %q", entry.Name())
			continue
		}

		log.Printf("Applying new migration %q", entry.Name())

		migrationPath := path.Join(migrationFolder, entry.Name())

		sqlStmts, err := os.ReadFile(migrationPath)
		if err != nil {
			return err
		}

		tx, err := db.Beginx()
		if err != nil {
			return err
		}

		if _, err := tx.Exec(string(sqlStmts)); err != nil {
			return err
		}

		if _, err := tx.Exec(`INSERT INTO migrations VALUES (?, ?)`,
			time.Now().Format(time.RFC3339),
			entry.Name(),
		); err != nil {
			return err
		}

		if err := tx.Commit(); err != nil {
			return err
		}
	}

	log.Printf("All migrations applied successfully, database up to date")

	return nil
}

func (db *sqliteDB) CreateDispensa(template Dispensa) (string, error) {
	template.Id = "dispensa/" + util.GenerateRandomString(8)
	template.CreatedAt = time.Now().Format(time.RFC3339)

	if _, err := db.NamedExec(`
		INSERT INTO 
			dispense(id, created_at, owner_id, title, description) 
		VALUES 
			(:id, :created_at, :owner_id, :title, :description)
	`, &template); err != nil {
		return "", err
	}

	return template.Id, nil
}

func (db *sqliteDB) GetDispensa(id string) (Dispensa, error) {
	var dispensa Dispensa
	if err := db.Get(&dispensa, `SELECT * FROM dispense WHERE id = ?`, id); err != nil {
		return Dispensa{}, err
	}

	return dispensa, nil
}

func (db *sqliteDB) AllDispense() ([]Dispensa, error) {
	var dispense []Dispensa
	if err := db.Select(&dispense, `SELECT * FROM dispense`); err != nil {
		return nil, err
	}

	return dispense, nil
}

func (db *sqliteDB) UpdateDispensa(d Dispensa) error {
	if _, err := db.NamedExec(`
		UPDATE 
			dispense
		SET 
			owner_id = :owner_id
		   	title = :title,
		    description = :description
		WHERE 
			id = :id
	`, &d); err != nil {
		return err
	}

	return nil
}

func (db *sqliteDB) DeleteDispensa(id string) error {
	panic("TODO: Not implemented")
}

func (db *sqliteDB) CreateUpload(template Upload) (string, error) {
	template.Id = "upload/" + util.GenerateRandomString(8)

	if _, err := db.NamedExec(`
		INSERT INTO 
			uploads(id, created_at, owner_id, dispensa_id, file) 
		VALUES 
			(:id, :created_at, :owner_id, :dispensa_id, :file)
	`, &template); err != nil {
		return "", err
	}

	return template.Id, nil
}

func (db *sqliteDB) GetUpload(id string) (Upload, error) {
	var upload Upload
	if err := db.Select(`SELECT * FROM uploads WHERE id = ?`, id); err != nil {
		return Upload{}, err
	}

	return upload, nil
}

func NewSqlite3Database(filename string) (*DB, error) {
	sqlDB, err := sqlx.Open("sqlite3", filename+"?_fk=1")
	if err != nil {
		panic(err)
	}

	if err := sqlDB.Ping(); err != nil {
		return nil, err
	}

	db := &sqliteDB{sqlDB}

	// in this case the type "sqliteDB" implements all the interfaces declared in "database.DB" so we can pass "db" to all the fields.
	return &DB{
		DBMigrate:  db,
		DBDispense: db,
		DBUploads:  db,
	}, nil
}