package model

import (
	"fmt"
	"log"

	"golang.org/x/crypto/bcrypt"
)

func (db *DB) AddUser(user *User, pass string) error {
	hashedPass, err := bcrypt.GenerateFromPassword([]byte(pass), bcrypt.DefaultCost)
	if err != nil {
		return fmt.Errorf("error creating password hash: %v", err)
	}

	query := `
    INSERT INTO users
        (username, password, first_name, last_name, role)
    VALUES (?, ?, ?, ?, ?)
    `
	if _, err = db.Exec(query, user.UserName, string(hashedPass), user.FirstName, user.LastName, user.Role); err != nil {
		return fmt.Errorf("error inserting user into DB: %v", err)
	}

	return nil
}

func (db *DB) GetID(userName string) (int64, error) {
	var id int64

	query := `
    SELECT id
    FROM users
    WHERE username = ?
    `
	row := db.QueryRow(query, userName)
	if err := row.Scan(&id); err != nil {
		return 0, fmt.Errorf("user not in DB: %v", err)
	}

	return id, nil
}

func (db *DB) CheckPassword(id int64, pass string) error {
	var queriedPass string

	query := `
    SELECT password
    FROM users
    WHERE id = ?
    `
	row := db.QueryRow(query, id)
	if err := row.Scan(&queriedPass); err != nil {
		return fmt.Errorf("error reading password from DB: %v", err)
	}

	if err := bcrypt.CompareHashAndPassword([]byte(queriedPass), []byte(pass)); err != nil {
		return fmt.Errorf("incorrect password: %v", err)
	}

	return nil
}

func (db *DB) ChangePassword(id int64, oldPass, newPass string) error {
	tx, err := db.Begin()
	if err != nil {
		return fmt.Errorf("error starting transaction: %v", err)
	}

	var queriedPass string
	getQuery := `
    SELECT password
    FROM users
    WHERE id = ?
    `
	row := tx.QueryRow(getQuery, id)
	if err := row.Scan(&queriedPass); err != nil {
		if rollbackErr := tx.Rollback(); rollbackErr != nil {
			log.Fatalf("error: transaction error: %v, rollback error: %v", err, rollbackErr)
		}
		return fmt.Errorf("error reading password from DB: %v", err)
	}

	if err := bcrypt.CompareHashAndPassword([]byte(queriedPass), []byte(oldPass)); err != nil {
		if rollbackErr := tx.Rollback(); rollbackErr != nil {
			log.Fatalf("error: transaction error: %v, rollback error: %v", err, rollbackErr)
		}
		return fmt.Errorf("incorrect password: %v", err)
	}

	newHashedPass, err := bcrypt.GenerateFromPassword([]byte(newPass), bcrypt.DefaultCost)
	if err != nil {
		if rollbackErr := tx.Rollback(); rollbackErr != nil {
			log.Fatalf("error: transaction error: %v, rollback error: %v", err, rollbackErr)
		}
		return fmt.Errorf("error creating password hash: %v", err)
	}

	setQuery := `
    UPDATE users
    SET password = ?
    WHERE id = ?
    `
	if _, err = tx.Exec(setQuery, string(newHashedPass), id); err != nil {
		if rollbackErr := tx.Rollback(); rollbackErr != nil {
			log.Fatalf("error: transaction error: %v, rollback error: %v", err, rollbackErr)
		}
		return fmt.Errorf("error updating password in DB: %v", err)
	}

	if err = tx.Commit(); err != nil {
		return fmt.Errorf("error committing transaction: %v", err)
	}

	return nil
}

// TODO: No need for ID field in general
func (db *DB) GetUser(id int64) (*User, error) {
	user := new(User)
	query := `
    SELECT id, username, first_name, last_name, role
    FROM users
    WHERE id = ?
    `

	row := db.QueryRow(query, id)
	if err := row.Scan(&user.ID, &user.UserName, &user.FirstName, &user.LastName, &user.Role); err != nil {
		return nil, fmt.Errorf("error reading user information: %v", err)
	}

	return user, nil
}