package repository

import (
	"database/sql"
	"errors"
	"fmt"
	models "vibeStonk/server/models/v1"
)

var (
	ErrTransactionNotFound = errors.New("transaction not found")
)

func newSqliteTransactionRepo(db *sql.DB) (TransactionRepo, error) {
	repo := &sqliteTransactionRepo{db: db}
	if err := repo.initialize(); err != nil {
		return nil, err
	}
	return repo, nil
}

type sqliteTransactionRepo struct {
	db *sql.DB
}

// initialize creates the transactions table if it doesn't exist
func (s *sqliteTransactionRepo) initialize() error {
	query := `
	CREATE TABLE IF NOT EXISTS transactions (
		id INTEGER PRIMARY KEY AUTOINCREMENT,
		purchase_id INTEGER NOT NULL,
		sale_id INTEGER NOT NULL,
		qty REAL NOT NULL,
		FOREIGN KEY (purchase_id) REFERENCES purchases(id),
		FOREIGN KEY (sale_id) REFERENCES sales(id)
	);
	`
	_, err := s.db.Exec(query)
	if err != nil {
		return fmt.Errorf("failed to create transactions table: %w", err)
	}

	query = `
	CREATE INDEX IF NOT EXISTS transactions_foreign_id
	ON transactions(purchase_id, sale_id);
	`
	_, err = s.db.Exec(query)
	if err != nil {
		return fmt.Errorf("failed to create purchase_id index for transactions table: %w", err)
	}

	return nil
}

func (s *sqliteTransactionRepo) Create(transaction *models.Transaction) (*models.Transaction, error) {
	query := `
	INSERT INTO transactions (purchase_id, sale_id, qty)
	VALUES (?, ?, ?)
	`
	result, err := s.db.Exec(query, transaction.PurchaseID, transaction.SaleID, transaction.Qty)
	if err != nil {
		return nil, fmt.Errorf("failed to create transaction: %w", err)
	}

	id, err := result.LastInsertId()
	if err != nil {
		return nil, fmt.Errorf("failed to get last insert ID: %w", err)
	}

	transaction.Id = id
	return transaction, nil
}

func (s *sqliteTransactionRepo) Get(id int64) (*models.Transaction, error) {
	query := `
	SELECT id, purchase_id, sale_id, qty
	FROM transactions
	WHERE id = ?
	`
	row := s.db.QueryRow(query, id)

	transaction := &models.Transaction{}
	err := row.Scan(&transaction.Id, &transaction.PurchaseID, &transaction.SaleID, &transaction.Qty)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrTransactionNotFound
		}
		return nil, fmt.Errorf("failed to get transaction: %w", err)
	}

	return transaction, nil
}

func (s *sqliteTransactionRepo) GetByPurchaseID(purchaseID int64) ([]*models.Transaction, error) {
	query := `
	SELECT id, purchase_id, sale_id, qty
	FROM transactions
	WHERE purchase_id = ?
	`
	rows, err := s.db.Query(query, purchaseID)
	if err != nil {
		return nil, fmt.Errorf("failed to get transactions by purchase ID: %w", err)
	}
	defer rows.Close()

	var transactions []*models.Transaction
	for rows.Next() {
		transaction := &models.Transaction{}
		err := rows.Scan(&transaction.Id, &transaction.PurchaseID, &transaction.SaleID, &transaction.Qty)
		if err != nil {
			return nil, fmt.Errorf("failed to scan transaction row: %w", err)
		}
		transactions = append(transactions, transaction)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating transaction rows: %w", err)
	}

	return transactions, nil
}

func (s *sqliteTransactionRepo) GetBySaleID(saleID int64) ([]*models.Transaction, error) {
	query := `
	SELECT id, purchase_id, sale_id, qty
	FROM transactions
	WHERE sale_id = ?
	`
	rows, err := s.db.Query(query, saleID)
	if err != nil {
		return nil, fmt.Errorf("failed to get transactions by sale ID: %w", err)
	}
	defer rows.Close()

	var transactions []*models.Transaction
	for rows.Next() {
		transaction := &models.Transaction{}
		err := rows.Scan(&transaction.Id, &transaction.PurchaseID, &transaction.SaleID, &transaction.Qty)
		if err != nil {
			return nil, fmt.Errorf("failed to scan transaction row: %w", err)
		}
		transactions = append(transactions, transaction)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating transaction rows: %w", err)
	}

	return transactions, nil
}

func (s *sqliteTransactionRepo) DeleteBySaleID(saleID int64) error {
	query := `
	DELETE FROM transactions
	WHERE sale_id = ?
	`
	result, err := s.db.Exec(query, saleID)
	if err != nil {
		return fmt.Errorf("failed to delete transaction: %w", err)
	}

	rowsAffected, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("failed to get rows affected: %w", err)
	}

	if rowsAffected == 0 {
		return ErrTransactionNotFound
	}

	return nil
}

func (s *sqliteTransactionRepo) List() ([]*models.Transaction, error) {
	query := `
	SELECT id, purchase_id, sale_id, qty
	FROM transactions
	`
	rows, err := s.db.Query(query)
	if err != nil {
		return nil, fmt.Errorf("failed to list transactions: %w", err)
	}
	defer rows.Close()

	var transactions []*models.Transaction
	for rows.Next() {
		transaction := &models.Transaction{}
		err := rows.Scan(&transaction.Id, &transaction.PurchaseID, &transaction.SaleID, &transaction.Qty)
		if err != nil {
			return nil, fmt.Errorf("failed to scan transaction row: %w", err)
		}
		transactions = append(transactions, transaction)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating transaction rows: %w", err)
	}

	return transactions, nil
}