package database

import (
	"fmt"

	"zombiezen.com/go/sqlite"
	"zombiezen.com/go/sqlite/sqlitex"
)

// DB wraps sqlite.Conn with simplified query methods
type DB struct {
	conn *sqlite.Conn
}

// Row represents a single database row with easy column access
type Row struct {
	stmt *sqlite.Stmt
}

// QueryFunc processes each row in a result set
type QueryFunc func(*Row) error

// Open creates a new database connection with common settings
func Open(path string) (*DB, error) {
	conn, err := sqlite.OpenConn(path, sqlite.OpenReadWrite|sqlite.OpenCreate)
	if err != nil {
		return nil, fmt.Errorf("failed to open database: %w", err)
	}

	// Enable foreign keys and WAL mode for better performance
	if err := sqlitex.ExecuteTransient(conn, "PRAGMA foreign_keys = ON", nil); err != nil {
		conn.Close()
		return nil, fmt.Errorf("failed to enable foreign keys: %w", err)
	}

	if err := sqlitex.ExecuteTransient(conn, "PRAGMA journal_mode = WAL", nil); err != nil {
		conn.Close()
		return nil, fmt.Errorf("failed to enable WAL mode: %w", err)
	}

	return &DB{conn: conn}, nil
}

// Close closes the database connection
func (db *DB) Close() error {
	return db.conn.Close()
}

// Exec executes a statement with parameters
func (db *DB) Exec(query string, args ...any) error {
	return sqlitex.Execute(db.conn, query, &sqlitex.ExecOptions{
		Args: args,
	})
}

// QueryRow executes a query expecting a single row result
func (db *DB) QueryRow(query string, args ...any) (*Row, error) {
	stmt, err := db.conn.Prepare(query)
	if err != nil {
		return nil, fmt.Errorf("prepare failed: %w", err)
	}

	// Bind parameters
	for i, arg := range args {
		if err := bindParam(stmt, i+1, arg); err != nil {
			stmt.Finalize()
			return nil, err
		}
	}

	hasRow, err := stmt.Step()
	if err != nil {
		stmt.Finalize()
		return nil, fmt.Errorf("query failed: %w", err)
	}
	if !hasRow {
		stmt.Finalize()
		return nil, nil // No row found
	}

	return &Row{stmt: stmt}, nil
}

// Query executes a query and calls fn for each row
func (db *DB) Query(query string, fn QueryFunc, args ...any) error {
	stmt, err := db.conn.Prepare(query)
	if err != nil {
		return fmt.Errorf("prepare failed: %w", err)
	}
	defer stmt.Finalize()

	// Bind parameters
	for i, arg := range args {
		if err := bindParam(stmt, i+1, arg); err != nil {
			return err
		}
	}

	row := &Row{stmt: stmt}
	for {
		hasRow, err := stmt.Step()
		if err != nil {
			return fmt.Errorf("query failed: %w", err)
		}
		if !hasRow {
			break
		}

		if err := fn(row); err != nil {
			return err
		}
	}

	return nil
}

// QuerySlice executes a query and returns all rows in a slice
func (db *DB) QuerySlice(query string, args ...any) ([]*Row, error) {
	var rows []*Row

	stmt, err := db.conn.Prepare(query)
	if err != nil {
		return nil, fmt.Errorf("prepare failed: %w", err)
	}
	defer stmt.Finalize()

	// Bind parameters
	for i, arg := range args {
		if err := bindParam(stmt, i+1, arg); err != nil {
			return nil, err
		}
	}

	for {
		hasRow, err := stmt.Step()
		if err != nil {
			return nil, fmt.Errorf("query failed: %w", err)
		}
		if !hasRow {
			break
		}

		// Create a snapshot of the current row
		rowData := &Row{stmt: stmt}
		rows = append(rows, rowData)
	}

	return rows, nil
}

// LastInsertID returns the last inserted row ID
func (db *DB) LastInsertID() int64 {
	return db.conn.LastInsertRowID()
}

// Changes returns the number of rows affected by the last statement
func (db *DB) Changes() int {
	return db.conn.Changes()
}

// Transaction executes fn within a database transaction
func (db *DB) Transaction(fn func(*DB) error) error {
	if err := sqlitex.ExecuteTransient(db.conn, "BEGIN", nil); err != nil {
		return fmt.Errorf("begin transaction failed: %w", err)
	}

	if err := fn(db); err != nil {
		sqlitex.ExecuteTransient(db.conn, "ROLLBACK", nil)
		return err
	}

	if err := sqlitex.ExecuteTransient(db.conn, "COMMIT", nil); err != nil {
		return fmt.Errorf("commit transaction failed: %w", err)
	}

	return nil
}

// Row column access methods

// Close releases the row's statement
func (r *Row) Close() {
	if r.stmt != nil {
		r.stmt.Finalize()
		r.stmt = nil
	}
}

// Int returns column as int
func (r *Row) Int(col int) int {
	return r.stmt.ColumnInt(col)
}

// Int64 returns column as int64
func (r *Row) Int64(col int) int64 {
	return r.stmt.ColumnInt64(col)
}

// Text returns column as string
func (r *Row) Text(col int) string {
	return r.stmt.ColumnText(col)
}

// Bool returns column as bool (0 = false, non-zero = true)
func (r *Row) Bool(col int) bool {
	return r.stmt.ColumnInt(col) != 0
}

// Float returns column as float64
func (r *Row) Float(col int) float64 {
	return r.stmt.ColumnFloat(col)
}

// IsNull checks if column is NULL
func (r *Row) IsNull(col int) bool {
	return r.stmt.ColumnType(col) == sqlite.TypeNull
}

// bindParam binds a parameter to a statement at the given index
func bindParam(stmt *sqlite.Stmt, index int, value any) error {
	switch v := value.(type) {
	case nil:
		stmt.BindNull(index)
	case int:
		stmt.BindInt64(index, int64(v))
	case int8:
		stmt.BindInt64(index, int64(v))
	case int16:
		stmt.BindInt64(index, int64(v))
	case int32:
		stmt.BindInt64(index, int64(v))
	case int64:
		stmt.BindInt64(index, v)
	case uint:
		stmt.BindInt64(index, int64(v))
	case uint8:
		stmt.BindInt64(index, int64(v))
	case uint16:
		stmt.BindInt64(index, int64(v))
	case uint32:
		stmt.BindInt64(index, int64(v))
	case uint64:
		stmt.BindInt64(index, int64(v))
	case float32:
		stmt.BindFloat(index, float64(v))
	case float64:
		stmt.BindFloat(index, v)
	case bool:
		if v {
			stmt.BindInt64(index, 1)
		} else {
			stmt.BindInt64(index, 0)
		}
	case string:
		stmt.BindText(index, v)
	case []byte:
		stmt.BindBytes(index, v)
	default:
		return fmt.Errorf("unsupported parameter type: %T", value)
	}
	return nil
}