package sql

import (
	"context"
	"fmt"

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

// SQLiteDriver implements the Driver interface for SQLite
type SQLiteDriver struct{}

func (d *SQLiteDriver) Name() string {
	return "sqlite"
}

func (d *SQLiteDriver) Open(dsn string) (Connection, error) {
	conn, err := sqlite.OpenConn(dsn, sqlite.OpenReadWrite|sqlite.OpenCreate)
	if err != nil {
		return nil, fmt.Errorf("sqlite: failed to open database: %w", err)
	}

	return &SQLiteConnection{conn: conn}, nil
}

// SQLiteConnection implements the Connection interface
type SQLiteConnection struct {
	conn *sqlite.Conn
}

func (c *SQLiteConnection) Close() error {
	return c.conn.Close()
}

func (c *SQLiteConnection) Ping(ctx context.Context) error {
	return sqlitex.ExecuteTransient(c.conn, "SELECT 1", nil)
}

func (c *SQLiteConnection) Begin(ctx context.Context) (Transaction, error) {
	if err := sqlitex.ExecuteTransient(c.conn, "BEGIN", nil); err != nil {
		return nil, fmt.Errorf("sqlite: failed to begin transaction: %w", err)
	}
	return &SQLiteTransaction{conn: c.conn}, nil
}

func (c *SQLiteConnection) Query(ctx context.Context, query string, args ...any) (Rows, error) {
	stmt, err := c.conn.Prepare(query)
	if err != nil {
		return nil, fmt.Errorf("sqlite: failed to prepare query: %w", err)
	}

	if err := c.bindArgs(stmt, args...); err != nil {
		stmt.Finalize()
		return nil, err
	}

	return &SQLiteRows{stmt: stmt, hasNext: true}, nil
}

func (c *SQLiteConnection) QueryRow(ctx context.Context, query string, args ...any) Row {
	rows, err := c.Query(ctx, query, args...)
	if err != nil {
		return &SQLiteRow{err: err}
	}
	return &SQLiteRow{rows: rows.(*SQLiteRows)}
}

func (c *SQLiteConnection) Exec(ctx context.Context, query string, args ...any) (Result, error) {
	stmt, err := c.conn.Prepare(query)
	if err != nil {
		return nil, fmt.Errorf("sqlite: failed to prepare statement: %w", err)
	}
	defer stmt.Finalize()

	if err := c.bindArgs(stmt, args...); err != nil {
		return nil, err
	}

	hasRow, err := stmt.Step()
	if err != nil {
		return nil, fmt.Errorf("sqlite: failed to execute statement: %w", err)
	}

	// Consume all rows if any
	for hasRow {
		hasRow, err = stmt.Step()
		if err != nil {
			return nil, fmt.Errorf("sqlite: error stepping through results: %w", err)
		}
	}

	return &SQLiteResult{
		lastInsertID: c.conn.LastInsertRowID(),
		rowsAffected: c.conn.Changes(),
	}, nil
}

func (c *SQLiteConnection) Prepare(ctx context.Context, query string) (Statement, error) {
	stmt, err := c.conn.Prepare(query)
	if err != nil {
		return nil, fmt.Errorf("sqlite: failed to prepare statement: %w", err)
	}
	return &SQLiteStatement{stmt: stmt, conn: c.conn}, nil
}

func (c *SQLiteConnection) bindArgs(stmt *sqlite.Stmt, args ...any) error {
	for i, arg := range args {
		paramIndex := i + 1

		if arg == nil {
			stmt.BindNull(paramIndex)
			continue
		}

		switch v := arg.(type) {
		case int:
			stmt.BindInt64(paramIndex, int64(v))
		case int64:
			stmt.BindInt64(paramIndex, v)
		case float64:
			stmt.BindFloat(paramIndex, v)
		case string:
			stmt.BindText(paramIndex, v)
		case bool:
			if v {
				stmt.BindInt64(paramIndex, 1)
			} else {
				stmt.BindInt64(paramIndex, 0)
			}
		case []byte:
			stmt.BindBytes(paramIndex, v)
		default:
			return fmt.Errorf("sqlite: unsupported parameter type: %T", arg)
		}
	}
	return nil
}

// SQLiteTransaction implements the Transaction interface
type SQLiteTransaction struct {
	conn *sqlite.Conn
}

func (t *SQLiteTransaction) Commit() error {
	return sqlitex.ExecuteTransient(t.conn, "COMMIT", nil)
}

func (t *SQLiteTransaction) Rollback() error {
	return sqlitex.ExecuteTransient(t.conn, "ROLLBACK", nil)
}

func (t *SQLiteTransaction) Query(ctx context.Context, query string, args ...any) (Rows, error) {
	conn := &SQLiteConnection{conn: t.conn}
	return conn.Query(ctx, query, args...)
}

func (t *SQLiteTransaction) QueryRow(ctx context.Context, query string, args ...any) Row {
	conn := &SQLiteConnection{conn: t.conn}
	return conn.QueryRow(ctx, query, args...)
}

func (t *SQLiteTransaction) Exec(ctx context.Context, query string, args ...any) (Result, error) {
	conn := &SQLiteConnection{conn: t.conn}
	return conn.Exec(ctx, query, args...)
}

func (t *SQLiteTransaction) Prepare(ctx context.Context, query string) (Statement, error) {
	conn := &SQLiteConnection{conn: t.conn}
	return conn.Prepare(ctx, query)
}

// SQLiteRows implements the Rows interface
type SQLiteRows struct {
	stmt    *sqlite.Stmt
	hasNext bool
	err     error
}

func (r *SQLiteRows) Next() bool {
	if r.err != nil {
		return false
	}

	if !r.hasNext {
		return false
	}

	var err error
	r.hasNext, err = r.stmt.Step()
	if err != nil {
		r.err = err
		return false
	}

	return r.hasNext
}

func (r *SQLiteRows) Scan(dest ...any) error {
	if r.err != nil {
		return r.err
	}

	for i, d := range dest {
		if i >= r.stmt.ColumnCount() {
			break
		}

		switch ptr := d.(type) {
		case *any:
			*ptr = r.getValue(i)
		case *string:
			*ptr = r.stmt.ColumnText(i)
		case *int:
			*ptr = int(r.stmt.ColumnInt64(i))
		case *int64:
			*ptr = r.stmt.ColumnInt64(i)
		case *float64:
			*ptr = r.stmt.ColumnFloat(i)
		case *bool:
			*ptr = r.stmt.ColumnInt64(i) != 0
		case *[]byte:
			if r.stmt.ColumnType(i) == sqlite.TypeBlob {
				// Get blob size first
				size := r.stmt.ColumnBytes(i, nil)
				if size == 0 {
					*ptr = []byte{}
				} else {
					buf := make([]byte, size)
					r.stmt.ColumnBytes(i, buf)
					*ptr = buf
				}
			} else {
				// Convert text to bytes
				*ptr = []byte(r.stmt.ColumnText(i))
			}
		default:
			return fmt.Errorf("sqlite: unsupported scan destination type: %T", d)
		}
	}

	return nil
}

func (r *SQLiteRows) getValue(index int) any {
	switch r.stmt.ColumnType(index) {
	case sqlite.TypeInteger:
		return r.stmt.ColumnInt64(index)
	case sqlite.TypeFloat:
		return r.stmt.ColumnFloat(index)
	case sqlite.TypeText:
		return r.stmt.ColumnText(index)
	case sqlite.TypeBlob:
		// For blob columns, we need to handle this differently
		// First, get the size by calling with nil buffer
		size := r.stmt.ColumnBytes(index, nil)
		if size == 0 {
			return []byte{}
		}
		// Now allocate buffer and get the actual data
		buf := make([]byte, size)
		r.stmt.ColumnBytes(index, buf)
		return buf
	case sqlite.TypeNull:
		return nil
	default:
		return r.stmt.ColumnText(index)
	}
}

func (r *SQLiteRows) Columns() ([]string, error) {
	if r.err != nil {
		return nil, r.err
	}

	columns := make([]string, r.stmt.ColumnCount())
	for i := range columns {
		columns[i] = r.stmt.ColumnName(i)
	}

	return columns, nil
}

func (r *SQLiteRows) Close() error {
	if r.stmt != nil {
		return r.stmt.Finalize()
	}
	return nil
}

func (r *SQLiteRows) Err() error {
	return r.err
}

// SQLiteRow implements the Row interface
type SQLiteRow struct {
	rows *SQLiteRows
	err  error
}

func (r *SQLiteRow) Scan(dest ...any) error {
	if r.err != nil {
		return r.err
	}

	if r.rows == nil {
		return fmt.Errorf("sqlite: no rows available")
	}

	if !r.rows.Next() {
		if r.rows.Err() != nil {
			return r.rows.Err()
		}
		return fmt.Errorf("sqlite: no rows in result set")
	}

	return r.rows.Scan(dest...)
}

// SQLiteResult implements the Result interface
type SQLiteResult struct {
	lastInsertID int64
	rowsAffected int
}

func (r *SQLiteResult) LastInsertId() (int64, error) {
	return r.lastInsertID, nil
}

func (r *SQLiteResult) RowsAffected() (int64, error) {
	return int64(r.rowsAffected), nil
}

// SQLiteStatement implements the Statement interface
type SQLiteStatement struct {
	stmt *sqlite.Stmt
	conn *sqlite.Conn
}

func (s *SQLiteStatement) Close() error {
	return s.stmt.Finalize()
}

func (s *SQLiteStatement) Query(ctx context.Context, args ...any) (Rows, error) {
	conn := &SQLiteConnection{conn: s.conn}
	if err := conn.bindArgs(s.stmt, args...); err != nil {
		return nil, err
	}

	return &SQLiteRows{stmt: s.stmt, hasNext: true}, nil
}

func (s *SQLiteStatement) QueryRow(ctx context.Context, args ...any) Row {
	rows, err := s.Query(ctx, args...)
	if err != nil {
		return &SQLiteRow{err: err}
	}
	return &SQLiteRow{rows: rows.(*SQLiteRows)}
}

func (s *SQLiteStatement) Exec(ctx context.Context, args ...any) (Result, error) {
	conn := &SQLiteConnection{conn: s.conn}
	if err := conn.bindArgs(s.stmt, args...); err != nil {
		return nil, err
	}

	hasRow, err := s.stmt.Step()
	if err != nil {
		return nil, fmt.Errorf("sqlite: failed to execute statement: %w", err)
	}

	// Consume all rows if any
	for hasRow {
		hasRow, err = s.stmt.Step()
		if err != nil {
			return nil, fmt.Errorf("sqlite: error stepping through results: %w", err)
		}
	}

	return &SQLiteResult{
		lastInsertID: s.conn.LastInsertRowID(),
		rowsAffected: s.conn.Changes(),
	}, nil
}