package adapter

import (
	"context"
	"database/sql"
)

// DBAdapter defines the interface for database operations
type DBAdapter interface {
	// Connect establishes a connection to the database
	Connect(ctx context.Context) error

	// Close closes the database connection
	Close() error

	// Ping checks if the database is reachable
	Ping(ctx context.Context) error

	// Begin starts a new transaction
	Begin(ctx context.Context) (DBTransaction, error)

	// Exec executes a query without returning rows
	Exec(ctx context.Context, query string, args ...interface{}) (sql.Result, error)

	// QueryRow executes a query that returns at most one row
	QueryRow(ctx context.Context, query string, args ...interface{}) DBRow

	// Query executes a query that returns rows
	Query(ctx context.Context, query string, args ...interface{}) (DBRows, error)

	// Listen starts listening on a PostgreSQL notification channel
	Listen(ctx context.Context, channel string, handler NotificationHandler) error

	// Unlisten stops listening on a channel
	Unlisten(ctx context.Context, channel string) error
}

// DBTransaction defines the interface for database transactions
type DBTransaction interface {
	// Exec executes a query within the transaction
	Exec(ctx context.Context, query string, args ...interface{}) (sql.Result, error)

	// QueryRow executes a query that returns at most one row within the transaction
	QueryRow(ctx context.Context, query string, args ...interface{}) DBRow

	// Query executes a query that returns rows within the transaction
	Query(ctx context.Context, query string, args ...interface{}) (DBRows, error)

	// Commit commits the transaction
	Commit() error

	// Rollback rolls back the transaction
	Rollback() error
}

// DBRow defines the interface for scanning a single row
type DBRow interface {
	Scan(dest ...interface{}) error
}

// DBRows defines the interface for scanning multiple rows
type DBRows interface {
	Next() bool
	Scan(dest ...interface{}) error
	Close() error
	Err() error
}

// Notification represents a PostgreSQL NOTIFY event
type Notification struct {
	Channel string
	Payload string
	PID     int
}

// NotificationHandler is called when a notification is received
type NotificationHandler func(notification *Notification)