// Package database provides database functionality
package database

import (
	"errors"
	"fmt"
)

// Common database error types
var (
	// ErrInvalidConfig indicates missing or invalid database configuration
	ErrInvalidConfig = errors.New("invalid database configuration")

	// ErrConnectionFailed indicates failure to connect to the database
	ErrConnectionFailed = errors.New("failed to connect to database")

	// ErrQueryFailed indicates a query execution failure
	ErrQueryFailed = errors.New("query execution failed")

	// ErrTransactionFailed indicates a transaction operation failure
	ErrTransactionFailed = errors.New("transaction operation failed")

	// ErrMigrationFailed indicates a database migration failure
	ErrMigrationFailed = errors.New("database migration failed")

	// ErrPragmaFailed indicates failure to set database pragma
	ErrPragmaFailed = errors.New("failed to set database pragma")

	// ErrInvalidPath indicates an invalid database file path
	ErrInvalidPath = errors.New("invalid database path")

	// ErrDatabaseLocked indicates the database is locked
	ErrDatabaseLocked = errors.New("database is locked")

	// ErrNoRows indicates no rows were found
	ErrNoRows = errors.New("no rows found")

	// ErrDuplicateKey indicates a unique constraint violation
	ErrDuplicateKey = errors.New("duplicate key violation")
)

// Error represents a database-specific error with detailed context
type Error struct {
	// Op is the operation that failed (e.g., "connect", "query", "migrate")
	Op string

	// Query is the SQL query that failed (if applicable)
	Query string

	// Err is the underlying error
	Err error

	// Details contains additional error context
	Details string
}

// Error returns a string representation of the error
func (e *Error) Error() string {
	msg := fmt.Sprintf("database %s failed", e.Op)
	if e.Query != "" {
		// Truncate long queries in the error message
		const maxQueryLen = 100
		query := e.Query
		if len(query) > maxQueryLen {
			query = query[:maxQueryLen] + "..."
		}
		msg = fmt.Sprintf("%s for query %q", msg, query)
	}
	if e.Details != "" {
		msg = fmt.Sprintf("%s: %s", msg, e.Details)
	}
	if e.Err != nil {
		msg = fmt.Sprintf("%s: %v", msg, e.Err)
	}
	return msg
}

// Unwrap returns the underlying error
func (e *Error) Unwrap() error {
	return e.Err
}

// Is reports whether target matches this error
func (e *Error) Is(target error) bool {
	return errors.Is(e.Err, target)
}

// NewError creates a new database error
func NewError(op string, err error, details string) *Error {
	return &Error{
		Op:      op,
		Err:     err,
		Details: details,
	}
}

// NewQueryError creates a new database error with query context
func NewQueryError(op string, query string, err error, details string) *Error {
	return &Error{
		Op:      op,
		Query:   query,
		Err:     err,
		Details: details,
	}
}

// IsLockError returns true if the error indicates a database lock
func IsLockError(err error) bool {
	var e *Error
	return errors.As(err, &e) && errors.Is(e.Err, ErrDatabaseLocked)
}

// IsNotFoundError returns true if the error indicates no rows were found
func IsNotFoundError(err error) bool {
	var e *Error
	return errors.As(err, &e) && errors.Is(e.Err, ErrNoRows)
}

// IsDuplicateError returns true if the error indicates a duplicate key
func IsDuplicateError(err error) bool {
	var e *Error
	return errors.As(err, &e) && errors.Is(e.Err, ErrDuplicateKey)
}