package face

import "errors"

// Sentinel errors for face operations
var (
	// Client errors
	ErrNoFacesDetected      = errors.New("no faces detected in image")
	ErrImageTooSmall        = errors.New("image too small for face detection")
	ErrImageTooLarge        = errors.New("image exceeds maximum size")
	ErrInvalidImageFormat   = errors.New("invalid image format")
	ErrImageProcessingFailed = errors.New("failed to process image")

	// Collection errors
	ErrCollectionNotFound   = errors.New("face collection not found")
	ErrCollectionExists     = errors.New("face collection already exists")
	ErrCollectionCreationFailed = errors.New("failed to create face collection")

	// Indexing errors
	ErrIndexingFailed       = errors.New("failed to index face")
	ErrFaceAlreadyIndexed   = errors.New("face already indexed")

	// Search errors
	ErrSearchFailed         = errors.New("face search failed")
	ErrNoMatchesFound       = errors.New("no matching faces found")

	// Configuration errors
	ErrMissingRegion        = errors.New("AWS region is required")
	ErrMissingCollectionID  = errors.New("collection ID is required")
	ErrInvalidMaxFaces      = errors.New("max faces must be positive")
	ErrInvalidThreshold     = errors.New("threshold must be between 0 and 100")

	// Rate limiting errors
	ErrRateLimitExceeded    = errors.New("rate limit exceeded")

	// AWS service errors
	ErrAWSServiceError      = errors.New("AWS Rekognition service error")
	ErrAWSAccessDenied      = errors.New("AWS access denied")
	ErrAWSThrottling        = errors.New("AWS request throttled")
	ErrAWSInvalidImage      = errors.New("invalid image for AWS Rekognition")
)

// FaceSearchError represents a structured error for face search operations
type FaceSearchError struct {
	Code    string `json:"code"`
	Message string `json:"message"`
	Details string `json:"details,omitempty"`
}

// Error implements the error interface
func (e *FaceSearchError) Error() string {
	return e.Message
}

// NewFaceSearchError creates a new FaceSearchError
func NewFaceSearchError(code, message, details string) *FaceSearchError {
	return &FaceSearchError{
		Code:    code,
		Message: message,
		Details: details,
	}
}

// Common error codes
const (
	ErrorCodeNoFaces         = "NO_FACES_DETECTED"
	ErrorCodeInvalidImage    = "INVALID_IMAGE"
	ErrorCodeRateLimited     = "RATE_LIMITED"
	ErrorCodeCollectionError = "COLLECTION_ERROR"
	ErrorCodeSearchFailed    = "SEARCH_FAILED"
	ErrorCodeIndexingFailed  = "INDEXING_FAILED"
	ErrorCodeInternalError   = "INTERNAL_ERROR"
)

// User-facing error messages
var UserErrorMessages = map[error]string{
	ErrNoFacesDetected:       "No faces detected in the image. Please upload a photo with clear faces.",
	ErrImageTooSmall:         "Image is too small. Please upload a larger image (minimum 100x100 pixels).",
	ErrImageTooLarge:         "Image is too large. Please upload an image smaller than 10MB.",
	ErrInvalidImageFormat:    "Invalid image format. Please upload a JPEG, PNG, or WebP image.",
	ErrCollectionNotFound:    "Face collection not found. Please contact support.",
	ErrRateLimitExceeded:     "Search limit exceeded. Please try again later.",
	ErrAWSServiceError:       "An error occurred while processing your request. Please try again.",
	ErrAWSAccessDenied:       "Access denied. Please contact support.",
	ErrAWSThrottling:         "Service is busy. Please try again in a few moments.",
}

// GetUserMessage returns a user-friendly error message
func GetUserMessage(err error) string {
	if msg, ok := UserErrorMessages[err]; ok {
		return msg
	}
	return "An unexpected error occurred. Please try again."
}