/**
 * Form Validation & Error Handling Utilities
 *
 * Shared helpers for form field validation and error display across all pages.
 * Provides reusable patterns for: error messages, field validation, API error extraction.
 */

/**
 * Display a field error message and mark its container with is-invalid class.
 * Finds the appropriate parent container (label, form group, consent row, etc.)
 * and toggles the is-invalid class based on whether msg is provided.
 *
 * @param {string} errorId - HTML ID of the error message element
 * @param {string} [msg] - Error message to display; empty/null to clear
 */
function showFieldError(errorId, msg) {
	var $el = $('#' + errorId);
	$el.text(msg || '');
	var $parent = $el.parent();
	var $container = $parent.is('label, .consent-inline') ? $parent : $el.prev();
	if (!$container.length || !$container.is('label, .consent-inline, .file-drop, .subscribe-row')) {
		$container = $el.closest('form');
	}
	$container.toggleClass('is-invalid', !!msg);
}

/**
 * Clear multiple field errors at once.
 * Calls showFieldError(id, '') for each error element ID.
 *
 * @param {string[]} errorIds - Array of HTML IDs to clear
 */
function clearFieldErrors(errorIds) {
	for (var i = 0; i < errorIds.length; i++) {
		showFieldError(errorIds[i], '');
	}
}

/**
 * Validate email format using a simple regex pattern.
 * Checks for: non-whitespace + @ + non-whitespace + . + non-whitespace
 *
 * @param {string} value - Email address to validate
 * @returns {boolean} - True if email format is valid
 */
function isValidEmail(value) {
	return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(String(value || '').trim());
}

/**
 * Extract user-facing error message from API response.
 *
 * Rules:
 * - 429 (rate limit) → return rateLimitKey translation
 * - 4xx with known error code → look up 'error.<code>' in i18n dictionary first
 * - 4xx with error body → return server's error message (intentional feedback)
 * - 5xx or no body → return fallbackKey translation
 *
 * @param {object|null} body - Parsed JSON response body
 * @param {number} status - HTTP status code
 * @param {string} fallbackKey - i18n key for 5xx/unknown errors (e.g., 'form.failed')
 * @param {string} [rateLimitKey] - Optional i18n key for 429 (defaults to 'form.rateLimited')
 * @returns {string} - User-facing error message
 */
function extractApiError(body, status, fallbackKey, rateLimitKey) {
	if (status === 429) {
		return window.MyAi.t(rateLimitKey || 'form.rateLimited');
	}
	if (status >= 400 && status < 500) {
		// Prefer i18n translation keyed on the machine-readable error code
		if (body && body.code) {
			var codeKey = 'error.' + body.code;
			var translated = window.MyAi.t(codeKey);
			if (translated !== codeKey) return translated;
		}
		var msg = body && (body.error || body.Error || body.title);
		if (msg) return msg;
	}
	return window.MyAi.t(fallbackKey);
}

// Expose helpers on window.MyAi for use by other scripts
window.MyAi = window.MyAi || {};
window.MyAi.showFieldError = showFieldError;
window.MyAi.clearFieldErrors = clearFieldErrors;
window.MyAi.isValidEmail = isValidEmail;
window.MyAi.extractApiError = extractApiError;