Reservair/includes/Services/Forms/RsvFormDefinitionValidator.php

<?php

use Reservair\Templating\RsvTemplateEngine;

/**
 * Validates a form definition before it is persisted.
 *
 * Template checks (symbols, syntax, custom elements) are delegated to the
 * common template validator; on top of that this enforces form-level rules,
 * such as requiring a submit button once the form defines any fields.
 */
final class RsvFormDefinitionValidator {

    /**
     * @param array<string,mixed> $definition The inner definition (elements, email_key, success_message).
     * @return list<string> Human-readable problems; empty when the definition is valid.
     */
    public function validate(array $definition): array {
        $elements = is_array($definition['elements'] ?? null) ? $definition['elements'] : [];
        $symbols  = $this->symbols($elements);
        $engine   = $this->engine();

        $errors = [];

        // Templates reference submitted values by form-element name.
        foreach ($this->templates($definition, $elements) as $label => $template) {
            foreach ($engine->validate($template, $symbols) as $problem) {
                $errors[] = "{$label}: {$problem}";
            }
        }

        // A form that collects fields must give the visitor a way to send them.
        if ($elements !== [] && !$this->has_submit($elements)) {
            $errors[] = 'Form must contain a submit button.';
        }

        return $errors;
    }

    /**
     * Names that templates may reference — the form's symbol table.
     *
     * @param array<int,mixed> $elements
     * @return list<string>
     */
    private function symbols(array $elements): array {
        $names = RsvFormCalculatedValues::names(); // calculated values are referencable too
        foreach ($elements as $el) {
            $name = is_array($el) ? ($el['name'] ?? '') : '';
            if (is_string($name) && $name !== '') {
                $names[] = $name;
            }
        }
        return $names;
    }

    /**
     * The definition's admin-authored templates, keyed by a label used to
     * prefix any problems found in them.
     *
     * @param array<string,mixed> $definition
     * @param array<int,mixed>    $elements
     * @return array<string,string>
     */
    private function templates(array $definition, array $elements): array {
        $templates = [];

        $success = $definition['success_message'] ?? '';
        if (is_string($success) && trim($success) !== '') {
            $templates['Success message'] = $success;
        }

        foreach ($elements as $el) {
            if (!is_array($el) || ($el['type'] ?? '') !== 'reservation') {
                continue;
            }
            $email_templates = $el['email_templates'] ?? [];
            if (!is_array($email_templates)) {
                continue;
            }
            foreach (['on_accepted' => 'accepted', 'on_refused' => 'refused'] as $key => $human) {
                $tpl = $email_templates[$key] ?? [];
                if (!is_array($tpl)) {
                    continue;
                }
                foreach (['subject', 'body'] as $part) {
                    $value = $tpl[$part] ?? '';
                    if (is_string($value) && trim($value) !== '') {
                        $templates["Email ({$human} {$part})"] = $value;
                    }
                }
            }
        }

        return $templates;
    }

    /** @param array<int,mixed> $elements */
    private function has_submit(array $elements): bool {
        foreach ($elements as $el) {
            if (is_array($el) && ($el['type'] ?? '') === 'button') {
                return true;
            }
        }
        return false;
    }

    private function engine(): RsvTemplateEngine {
        global $rsv_template_registry;
        return new RsvTemplateEngine(registry: $rsv_template_registry);
    }
}