<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\Payment;

use Unsupervised\Schedular\Auth\RoleManager;
use Unsupervised\Schedular\Val;

/**
 * Admin screen for viewing and editing the payment-due email template, with a
 * live preview rendered from sample values. Save is a plain POST (nonce +
 * capability checked); the preview updates client-side against a REST endpoint
 * so an admin sees the effect of an edit before saving it.
 */
class PaymentEmailController {

	public const NONCE_ACTION = 'usc_payment_email_action';

	public function __construct( private PaymentDueEmailTemplate $template = new PaymentDueEmailTemplate() ) {}

	public function renderPage(): void {
		if ( ! current_user_can( RoleManager::CAP_MANAGE_BILLING ) ) {
			wp_die( esc_html__( 'You do not have permission to manage billing settings.', 'unsupervised-schedular' ) );
		}

		$notice = '';
		if ( isset( $_POST['usc_action'] ) && check_admin_referer( self::NONCE_ACTION ) ) {
			// phpcs:ignore WordPress.Security.NonceVerification.Missing -- verified immediately above.
			$action = sanitize_key( Val::string( wp_unslash( $_POST['usc_action'] ) ) );
			if ( 'reset' === $action ) {
				$this->reset();
				$notice = __( 'Template reset to the built-in default.', 'unsupervised-schedular' );
			} else {
				$this->save();
				$notice = __( 'Payment due email template saved.', 'unsupervised-schedular' );
			}
		}

		$subject      = $this->template->subject();
		$body         = $this->template->body();
		$itemLine     = $this->template->itemLine();
		$tokens       = PaymentDueEmailTemplate::tokens();
		$itemTokens   = PaymentDueEmailTemplate::itemTokens();
		$previewNonce = wp_create_nonce( 'wp_rest' );
		$previewUrl   = rest_url( 'us-scheduler/v1/payment-email/preview' );

		// Server-render the initial preview from sample values so the panel is
		// populated before any JavaScript runs (and if it never does).
		$preview = self::renderSample( $this->template, $subject, $body, $itemLine );

		include USC_PLUGIN_DIR . 'templates/admin/payment-email.php';
	}

	/**
	 * Render the given template text against a fixed set of sample values, using
	 * the real mailer so the preview matches a genuine scan exactly. The passed
	 * subject/body/item-line override the stored ones so an unsaved edit can be
	 * previewed.
	 *
	 * @return array{subject: string, body: string}
	 */
	public static function renderSample( PaymentDueEmailTemplate $stored, string $subject, string $body, string $itemLine ): array {
		// A throwaway template returning the supplied (possibly unsaved) text.
		$draft = new class( $subject, $body, $itemLine ) extends PaymentDueEmailTemplate {
			public function __construct(
				private string $draftSubject,
				private string $draftBody,
				private string $draftItemLine,
			) {}

			public function subject(): string {
				return '' !== $this->draftSubject ? $this->draftSubject : self::defaultSubject();
			}

			public function body(): string {
				return '' !== $this->draftBody ? $this->draftBody : self::defaultBody();
			}

			public function itemLine(): string {
				return '' !== $this->draftItemLine ? $this->draftItemLine : self::defaultItemLine();
			}
		};

		$mailer = new PaymentDueMailer( $draft );
		$tokens = $mailer->buildTokens( self::sampleStudentName(), self::sampleItems(), self::sampleReference(), self::sampleCredit() );

		return [
			'subject' => $draft->renderSubject( $tokens ),
			'body'    => $draft->renderBody( $tokens ),
		];
	}

	public static function sampleStudentName(): string {
		return __( 'Alex Student', 'unsupervised-schedular' );
	}

	public static function sampleReference(): string {
		return 'REF12345';
	}

	public static function sampleCredit(): float {
		return 20.0;
	}

	/**
	 * The sample charges the preview is rendered against — two lessons on
	 * different dates so the {items} block and grand total are both exercised.
	 *
	 * @return list<array{label: string, amount: float, currency: string, due_date: ?string, etransfer_email: ?string}>
	 */
	public static function sampleItems(): array {
		return [
			[
				'label'           => __( 'Piano lesson', 'unsupervised-schedular' ),
				'amount'          => 35.0,
				'currency'        => 'CAD',
				'due_date'        => '2026-07-15',
				'etransfer_email' => 'pay@studio.test',
			],
			[
				'label'           => __( 'Guitar lesson', 'unsupervised-schedular' ),
				'amount'          => 40.0,
				'currency'        => 'CAD',
				'due_date'        => '2026-07-22',
				'etransfer_email' => 'pay@studio.test',
			],
		];
	}

	private function save(): void {
		// Nonce is verified by the caller (renderPage) before this method runs.
		// phpcs:disable WordPress.Security.NonceVerification.Missing
		$this->template->saveSubject( sanitize_text_field( Val::string( wp_unslash( $_POST['subject'] ?? '' ) ) ) );
		$this->template->saveBody( sanitize_textarea_field( Val::string( wp_unslash( $_POST['body'] ?? '' ) ) ) );
		$this->template->saveItemLine( sanitize_text_field( Val::string( wp_unslash( $_POST['item_line'] ?? '' ) ) ) );
		// phpcs:enable WordPress.Security.NonceVerification.Missing
	}

	private function reset(): void {
		$this->template->saveSubject( '' );
		$this->template->saveBody( '' );
		$this->template->saveItemLine( '' );
	}
}