<?php
namespace Advently\Rest;

use Advently\Calendar\Config;
use Advently\Calendar\Option;
use Advently\Calendar\Page;
use Advently\Calendar\Seed;
use Advently\Data\Privacy;
use Advently\Data\SubscriberList;
use Advently\Stats\Report;

defined( 'ABSPATH' ) || exit;

/**
 * The store owner's API, behind manage_woocommerce on every route.
 *
 *   GET  /advently/v1/admin/settings        the calendar config + context for the editor
 *   POST /advently/v1/admin/settings        save; answers with what was actually stored
 *   GET  /advently/v1/admin/products        product search / lookup by id for door pickers
 *   GET  /advently/v1/admin/categories      product category search / lookup by id
 */
final class AdminController {

	const NS = 'advently/v1';

	/** Texts allowed in the consent sentence next to the email box. */
	const CONSENT_HTML = [
		'a'      => [
			'href'   => true,
			'target' => true,
			'rel'    => true,
		],
		'strong' => [],
		'em'     => [],
	];

	public function register(): void {
		$permission = [ $this, 'canManage' ];

		register_rest_route(
			self::NS,
			'/admin/settings',
			[
				[
					'methods'             => 'GET',
					'callback'            => [ $this, 'getSettings' ],
					'permission_callback' => $permission,
				],
				[
					'methods'             => 'POST',
					'callback'            => [ $this, 'saveSettings' ],
					'permission_callback' => $permission,
					'args'                => [
						'config' => [
							'type'     => 'object',
							'required' => true,
						],
						'seed'   => [
							'type'    => 'boolean',
							'default' => false,
						],
					],
				],
			]
		);
		register_rest_route(
			self::NS,
			'/admin/page',
			[
				'methods'             => 'POST',
				'callback'            => [ $this, 'createPage' ],
				'permission_callback' => $permission,
			]
		);
		register_rest_route(
			self::NS,
			'/admin/pages',
			[
				'methods'             => 'GET',
				'callback'            => [ $this, 'pages' ],
				'permission_callback' => $permission,
				'args'                => self::lookupArgs(),
			]
		);
		register_rest_route(
			self::NS,
			'/admin/report',
			[
				'methods'             => 'GET',
				'callback'            => [ $this, 'report' ],
				'permission_callback' => $permission,
			]
		);
		register_rest_route(
			self::NS,
			'/admin/subscribers',
			[
				'methods'             => 'GET',
				'callback'            => [ $this, 'subscribers' ],
				'permission_callback' => $permission,
				'args'                => [
					'page'     => [
						'type'    => 'integer',
						'default' => 1,
						'minimum' => 1,
					],
					'per_page' => [
						'type'    => 'integer',
						'default' => 20,
						'minimum' => 1,
						'maximum' => 100,
					],
					'search'   => [
						'type'    => 'string',
						'default' => '',
					],
				],
			]
		);
		register_rest_route(
			self::NS,
			'/admin/subscribers/(?P<id>\d+)',
			[
				'methods'             => 'DELETE',
				'callback'            => [ $this, 'deleteSubscriber' ],
				'permission_callback' => $permission,
			]
		);
		register_rest_route(
			self::NS,
			'/admin/products',
			[
				'methods'             => 'GET',
				'callback'            => [ $this, 'products' ],
				'permission_callback' => $permission,
				'args'                => self::lookupArgs(),
			]
		);
		register_rest_route(
			self::NS,
			'/admin/categories',
			[
				'methods'             => 'GET',
				'callback'            => [ $this, 'categories' ],
				'permission_callback' => $permission,
				'args'                => self::lookupArgs(),
			]
		);
	}

	public function canManage(): bool {
		return current_user_can( 'manage_woocommerce' );
	}

	public function getSettings(): \WP_REST_Response {
		return self::settingsResponse( Option::get() );
	}

	public function saveSettings( \WP_REST_Request $request ): \WP_REST_Response {
		$raw = $request->get_param( 'config' );
		$raw = is_array( $raw ) ? $raw : [];
		if ( true === $request->get_param( 'seed' ) ) {
			// The wizard's last step: fill every door with the ready-made calendar.
			$doors = Config::sanitize( $raw )['doors'];
			/**
			 * Filters the product the ready-made calendar gives away on its free-gift doors.
			 * Without one (0), those doors get a percentage coupon instead.
			 *
			 * @param int $product_id Product id, or 0.
			 */
			$free = (int) apply_filters( 'advently_seed_free_product', 0 );
			// Gift ideas suggest something else than the free gift.
			$gifts            = array_values( array_diff( self::giftProducts(), [ $free ] ) );
			$raw['door_list'] = Seed::doors( $doors, $gifts, $free, self::seedTexts() );
		}
		return self::settingsResponse( Option::save( self::clean( $raw ) ) );
	}

	/**
	 * Best sellers first (newest when nothing has sold yet), for gift-idea doors.
	 *
	 * @return int[]
	 */
	private static function giftProducts(): array {
		$ids = get_posts(
			[
				'post_type'      => 'product',
				'post_status'    => 'publish',
				'posts_per_page' => 6,
				'fields'         => 'ids',
				// phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key -- runs once, when the wizard finishes.
				'meta_key'       => 'total_sales',
				'orderby'        => [
					'meta_value_num' => 'DESC',
					'date'           => 'DESC',
				],
			]
		);
		return array_values( array_filter( array_map( 'intval', $ids ), [ self::class, 'buyable' ] ) );
	}

	private static function buyable( int $id ): bool {
		$product = wc_get_product( $id );
		return $product && $product->is_purchasable() && $product->is_in_stock() && $product->is_visible();
	}

	/**
	 * @return array<string, array{title:string, message:string, button:string}>
	 */
	private static function seedTexts(): array {
		return [
			'gift'          => [
				'title'   => __( 'Gift idea of the day', 'advently' ),
				'message' => __( 'Stuck for a present? This one is a favourite with our customers.', 'advently' ),
				'button'  => __( 'Take a look', 'advently' ),
			],
			'halfway'       => [
				'title'   => __( 'Halfway to Christmas', 'advently' ),
				'message' => __( 'Twelve doors down, twelve to go. Here is a bigger thank-you for coming back every day.', 'advently' ),
				'button'  => '',
			],
			'last_shipping' => [
				'title'   => __( 'Order in time for Christmas', 'advently' ),
				'message' => __( 'These are the last days to order and have it under the tree. Shipping is on us today.', 'advently' ),
				'button'  => '',
			],
			'finale'        => [
				'title'   => __( 'Merry Christmas!', 'advently' ),
				'message' => __( 'Thank you for opening every door with us. Our biggest offer of the season is yours until the calendar ends.', 'advently' ),
				'button'  => '',
			],
		];
	}

	/**
	 * WordPress-side cleaning on top of Option::sanitize(), which owns the
	 * schema (types, ranges, allowed values) but knows nothing of HTML.
	 */
	public static function clean( array $raw ): array {
		$config = Option::sanitize( $raw, (int) wp_date( 'Y' ) );

		$config['consent_text'] = wp_kses( $config['consent_text'], self::CONSENT_HTML );

		foreach ( $config['door_list'] as $n => $door ) {
			$content                              = $door['content'];
			$config['door_list'][ $n ]['content'] = [
				'title'        => sanitize_text_field( $content['title'] ),
				'message'      => wp_kses_post( $content['message'] ),
				'image_id'     => self::attachment( $content['image_id'] ),
				'product_id'   => $content['product_id'],
				'button_label' => sanitize_text_field( $content['button_label'] ),
			];
		}
		$config['background_id'] = self::attachment( $config['background_id'] );

		return $config;
	}

	/**
	 * Creates the calendar page and stores it as the calendar's page.
	 */
	public function createPage(): \WP_REST_Response {
		$id = Page::create();
		if ( ! $id ) {
			return new \WP_REST_Response( [ 'message' => __( 'The page could not be created.', 'advently' ) ], 500 );
		}
		$config            = Option::get();
		$config['page_id'] = $id;
		return self::settingsResponse( Option::save( $config ) );
	}

	public function pages( \WP_REST_Request $request ): \WP_REST_Response {
		$include = self::includeIds( $request );
		$args    = [
			'post_type'      => 'page',
			'post_status'    => 'publish',
			'posts_per_page' => 20,
			'orderby'        => 'title',
			'order'          => 'ASC',
		];
		if ( $include ) {
			$args['post__in'] = $include;
		} else {
			$args['s'] = sanitize_text_field( (string) $request->get_param( 'search' ) );
		}
		$items = [];
		foreach ( get_posts( $args ) as $page ) {
			$items[] = [
				'id'   => (int) $page->ID,
				'name' => wp_strip_all_tags( get_the_title( $page ) ),
			];
		}
		return new \WP_REST_Response( $items );
	}

	public function report(): \WP_REST_Response {
		$response = new \WP_REST_Response( Report::build( Option::get() ) );
		$response->header( 'Cache-Control', 'no-store, private' );
		return $response;
	}

	public function subscribers( \WP_REST_Request $request ): \WP_REST_Response {
		$perPage  = (int) $request->get_param( 'per_page' );
		$result   = ( new SubscriberList( Option::get()['start'] ) )->page(
			(int) $request->get_param( 'page' ),
			$perPage,
			sanitize_text_field( (string) $request->get_param( 'search' ) )
		);
		$response = new \WP_REST_Response( $result );
		$response->header( 'X-WP-Total', (string) $result['total'] );
		$response->header( 'X-WP-TotalPages', (string) max( 1, (int) ceil( $result['total'] / $perPage ) ) );
		$response->header( 'Cache-Control', 'no-store, private' );
		return $response;
	}

	/**
	 * Removes a subscriber: their sign-up, door history and unused coupons.
	 */
	public function deleteSubscriber( \WP_REST_Request $request ): \WP_REST_Response {
		if ( ! Privacy::erase( (int) $request->get_param( 'id' ) ) ) {
			return new \WP_REST_Response( [ 'message' => __( 'That subscriber no longer exists.', 'advently' ) ], 404 );
		}
		return new \WP_REST_Response( [ 'ok' => true ] );
	}

	public function products( \WP_REST_Request $request ): \WP_REST_Response {
		$include = self::includeIds( $request );
		$args    = [
			'status' => 'publish',
			'limit'  => $include ? count( $include ) : 20,
			'return' => 'objects',
		];
		if ( $include ) {
			$args['include'] = $include;
		} else {
			$search = sanitize_text_field( (string) $request->get_param( 'search' ) );
			if ( '' !== $search ) {
				$args['s'] = $search;
			}
			$args['orderby'] = 'title';
			$args['order']   = 'ASC';
		}

		$items = [];
		foreach ( wc_get_products( $args ) as $product ) {
			$image   = wp_get_attachment_image_src( $product->get_image_id(), 'thumbnail' );
			$items[] = [
				'id'    => $product->get_id(),
				'name'  => wp_strip_all_tags( $product->get_name() ),
				'price' => html_entity_decode( wp_strip_all_tags( wc_price( (float) $product->get_price() ) ), ENT_QUOTES, 'UTF-8' ),
				'image' => $image ? $image[0] : '',
				'type'  => $product->get_type(),
			];
		}
		return new \WP_REST_Response( $items );
	}

	public function categories( \WP_REST_Request $request ): \WP_REST_Response {
		$include = self::includeIds( $request );
		$args    = [
			'taxonomy'   => 'product_cat',
			'hide_empty' => false,
			'number'     => 50,
		];
		if ( $include ) {
			$args['include'] = $include;
		} else {
			$search = sanitize_text_field( (string) $request->get_param( 'search' ) );
			if ( '' !== $search ) {
				$args['search'] = $search;
			}
		}

		$terms = get_terms( $args );
		$items = [];
		foreach ( is_array( $terms ) ? $terms : [] as $term ) {
			$items[] = [
				'id'    => (int) $term->term_id,
				'name'  => wp_strip_all_tags( $term->name ),
				'count' => (int) $term->count,
			];
		}
		return new \WP_REST_Response( $items );
	}

	private static function settingsResponse( array $config ): \WP_REST_Response {
		$schedule = Option::schedule( $config );
		$response = new \WP_REST_Response(
			[
				'config' => $config,
				'saved'  => Option::exists(),
				'today'  => $schedule->statuses( Option::now() ),
				'end'    => Config::endDate( $config ),
				'page'   => [
					'id'    => Page::id( $config ),
					'url'   => Page::url( $config ),
					'title' => Page::id( $config ) ? wp_strip_all_tags( get_the_title( Page::id( $config ) ) ) : '',
				],
			]
		);
		$response->header( 'Cache-Control', 'no-store, private' );
		return $response;
	}

	/**
	 * Only images in the media library are kept.
	 */
	private static function attachment( int $id ): int {
		return $id && wp_attachment_is_image( $id ) ? $id : 0;
	}

	/**
	 * @return int[]
	 */
	private static function includeIds( \WP_REST_Request $request ): array {
		$raw = $request->get_param( 'include' );
		$ids = is_array( $raw ) ? $raw : explode( ',', (string) $raw );
		return array_values( array_filter( array_map( 'absint', $ids ) ) );
	}

	private static function lookupArgs(): array {
		return [
			'search'  => [
				'type'    => 'string',
				'default' => '',
			],
			'include' => [
				'type'    => [ 'string', 'array' ],
				'default' => '',
			],
		];
	}
}