<?php

namespace Glovario\Usage;

use Glovario\Domain\BuiltinVariables;
use Glovario\Domain\NestedReferenceParser;
use Glovario\Domain\TokenParser;
use Glovario\Repository\RuleRepository;
use Glovario\Repository\VariableRepository;

defined( 'ABSPATH' ) || exit;

final class UsageScanner {
	private $variables;
	private $rules;
	private $references;
	private $tokens;
	private $builtins;

	public function __construct( VariableRepository $variables, RuleRepository $rules, ?NestedReferenceParser $references = null, ?TokenParser $tokens = null, ?BuiltinVariables $builtins = null ) {
		$this->variables  = $variables;
		$this->rules      = $rules;
		$this->references = $references ? $references : new NestedReferenceParser();
		$this->tokens     = $tokens ? $tokens : new TokenParser();
		$this->builtins   = $builtins ? $builtins : new BuiltinVariables();
	}

	public function summaries() {
		$index     = $this->build_index();
		$summaries = array();
		foreach ( $this->all_variables() as $variable ) {
			$variable['usage_count'] = count( $index[ $variable['variable_key'] ] ?? array() );
			$summaries[]             = $variable;
		}
		return $summaries;
	}

	public function scan( $key, $page = 1, $per_page = 50 ) {
		$key      = sanitize_key( $key );
		$page     = max( 1, absint( $page ) );
		$per_page = min( 100, max( 1, absint( $per_page ) ) );
		$matches  = $this->matches( $key );
		$total    = count( $matches );
		return array(
			'matches' => array_slice( $matches, ( $page - 1 ) * $per_page, $per_page ),
			'total'   => $total,
			'page'    => $page,
			'pages'   => max( 1, (int) ceil( $total / $per_page ) ),
		);
	}

	public function matches( $key ) {
		$key = sanitize_key( $key );
		return $this->build_index()[ $key ] ?? array();
	}

	private function build_index() {
		$variables = $this->all_variables();
		$by_id     = array();
		$index     = array();
		foreach ( $variables as $variable ) {
			if ( empty( $variable['builtin'] ) ) {
				$by_id[ (int) $variable['id'] ] = $variable;
				$this->index_nested_value( $index, $variable, $variable['value'], __( 'Base value', 'glovario' ), array( 'storage' => 'variable' ) );
			}
		}

		/*
		 * Stored rules are references even when their conditions are not applied.
		 * Keeping them in the index prevents a rename or deletion from leaving
		 * dormant references behind.
		 */
		foreach ( $this->rules->all() as $rule ) {
			$variable_id = (int) $rule['variable_id'];
			if ( ! isset( $by_id[ $variable_id ] ) ) {
				continue;
			}
			/* translators: %s: conditional rule name. */
			$context = sprintf( __( 'Rule: %s', 'glovario' ), $rule['name'] ? $rule['name'] : __( 'Unnamed rule', 'glovario' ) );
			$this->index_nested_value(
				$index,
				$by_id[ $variable_id ],
				$rule['alternative_value'],
				$context,
				array(
					'storage' => 'rule',
					'rule_id' => (int) $rule['id'],
				)
			);
		}
		foreach ( $this->content_candidates() as $batch ) {
			foreach ( $batch as $post ) {
				if ( 'nav_menu_item' !== $post['post_type'] ) {
					$this->index_post_field( $index, $post, 'post_content', true, true, true );
					$this->index_post_field( $index, $post, 'post_excerpt', false, true, false );
				}
				$this->index_post_field( $index, $post, 'post_title', true, false, false );
			}
		}
		$this->index_text_widgets( $index );
		$this->index_block_widgets( $index );
		return $index;
	}

	private function index_post_field( &$index, $post, $field, $shortcodes, $tokens, $blocks ) {
		$content        = (string) ( $post[ $field ] ?? '' );
		$shortcode_keys = $shortcodes ? $this->shortcode_keys_in_html_text( $content ) : array();
		$token_keys     = $tokens ? $this->tokens->keys_in_html_text( $content ) : array();
		$block_keys     = $blocks ? $this->block_keys( parse_blocks( $content ) ) : array();
		$field_labels   = array(
			'post_content' => __( 'Content', 'glovario' ),
			'post_title'   => __( 'Title or menu label', 'glovario' ),
			'post_excerpt' => __( 'Excerpt', 'glovario' ),
		);
		foreach ( array_unique( array_merge( $shortcode_keys, $token_keys, $block_keys ) ) as $key ) {
			$sources = array();
			if ( in_array( $key, $shortcode_keys, true ) ) {
				$sources[] = 'shortcode';
			}
			if ( in_array( $key, $block_keys, true ) ) {
				$sources[] = 'block';
			}
			if ( in_array( $key, $token_keys, true ) ) {
				$sources[] = 'token';
			}
			$title = get_the_title( $post['ID'] );
			$index[ $key ][] = array(
				'kind'      => 'content',
				'storage'   => $field,
				'id'        => (int) $post['ID'],
				'title'     => $title ? $title : __( '(no title)', 'glovario' ),
				'item_type' => $post['post_type'],
				'context'   => ( $field_labels[ $field ] ?? $field ) . ' — ' . $post['post_status'],
				'edit_link' => get_edit_post_link( $post['ID'], 'raw' ),
				'sources'   => $sources,
			);
		}
	}

	private function index_text_widgets( &$index ) {
		$widgets = get_option( 'widget_text', array() );
		if ( ! is_array( $widgets ) ) {
			return;
		}
		foreach ( $widgets as $instance => $widget ) {
			if ( ! is_numeric( $instance ) || ! is_array( $widget ) ) {
				continue;
			}
			$content        = (string) ( $widget['text'] ?? '' );
			$shortcode_keys = $this->shortcode_keys_in_html_text( $content );
			$token_keys     = $this->tokens->keys_in_html_text( $content );
			foreach ( array_unique( array_merge( $shortcode_keys, $token_keys ) ) as $key ) {
				$sources = array();
				if ( in_array( $key, $shortcode_keys, true ) ) {
					$sources[] = 'shortcode';
				}
				if ( in_array( $key, $token_keys, true ) ) {
					$sources[] = 'token';
				}
				/* translators: %d: text widget instance number. */
				$title = sprintf( __( 'Text widget #%d', 'glovario' ), $instance );
				$index[ $key ][] = array(
					'kind'      => 'widget',
					'storage'   => 'widget_text',
					'id'        => (int) $instance,
					'title'     => ! empty( $widget['title'] ) ? $widget['title'] . ' — ' . $title : $title,
					'item_type' => 'widget',
					'context'   => __( 'Text widget content', 'glovario' ),
					'edit_link' => admin_url( 'widgets.php' ),
					'sources'   => $sources,
				);
			}
		}
	}

	/**
	 * Block widgets (the default widget editor since WordPress 5.8) store block
	 * markup in the widget_block option.
	 *
	 * @param array $index Usage index.
	 */
	private function index_block_widgets( &$index ) {
		$widgets = get_option( 'widget_block', array() );
		if ( ! is_array( $widgets ) ) {
			return;
		}
		foreach ( $widgets as $instance => $widget ) {
			if ( ! is_numeric( $instance ) || ! is_array( $widget ) ) {
				continue;
			}
			$content        = (string) ( $widget['content'] ?? '' );
			$shortcode_keys = $this->shortcode_keys_in_html_text( $content );
			$token_keys     = $this->tokens->keys_in_html_text( $content );
			$block_keys     = $this->block_keys( parse_blocks( $content ) );
			foreach ( array_unique( array_merge( $shortcode_keys, $token_keys, $block_keys ) ) as $key ) {
				$sources = array();
				foreach ( array(
					'shortcode' => $shortcode_keys,
					'block' => $block_keys,
					'token' => $token_keys,
				) as $source => $keys ) {
					if ( in_array( $key, $keys, true ) ) {
						$sources[] = $source;
					}
				}
				$index[ $key ][] = array(
					'kind'      => 'widget',
					'storage'   => 'widget_block',
					'id'        => (int) $instance,
					/* translators: %d: block widget instance number. */
					'title'     => sprintf( __( 'Block widget #%d', 'glovario' ), $instance ),
					'item_type' => 'widget',
					'context'   => __( 'Block widget content', 'glovario' ),
					'edit_link' => admin_url( 'widgets.php' ),
					'sources'   => $sources,
				);
			}
		}
	}

	private function shortcode_keys_in_html_text( $content ) {
		$keys  = array();
		$parts = preg_split( '~(<(?:script|style|pre|code)\b[^>]*>.*?</(?:script|style|pre|code)>|<!--.*?-->|<[^>]+>)~is', (string) $content, -1, PREG_SPLIT_DELIM_CAPTURE );
		foreach ( $parts as $index => $part ) {
			if ( 0 === $index % 2 ) {
				$keys = array_merge( $keys, $this->references->keys( $part ) );
			}
		}
		return array_values( array_unique( array_filter( $keys ) ) );
	}

	private function index_nested_value( &$index, $variable, $value, $context, $metadata = array() ) {
		foreach ( $this->references->keys( $value ) as $key ) {
			$index[ $key ][] = array_merge(
				array(
					'kind'      => 'variable',
					'id'        => (int) $variable['id'],
					'title'     => $variable['label'] . ' (' . $variable['variable_key'] . ')',
					'item_type' => 'glovario_variable',
					'context'   => $context,
					'edit_link' => add_query_arg(
						array(
							'page' => 'glovario',
							'action' => 'edit',
							'id' => $variable['id'],
						),
						admin_url( 'admin.php' )
					),
					'sources'   => array( 'nested' ),
				),
				$metadata
			);
		}
	}

	/**
	 * Posts that may reference a variable, in batches of 200 so that sites with
	 * thousands of long posts do not run out of memory. Every candidate is
	 * read: deletion and key migration must find every reference.
	 *
	 * @return \Generator Lists of post rows.
	 */
	private function content_candidates() {
		global $wpdb;
		$like_shortcode = '%' . $wpdb->esc_like( '[glvr' ) . '%';
		$like_block     = '%' . $wpdb->esc_like( 'wp:glovario/site-variable' ) . '%';
		$like_token     = '%' . $wpdb->esc_like( '{{glvr:' ) . '%';
		$ids            = $wpdb->get_col( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- A content search WP_Query cannot express (LIKE on content, title, and excerpt), run when an administrator scans.
			$wpdb->prepare(
				"SELECT ID FROM %i WHERE post_status NOT IN ('trash','auto-draft','inherit') AND post_type <> 'revision' AND (post_content LIKE %s OR post_content LIKE %s OR post_content LIKE %s OR post_title LIKE %s OR post_excerpt LIKE %s) ORDER BY ID DESC",
				$wpdb->posts,
				$like_shortcode,
				$like_token,
				$like_block,
				$like_shortcode,
				$like_token
			)
		);
		foreach ( array_chunk( array_map( 'absint', $ids ), 200 ) as $chunk ) {
			$placeholders = implode( ',', array_fill( 0, count( $chunk ), '%d' ) );
			yield $wpdb->get_results( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Reads the matched posts in batches of 200 during the same administrator scan.
				$wpdb->prepare( "SELECT ID, post_title, post_type, post_status, post_content, post_excerpt FROM %i WHERE ID IN ({$placeholders}) ORDER BY ID DESC", array_merge( array( $wpdb->posts ), $chunk ) ), // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare -- $placeholders is a list of %d placeholders, one per ID.
				ARRAY_A
			);
		}
	}

	private function all_variables() {
		$variables = $this->builtins->all();
		$offset    = 0;
		$count     = 0;
		do {
			$batch     = $this->variables->all(
				array(
					'number' => 500,
					'offset' => $offset,
				)
			);
			$variables = array_merge( $variables, $batch );
			$count     = count( $batch );
			$offset   += $count;
		} while ( 500 === $count );
		return $variables;
	}

	private function block_keys( $blocks ) {
		$keys = array();
		foreach ( $blocks as $block ) {
			if ( 'glovario/site-variable' === $block['blockName'] && ! empty( $block['attrs']['key'] ) ) {
				$keys[] = sanitize_key( $block['attrs']['key'] );
			}
			if ( in_array( $block['blockName'], array( 'core/navigation', 'core/navigation-link', 'core/navigation-submenu', 'core/page-list' ), true ) ) {
				foreach ( (array) ( $block['attrs'] ?? array() ) as $attribute ) {
					if ( is_string( $attribute ) ) {
						$keys = array_merge( $keys, $this->references->keys( $attribute ) );
					}
				}
			}
			if ( ! empty( $block['innerBlocks'] ) ) {
				$keys = array_merge( $keys, $this->block_keys( $block['innerBlocks'] ) );
			}
		}
		return array_values( array_unique( array_filter( $keys ) ) );
	}
}