<?php

namespace Glovario\Usage;

use Glovario\Database\Transaction;
use Glovario\Domain\TokenParser;
use Glovario\Repository\RuleRepository;
use Glovario\Repository\VariableRepository;

defined( 'ABSPATH' ) || exit;

final class ReferenceReplacementService {
	const PREVIEW_START = '__GLOVARIO_REPLACEMENT_START__';
	const PREVIEW_END   = '__GLOVARIO_REPLACEMENT_END__';

	private $variables;
	private $rules;
	private $tokens;

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

	public function replace( $variable, $matches, $strategy, $finalize = null ) {
		if ( ! in_array( $strategy, array( 'value', 'empty' ), true ) ) {
			return new \WP_Error( 'invalid_replacement_strategy', __( 'Select a valid reference replacement option.', 'glovario' ) );
		}
		$replacement = 'value' === $strategy ? (string) $variable['value'] : '';
		$locations   = $this->unique_locations( $matches );
		foreach ( $locations as $match ) {
			if ( 'content' === $match['kind'] && ! current_user_can( 'edit_post', $match['id'] ) ) {
				return new \WP_Error( 'replacement_forbidden', __( 'You do not have permission to update every detected content item, so no deletion was attempted.', 'glovario' ) );
			}
		}

		return Transaction::run(
			function () use ( $variable, $replacement, $locations, $finalize ) {
				$result = $this->apply( $variable['variable_key'], $replacement, $locations, 'replace' );
				return is_wp_error( $result ) || ! is_callable( $finalize ) ? $result : call_user_func( $finalize, $result );
			}
		);
	}

	public function migrate_key( $variable, $new_key, $matches, $finalize = null ) {
		$new_key = sanitize_key( $new_key );
		if ( '' === $new_key || $new_key === $variable['variable_key'] ) {
			return new \WP_Error( 'invalid_migration_key', __( 'Enter a different valid key before migrating references.', 'glovario' ) );
		}
		$locations = $this->unique_locations( $matches );
		foreach ( $locations as $match ) {
			if ( $this->is_post_storage( $match['storage'] ?? $match['kind'] ) && ! current_user_can( 'edit_post', $match['id'] ) ) {
				return new \WP_Error( 'replacement_forbidden', __( 'You do not have permission to update every detected content item, so no migration was attempted.', 'glovario' ) );
			}
		}
		return Transaction::run(
			function () use ( $variable, $new_key, $locations, $finalize ) {
				$result = $this->apply( $variable['variable_key'], $new_key, $locations, 'key' );
				return is_wp_error( $result ) || ! is_callable( $finalize ) ? $result : call_user_func( $finalize, $result );
			}
		);
	}

	public function preview( $variable, $match, $strategy ) {
		$source = $this->source_content( $match );
		if ( null === $source ) {
			return null;
		}
		$replacement = 'value' === $strategy ? (string) $variable['value'] : '';
		if ( 'keep' === $strategy ) {
			$after = $source;
		} elseif ( 'post_content' === ( $match['storage'] ?? $match['kind'] ) || 'content' === ( $match['storage'] ?? $match['kind'] ) ) {
			$after = $this->replace_post_content( $source, $variable['variable_key'], $replacement );
		} else {
			$after = $this->replace_references( $source, $variable['variable_key'], $replacement );
		}
		$after_display = $after;
		if ( 'value' === $strategy ) {
			$marked_replacement = self::PREVIEW_START . $replacement . self::PREVIEW_END;
			if ( 'post_content' === ( $match['storage'] ?? $match['kind'] ) || 'content' === ( $match['storage'] ?? $match['kind'] ) ) {
				$after_display = $this->replace_post_content( $source, $variable['variable_key'], $marked_replacement );
			} else {
				$after_display = $this->replace_references( $source, $variable['variable_key'], $marked_replacement );
			}
		}
		return array(
			'location'      => $match['title'],
			'before'        => $this->excerpt( $source, $variable['variable_key'] ),
			'after'         => $this->excerpt( $after, $variable['variable_key'] ),
			'after_display' => $this->excerpt( $after_display, $variable['variable_key'] ),
		);
	}

	private function unique_locations( $matches ) {
		$locations = array();
		foreach ( (array) $matches as $match ) {
			$storage = $match['storage'] ?? $match['kind'];
			$id      = 'rule' === $storage ? absint( $match['rule_id'] ?? 0 ) : absint( $match['id'] ?? 0 );
			if ( ! $id ) {
				continue;
			}
			$locations[ $storage . ':' . $id ] = $match;
		}
		return array_values( $locations );
	}

	private function apply( $key, $replacement, $locations, $mode ) {
		do_action( 'glovario_before_reference_batch', $locations, $mode );
		$updated = 0;
		foreach ( $locations as $match ) {
			$result = $this->replace_location( $key, $replacement, $match, $mode );
			if ( is_wp_error( $result ) ) {
				return $result;
			}
			$updated += $result ? 1 : 0;
		}
		$result = array( 'updated_locations' => $updated );
		do_action( 'glovario_after_reference_batch', $locations, $mode );
		return $result;
	}

	private function replace_location( $key, $replacement, $match, $mode = 'replace' ) {
		$storage = $match['storage'] ?? $match['kind'];
		if ( $this->is_post_storage( $storage ) ) {
			$post = get_post( $match['id'] );
			if ( ! $post ) {
				return new \WP_Error( 'replacement_content_missing', __( 'A detected content item no longer exists.', 'glovario' ) );
			}
			$field   = 'content' === $storage ? 'post_content' : $storage;
			$source  = (string) $post->{$field};
			$content = 'post_content' === $field ? $this->replace_post_content( $source, $key, $replacement, $mode ) : $this->replace_references( $source, $key, $replacement, $mode );
			if ( $content === $source ) {
				return false;
			}
			if ( \Glovario\Migration\ContentConversionService::would_lose_markup( $content, $field ) ) {
				return new \WP_Error(
					'replacement_markup',
					/* translators: %s: title of the content item. */
					sprintf( __( '“%s” contains markup that your account cannot save (such as an embedded frame or a script). Nothing was changed; a user who can save unfiltered HTML must make this change.', 'glovario' ), $post->post_title )
				);
			}
			// wp_update_post() unslashes what it is given: slash it, or every backslash is lost.
			$result = wp_update_post(
				wp_slash(
					array(
						'ID'   => $post->ID,
						$field => $content,
					)
				),
				true
			);
			return is_wp_error( $result ) ? $result : true;
		}
		if ( 'widget_text' === $storage ) {
			$widgets = get_option( 'widget_text', array() );
			$id      = absint( $match['id'] ?? 0 );
			if ( ! isset( $widgets[ $id ] ) || ! is_array( $widgets[ $id ] ) ) {
				return new \WP_Error( 'replacement_widget_missing', __( 'A detected text widget no longer exists.', 'glovario' ) );
			}
			$source  = (string) ( $widgets[ $id ]['text'] ?? '' );
			$content = $this->replace_html_text( $source, $key, $replacement, $mode );
			if ( $content === $source ) {
				return false;
			}
			$widgets[ $id ]['text'] = $content;
			return update_option( 'widget_text', $widgets ) ? true : new \WP_Error( 'replacement_widget_failed', __( 'A detected text widget could not be updated.', 'glovario' ) );
		}
		if ( 'widget_block' === $storage ) {
			$widgets = get_option( 'widget_block', array() );
			$id      = absint( $match['id'] ?? 0 );
			if ( ! isset( $widgets[ $id ] ) || ! is_array( $widgets[ $id ] ) ) {
				return new \WP_Error( 'replacement_widget_missing', __( 'A detected text widget no longer exists.', 'glovario' ) );
			}
			$source  = (string) ( $widgets[ $id ]['content'] ?? '' );
			$content = $this->replace_post_content( $source, $key, $replacement, $mode );
			if ( $content === $source ) {
				return false;
			}
			$widgets[ $id ]['content'] = $content;
			return update_option( 'widget_block', $widgets ) ? true : new \WP_Error( 'replacement_widget_failed', __( 'A detected text widget could not be updated.', 'glovario' ) );
		}
		if ( 'rule' === $storage ) {
			$rule = $this->rules->find( $match['rule_id'] ?? 0 );
			if ( ! $rule ) {
				return new \WP_Error( 'replacement_rule_missing', __( 'A detected conditional rule no longer exists.', 'glovario' ) );
			}
			$rule['alternative_value'] = $this->replace_references( $rule['alternative_value'], $key, $replacement, $mode );
			$result = $this->rules->save( $rule, $rule['id'] );
			return is_wp_error( $result ) ? $result : true;
		}
		$source = $this->variables->find( $match['id'] );
		if ( ! $source || $source['variable_key'] === $key ) {
			return false;
		}
		$source['value'] = $this->replace_references( $source['value'], $key, $replacement, $mode );
		$result          = $this->variables->update( $source['id'], $source );
		return is_wp_error( $result ) ? $result : true;
	}

	private function source_content( $match ) {
		$storage = $match['storage'] ?? $match['kind'];
		if ( $this->is_post_storage( $storage ) ) {
			$post = get_post( $match['id'] );
			$field = 'content' === $storage ? 'post_content' : $storage;
			return $post ? $post->{$field} : null;
		}
		if ( 'widget_text' === $storage ) {
			$widgets = get_option( 'widget_text', array() );
			return isset( $widgets[ $match['id'] ]['text'] ) ? $widgets[ $match['id'] ]['text'] : null;
		}
		if ( 'widget_block' === $storage ) {
			$widgets = get_option( 'widget_block', array() );
			return isset( $widgets[ $match['id'] ]['content'] ) ? $widgets[ $match['id'] ]['content'] : null;
		}
		if ( 'rule' === $storage ) {
			$rule = $this->rules->find( $match['rule_id'] ?? 0 );
			return $rule ? $rule['alternative_value'] : null;
		}
		$variable = $this->variables->find( $match['id'] );
		return $variable ? $variable['value'] : null;
	}

	private function replace_post_content( $content, $key, $replacement, $mode = 'replace' ) {
		$blocks = parse_blocks( $content );
		$blocks = $this->replace_blocks( $blocks, $key, $replacement, $mode );
		return serialize_blocks( $blocks );
	}

	private function replace_blocks( $blocks, $key, $replacement, $mode = 'replace' ) {
		$result = array();
		foreach ( $blocks as $block ) {
			if ( 'glovario/site-variable' === $block['blockName'] && sanitize_key( $block['attrs']['key'] ?? '' ) === $key ) {
				if ( 'key' === $mode ) {
					$block['attrs']['key'] = $replacement;
					$result[]              = $block;
					continue;
				}
				$text     = $this->escape_text_replacement( $replacement );
				$result[] = array(
					'blockName' => null,
					'attrs' => array(),
					'innerBlocks' => array(),
					'innerHTML' => $text,
					'innerContent' => array( $text ),
				);
				continue;
			}
			if ( 'key' === $mode && in_array( $block['blockName'], array( 'core/navigation', 'core/navigation-link', 'core/navigation-submenu', 'core/page-list' ), true ) ) {
				foreach ( (array) ( $block['attrs'] ?? array() ) as $attribute => $value ) {
					if ( is_string( $value ) ) {
						$block['attrs'][ $attribute ] = $this->replace_references( $value, $key, $replacement, $mode );
					}
				}
			}
			if ( ! empty( $block['innerBlocks'] ) ) {
				$block['innerBlocks'] = $this->replace_blocks( $block['innerBlocks'], $key, $replacement, $mode );
			}
			if ( ! empty( $block['innerContent'] ) ) {
				foreach ( $block['innerContent'] as $index => $inner ) {
					if ( is_string( $inner ) ) {
						$block['innerContent'][ $index ] = $this->replace_html_text( $inner, $key, $replacement, $mode );
					}
				}
			}
			$block['innerHTML'] = $this->replace_html_text( $block['innerHTML'] ?? '', $key, $replacement, $mode );
			$result[]           = $block;
		}
		return $result;
	}

	private function replace_html_text( $content, $key, $replacement, $mode = 'replace' ) {
		$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 ) {
				$parts[ $index ] = $this->replace_references( $part, $key, 'key' === $mode ? $replacement : $this->escape_text_replacement( $replacement ), $mode );
			}
		}
		return implode( '', $parts );
	}

	private function escape_text_replacement( $replacement ) {
		return str_replace( array( '&quot;', '&#039;' ), array( '"', "'" ), esc_html( (string) $replacement ) );
	}

	private function replace_references( $content, $key, $replacement, $mode = 'replace' ) {
		$content = $this->tokens->replace(
			$content,
			static function ( $found, $original ) use ( $key, $replacement, $mode ) {
				if ( $found !== $key ) {
					return $original;
				}
				return 'key' === $mode ? str_replace( '{{glvr:' . $key, '{{glvr:' . $replacement, $original ) : $replacement;
			}
		);
		if ( false === strpos( $content, '[glvr' ) ) {
			return $content;
		}
		$pattern = '/' . get_shortcode_regex( array( 'glvr' ) ) . '/s';
		$result  = preg_replace_callback(
			$pattern,
			static function ( $matches ) use ( $key, $replacement, $mode ) {
				if ( '[' === $matches[1] && ']' === $matches[6] ) {
					return $matches[0];
				}
				$attributes = shortcode_parse_atts( $matches[3] );
				$found      = sanitize_key( is_array( $attributes ) ? ( $attributes['key'] ?? '' ) : '' );
				if ( $found !== $key ) {
					return $matches[0];
				}
				if ( 'key' !== $mode ) {
					return $replacement;
				}
				$attribute_pattern = '/(\bkey\s*=\s*)(["\']?)' . preg_quote( $key, '/' ) . '\\2/i';
				$migrated          = preg_replace( $attribute_pattern, '$1$2' . $replacement . '$2', $matches[0], 1 );
				return null === $migrated ? $matches[0] : $migrated;
			},
			$content
		);
		return null === $result ? $content : $result;
	}

	private function is_post_storage( $storage ) {
		return in_array( $storage, array( 'content', 'post_content', 'post_title', 'post_excerpt' ), true );
	}

	private function excerpt( $content, $key ) {
		$text = trim( preg_replace( '/\s+/', ' ', wp_strip_all_tags( (string) $content ) ) );
		if ( '' === $text && false !== strpos( (string) $content, 'glovario/site-variable' ) ) {
			$text = '<Site Variable block: ' . $key . '>';
		}
		$marked_excerpt = $this->marked_excerpt( $text );
		if ( null !== $marked_excerpt ) {
			return $marked_excerpt;
		}
		return wp_html_excerpt( $text, 220, '…' );
	}

	private function marked_excerpt( $text ) {
		$start = strpos( $text, self::PREVIEW_START );
		if ( false === $start ) {
			return null;
		}
		$value_start = $start + strlen( self::PREVIEW_START );
		$end         = strpos( $text, self::PREVIEW_END, $value_start );
		if ( false === $end ) {
			return null;
		}

		$before     = substr( $text, 0, $start );
		$replacement = substr( $text, $value_start, $end - $value_start );
		$after       = substr( $text, $end + strlen( self::PREVIEW_END ) );

		return $this->tail_excerpt( $before, 80 )
			. self::PREVIEW_START
			. wp_html_excerpt( $replacement, 140, '…' )
			. self::PREVIEW_END
			. wp_html_excerpt( $after, 60, '…' );
	}

	private function tail_excerpt( $text, $length ) {
		$text_length = function_exists( 'mb_strlen' ) ? mb_strlen( $text ) : strlen( $text );
		if ( $text_length <= $length ) {
			return $text;
		}
		$tail = function_exists( 'mb_substr' ) ? mb_substr( $text, -$length ) : substr( $text, -$length );
		return '…' . $tail;
	}
}