<?php
/**
 * Hooktrail_Diff
 *
 * Compares two Hooktrail maps (from Export JSON or "wp hooktrail record"):
 * hooks that only fired in one of them, callbacks added, missing or moved
 * to a different priority, scripts and styles added or missing, and the
 * totals. High-volume hooks are ignored, as they change with content.
 *
 * The drawer's Compare tab applies the same rules in JavaScript.
 *
 * @package Hooktrail
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class Hooktrail_Diff {

	/**
	 * Whether a decoded JSON value looks like a Hooktrail map.
	 *
	 * @param mixed $map Decoded JSON.
	 * @return bool
	 */
	public static function is_map( $map ) {
		return is_array( $map ) && isset( $map['hooks'], $map['summary'] ) && is_array( $map['hooks'] );
	}

	/**
	 * @param array $a Earlier map.
	 * @param array $b Later map.
	 * @return array
	 */
	public static function compare( array $a, array $b ) {
		$hooks_a = self::hook_names( $a );
		$hooks_b = self::hook_names( $b );
		$cbs_a   = self::callbacks( $a );
		$cbs_b   = self::callbacks( $b );

		$moved = array();
		foreach ( array_intersect_key( $cbs_a, $cbs_b ) as $key => $cb ) {
			if ( $cb['priorities'] !== $cbs_b[ $key ]['priorities'] ) {
				$moved[] = $cb + array( 'to' => $cbs_b[ $key ]['priorities'] );
			}
		}

		$assets_a = self::assets( $a );
		$assets_b = self::assets( $b );

		$totals = array();
		foreach ( array( 'hooks', 'callbacks', 'queries', 'errors' ) as $key ) {
			$totals[ $key ] = array(
				'a' => isset( $a['summary'][ $key ] ) ? (int) $a['summary'][ $key ] : 0,
				'b' => isset( $b['summary'][ $key ] ) ? (int) $b['summary'][ $key ] : 0,
			);
		}

		return array(
			'hooksOnlyA'    => array_values( array_diff( $hooks_a, $hooks_b ) ),
			'hooksOnlyB'    => array_values( array_diff( $hooks_b, $hooks_a ) ),
			'cbAdded'       => array_values( array_diff_key( $cbs_b, $cbs_a ) ),
			'cbRemoved'     => array_values( array_diff_key( $cbs_a, $cbs_b ) ),
			'cbMoved'       => $moved,
			'assetsAdded'   => array_values( array_diff( $assets_b, $assets_a ) ),
			'assetsRemoved' => array_values( array_diff( $assets_a, $assets_b ) ),
			'totals'        => $totals,
		);
	}

	/**
	 * Whether a comparison found any structural difference.
	 *
	 * @param array $diff From compare().
	 * @return bool
	 */
	public static function has_changes( array $diff ) {
		foreach ( array( 'hooksOnlyA', 'hooksOnlyB', 'cbAdded', 'cbRemoved', 'cbMoved', 'assetsAdded', 'assetsRemoved' ) as $key ) {
			if ( ! empty( $diff[ $key ] ) ) {
				return true;
			}
		}
		return false;
	}

	private static function hook_names( $map ) {
		$names = array();
		foreach ( $map['hooks'] as $hook ) {
			if ( empty( $hook['z'] ) ) {
				$names[] = (string) $hook['n'];
			}
		}
		return $names;
	}

	/**
	 * Callbacks keyed by hook, callback and owner, with their priorities.
	 */
	private static function callbacks( $map ) {
		$components = isset( $map['components'] ) && is_array( $map['components'] ) ? $map['components'] : array();
		$out        = array();

		foreach ( $map['hooks'] as $hook ) {
			if ( ! empty( $hook['z'] ) || empty( $hook['cb'] ) ) {
				continue;
			}
			foreach ( $hook['cb'] as $cb ) {
				// Closures have no stable name, so they are identified by file.
				$label = 'Closure' === $cb['l'] ? 'Closure@' . $cb['f'] : $cb['l'];
				$key   = $hook['n'] . '|' . $label . '|' . $cb['c'];

				if ( ! isset( $out[ $key ] ) ) {
					$out[ $key ] = array(
						'hook'       => (string) $hook['n'],
						'callback'   => (string) $label,
						'component'  => isset( $components[ $cb['c'] ]['name'] ) ? (string) $components[ $cb['c'] ]['name'] : (string) $cb['c'],
						'priorities' => array(),
					);
				}
				$out[ $key ]['priorities'][] = (int) $cb['p'];
			}
		}

		foreach ( $out as $key => $cb ) {
			sort( $out[ $key ]['priorities'] );
		}

		return $out;
	}

	private static function assets( $map ) {
		$out = array();
		if ( empty( $map['assets'] ) || ! is_array( $map['assets'] ) ) {
			return $out;
		}
		foreach ( array( 'scripts', 'styles' ) as $type ) {
			if ( empty( $map['assets'][ $type ] ) ) {
				continue;
			}
			foreach ( $map['assets'][ $type ] as $asset ) {
				$out[] = $type . ':' . $asset['h'];
			}
		}
		return $out;
	}

	/**
	 * Plain-text report for the command line.
	 *
	 * @param array $diff From compare().
	 * @return string
	 */
	public static function to_text( array $diff ) {
		$lines = array();

		$sections = array(
			'hooksOnlyA'    => 'Hooks only in A',
			'hooksOnlyB'    => 'Hooks only in B',
			'assetsAdded'   => 'Assets added in B',
			'assetsRemoved' => 'Assets missing in B',
		);
		foreach ( $sections as $key => $title ) {
			if ( $diff[ $key ] ) {
				$lines[] = $title . ':';
				foreach ( $diff[ $key ] as $item ) {
					$lines[] = '  ' . $item;
				}
			}
		}

		$cb_sections = array(
			'cbAdded'   => 'Callbacks added in B',
			'cbRemoved' => 'Callbacks missing in B',
			'cbMoved'   => 'Callbacks with a different priority',
		);
		foreach ( $cb_sections as $key => $title ) {
			if ( $diff[ $key ] ) {
				$lines[] = $title . ':';
				foreach ( $diff[ $key ] as $cb ) {
					$line = sprintf( '  %s  %s  (%s, priority %s', $cb['hook'], $cb['callback'], $cb['component'], implode( ',', $cb['priorities'] ) );
					if ( isset( $cb['to'] ) ) {
						$line .= ' -> ' . implode( ',', $cb['to'] );
					}
					$lines[] = $line . ')';
				}
			}
		}

		$lines[] = 'Totals (A -> B):';
		foreach ( $diff['totals'] as $key => $pair ) {
			$lines[] = sprintf( '  %-10s %d -> %d', $key, $pair['a'], $pair['b'] );
		}

		return implode( "\n", $lines );
	}
}