<?php
/**
 * Records customers moving between groups, and tells other plugins (like Hookbird).
 *
 * @package Statbird
 */

namespace Statbird;

defined( 'ABSPATH' ) || exit;

/**
 * The wp_statbird_changes log.
 */
class Changes {

	/**
	 * Table name.
	 *
	 * @return string
	 */
	public static function table() {
		global $wpdb;
		return $wpdb->prefix . 'statbird_changes';
	}

	/**
	 * Saves group moves and fires an action for each.
	 *
	 * A first group (from '' on a new customer) is a new customer, not a move, and is skipped.
	 *
	 * @param array[] $changes Each: customer key, from group, to group.
	 * @param string  $when    MySQL datetime (GMT).
	 */
	public static function record( array $changes, $when ) {
		global $wpdb;
		$changes = array_values(
			array_filter(
				$changes,
				static function ( $c ) {
					return '' !== $c[1] && $c[1] !== $c[2];
				}
			)
		);
		if ( ! $changes ) {
			return;
		}
		$table = self::table();
		foreach ( array_chunk( $changes, 500 ) as $chunk ) {
			$values = array();
			foreach ( $chunk as $c ) {
				$values[] = $wpdb->prepare( '(%s, %s, %s, %s)', $c[0], $c[1], $c[2], $when );
			}
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- values prepared above.
			$wpdb->query( "INSERT INTO $table (customer_key, from_segment, to_segment, changed_at) VALUES " . implode( ',', $values ) );
		}
		foreach ( $changes as $c ) {
			/**
			 * Fires when a customer moves to another group.
			 *
			 * @param string $customer_key MD5 key.
			 * @param string $from         Previous group key.
			 * @param string $to           New group key.
			 */
			do_action( 'statbird_segment_changed', $c[0], $c[1], $c[2] );
		}
	}

	/**
	 * Recent moves with customer details, newest first.
	 *
	 * @param int $days  Look-back window.
	 * @param int $limit Maximum rows.
	 * @return array[]
	 */
	public static function recent( $days = 30, $limit = 8 ) {
		global $wpdb;
		$c = self::table();
		$s = Store::table();
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table names only.
		return (array) $wpdb->get_results( $wpdb->prepare( "SELECT ch.*, cu.name, cu.email, cu.user_id, cu.spent FROM $c ch LEFT JOIN $s cu ON cu.customer_key = ch.customer_key WHERE ch.changed_at >= %s ORDER BY ch.changed_at DESC, cu.spent DESC LIMIT %d", gmdate( 'Y-m-d H:i:s', time() - $days * DAY_IN_SECONDS ), $limit ), ARRAY_A );
	}

	/**
	 * Count of moves between each pair of groups in a window.
	 *
	 * @param int $days Look-back window.
	 * @return array[] Rows of from_segment, to_segment, n.
	 */
	public static function flows( $days = 30 ) {
		global $wpdb;
		$c = self::table();
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name only.
		return (array) $wpdb->get_results( $wpdb->prepare( "SELECT from_segment, to_segment, COUNT(*) AS n FROM $c WHERE changed_at >= %s GROUP BY from_segment, to_segment ORDER BY n DESC", gmdate( 'Y-m-d H:i:s', time() - $days * DAY_IN_SECONDS ) ), ARRAY_A );
	}
}