<?php
/**
 * Exporting entries to a spreadsheet.
 *
 * A CSV is written, not an XLSX. The reason is not laziness:
 *
 * 1. An XLSX is really a zip with a few XML files inside. Building one properly
 *    would need a library of several megabytes, while the whole plugin weighs
 *    less than one. That would mean everyone who installs the plugin carries
 *    that library, while the export is used by few people
 * 2. A CSV opens in Excel, in Google Sheets and in Numbers, with no addon at all
 *
 * Two traps that are already dealt with here:
 *
 * - **Excel eats leading zeros and turns things into dates.** The phone number
 *   `0611234567` becomes `611234567`, and `1-2` becomes `2 January`. So every
 *   field is written as text, not as a number
 * - **A formula in an entry is an attack, not a mistake.** If a visitor types
 *   `=HYPERLINK(...)` in, Excel runs it when the file is opened. So an apostrophe
 *   is put in front of every character that starts a formula
 *
 * Copyright (c) 2026 Quantum, Serbia. https://2ranq.com
 *
 * This program is free software: you can redistribute it and change it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 2 of the License, or any later version. The full
 * text is in LICENSE.txt, next to this file.
 *
 * @package Ranq_Forms
 */

defined( 'ABSPATH' ) || exit;

/**
 * Ranq_Forms_Export
 */
class Ranq_Forms_Export {

	/**
	 * The name of the action.
	 */
	const ACTION = 'ranq_forms_export';

	/**
	 * How many rows are read at a time.
	 *
	 * Everything is not read into memory, because a form with a hundred thousand
	 * entries would bring the server down that way. It is read in chunks and
	 * printed straight away.
	 */
	const CHUNK = 500;

	/**
	 * Hooks up.
	 *
	 * @return void
	 */
	public static function hooks() {

		add_action( 'admin_post_' . self::ACTION, array( __CLASS__, 'download' ) );
	}

	/**
	 * The download address.
	 *
	 * @param int $form_id The form id.
	 *
	 * @return string
	 */
	public static function url( $form_id ) {

		return wp_nonce_url(
			admin_url( 'admin-post.php?action=' . self::ACTION . '&form_id=' . absint( $form_id ) ),
			self::ACTION . '_' . absint( $form_id )
		);
	}

	/**
	 * Sends the file.
	 *
	 * @return void
	 */
	public static function download() {

		$form_id = isset( $_GET['form_id'] ) ? absint( wp_unslash( $_GET['form_id'] ) ) : 0;

		check_admin_referer( self::ACTION . '_' . $form_id );

		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( esc_html__( 'You do not have permission to do that.', '2ranq-forms' ) );
		}

		$form = get_post( $form_id );

		if ( ! $form instanceof WP_Post || Ranq_Forms_Post_Type::POST_TYPE !== $form->post_type ) {
			wp_die( esc_html__( 'That form does not exist.', '2ranq-forms' ) );
		}

		$fields = self::input_fields( $form_id );

		nocache_headers();

		header( 'Content-Type: text/csv; charset=UTF-8' );
		header( 'Content-Disposition: attachment; filename="' . self::filename( $form ) . '"' );

		$out = fopen( 'php://output', 'w' ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fopen -- this is not a file on disk but the output to the browser.

		// The mark at the start of the file. Without it Excel on Windows reads our
		// letters as rubbish, and "Đorđe" becomes "Ä‘orÄ‘e".
		echo "\xEF\xBB\xBF"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- three bytes of the mark, there is nothing to escape.

		$header = array(
			__( 'Entry', '2ranq-forms' ),
			__( 'Date', '2ranq-forms' ),
		);

		foreach ( $fields as $field ) {
			$header[] = isset( $field['label'] ) && '' !== $field['label'] ? $field['label'] : $field['id'];
		}

		$header[] = __( 'IP address', '2ranq-forms' );

		fputcsv( $out, $header );

		$offset = 0;

		do {
			$rows = Ranq_Forms_Entries::get_for_form( $form_id, self::CHUNK, $offset );

			foreach ( $rows as $row ) {
				fputcsv( $out, self::line( $row, $fields ) );
			}

			$offset += self::CHUNK;

			// The output is pushed to the browser at once, so a large export does not wait in memory.
			flush();

		} while ( count( $rows ) === self::CHUNK );

		fclose( $out ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose -- output to the browser, not a file on disk.

		exit;
	}

	/**
	 * One row.
	 *
	 * @param array $row    The record out of the database.
	 * @param array $fields The form fields.
	 *
	 * @return array
	 */
	private static function line( $row, $fields ) {

		$values = json_decode( isset( $row['fields'] ) ? $row['fields'] : '', true );
		$values = is_array( $values ) ? $values : array();

		$line = array(
			self::safe( $row['id'] ),
			self::safe( get_date_from_gmt( $row['created_at'], 'Y-m-d H:i' ) ),
		);

		foreach ( $fields as $field ) {

			$key    = $field['id'];
			$object = Ranq_Forms_Fields::get( $field['type'] );
			$value  = isset( $values[ $key ] ) ? $values[ $key ] : '';

			if ( $object instanceof Ranq_Forms_Field ) {
				$value = $object->format_value( $value, $field );
			}

			$line[] = self::safe( $value );
		}

		$line[] = self::safe( isset( $row['ip'] ) ? $row['ip'] : '' );

		return $line;
	}

	/**
	 * Prepares one value for the spreadsheet.
	 *
	 * @param mixed $value The value.
	 *
	 * @return string
	 */
	private static function safe( $value ) {

		if ( is_array( $value ) ) {
			$value = implode( ', ', array_map( 'strval', $value ) );
		}

		$value = (string) $value;

		// A formula in an entry is an attack, not a mistake. Excel runs whatever starts
		// with these characters the moment the file is opened, so an apostrophe goes in
		// front of them, which the spreadsheet does not show but the formula dies on.
		if ( '' !== $value && false !== strpos( "=+-@\t\r", $value[0] ) ) {
			$value = "'" . $value;
		}

		return $value;
	}

	/**
	 * The fields that really take input.
	 *
	 * @param int $form_id The form id.
	 *
	 * @return array
	 */
	private static function input_fields( $form_id ) {

		$out = array();

		foreach ( Ranq_Forms_Fields::get_form_fields( $form_id ) as $field ) {

			$object = isset( $field['type'] ) ? Ranq_Forms_Fields::get( $field['type'] ) : null;

			if ( $object instanceof Ranq_Forms_Field && $object->is_input() ) {
				$out[] = $field;
			}
		}

		return $out;
	}

	/**
	 * The file name.
	 *
	 * @param WP_Post $form The form.
	 *
	 * @return string
	 */
	private static function filename( $form ) {

		$slug = sanitize_title( get_the_title( $form ) );
		$slug = $slug ? $slug : 'form-' . $form->ID;

		return $slug . '-' . gmdate( 'Y-m-d' ) . '.csv';
	}
}