<?php
/**
 * CSV export.
 *
 * @package A360_Insights
 */

defined( 'ABSPATH' ) || exit;

/**
 * CSV export handler.
 */
class A360_Insights_Export {
	/**
	 * Init hooks.
	 *
	 * @return void
	 */
	public function init() {
		add_action( 'admin_post_a360_insights_export_csv', array( $this, 'export_csv' ) );
	}

	/**
	 * Export CSV.
	 *
	 * @return void
	 */
	public function export_csv() {
		$post_id = isset( $_POST['post_id'] ) ? absint( $_POST['post_id'] ) : 0;
		$nonce   = isset( $_POST['_wpnonce'] ) ? sanitize_text_field( wp_unslash( $_POST['_wpnonce'] ) ) : '';

		if ( ! $post_id || ! wp_verify_nonce( $nonce, 'a360_insights_export_' . $post_id ) || ! current_user_can( 'edit_post', $post_id ) ) {
			wp_die( esc_html__( 'Invalid export request.', 'a360-insights' ) );
		}

		$rows     = A360_Insights_DB::get_export_rows( $post_id );
		$filename = 'a360-insights-' . $post_id . '-' . gmdate( 'Y-m-d' ) . '.csv';

		nocache_headers();
		header( 'Content-Type: text/csv; charset=utf-8' );
		header( 'Content-Disposition: attachment; filename="' . sanitize_file_name( $filename ) . '"' );

		echo esc_html( $this->csv_line( array( 'viewed_at', 'source', 'referrer_host', 'utm_source', 'utm_medium', 'utm_campaign' ) ) );

		foreach ( $rows as $row ) {
			echo esc_html(
				$this->csv_line(
					array(
						$row['viewed_at'] ?? '',
						$row['source'] ?? '',
						$row['referrer_host'] ?? '',
						$row['utm_source'] ?? '',
						$row['utm_medium'] ?? '',
						$row['utm_campaign'] ?? '',
					)
				)
			);
		}

		exit;
	}

	/**
	 * Build CSV line without direct file operations.
	 *
	 * @param array $fields Fields.
	 * @return string
	 */
	private function csv_line( array $fields ) {
		$escaped = array();

		foreach ( $fields as $field ) {
			$field     = (string) $field;
			$field     = str_replace( '"', '""', $field );
			$escaped[] = '"' . $field . '"';
		}

		return implode( ',', $escaped ) . "\r\n";
	}
}