<?php
if (!defined('ABSPATH')) exit;

/**
 * Exports analytics data to CSV / ZIP and handles cleanup.
 *
 * @package Statinform
 */
class EISTAT_Exporter {

    public static function tables() {
        return ['daily', 'sessions', 'pageviews', 'sources', 'transitions', 'events'];
    }

    public static function archive_dir() {
        return eistat_get_archive_dir();
    }

    private static function full_table($table) {
        global $wpdb;
        return $wpdb->prefix . 'eistat_' . $table;
    }

    private static function is_valid_table($table) {
        return in_array($table, self::tables(), true);
    }

    public static function export_table_to_csv($table, $from, $to) {
        global $wpdb;

        if (!self::is_valid_table($table)) return false;

        $full = self::full_table($table);

        $tmp = wp_tempnam('eistat_' . $table . '_');
        if (!$tmp) return false;

        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fopen
        $fp = fopen($tmp, 'w');
        if (!$fp) return false;

        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fwrite
        fwrite($fp, "\xEF\xBB\xBF");

        $sql_cols = "SHOW COLUMNS FROM " . $full;
        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
        $columns = $wpdb->get_col($sql_cols, 0);
        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fwrite
        fputcsv($fp, $columns, ',');

        $offset = 0;
        $limit  = 5000;

        while (true) {
            $sql = "SELECT * FROM " . $full . "
                    WHERE date >= %s AND date <= %s
                    ORDER BY date ASC
                    LIMIT %d OFFSET %d";
            // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
            $rows = $wpdb->get_results($wpdb->prepare($sql, $from, $to, $limit, $offset), ARRAY_A);

            if (!$rows) break;

            foreach ($rows as $row) {
                // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fwrite
                fputcsv($fp, $row, ',');
            }

            $offset += $limit;
            if (count($rows) < $limit) break;
        }

        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose
        fclose($fp);
        return $tmp;
    }

    public static function download_csv($table, $from, $to) {
        $tmp = self::export_table_to_csv($table, $from, $to);
        if (!$tmp) {
            wp_die(esc_html__('Failed to generate CSV.', 'statinform'));
        }

        $filename = 'eistat_' . $table . '_' . $from . '_' . $to . '.csv';

        header('Content-Type: text/csv; charset=utf-8');
        header('Content-Disposition: attachment; filename="' . $filename . '"');
        header('Content-Length: ' . filesize($tmp));
        header('Cache-Control: no-cache, no-store, must-revalidate');

        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_readfile
        readfile($tmp);
        wp_delete_file($tmp);
        exit;
    }

    public static function create_archive($tables, $from, $to) {
        if (!class_exists('ZipArchive')) return false;

        $dir = self::archive_dir();
        if (!file_exists($dir)) wp_mkdir_p($dir);

        $filename = 'eistat_archive_' . $from . '_' . $to . '_' . wp_date('His') . '.zip';
        $path = $dir . $filename;

        $zip = new ZipArchive();
        if ($zip->open($path, ZipArchive::CREATE | ZipArchive::OVERWRITE) !== true) {
            return false;
        }

        $manifest = [
            'plugin'     => 'StatInform',
            'version'    => EISTAT_VERSION,
            'created_at' => current_time('mysql'),
            'from'       => $from,
            'to'         => $to,
            'tables'     => [],
        ];

        $tmp_files = [];

        foreach ($tables as $table) {
            if (!self::is_valid_table($table)) continue;

            $tmp = self::export_table_to_csv($table, $from, $to);
            if (!$tmp) continue;

            $name = $table . '_' . $from . '_' . $to . '.csv';
            $zip->addFile($tmp, $name);
            $tmp_files[] = $tmp;

            $manifest['tables'][$table] = [
                'file' => $name,
                'size' => filesize($tmp),
            ];
        }

        $zip->addFromString(
            'manifest.json',
            wp_json_encode($manifest, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE)
        );
        $zip->close();

        foreach ($tmp_files as $tmp) {
            wp_delete_file($tmp);
        }

        return $filename;
    }

    public static function list_archives() {
        $dir = self::archive_dir();
        $files = glob($dir . '*.zip');
        if (!$files) return [];

        $result = [];
        foreach ($files as $f) {
            $result[] = [
                'name' => basename($f),
                'size' => filesize($f),
                'date' => filemtime($f),
            ];
        }
        usort($result, function ($a, $b) { return $b['date'] - $a['date']; });
        return $result;
    }

    public static function download_archive($name) {
        $name = basename($name);
        if (!preg_match('/^eistat_archive_[\d\-_]+\.zip$/', $name)) {
            wp_die(esc_html__('Invalid filename.', 'statinform'));
        }

        $path = self::archive_dir() . $name;
        if (!file_exists($path)) {
            wp_die(esc_html__('Archive not found.', 'statinform'));
        }

        header('Content-Type: application/zip');
        header('Content-Disposition: attachment; filename="' . $name . '"');
        header('Content-Length: ' . filesize($path));
        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_readfile
        readfile($path);
        exit;
    }

    public static function delete_archive($name) {
        $name = basename($name);
        if (!preg_match('/^eistat_archive_[\d\-_]+\.zip$/', $name)) return false;

        $path = self::archive_dir() . $name;
        if (!file_exists($path)) return false;

        return wp_delete_file($path);
    }

    public static function delete_before($date) {
        global $wpdb;
        $result = [];

        foreach (self::tables() as $table) {
            $full = self::full_table($table);
            $sql = "DELETE FROM " . $full . " WHERE date < %s";
            // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
            $deleted = $wpdb->query($wpdb->prepare($sql, $date));
            $result[$table] = (int)$deleted;
        }

        delete_transient('eistat_db_size_info');
        return $result;
    }

    public static function db_size_info() {
        global $wpdb;
        $total_mb = 0;
        $total_rows = 0;

        foreach (self::tables() as $t) {
            $full = self::full_table($t);
            // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
            $row = $wpdb->get_row($wpdb->prepare("SHOW TABLE STATUS LIKE %s", $full));
            if ($row) {
                $total_mb += ($row->Data_length + $row->Index_length) / 1024 / 1024;
                $total_rows += (int)$row->Rows;
            }
        }

        return ['mb' => round($total_mb, 1), 'rows' => $total_rows];
    }
}