<?php

declare(strict_types=1);

namespace WordPress\CloudflareWorkersAiProvider\Activity;

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

/**
 * The log as CSV: one row per change, or one row for an entry that changed nothing.
 *
 * Written straight to a stream page by page, so a large log needs neither much memory nor
 * one long query. UTF-8 with a byte-order mark, so Excel reads non-English text correctly.
 */
final class Export
{
    /** Entries per query. A Backfill entry can list up to 400 changes, so pages stay small. */
    private const PAGE = 50;

    /**
     * @return list<string>
     */
    public static function header(): array
    {
        return [
            __('Entry', 'aipcf-ai-provider-for-cloudflare'),
            __('Time (UTC)', 'aipcf-ai-provider-for-cloudflare'),
            __('Who', 'aipcf-ai-provider-for-cloudflare'),
            __('Tool', 'aipcf-ai-provider-for-cloudflare'),
            __('Action', 'aipcf-ai-provider-for-cloudflare'),
            __('Status', 'aipcf-ai-provider-for-cloudflare'),
            __('Message', 'aipcf-ai-provider-for-cloudflare'),
            __('Neurons', 'aipcf-ai-provider-for-cloudflare'),
            __('Type', 'aipcf-ai-provider-for-cloudflare'),
            __('ID', 'aipcf-ai-provider-for-cloudflare'),
            __('Title', 'aipcf-ai-provider-for-cloudflare'),
            __('URL', 'aipcf-ai-provider-for-cloudflare'),
            __('Field', 'aipcf-ai-provider-for-cloudflare'),
            __('Old value', 'aipcf-ai-provider-for-cloudflare'),
            __('New value', 'aipcf-ai-provider-for-cloudflare'),
            __('Result', 'aipcf-ai-provider-for-cloudflare'),
            __('Reason', 'aipcf-ai-provider-for-cloudflare'),
        ];
    }

    /**
     * Writes the entries matching the filters, newest first. Returns the number of rows written.
     *
     * @param resource             $out
     * @param array<string, mixed> $filters
     */
    public static function write($out, array $filters): int
    {
        fwrite($out, "\xEF\xBB\xBF"); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fwrite -- streaming to the download or WP-CLI output
        self::put($out, self::header());
        $rows   = 0;
        $before = PHP_INT_MAX;
        do {
            $entries = ActivityLog::entriesBefore($filters, $before, self::PAGE);
            if ($entries === []) {
                break;
            }
            $ids   = array_column($entries, 'id');
            $items = ActivityLog::items($ids);
            $posts = [];
            foreach ($items as $list) {
                foreach ($list as $i) {
                    if ($i['object_id'] > 0 && in_array($i['object_type'], ['post', 'attachment'], true)) {
                        $posts[] = $i['object_id'];
                    }
                }
            }
            if ($posts !== []) {
                _prime_post_caches(array_values(array_unique($posts)), false, false);
            }
            foreach ($entries as $e) {
                $base = [
                    (string) $e['id'],
                    gmdate('Y-m-d\TH:i:s\Z', (int) strtotime($e['ts'] . ' UTC')),
                    Labels::who($e),
                    Labels::tool((string) $e['tool']),
                    Labels::action((string) $e['action']),
                    Labels::status((string) $e['status']),
                    (string) $e['message'],
                    $e['neurons'] > 0 ? (string) round($e['neurons'], 2) : '',
                ];
                $list = $items[$e['id']] ?? [];
                if ($list === []) {
                    self::put($out, array_merge($base, array_fill(0, 9, '')));
                    $rows++;
                    continue;
                }
                foreach ($list as $i) {
                    self::put($out, array_merge($base, self::itemCells($i)));
                    $rows++;
                }
            }
            $before = (int) end($entries)['id'];
            if (function_exists('wp_cache_supports') && wp_cache_supports('flush_runtime')) {
                wp_cache_flush_runtime(); // keep memory flat on a long export
            }
        } while (count($entries) === self::PAGE);
        return $rows;
    }

    /**
     * A cell a spreadsheet could take for a formula gets a leading apostrophe, so generated
     * text, a post title or a setting value can never run as one. Leading spaces and line
     * breaks are looked past (some importers trim them), and the full-width signs count too.
     */
    public static function cell(string $value): string
    {
        $start = ltrim($value, " \t\r\n\0\x0B");
        if ($start === '') {
            return $value;
        }
        $first = mb_substr($start, 0, 1);
        return in_array($first, ['=', '+', '-', '@', "\u{FF1D}", "\u{FF0B}", "\u{FF0D}", "\u{FF20}"], true) || $value[0] === "\t" || $value[0] === "\r" ? "'" . $value : $value;
    }

    /**
     * @param array<string, mixed> $i
     * @return list<string>
     */
    private static function itemCells(array $i): array
    {
        $type  = (string) $i['object_type'];
        $id    = (int) $i['object_id'];
        $title = '';
        $url   = '';
        if ($id > 0 && in_array($type, ['post', 'attachment'], true)) {
            $post = get_post($id);
            if ($post instanceof \WP_Post) {
                $title = get_the_title($post);
                $url   = $type === 'attachment' ? (string) wp_get_attachment_url($id) : (string) get_permalink($post);
            }
        }
        return [
            $type,
            $id > 0 ? (string) $id : '',
            $title,
            $url,
            self::field((string) $i['field']),
            Labels::value((string) $i['old_value']),
            Labels::value((string) $i['new_value']),
            Labels::result((string) $i['result']),
            (string) $i['reason'],
        ];
    }

    /**
     * The field's name, with the stored key when they differ: "Meta description (rank_math_description)".
     */
    private static function field(string $key): string
    {
        $label = Labels::field($key);
        return $label === $key || $key === '' ? $key : $label . ' (' . $key . ')';
    }

    /**
     * @param resource     $out
     * @param list<string> $row
     */
    private static function put($out, array $row): void
    {
        fputcsv($out, array_map([self::class, 'cell'], $row), ',', '"', '');
    }
}