import { appendFileSync, mkdirSync } from 'fs';
import { dirname, resolve } from 'path';
import { fileURLToPath } from 'url';
import { prettyJson } from '../util/prettyJson.js';
import { createLogger } from '../util/logger.js';

const log = createLogger('error-log');

const __dirname = dirname(fileURLToPath(import.meta.url));
const LOG_DIR = process.env.ERROR_LOG_DIR || resolve(__dirname, '../../logs/errors');
const LOG_PREFIX = 'error-';

let dirEnsured = false;

function ensureLogDir() {
    if (dirEnsured) return;
    mkdirSync(LOG_DIR, { recursive: true });
    dirEnsured = true;
}

/**
 * Writes a plain-text error log file (no ANSI colors) to the error log
 * directory and returns the file path. Never throws.
 * @param {string} label Short description, e.g. "POST /api/delivery 500"
 * @param {Record<string, unknown>} sections Named sections (request, body, response, error…)
 * @returns {string | null} Path of the log file, or null on failure
 */
export function writeErrorLog(label, sections) {
    try {
        ensureLogDir();
        const stamp = new Date().toISOString().replace(/[:.]/g, '-');
        const safeLabel = label
            .toLowerCase()
            .replace(/[^a-z0-9]+/g, '-')
            .replace(/^-+|-+$/g, '')
            .slice(0, 40);
        const filePath = resolve(LOG_DIR, `${LOG_PREFIX}${stamp}-${safeLabel}.log`);
        const divider = '='.repeat(80);

        const parts = [
            `Timestamp: ${new Date().toISOString()}`,
            `Label:     ${label}`,
            divider,
        ];

        for (const [name, value] of Object.entries(sections)) {
            parts.push(`--- ${name} ${'-'.repeat(Math.max(0, 74 - name.length))}`);
            parts.push(prettyJson(value, { colors: false }));
        }

        appendFileSync(filePath, `${parts.join('\n')}\n`);
        log.info(`Wrote ${filePath}`);
        return filePath;
    } catch (err) {
        log.error('Failed to write error log:', err.message);
        return null;
    }
}