import fs from 'fs';
import path from 'path';
import { createCorrelationId, getCorrelationId, runWithCorrelationId } from './correlation.js';

const LOG_LEVELS = { error: 0, warn: 1, info: 2, debug: 3 };

export function createLogger(config) {
    const currentLogLevel = LOG_LEVELS[config.logLevel?.toLowerCase()] ?? LOG_LEVELS.info;

    function formatError(error) {
        if (!error) return 'Unknown error';
        if (typeof error === 'string') return error;
        if (error.response?.data) {
            return `${error.message || 'Request failed'}: ${JSON.stringify(error.response.data)}`;
        }
        return error.stack || error.message || String(error);
    }

    function correlationPrefix() {
        const correlationId = getCorrelationId();
        return correlationId ? `[${correlationId}] ` : '';
    }

    function writeLog(level, activeFunction, message) {
        if (LOG_LEVELS[level] > currentLogLevel) return;
        const line = `${new Date().toISOString()} [${level.toUpperCase()}] ${correlationPrefix()}${activeFunction}: ${message}`;
        if (level === 'error') console.error(line);
        else if (level === 'warn') console.warn(line);
        else console.log(line);
    }

    function logger(activeFunction, logLine) {
        writeLog('info', activeFunction, logLine);
    }

    function logWarn(activeFunction, logLine) {
        writeLog('warn', activeFunction, logLine);
    }

    function logError(activeFunction, logLine, error) {
        const detail = error !== undefined ? ` ${formatError(error)}` : '';
        writeLog('error', activeFunction, `${logLine}${detail}`);
    }

    function logDebug(activeFunction, logLine) {
        writeLog('debug', activeFunction, logLine);
    }

    function safeProcess(context, fn, meta = {}) {
        const correlationId = meta.correlationId || createCorrelationId(meta);
        runWithCorrelationId(correlationId, () => {
            Promise.resolve()
                .then(fn)
                .catch(error => logError(context, 'Unhandled error during async processing', error));
        });
    }

    function logFile(provider, jsonData) {
        const d = new Date();
        const year = d.getFullYear();
        const month = (d.getMonth() + 1).toString().padStart(2, '0');
        const day = d.getDate().toString().padStart(2, '0');
        const logFilePath = path.join(`./logs/${provider}-${year}${month}${day}.log`);
        const correlationId = getCorrelationId();
        const correlationLine = correlationId ? ` [${correlationId}]` : '';
        const content = `${d.toISOString()}${correlationLine}\n${JSON.stringify(jsonData)}\n`;

        fs.appendFile(logFilePath, content, (error) => {
            if (error) {
                logError('logFile', `Failed to write ${provider} webhook log`, error);
            }
        });
    }

    return {
        logger,
        logWarn,
        logError,
        logDebug,
        safeProcess,
        logFile,
        writeLog,
        formatError,
        runWithCorrelationId,
        createCorrelationId,
        getCorrelationId,
    };
}