/**
 * Logger for Electron main/preload.
 *
 * Always uses `console` when available so output shows in the terminal if you
 * start the app from a shell (dev or packaged). Preload logs typically appear
 * in DevTools, not the parent terminal.
 *
 * In the main process only, logs are also appended asynchronously to
 * userData/logs/qortalHub.log (batched, non-blocking). Rotates at ~10 MiB to
 * qortalHub.log.1. Preload does not touch the filesystem here (no electron.app).
 */
import * as fs from 'fs';
import * as path from 'path';
import { createRequire } from 'module';
import { format } from 'util';

const nodeRequire = createRequire(__filename);

const noop = (..._args: unknown[]) => {};

export const DEV_LOGS_DISABLED_STORAGE_KEY = 'qortal_disable_dev_logs';

let disableDevLogs = true;

export function setDisableDevLogs(value: boolean): void {
  disableDevLogs = value;
}

const IMPORTANT_LOG_PATTERNS = [
  /\bfailed\b/i,
  /\bfailure\b/i,
  /\berror\b/i,
  /\bexception\b/i,
  /\btimeout\b/i,
  /\btimed out\b/i,
  /\bnot starting\b/i,
  /\bdid not start\b/i,
  /\btoo many instances\b/i,
  /\bbridge missing\b/i,
  /\bbridge startup\b/i,
  /\bdegraded\b/i,
  /\bshutdown\b/i,
];

function isImportantLog(args: readonly unknown[]): boolean {
  const first = args[0];
  if (typeof first !== 'string') return false;
  return IMPORTANT_LOG_PATTERNS.some((pattern) => pattern.test(first));
}

function shouldEmitLog(
  method: 'log' | 'error' | 'warn' | 'debug' | 'info',
  args: readonly unknown[]
): boolean {
  if (method === 'error' || method === 'warn') return true;
  if (process.type !== 'browser') return true;
  if (!disableDevLogs) return true;
  return isImportantLog(args);
}

/** Stdio can be a closed pipe (AppImage, desktop launcher, detached parent). Ignore benign write failures. */
function isBenignStdioWriteError(err: unknown): boolean {
  const code = (err as NodeJS.ErrnoException)?.code;
  return (
    code === 'EPIPE' ||
    code === 'EIO' ||
    code === 'ENOTCONN' ||
    code === 'EBADF'
  );
}

function emitToConsole(
  c: Console,
  method: 'log' | 'error' | 'warn' | 'debug' | 'info',
  args: readonly unknown[]
): void {
  try {
    (c[method] as (...args: unknown[]) => void).apply(c, args);
  } catch (err: unknown) {
    if (!isBenignStdioWriteError(err)) throw err;
  }
}

const LOG_FILE = 'qortalHub.log';
const MAX_LOG_BYTES = 10 * 1024 * 1024;

const pendingLines: string[] = [];
let flushScheduled = false;
let logFilePath: string | null = null;
let logUserDataPath: string | null = null;
/** Byte length of current log file on disk (UTF-8), best-effort. */
let currentFileBytes = 0;

let ioChain: Promise<void> = Promise.resolve();

function resolveLogFilePath(): string | null {
  if (process.type !== 'browser') return null;
  try {
    const { app } = nodeRequire('electron') as typeof import('electron');
    const userDataPath = app.getPath('userData');
    if (logFilePath !== null && logUserDataPath === userDataPath) {
      return logFilePath;
    }
    const dir = path.join(userDataPath, 'logs');
    fs.mkdirSync(dir, { recursive: true });
    logFilePath = path.join(dir, LOG_FILE);
    logUserDataPath = userDataPath;
    if (fs.existsSync(logFilePath)) {
      currentFileBytes = fs.statSync(logFilePath).size;
    } else {
      currentFileBytes = 0;
    }
    return logFilePath;
  } catch {
    logFilePath = null;
    logUserDataPath = null;
    return null;
  }
}

function rotateLogFileSync(): void {
  if (!logFilePath) return;
  const rotated = `${logFilePath}.1`;
  try {
    if (fs.existsSync(rotated)) fs.unlinkSync(rotated);
  } catch {
    /* ignore */
  }
  try {
    if (fs.existsSync(logFilePath)) fs.renameSync(logFilePath, rotated);
  } catch {
    /* ignore */
  }
  currentFileBytes = 0;
}

function scheduleFileFlush(): void {
  if (flushScheduled) return;
  flushScheduled = true;
  setImmediate(() => {
    flushScheduled = false;
    const chunk = pendingLines.splice(0, pendingLines.length).join('');
    if (!chunk || !logFilePath) return;
    ioChain = ioChain
      .then(async () => {
        const byteLen = Buffer.byteLength(chunk, 'utf8');
        try {
          if (currentFileBytes + byteLen > MAX_LOG_BYTES) {
            rotateLogFileSync();
          }
          await fs.promises.appendFile(logFilePath!, chunk, 'utf8');
          currentFileBytes += byteLen;
        } catch {
          /* disk full / permissions — avoid throwing into unhandledRejection */
        }
      })
      .catch(() => {});
  });
}

function queueFileLine(level: string, args: readonly unknown[]): void {
  if (process.type !== 'browser') return;
  if (!resolveLogFilePath()) return;
  const line = `[${new Date().toISOString()}] [${level}] ${format(...args)}\n`;
  pendingLines.push(line);
  scheduleFileFlush();
}

function makeLogger(
  method: 'log' | 'error' | 'warn' | 'debug' | 'info',
  fileLevel: string
): (...args: unknown[]) => void {
  try {
    const c = typeof console !== 'undefined' ? console : null;
    return c && typeof c[method] === 'function'
      ? (...args: unknown[]) => {
          if (!shouldEmitLog(method, args)) return;
          emitToConsole(c, method, args);
          queueFileLine(fileLevel, args);
        }
      : noop;
  } catch {
    return noop;
  }
}

export const log = makeLogger('log', 'LOG');
export const error = makeLogger('error', 'ERROR');
export const warn = makeLogger('warn', 'WARN');
export const debug = makeLogger('debug', 'DEBUG');
export const info = makeLogger('info', 'INFO');

export default { log, error, warn, debug, info };