import * as fs from 'fs';
import * as path from 'path';

export enum LogLevel {
  DEBUG = 'debug',
  INFO = 'info',
  WARN = 'warn',
  ERROR = 'error'
}

interface LogEntry {
  timestamp: string;
  level: LogLevel;
  message: string;
  context?: Record<string, unknown>;
}

export class Logger {
  private static instance: Logger;
  private logDir: string;
  private logFile: string;
  private logLevel: LogLevel;
  private context: Record<string, unknown>;

  private constructor(logDir: string = 'test-results/logs') {
    this.logDir = logDir;
    this.logFile = path.join(logDir, `test-run-${new Date().toISOString().replace(/[:.]/g, '-')}.log`);
    this.logLevel = this.parseLogLevel(process.env.LOG_LEVEL || 'info');
    this.context = {};
    this.ensureLogDir();
  }

  static getInstance(logDir?: string): Logger {
    if (!Logger.instance) {
      Logger.instance = new Logger(logDir);
    }
    return Logger.instance;
  }

  private parseLogLevel(level: string): LogLevel {
    switch (level.toLowerCase()) {
      case 'debug': return LogLevel.DEBUG;
      case 'info': return LogLevel.INFO;
      case 'warn': return LogLevel.WARN;
      case 'error': return LogLevel.ERROR;
      default: return LogLevel.INFO;
    }
  }

  private ensureLogDir(): void {
    if (!fs.existsSync(this.logDir)) {
      fs.mkdirSync(this.logDir, { recursive: true });
    }
  }

  setContext(context: Record<string, unknown>): this {
    this.context = { ...this.context, ...context };
    return this;
  }

  clearContext(): this {
    this.context = {};
    return this;
  }

  private formatTimestamp(): string {
    return new Date().toISOString();
  }

  private formatMessage(level: LogLevel, message: string): string {
    const timestamp = this.formatTimestamp();
    const levelStr = level.toUpperCase().padEnd(5);
    const contextStr = Object.keys(this.context).length > 0
      ? ` [${JSON.stringify(this.context)}]`
      : '';
    return `${timestamp} | ${levelStr} |${contextStr} ${message}`;
  }

  private shouldLog(level: LogLevel): boolean {
    const levels = [LogLevel.DEBUG, LogLevel.INFO, LogLevel.WARN, LogLevel.ERROR];
    return levels.indexOf(level) >= levels.indexOf(this.logLevel);
  }

  private writeToFile(entry: LogEntry): void {
    try {
      this.ensureLogDir();
      const logLine = JSON.stringify(entry) + '\n';
      fs.appendFileSync(this.logFile, logLine, 'utf-8');
    } catch {
      // Ignore file write errors
    }
  }

  private log(level: LogLevel, message: string, context?: Record<string, unknown>): void {
    if (!this.shouldLog(level)) return;

    const entry: LogEntry = {
      timestamp: this.formatTimestamp(),
      level,
      message,
      context: { ...this.context, ...context }
    };

    this.writeToFile(entry);

    const formattedMessage = this.formatMessage(level, message);
    const colors: Record<LogLevel, string> = {
      [LogLevel.DEBUG]: '\x1b[36m',
      [LogLevel.INFO]: '\x1b[32m',
      [LogLevel.WARN]: '\x1b[33m',
      [LogLevel.ERROR]: '\x1b[31m'
    };
    const reset = '\x1b[0m';
    console.log(`${colors[level]}${formattedMessage}${reset}`);
  }

  debug(message: string, context?: Record<string, unknown>): void {
    this.log(LogLevel.DEBUG, message, context);
  }

  info(message: string, context?: Record<string, unknown>): void {
    this.log(LogLevel.INFO, message, context);
  }

  warn(message: string, context?: Record<string, unknown>): void {
    this.log(LogLevel.WARN, message, context);
  }

  error(message: string, error?: Error | unknown, context?: Record<string, unknown>): void {
    const errorContext = error instanceof Error
      ? { errorMessage: error.message, stack: error.stack, ...context }
      : { error, ...context };
    this.log(LogLevel.ERROR, message, errorContext);
  }

  section(title: string): void {
    const separator = '='.repeat(60);
    console.log(`\n${separator}`);
    console.log(`  ${title}`);
    console.log(`${separator}\n`);
    this.info(`=== ${title} ===`);
  }

  progress(current: number, total: number, message: string): void {
    const percentage = Math.round((current / total) * 100);
    const bar = this.createProgressBar(percentage);
    process.stdout.write(`\r${bar} ${percentage}% - ${message}`);
    if (current === total) {
      process.stdout.write('\n');
    }
  }

  private createProgressBar(percentage: number, width: number = 30): string {
    const filled = Math.round((percentage / 100) * width);
    const empty = width - filled;
    return `[${'█'.repeat(filled)}${'░'.repeat(empty)}]`;
  }

  getLogFile(): string {
    return this.logFile;
  }
}

export const logger = Logger.getInstance();