/**
 * Logger Utility
 * 统一日志工具
 */

import { appConfig } from '../config/app'

/**
 * 日志级别
 */
export enum LogLevel {
  DEBUG = 0,
  INFO = 1,
  WARN = 2,
  ERROR = 3
}

/**
 * 日志级别映射
 */
const LOG_LEVEL_MAP: Record<string, LogLevel> = {
  debug: LogLevel.DEBUG,
  info: LogLevel.INFO,
  warn: LogLevel.WARN,
  error: LogLevel.ERROR
}

function parseBooleanEnv(value: string | undefined): boolean | undefined {
  if (typeof value !== 'string') {
    return undefined
  }

  const normalized = value.trim().toLowerCase()
  if (['1', 'true', 'yes', 'on'].includes(normalized)) {
    return true
  }
  if (['0', 'false', 'no', 'off'].includes(normalized)) {
    return false
  }
  return undefined
}

/**
 * 当前日志级别
 */
const currentLogLevel = LOG_LEVEL_MAP[appConfig.logging.level] || LogLevel.INFO
const prodSummaryLogOnly =
  appConfig.nodeEnv === 'production' &&
  (parseBooleanEnv(process.env.PROD_SUMMARY_LOG_ONLY) ?? true)

/**
 * 格式化时间戳
 */
function formatTimestamp(): string {
  return new Date().toISOString()
}

/**
 * 安全的 JSON 序列化，处理大对象和循环引用
 */
function safeStringify(obj: any, maxLength?: number): string {
  try {
    const seen = new WeakSet()
    const json = JSON.stringify(obj, (key, value) => {
      // 处理循环引用
      if (typeof value === 'object' && value !== null) {
        if (seen.has(value)) {
          return '[Circular]'
        }
        seen.add(value)
      }
      return value
    }, 2)
    
    // 如果指定了最大长度且超出，则截断
    if (maxLength && json.length > maxLength) {
      return json.slice(0, maxLength) + `...(truncated, total ${json.length} chars)`
    }
    
    return json
  } catch (error) {
    return '[Serialization Error]'
  }
}

/**
 * 格式化日志消息
 */
function formatMessage(level: string, message: string, meta?: any): string {
  const timestamp = formatTimestamp()
  
  // 智能处理 meta 数据
  let metaStr = ''
  if (meta) {
    // 对于大文本字段，不进行截断（如 AI 响应、代码等）
    const largeTextFields = ['content', 'code', 'response', 'aiResponse', 'stdout', 'stderr', 'output']
    const hasLargeText = largeTextFields.some(field => field in meta)
    
    if (hasLargeText) {
      // 包含大文本，使用更大的限制或不限制
      metaStr = ` ${safeStringify(meta)}`
    } else {
      // 普通元数据，可以适当限制
      metaStr = ` ${safeStringify(meta, 5000)}`
    }
  }
  
  if (appConfig.logging.pretty) {
    // 开发环境：带颜色的格式
    const colors: Record<string, string> = {
      DEBUG: '\x1b[36m',  // Cyan
      INFO: '\x1b[32m',   // Green
      WARN: '\x1b[33m',   // Yellow
      ERROR: '\x1b[31m'   // Red
    }
    const reset = '\x1b[0m'
    const color = colors[level] || ''
    
    return `${color}[${timestamp}] ${level}${reset}: ${message}${metaStr}`
  } else {
    // 生产环境：JSON 格式
    return JSON.stringify({
      timestamp,
      level,
      message,
      ...meta
    })
  }
}

/**
 * Logger 类
 */
class Logger {
  private context?: string

  constructor(context?: string) {
    this.context = context
  }

  /**
   * 添加上下文信息
   */
  private addContext(meta?: any): any {
    if (!this.context) return meta
    return { ...meta, context: this.context }
  }

  private shouldEmit(level: LogLevel, meta?: any): boolean {
    if (!prodSummaryLogOnly) {
      return true
    }

    // In production summary-only mode, always keep warnings/errors visible.
    if (level >= LogLevel.WARN) {
      return true
    }

    return meta && typeof meta === 'object' && meta._logType === 'job_summary'
  }

  /**
   * 调试日志
   */
  debug(message: string, meta?: any): void {
    const contextMeta = this.addContext(meta)
    if (currentLogLevel <= LogLevel.DEBUG && this.shouldEmit(LogLevel.DEBUG, contextMeta)) {
      console.debug(formatMessage('DEBUG', message, contextMeta))
    }
  }

  /**
   * 信息日志
   */
  info(message: string, meta?: any): void {
    const contextMeta = this.addContext(meta)
    if (currentLogLevel <= LogLevel.INFO && this.shouldEmit(LogLevel.INFO, contextMeta)) {
      console.log(formatMessage('INFO', message, contextMeta))
    }
  }

  /**
   * 警告日志
   */
  warn(message: string, meta?: any): void {
    const contextMeta = this.addContext(meta)
    if (currentLogLevel <= LogLevel.WARN && this.shouldEmit(LogLevel.WARN, contextMeta)) {
      console.warn(formatMessage('WARN', message, contextMeta))
    }
  }

  /**
   * 错误日志
   */
  error(message: string, meta?: any): void {
    const contextMeta = this.addContext(meta)
    if (currentLogLevel <= LogLevel.ERROR && this.shouldEmit(LogLevel.ERROR, contextMeta)) {
      console.error(formatMessage('ERROR', message, contextMeta))
    }
  }

  /**
   * 创建子 logger 带上下文
   */
  child(context: string): Logger {
    const childContext = this.context ? `${this.context}:${context}` : context
    return new Logger(childContext)
  }
}

/**
 * 默认 logger 实例
 */
export const logger = new Logger()

/**
 * 创建带上下文的 logger
 */
export function createLogger(context: string): Logger {
  return new Logger(context)
}