import { Platform } from 'react-native'
import { getConfig, isInitialized, getUserId } from '@xuqm/rn-common'
import { LogQueue } from './queue/LogQueue'
import { ErrorCapture } from './capture/ErrorCapture'
import { computeFingerprint } from './fingerprint'
import { FunnelTracker } from './funnel/FunnelTracker'
import type { LogLevel, Environment, IssueEvent, LogEvent, XLogEvent } from './types'

// ─── Internal state ───────────────────────────────────────────────────────────

let _logLevel: LogLevel = 'warn'
let _environment: Environment = 'production'
let _queue: LogQueue | null = null
let _errorCaptureStarted = false

// Stable session id for the lifetime of the JS runtime
const _sessionId: string = _generateSessionId()

function _generateSessionId(): string {
  return 'xxxx-xxxx'.replace(/x/g, () => ((Math.random() * 16) | 0).toString(16))
}

function _levelNum(level: LogLevel): number {
  return { debug: 0, info: 1, warn: 2, error: 3 }[level]
}

function _getPlatform(): 'ios' | 'android' {
  return Platform.OS === 'ios' ? 'ios' : 'android'
}

function _getAppVersion(): string {
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  const constants = Platform.constants as Record<string, unknown>
  const v = constants['appVersion'] ?? constants['Version']
  return typeof v === 'string' ? v : String(v ?? '0.0.0')
}

function _enqueue(event: XLogEvent): void {
  if (!_queue) {
    const cfg = getConfig()
    if (!cfg.logApiUrl || !cfg.logEnabled) return
    _queue = new LogQueue({ logApiUrl: cfg.logApiUrl, appKey: cfg.appKey })
  }
  void _queue.push(event)
}

// ─── XLog public API ──────────────────────────────────────────────────────────

export const XLog = {
  /** Set the minimum log level. Events below this level are discarded. */
  setLogLevel(level: LogLevel): void {
    _logLevel = level
  },

  /** Set an environment tag attached to every log event. */
  setEnvironment(env: Environment): void {
    _environment = env
  },

  /**
   * Record a custom analytics event (funnel analysis, behaviour tracking).
   * Also automatically advances any matching funnel step.
   */
  event(name: string, properties?: Record<string, unknown>): void {
    if (!isInitialized()) return
    const event: LogEvent = {
      type: 'event',
      name,
      properties: properties ? { ...properties, environment: _environment } : { environment: _environment },
      timestamp: Date.now(),
      userId: getUserId() ?? undefined,
      sessionId: _sessionId,
      appKey: getConfig().appKey,
      platform: _getPlatform(),
      appVersion: _getAppVersion(),
    }
    _enqueue(event)
    FunnelTracker.track(name, properties)
  },

  /** Upload a JS exception to the log service. */
  captureError(error: unknown, metadata?: Record<string, unknown>): void {
    if (!isInitialized()) return
    const err = error instanceof Error ? error : new Error(String(error))
    const issue: IssueEvent = {
      type: 'js_error',
      message: err.message,
      stack: err.stack,
      fingerprint: computeFingerprint('js_error', err.message, err.stack),
      timestamp: Date.now(),
      userId: getUserId() ?? undefined,
      sessionId: _sessionId,
      appKey: getConfig().appKey,
      platform: _getPlatform(),
      appVersion: _getAppVersion(),
      metadata: metadata ? { ...metadata, environment: _environment } : { environment: _environment },
    }
    _enqueue(issue)
  },

  /** Log a warning (if log level allows). */
  warn(message: string, metadata?: Record<string, unknown>): void {
    if (_levelNum(_logLevel) > _levelNum('warn')) return
    XLog.captureError(new Error(message), { ...metadata, level: 'warn' })
  },

  /** Log an informational event (if log level allows). */
  info(message: string, metadata?: Record<string, unknown>): void {
    if (_levelNum(_logLevel) > _levelNum('info')) return
    XLog.event('__log_info', { message, ...metadata })
  },

  /**
   * Enable automatic capture of JS global errors and unhandled Promise rejections.
   * Call once at app startup after XuqmSDK.initialize().
   */
  startCapture(): void {
    if (_errorCaptureStarted) return
    _errorCaptureStarted = true
    ErrorCapture.start(XLog.captureError.bind(XLog))
  },

  /** Define a funnel for step-by-step conversion tracking. */
  defineFunnel: FunnelTracker.define.bind(FunnelTracker),

  /** Get client-side funnel progress (server aggregates across sessions). */
  getFunnelProgress: FunnelTracker.getProgress.bind(FunnelTracker),

  /** Flush any pending events immediately (e.g. before app goes to background). */
  async flush(): Promise<void> {
    if (_queue) await _queue.flush()
  },

  /** Clean up resources (timers, etc.). Call on app termination if needed. */
  destroy(): void {
    if (_queue) {
      _queue.destroy()
      _queue = null
    }
  },
}