/**
 * Analytics & Performance Monitoring
 * Supports Google Analytics, Plausible, and custom events
 */

// Types
export interface PageViewEvent {
  url: string
  title: string
  referrer?: string
}

export interface CustomEvent {
  name: string
  properties?: Record<string, any>
}

export interface PerformanceMetrics {
  fcp?: number // First Contentful Paint
  lcp?: number // Largest Contentful Paint
  fid?: number // First Input Delay
  cls?: number // Cumulative Layout Shift
  ttfb?: number // Time to First Byte
}

/**
 * Track page view
 */
export function trackPageView(event: PageViewEvent) {
  // Google Analytics (gtag)
  if (typeof window !== 'undefined' && (window as any).gtag) {
    ;(window as any).gtag('config', process.env.NEXT_PUBLIC_GA_ID, {
      page_path: event.url,
      page_title: event.title,
    })
  }

  // Plausible Analytics (privacy-friendly)
  if (typeof window !== 'undefined' && (window as any).plausible) {
    ;(window as any).plausible('pageview', {
      u: event.url,
      props: {
        title: event.title,
        ...(event.referrer && { referrer: event.referrer }),
      },
    })
  }

  // Custom analytics endpoint (optional)
  if (process.env.NEXT_PUBLIC_ANALYTICS_ENDPOINT) {
    fetch(process.env.NEXT_PUBLIC_ANALYTICS_ENDPOINT, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        type: 'pageview',
        ...event,
        timestamp: new Date().toISOString(),
      }),
    }).catch(() => {}) // Silent fail
  }
}

/**
 * Track custom event
 */
export function trackEvent(event: CustomEvent) {
  // Google Analytics
  if (typeof window !== 'undefined' && (window as any).gtag) {
    ;(window as any).gtag('event', event.name, event.properties || {})
  }

  // Plausible
  if (typeof window !== 'undefined' && (window as any).plausible) {
    ;(window as any).plausible(event.name, { props: event.properties || {} })
  }

  // Custom endpoint
  if (process.env.NEXT_PUBLIC_ANALYTICS_ENDPOINT) {
    fetch(process.env.NEXT_PUBLIC_ANALYTICS_ENDPOINT, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        type: 'event',
        ...event,
        timestamp: new Date().toISOString(),
      }),
    }).catch(() => {})
  }
}

/**
 * Track search query
 */
export function trackSearch(query: string, results: number) {
  trackEvent({
    name: 'search',
    properties: {
      query,
      results,
    },
  })
}

/**
 * Track domain view
 */
export function trackDomainView(domain: string, price?: number) {
  trackEvent({
    name: 'domain_view',
    properties: {
      domain,
      ...(price && { price }),
    },
  })
}

/**
 * Track listing inquiry
 */
export function trackInquiry(domain: string) {
  trackEvent({
    name: 'listing_inquiry',
    properties: {
      domain,
    },
  })
}

/**
 * Track signup
 */
export function trackSignup(method: 'email' | 'google' | 'github') {
  trackEvent({
    name: 'signup',
    properties: {
      method,
    },
  })
}

/**
 * Track subscription
 */
export function trackSubscription(tier: 'scout' | 'trader' | 'tycoon', price: number) {
  trackEvent({
    name: 'subscription',
    properties: {
      tier,
      price,
    },
  })
}

/**
 * Measure Web Vitals (Core Performance Metrics)
 */
export function measureWebVitals() {
  if (typeof window === 'undefined') return

  // Use Next.js built-in web vitals reporting
  const reportWebVitals = (metric: PerformanceMetrics) => {
    // Send to Google Analytics
    if ((window as any).gtag) {
      ;(window as any).gtag('event', metric, {
        event_category: 'Web Vitals',
        non_interaction: true,
      })
    }

    // Send to custom endpoint
    if (process.env.NEXT_PUBLIC_ANALYTICS_ENDPOINT) {
      fetch(process.env.NEXT_PUBLIC_ANALYTICS_ENDPOINT, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          type: 'web_vital',
          ...metric,
          timestamp: new Date().toISOString(),
        }),
      }).catch(() => {})
    }
  }

  // Measure FCP (First Contentful Paint)
  const paintEntries = performance.getEntriesByType('paint')
  const fcpEntry = paintEntries.find((entry) => entry.name === 'first-contentful-paint')
  if (fcpEntry) {
    reportWebVitals({ fcp: fcpEntry.startTime })
  }

  // Observe LCP (Largest Contentful Paint)
  if ('PerformanceObserver' in window) {
    const observer = new PerformanceObserver((list) => {
      const entries = list.getEntries()
      const lastEntry = entries[entries.length - 1]
      reportWebVitals({ lcp: lastEntry.startTime })
    })
    observer.observe({ entryTypes: ['largest-contentful-paint'] })
  }

  // Measure CLS (Cumulative Layout Shift)
  if ('PerformanceObserver' in window) {
    let clsValue = 0
    const observer = new PerformanceObserver((list) => {
      for (const entry of list.getEntries()) {
        if (!(entry as any).hadRecentInput) {
          clsValue += (entry as any).value
        }
      }
      reportWebVitals({ cls: clsValue })
    })
    observer.observe({ entryTypes: ['layout-shift'] })
  }

  // Measure TTFB (Time to First Byte)
  const navigationEntry = performance.getEntriesByType('navigation')[0] as PerformanceNavigationTiming
  if (navigationEntry) {
    reportWebVitals({ ttfb: navigationEntry.responseStart - navigationEntry.requestStart })
  }
}

/**
 * Initialize analytics
 */
export function initAnalytics() {
  if (typeof window === 'undefined') return

  // Measure web vitals on load
  if (document.readyState === 'complete') {
    measureWebVitals()
  } else {
    window.addEventListener('load', measureWebVitals)
  }

  // Track page views on navigation
  const handleRouteChange = () => {
    trackPageView({
      url: window.location.pathname + window.location.search,
      title: document.title,
      referrer: document.referrer,
    })
  }

  // Initial page view
  handleRouteChange()

  // Listen for route changes (for SPA navigation)
  window.addEventListener('popstate', handleRouteChange)

  return () => {
    window.removeEventListener('popstate', handleRouteChange)
  }
}

/**
 * Error tracking
 */
export function trackError(error: Error, context?: Record<string, any>) {
  trackEvent({
    name: 'error',
    properties: {
      message: error.message,
      stack: error.stack,
      ...context,
    },
  })

  // Also log to console in development
  if (process.env.NODE_ENV === 'development') {
    console.error('Error tracked:', error, context)
  }
}

/**
 * A/B Test tracking
 */
export function trackABTest(testName: string, variant: string) {
  trackEvent({
    name: 'ab_test',
    properties: {
      test: testName,
      variant,
    },
  })
}

/**
 * Consent management
 */
export function hasAnalyticsConsent(): boolean {
  if (typeof window === 'undefined') return false
  const consent = localStorage.getItem('analytics_consent')
  return consent === 'true'
}

export function setAnalyticsConsent(consent: boolean) {
  if (typeof window === 'undefined') return
  localStorage.setItem('analytics_consent', String(consent))

  if (consent) {
    initAnalytics()
  }
}