const DEFAULT_NAV_CONTENT_HEIGHT = 44
const DEFAULT_GAP = 8
const DEFAULT_HORIZONTAL_PADDING = 8

function getSystemInfo() {
  try {
    return uni.getSystemInfoSync() || {}
  } catch (error) {
    return {}
  }
}

function getMenuButtonRect() {
  try {
    const rect = uni.getMenuButtonBoundingClientRect?.()
    return rect && rect.width ? rect : null
  } catch (error) {
    return null
  }
}

export function computeSafeAreaMetrics() {
  const systemInfo = getSystemInfo()
  const menuRect = getMenuButtonRect()
  const statusBarHeight = Number(systemInfo.statusBarHeight || 20)
  const windowWidth = Number(systemInfo.windowWidth || 375)

  let navContentHeight = DEFAULT_NAV_CONTENT_HEIGHT
  let navTopGap = DEFAULT_GAP
  let capsuleWidth = 0
  let capsuleRightSafeWidth = 0

  if (menuRect) {
    navTopGap = Math.max(Number(menuRect.top || 0) - statusBarHeight, DEFAULT_GAP)
    navContentHeight = Math.max(Number(menuRect.height || 0) + navTopGap * 2, DEFAULT_NAV_CONTENT_HEIGHT)
    capsuleWidth = Number(menuRect.width || 0)
    const rightInset = Math.max(windowWidth - Number(menuRect.right || windowWidth), 0)
    capsuleRightSafeWidth = Math.max(capsuleWidth + rightInset + DEFAULT_HORIZONTAL_PADDING, 96)
  } else {
    // 无胶囊位（H5、无自定义导航栏等）：不预留右侧占位；样式里已有 32rpx 水平内边距
    capsuleRightSafeWidth = 0
  }

  const topSafeHeight = statusBarHeight
  const headerHeight = topSafeHeight + navContentHeight

  return {
    statusBarHeight,
    topSafeHeight,
    navContentHeight,
    headerHeight,
    navTopGap,
    capsuleWidth,
    capsuleRightSafeWidth,
  }
}

export function applySafeAreaCssVars(metrics) {
  if (typeof document === 'undefined' || !document?.documentElement) return
  const root = document.documentElement.style
  root.setProperty('--sq-safe-top', `${metrics.topSafeHeight}px`)
  root.setProperty('--sq-nav-height', `${metrics.navContentHeight}px`)
  root.setProperty('--sq-header-height', `${metrics.headerHeight}px`)
  root.setProperty('--sq-capsule-right-safe', `${metrics.capsuleRightSafeWidth}px`)
}

export function initGlobalSafeArea() {
  const metrics = computeSafeAreaMetrics()
  const app = getApp?.()
  if (app) {
    app.globalData = app.globalData || {}
    app.globalData.safeArea = metrics
  }
  applySafeAreaCssVars(metrics)
  return metrics
}

export function getGlobalSafeArea() {
  const app = getApp?.()
  return app?.globalData?.safeArea || computeSafeAreaMetrics()
}