'use strict'

const os = require('os')
const { BrowserWindow, screen } = require('electron')

const SELECTION = {
  ALL_SECONDARY: 'all-secondary',
  ALL: 'all',
  SPECIFIED: 'specified'
}

// 大屏窗口管理：按显示器枚举结果开窗，绝不写死坐标。
// 坐标一律用 DIP（display.bounds），页面内部再用 CSS 缩放适配，两边互不干扰。
class DisplayManager {
  constructor({ values, server, log }) {
    this.display = values.display
    this.server = server
    this.log = log

    this.enabled = false
    this.single = true
    this.boundSingle = null
    this.windows = new Map() // displayId -> { win, page, reloadTimer }
    this.screenListeners = []
    this.layoutTimer = null
  }

  enable() {
    if (this.enabled) return
    this.enabled = true
    this.layout()
  }

  pageFor(index) {
    const pages = Array.isArray(this.display.pages) && this.display.pages.length ? this.display.pages : ['standings']
    // 单屏没有编排可言，固定锁第一页（默认总积分榜）
    if (this.single) return pages[0]
    return pages[index % pages.length]
  }

  pickDisplays() {
    const all = screen.getAllDisplays()
    const primary = screen.getPrimaryDisplay()

    // 单屏机器上谈「扩展屏编排」没有意义，直接窗口化
    if (all.length <= 1) return { single: true, displays: all.slice(0, 1) }

    const selection = this.display.selection || SELECTION.ALL_SECONDARY
    let picked
    if (selection === SELECTION.ALL) {
      picked = all.slice()
    } else if (selection === SELECTION.SPECIFIED) {
      picked = this.pickSpecified(all)
    } else {
      picked = this.pickSecondary(all, primary)
    }

    // 只有整机就一块屏时才是「单屏测试模式」；笔记本 + 一块扩展屏属于多屏场景，
    // 扩展屏要正常 kiosk，不能退化成窗口化
    if (!picked.length) return { single: true, displays: [primary] }
    return { single: false, displays: picked }
  }

  // 默认策略是「除内置屏外的每块屏」（doc 06 §6.2）。用 display.internal 判断，
  // 而不是拿主屏当替身：现场常把主屏设成外接 HDMI，用主屏排除会把 kiosk 开到笔记本屏。
  // 全部屏都报 internal=false 时（纯台式机）退回「排除主屏」的旧口径。
  pickSecondary(all, primary) {
    const external = all.filter((item) => item.internal === false)
    if (external.length && external.length < all.length) return external
    return all.filter((item) => item.id !== primary.id)
  }

  // displays 配置里可以写 display.id，也可以写 0 起的序号
  pickSpecified(all) {
    const wanted = Array.isArray(this.display.displays) ? this.display.displays : []
    const picked = []
    for (const key of wanted) {
      const match = typeof key === 'number' ? all.find((item) => item.id === key) || all[key] : all.find((item) => String(item.id) === String(key))
      if (match && !picked.includes(match)) picked.push(match)
    }
    return picked
  }

  layout() {
    if (!this.enabled) return
    const { single, displays } = this.pickDisplays()
    this.single = single
    this.bindScreenListeners(single)

    const wanted = new Set(displays.map((item) => item.id))
    for (const [displayId, entry] of [...this.windows]) {
      if (!wanted.has(displayId)) {
        this.destroyEntry(displayId, entry)
      }
    }

    displays.forEach((display, index) => {
      const page = this.pageFor(index)
      const existing = this.windows.get(display.id)
      if (existing) {
        this.applyGeometry(existing.win, display, single)
        if (existing.page !== page) {
          existing.page = page
          this.loadPage(existing, display, page, single)
        }
        return
      }
      this.windows.set(display.id, this.createWindow(display, index, single, page))
    })

    this.log.push('console', `大屏排布完成：${single ? '单屏窗口化' : `多屏 kiosk × ${displays.length}`}，显示器 ${displays.map((d) => d.id).join(', ')}`)
  }

  createWindow(display, index, single, page) {
    const bounds = display.bounds
    const win = new BrowserWindow({
      ...this.geometryFor(display, single),
      show: false,
      // 窗口化模式由页面自绘标题栏（与应用其它窗口同风格），保留原生边框会多出一条标题栏；
      // 多屏 kiosk 本来就不要边框
      frame: false,
      // 与 Console 主窗口同一套兜底：个别平台会忽略 frame:false
      titleBarStyle: 'hidden',
      kiosk: !single && this.display.kiosk !== false,
      autoHideMenuBar: true,
      backgroundColor: this.display.backgroundColor || '#000000',
      title: `大屏 · ${page}`,
      webPreferences: {
        contextIsolation: true,
        nodeIntegration: false,
        sandbox: true,
        // 大屏常年在后台焦点之外，默认节流会冻结动画和定时器
        backgroundThrottling: false
      }
    })

    // 大屏页零交互控件；窗口层再兜一道，防止现场误触鼠标
    if (!single && this.display.ignoreMouse !== false) {
      win.setIgnoreMouseEvents(true)
    }

    // F11 只在单屏模式下有意义（现场调试用），多屏 kiosk 不允许切走
    if (single) {
      win.webContents.on('before-input-event', (event, input) => {
        if (input.type === 'keyDown' && input.key === 'F11') {
          event.preventDefault()
          win.setFullScreen(!win.isFullScreen())
        }
      })
    }

    win.once('ready-to-show', () => {
      if (!win.isDestroyed()) win.show()
    })

    win.webContents.on('render-process-gone', (_event, details) => {
      this.log.push('console', `大屏渲染进程异常（display=${display.id}，${details.reason}），将重载`)
      if (!win.isDestroyed()) win.webContents.reload()
    })

    const entry = { win, page, reloadTimer: null }

    // 无人值守跑 24h 以上，定时重载兜底内存与连接泄漏
    const hours = Number(this.display.reloadEveryHours) || 0
    if (hours > 0) {
      entry.reloadTimer = setInterval(() => {
        if (!win.isDestroyed()) win.webContents.reload()
      }, hours * 3600 * 1000)
    }

    this.applyGeometry(win, display, single)
    this.loadPage(entry, display, page, single)
    this.log.push('console', `打开大屏窗口 display=${display.id} bounds=${bounds.width}x${bounds.height}@${bounds.x},${bounds.y} page=${page}`)
    return entry
  }

  geometryFor(display, single) {
    const bounds = display.bounds
    if (!single) return { x: bounds.x, y: bounds.y, width: bounds.width, height: bounds.height }
    // 单屏窗口化：不铺满，留出边距方便看管理窗口和调试
    const width = Math.round(bounds.width * 0.8)
    const height = Math.round(bounds.height * 0.8)
    return {
      x: bounds.x + Math.round((bounds.width - width) / 2),
      y: bounds.y + Math.round((bounds.height - height) / 2),
      width,
      height
    }
  }

  applyGeometry(win, display, single) {
    if (!win || win.isDestroyed()) return
    if (single) {
      if (win.isKiosk()) win.setKiosk(false)
      if (win.isFullScreen()) win.setFullScreen(false)
    } else if (this.display.kiosk !== false) {
      win.setKiosk(true)
    }
    win.setBounds(this.geometryFor(display, single))
  }

  loadPage(entry, display, page, single) {
    if (!entry || !entry.win || entry.win.isDestroyed()) return
    const url = this.urlFor(display, page, single)
    this.log.push('console', `大屏加载 ${url}`)
    entry.win.loadURL(url).catch((err) => {
      // 服务端还没起来时加载失败是正常的，健康检查通过后会重排重载
      this.log.push('console', `大屏加载失败（display=${display.id}）：${err.message}`)
    })
  }

  urlFor(display, page, single) {
    const params = new URLSearchParams()
    params.set(this.display.pageParam || 'page', page)
    // lock=1 告知页面锁死单页，不参与轮播
    params.set('lock', '1')
    params.set('screen', String(display.id))
    params.set('instance', `${os.hostname()}-${display.id}`)
    // 只有单屏窗口化才画标题栏；多屏 kiosk 全屏无人值守，不能占高度
    if (single) params.set('windowed', '1')
    return `http://127.0.0.1:${this.server.port}/display?${params.toString()}`
  }

  // 单屏模式要「行为冻结」：不跟随屏幕变化重排，所以连监听都不挂
  bindScreenListeners(single) {
    if (this.screenListeners.length && this.boundSingle === single) return
    this.unbindScreenListeners()
    this.boundSingle = single
    if (single) return

    const schedule = () => {
      if (this.layoutTimer) clearTimeout(this.layoutTimer)
      // 分辨率/缩放变化会连续触发多次，防抖后再重排
      this.layoutTimer = setTimeout(() => {
        this.layoutTimer = null
        this.layout()
      }, 600)
    }

    screen.on('display-metrics-changed', schedule)
    screen.on('display-added', schedule)
    screen.on('display-removed', schedule)
    this.screenListeners = [
      ['display-metrics-changed', schedule],
      ['display-added', schedule],
      ['display-removed', schedule]
    ]
  }

  unbindScreenListeners() {
    for (const [event, handler] of this.screenListeners) {
      screen.removeListener(event, handler)
    }
    this.screenListeners = []
  }

  destroyEntry(displayId, entry) {
    if (entry.reloadTimer) clearInterval(entry.reloadTimer)
    if (entry.win && !entry.win.isDestroyed()) entry.win.destroy()
    this.windows.delete(displayId)
    this.log.push('console', `关闭大屏窗口 display=${displayId}`)
  }

  relayout() {
    if (!this.enabled) return
    for (const [, entry] of this.windows) {
      if (entry.win && !entry.win.isDestroyed()) entry.win.webContents.reload()
    }
    this.layout()
  }

  getInfo() {
    return [...this.windows.entries()].map(([displayId, entry]) => ({
      displayId,
      page: entry.page,
      url: entry.win && !entry.win.isDestroyed() ? entry.win.webContents.getURL() : '',
      bounds: entry.win && !entry.win.isDestroyed() ? entry.win.getBounds() : null
    }))
  }

  closeAll() {
    if (this.layoutTimer) clearTimeout(this.layoutTimer)
    this.unbindScreenListeners()
    for (const [displayId, entry] of [...this.windows]) {
      this.destroyEntry(displayId, entry)
    }
    this.enabled = false
  }
}

module.exports = { DisplayManager, SELECTION }