/**
 * 早安电台 — 音频管理器
 * 封装 wx.getBackgroundAudioManager()，管理全局背景播放
 * 确保小程序切后台后音频不断
 * 播放时自动上报收听历史
 */

const api = require('./api')

let bgAudioManager = null
let appInstance = null
let _switching = false   // 切换音频时的锁，防止 onStop 事件干扰
let _ended = false       // 标记音频是否已自然播放完毕

/**
 * 初始化音频管理器
 * @param {Object} app - App 实例
 */
function init(app) {
    appInstance = app
    bgAudioManager = wx.getBackgroundAudioManager()

    // 绑定音频事件
    bgAudioManager.onPlay(() => {
        _switching = false  // 新音频开始播放，释放锁
        updatePlayState(true)
    })

    bgAudioManager.onPause(() => {
        updatePlayState(false)
        // 暂停时上报进度
        reportHistory()
    })

    bgAudioManager.onStop(() => {
        // 如果正在切换音频，不处理 onStop（新的 src 设置会触发旧的 onStop）
        if (_switching) return

        reportHistory()
        updatePlayState(false)
        appInstance.globalData.currentTime = 0
        appInstance.emit('playerStateChange', getState())
    })

    bgAudioManager.onEnded(() => {
        _ended = true
        reportHistory()
        updatePlayState(false)
        appInstance.globalData.currentTime = appInstance.globalData.duration
        appInstance.emit('playerStateChange', getState())
    })

    // 进度更新回调
    bgAudioManager.onTimeUpdate(() => {
        if (_switching) return
        const ct = Math.floor(bgAudioManager.currentTime || 0)
        const dur = Math.floor(bgAudioManager.duration || 0)
        appInstance.globalData.currentTime = ct
        if (dur > 0) {
            appInstance.globalData.duration = dur
        }
        appInstance.emit('timeUpdate', { currentTime: ct, duration: dur })
    })

    bgAudioManager.onError((err) => {
        console.error('[AudioManager] 播放出错：', err)
        _switching = false
        updatePlayState(false)
    })

    bgAudioManager.onWaiting(() => {
        console.log('[AudioManager] 缓冲中...')
    })
}

/**
 * 更新播放状态并通知
 */
function updatePlayState(isPlaying) {
    appInstance.globalData.isPlaying = isPlaying
    appInstance.emit('playerStateChange', getState())
}

/**
 * 获取当前播放器状态
 */
function getState() {
    return {
        activeContent: appInstance.globalData.activeContent,
        isPlaying: appInstance.globalData.isPlaying,
        currentTime: appInstance.globalData.currentTime,
        duration: appInstance.globalData.duration,
        playbackRate: appInstance.globalData.playbackRate
    }
}

/**
 * 获取音频 URL
 */
function getAudioUrl(content) {
    if (!content) return ''
    if (content.audio && content.audio.url) return content.audio.url
    if (content.audioUrl) return content.audioUrl
    return ''
}

/**
 * 上报收听历史到后端
 */
function reportHistory() {
    const content = appInstance.globalData.activeContent
    if (!content || !content.id) return

    api.addHistory({
        programId: content.id,
        progress: appInstance.globalData.currentTime || 0,
        duration: appInstance.globalData.duration || content.duration || 0
    }).catch(function (err) {
        console.warn('[AudioManager] 上报历史失败:', err)
    })
}

/**
 * 播放指定内容
 * @param {Object} content - 音频内容对象 { id, title, duration, audioUrl/audio.url, ... }
 */
function playContent(content) {
    if (!bgAudioManager || !content) return

    var audioUrl = getAudioUrl(content)
    if (!audioUrl) {
        console.error('[AudioManager] 音频内容缺少 audioUrl:', content)
        wx.showToast({ title: '音频地址无效', icon: 'none' })
        return
    }

    // 如果当前有播放内容，先上报历史
    var oldContent = appInstance.globalData.activeContent
    if (oldContent && oldContent.id && oldContent.id !== content.id) {
        reportHistory()
    }

    // 标记正在切换，防止旧音频的 onStop 干扰
    _switching = true
    _ended = false  // 重置结束标记

    appInstance.globalData.activeContent = content
    appInstance.globalData.currentTime = 0
    appInstance.globalData.duration = content.duration || 0

    // 设置背景音频属性（必须设置 title，否则 iOS 上不允许播放）
    bgAudioManager.title = content.title || '早安电台'
    bgAudioManager.singer = '早安电台'
    bgAudioManager.epname = content.title || '早安电台'
    bgAudioManager.coverImgUrl = (content.cover && content.cover.url) || content.coverUrl || ''

    // 设置音频源（这会触发旧音频的 onStop，然后自动开始播放新音频）
    bgAudioManager.src = audioUrl

    appInstance.emit('playerStateChange', getState())
}

/**
 * 切换播放/暂停
 * 关键：如果音频已结束或 src 被回收，需要重新设置 src 才能恢复播放
 */
function togglePlay() {
    if (!bgAudioManager || !appInstance.globalData.activeContent) return

    if (appInstance.globalData.isPlaying) {
        bgAudioManager.pause()
    } else {
        // 音频已自然播放完毕，或 src 被系统回收 → 从头重新播放
        var srcEmpty = false
        try { srcEmpty = !bgAudioManager.src } catch (e) { srcEmpty = true }

        if (_ended || srcEmpty) {
            _ended = false
            playContent(appInstance.globalData.activeContent)
        } else {
            bgAudioManager.play()
        }
    }
}

/**
 * 跳转到指定时间（秒）
 */
function seekTo(time) {
    if (!bgAudioManager) return
    bgAudioManager.seek(time)
    appInstance.globalData.currentTime = time
    appInstance.emit('timeUpdate', {
        currentTime: time,
        duration: appInstance.globalData.duration
    })
}

/**
 * 设置播放速率
 * @param {number} rate - 0.5 / 0.75 / 1.0 / 1.25 / 1.5 / 2.0
 */
function setPlaybackRate(rate) {
    if (!bgAudioManager) return
    bgAudioManager.playbackRate = rate
    appInstance.globalData.playbackRate = rate
    appInstance.emit('playerStateChange', getState())
}

module.exports = {
    init,
    getState,
    playContent,
    togglePlay,
    seekTo,
    setPlaybackRate
}