package com.xuqm.sdk.update

import android.content.Context
import android.util.Log
import com.google.gson.Gson
import com.xuqm.sdk.core.ServiceEndpointRegistry
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.Response
import okhttp3.WebSocket
import okhttp3.WebSocketListener
import java.util.concurrent.TimeUnit

/**
 * WebSocket 客户端，用于接收版本发布的实时通知。
 *
 * 工作流程：
 * 1. 服务端发布新版本时，通过 WebSocket 发送轻量通知
 * 2. SDK 收到通知后自动调用 [UpdateSDK.checkAppUpdate]（尊重灰度发布规则）
 * 3. 根据检查结果回调 [UpdateListener]
 *
 * App 只需注册监听并调用 [connect]，无需关心底层通信细节。
 *
 * 使用方式:
 * ```
 * // 创建并注册监听
 * val ws = UpdateSDK.createWebSocket(context, object : UpdateListener {
 *     override fun onUpdateAvailable(updateInfo: UpdateInfo) {
 *         showUpdateDialog(updateInfo)
 *     }
 *     override fun onNoUpdate() { }
 *     override fun onError(error: Throwable) { }
 * })
 * ws.connect()
 *
 * // 页面销毁时
 * ws.disconnect()
 * ```
 */
class UpdateWebSocket internal constructor(
    private val context: Context,
    private val appKey: String,
    private val listener: UpdateListener,
) {

    companion object {
        private const val TAG = "UpdateWebSocket"
        private const val RECONNECT_DELAY_MS = 5_000L
        private const val MAX_RECONNECT_DELAY_MS = 300_000L  // 5 minutes
    }

    private val gson = Gson()
    private val client = OkHttpClient.Builder()
        .pingInterval(30, TimeUnit.SECONDS)
        .build()

    private var webSocket: WebSocket? = null
    @Volatile private var connected = false
    @Volatile private var manuallyClosed = false
    @Volatile private var reconnectDelay = RECONNECT_DELAY_MS

    fun isConnected(): Boolean = connected

    /**
     * 建立 WebSocket 连接并注册监听。
     * 如果已连接，不会重复连接。
     */
    fun connect() {
        if (connected) return
        manuallyClosed = false
        reconnectDelay = RECONNECT_DELAY_MS
        doConnect()
    }

    /**
     * 断开 WebSocket 连接并移除监听。
     * 调用后不会自动重连。
     */
    fun disconnect() {
        manuallyClosed = true
        webSocket?.close(1000, "Client closing")
        webSocket = null
        connected = false
    }

    private fun doConnect() {
        val baseUrl = ServiceEndpointRegistry.updateBaseUrl
            .replace("^https://".toRegex(), "wss://")
            .replace("^http://".toRegex(), "ws://")
            .trimEnd('/')
        val url = "$baseUrl/ws/updates?appKey=$appKey"

        Log.d(TAG, "Connecting to $url")

        val request = Request.Builder()
            .url(url)
            .build()

        webSocket = client.newWebSocket(request, object : WebSocketListener() {

            override fun onOpen(webSocket: WebSocket, response: Response) {
                Log.d(TAG, "Connected")
                connected = true
                reconnectDelay = RECONNECT_DELAY_MS
            }

            override fun onMessage(webSocket: WebSocket, text: String) {
                Log.d(TAG, "Received: $text")
                handleMessage(text)
            }

            override fun onClosing(webSocket: WebSocket, code: Int, reason: String) {
                Log.d(TAG, "Server closing: $code $reason")
                webSocket.close(code, reason)
            }

            override fun onClosed(webSocket: WebSocket, code: Int, reason: String) {
                Log.d(TAG, "Closed: $code $reason")
                connected = false
                scheduleReconnect()
            }

            override fun onFailure(webSocket: WebSocket, t: Throwable, response: Response?) {
                Log.w(TAG, "Connection failed: ${t.message}")
                connected = false
                scheduleReconnect()
            }
        })
    }

    /**
     * 处理服务端推送的消息。
     * 收到 "new_version_available" 事件后，自动调用 checkUpdate 接口。
     */
    private fun handleMessage(text: String) {
        try {
            val json = gson.fromJson(text, Map::class.java)
            val event = json["event"] as? String ?: return
            if (event == "new_version_available") {
                Log.d(TAG, "New version notification received, checking update...")
                checkUpdateAndNotify()
            }
        } catch (e: Exception) {
            Log.w(TAG, "Failed to parse message: ${e.message}")
        }
    }

    /**
     * 调用 checkUpdate 接口，根据结果回调 listener。
     * 此方法在 IO 线程执行，回调在主线程执行。
     */
    private fun checkUpdateAndNotify() {
        Thread {
            try {
                val updateInfo = kotlinx.coroutines.runBlocking {
                    UpdateSDK.checkAppUpdate(context, bypassIgnore = false)
                }
                android.os.Handler(android.os.Looper.getMainLooper()).post {
                    if (updateInfo != null && updateInfo.needsUpdate) {
                        Log.d(TAG, "Update available: ${updateInfo.versionName} (${updateInfo.versionCode})")
                        listener.onUpdateAvailable(updateInfo)
                    } else {
                        Log.d(TAG, "No update available")
                        listener.onNoUpdate()
                    }
                }
            } catch (e: Exception) {
                Log.w(TAG, "checkUpdate failed: ${e.message}")
                android.os.Handler(android.os.Looper.getMainLooper()).post {
                    listener.onError(e)
                }
            }
        }.start()
    }

    private fun scheduleReconnect() {
        if (manuallyClosed) return
        Log.d(TAG, "Reconnecting in ${reconnectDelay}ms")
        Thread {
            Thread.sleep(reconnectDelay)
            if (!manuallyClosed && !connected) {
                reconnectDelay = (reconnectDelay * 2).coerceAtMost(MAX_RECONNECT_DELAY_MS)
                doConnect()
            }
        }.start()
    }
}