package com.example.myapplication

import android.os.Bundle
import android.view.View
import android.widget.Toast
import androidx.activity.OnBackPressedCallback
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.lifecycleScope
import androidx.navigation.NavController
import androidx.navigation.fragment.NavHostFragment
import com.example.myapplication.network.AuthEvent
import com.example.myapplication.network.AuthEventBus
import com.example.myapplication.utils.EncryptedSharedPreferencesUtil
import com.google.android.material.bottomnavigation.BottomNavigationView
import kotlinx.coroutines.flow.collectLatest
import kotlinx.coroutines.launch

class MainActivity : AppCompatActivity() {

    private lateinit var bottomNav: BottomNavigationView

    private val TAB_HOME = "tab_home"
    private val TAB_SHOP = "tab_shop"
    private val TAB_MINE = "tab_mine"
    private val GLOBAL_HOST = "global_host"

    private var currentTabTag = TAB_HOME
    private var pendingTabAfterLogin: String? = null

    private val protectedTabs = setOf(
        R.id.shop_graph,
        R.id.mine_graph
    )

    private val tabMap by lazy {
        mapOf(
            R.id.home_graph to TAB_HOME,
            R.id.shop_graph to TAB_SHOP,
            R.id.mine_graph to TAB_MINE
        )
    }

    private lateinit var homeHost: NavHostFragment
    private lateinit var shopHost: NavHostFragment
    private lateinit var mineHost: NavHostFragment
    private lateinit var globalHost: NavHostFragment
    private var lastGlobalDestId: Int = R.id.globalEmptyFragment

    private val currentTabHost: NavHostFragment
        get() = when (currentTabTag) {
            TAB_SHOP -> shopHost
            TAB_MINE -> mineHost
            else -> homeHost
        }

    private val currentTabNavController: NavController
        get() = currentTabHost.navController

    private val globalNavController: NavController
        get() = globalHost.navController

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        bottomNav = findViewById(R.id.bottom_nav)
        bottomNav.itemIconTintList = null
        bottomNav.setOnItemReselectedListener { /* ignore */ }

        // 1) 恢复当前tab
        currentTabTag = savedInstanceState?.getString("current_tab_tag") ?: TAB_HOME

        // 2) 初始化/找回 3个Tab host + global host
        initHosts()

        // 3) 底栏点击：show/hide 切 tab（带登录拦截 + 防 stateSaved）
        bottomNav.setOnItemSelectedListener { item ->
            val tabTag = tabMap[item.itemId] ?: return@setOnItemSelectedListener false

            // 登录拦截：未登录点受保护tab => 打开全局login
            if (!isLoggedIn() && item.itemId in protectedTabs) {
                // 强制回到当前tab的选中状态，避免底栏短暂闪一下
                bottomNav.selectedItemId = when (currentTabTag) {
                    TAB_SHOP -> R.id.shop_graph
                    TAB_MINE -> R.id.mine_graph
                    else -> R.id.home_graph
                }
                pendingTabAfterLogin = tabTag  // 记录目标tab
                openGlobal(R.id.loginFragment)
                return@setOnItemSelectedListener false
            }

            switchTab(tabTag)
            true
        }

        // 4) token过期：走全局 overlay，且避免重复打开
        lifecycleScope.launch {
            AuthEventBus.events.collectLatest { event ->
                when (event) {
                    is AuthEvent.TokenExpired -> {
                        pendingTabAfterLogin = null
                        // 已经在login就别重复
                        if (!isGlobalVisible() || globalNavController.currentDestination?.id != R.id.loginFragment) {
                            openGlobal(R.id.loginFragment)
                        }
                    }
                    is AuthEvent.GenericError -> {
                        Toast.makeText(this@MainActivity, event.message, Toast.LENGTH_SHORT).show()
                    }
                    // 登录成功事件处理
                    is AuthEvent.LoginSuccess -> {
                        // 关闭 global overlay：回到 empty
                        globalNavController.popBackStack(R.id.globalEmptyFragment, false)

                        // 如果之前想去商城/我的，登录成功后自动切过去
                        pendingTabAfterLogin?.let { tag ->
                            switchTab(tag)
                            bottomNav.selectedItemId = when (tag) {
                                TAB_SHOP -> R.id.shop_graph
                                TAB_MINE -> R.id.mine_graph
                                else -> R.id.home_graph
                            }
                        }
                        pendingTabAfterLogin = null
                    }
                    // 登出事件处理
                    is AuthEvent.Logout -> {
                        pendingTabAfterLogin = event.returnTabTag
                        
                        // ✅ 用户没登录按返回，应回首页，所以先切到首页
                        switchTab(TAB_HOME, force = true)
                        
                        bottomNav.post {
                            bottomNav.selectedItemId = R.id.home_graph
                            openGlobal(R.id.loginFragment) // ✅ 退出登录后立刻打开登录页
                        }
                    }
                    // 打开全局页面事件处理
                    is AuthEvent.OpenGlobalPage -> {
                        // 打开指定的全局页面
                        openGlobal(event.destinationId, event.bundle)
                    }
                }
            }
        }

        // 5) intent跳转（充值等）统一走全局 overlay
        handleNavigationFromIntent()

        // 6) 返回键规则：优先关闭global，其次pop当前tab
        setupBackPress()

        // 7) 初始选中正确tab（不会触发二次创建）
        bottomNav.post {
            bottomNav.selectedItemId = when (currentTabTag) {
                TAB_SHOP -> R.id.shop_graph
                TAB_MINE -> R.id.mine_graph
                else -> R.id.home_graph
            }
        }
    }

    private fun initHosts() {
        val fm = supportFragmentManager

        homeHost = fm.findFragmentByTag(TAB_HOME) as? NavHostFragment
            ?: NavHostFragment.create(R.navigation.home_graph)
        shopHost = fm.findFragmentByTag(TAB_SHOP) as? NavHostFragment
            ?: NavHostFragment.create(R.navigation.shop_graph)
        mineHost = fm.findFragmentByTag(TAB_MINE) as? NavHostFragment
            ?: NavHostFragment.create(R.navigation.mine_graph)

        globalHost = fm.findFragmentByTag(GLOBAL_HOST) as? NavHostFragment
            ?: NavHostFragment.create(R.navigation.global_graph)

        // 第一次创建时 add；后续进程重建会自动恢复，无需重复 add
        if (fm.findFragmentByTag(TAB_HOME) == null) {
            fm.beginTransaction()
                .setReorderingAllowed(true)
                .add(R.id.tab_container, homeHost, TAB_HOME)
                .add(R.id.tab_container, shopHost, TAB_SHOP).hide(shopHost)
                .add(R.id.tab_container, mineHost, TAB_MINE).hide(mineHost)
                .commitNow()
        }

        if (fm.findFragmentByTag(GLOBAL_HOST) == null) {
            fm.beginTransaction()
                .setReorderingAllowed(true)
                .add(R.id.global_container, globalHost, GLOBAL_HOST)
                .commitNow()
        }

        // 确保当前tab可见
        switchTab(currentTabTag, force = true)

        // 绑定全局导航可见性监听
        bindGlobalVisibility()
        
        // 绑定底部导航栏可见性监听
        bindBottomNavVisibilityForTabs()
    }

    private fun bindGlobalVisibility() {
        globalNavController.addOnDestinationChangedListener { _, dest, _ ->
            val isEmpty = dest.id == R.id.globalEmptyFragment
            
            findViewById<View>(R.id.global_container).visibility = 
                if (isEmpty) View.GONE else View.VISIBLE
            bottomNav.visibility = 
                if (isEmpty) View.VISIBLE else View.GONE

            // ✅ 只在"刚从某个全局页关闭回 empty"时触发回退逻辑
            val justClosedOverlay = (dest.id == R.id.globalEmptyFragment && lastGlobalDestId != R.id.globalEmptyFragment)
            lastGlobalDestId = dest.id

            if (justClosedOverlay) {
                val currentTabGraphId = when (currentTabTag) {
                    TAB_SHOP -> R.id.shop_graph
                    TAB_MINE -> R.id.mine_graph
                    else -> R.id.home_graph
                }
                // 未登录且当前处在受保护tab：强制回首页
                if (!isLoggedIn() && currentTabGraphId in protectedTabs) {
                    switchTab(TAB_HOME, force = true)
                    bottomNav.selectedItemId = R.id.home_graph
                }

                // ✅ 只有"没登录就关闭登录页"才清 pending
                if (!isLoggedIn()) {
                    pendingTabAfterLogin = null
                }
            }
        }
    }

    private fun switchTab(targetTag: String, force: Boolean = false) {
        if (!force && targetTag == currentTabTag) return

        val fm = supportFragmentManager
        if (fm.isStateSaved) return  // ✅ 防崩：stateSaved 时不做事务

        currentTabTag = targetTag

        fm.beginTransaction()
            .setReorderingAllowed(true)
            .hide(homeHost)
            .hide(shopHost)
            .hide(mineHost)
            .also { ft ->
                when (targetTag) {
                    TAB_SHOP -> ft.show(shopHost)
                    TAB_MINE -> ft.show(mineHost)
                    else -> ft.show(homeHost)
                }
            }
            .commit()
    }

    /** 打开全局页（login/recharge等） */
    private fun openGlobal(destId: Int, bundle: Bundle? = null) {
        val fm = supportFragmentManager
        if (fm.isStateSaved) return  // ✅ 防崩

        try {
            if (bundle != null) {
                globalNavController.navigate(destId, bundle)
            } else {
                globalNavController.navigate(destId)
            }
        } catch (e: IllegalArgumentException) {
            // 可选：防止偶发重复 navigate 崩溃
            e.printStackTrace()
        }
    }

    /** 关闭全局页：pop到 empty */
    private fun bindBottomNavVisibilityForTabs() {
        fun shouldHideBottomNav(destId: Int): Boolean {
            return destId in setOf(
                R.id.searchFragment,
                R.id.searchResultFragment,
                R.id.MySkin
                // 你还有其他需要全屏的页，也加在这里
            )
        }

        val listener = NavController.OnDestinationChangedListener { _, dest, _ ->
            // 只要 global overlay 打开了，仍然以 overlay 为准（你已有逻辑）
            if (isGlobalVisible()) return@OnDestinationChangedListener
            bottomNav.visibility = if (shouldHideBottomNav(dest.id)) View.GONE else View.VISIBLE
        }
        
        homeHost.navController.addOnDestinationChangedListener(listener)
        shopHost.navController.addOnDestinationChangedListener(listener)
        mineHost.navController.addOnDestinationChangedListener(listener)
    }

    private fun closeGlobalIfPossible(): Boolean {
        if (!isGlobalVisible()) return false

        val popped = globalNavController.popBackStack()
        val stillVisible = globalNavController.currentDestination?.id != R.id.globalEmptyFragment
        return popped || stillVisible
    }

    private fun isGlobalVisible(): Boolean {
        return findViewById<View>(R.id.global_container).visibility == View.VISIBLE
    }

    private fun setupBackPress() {
        onBackPressedDispatcher.addCallback(this, object : OnBackPressedCallback(true) {
            override fun handleOnBackPressed() {
                // 1) 优先关 global
                if (closeGlobalIfPossible()) return

                // 2) 再 pop 当前tab
                val popped = currentTabNavController.popBackStack()
                if (popped) return

                // 3) 当前tab到根了：如果不是home，切回home；否则退出
	                if (currentTabTag != TAB_HOME) {
	                    bottomNav.post {
	                        bottomNav.selectedItemId = R.id.home_graph
	                    }
	                    switchTab(TAB_HOME)
                } else {
                    finish()
                }
            }
        })
    }

    private fun handleNavigationFromIntent() {
        val navigateTo = intent.getStringExtra("navigate_to")
        if (navigateTo == "recharge_fragment") {
            bottomNav.post {
                if (!isLoggedIn()) {
                    openGlobal(R.id.loginFragment)
                    return@post 
                }
                openGlobal(R.id.rechargeFragment)
            }
        }
    }

    private fun isLoggedIn(): Boolean {
        return EncryptedSharedPreferencesUtil.contains(this, "user")
    }

    override fun onSaveInstanceState(outState: Bundle) {
        outState.putString("current_tab_tag", currentTabTag)
        super.onSaveInstanceState(outState)
    }
}