package io.oxygenhub.android.ui.nav

import androidx.compose.material.icons.Icons

import androidx.compose.material.icons.filled.AccountCircle

import androidx.compose.material.icons.filled.Book

import androidx.compose.material.icons.filled.Dashboard

import androidx.compose.material.icons.filled.Inbox

import androidx.compose.material.icons.outlined.AccountCircle

import androidx.compose.material.icons.outlined.Book

import androidx.compose.material.icons.outlined.Dashboard

import androidx.compose.material.icons.outlined.Inbox

import androidx.compose.material3.Badge

import androidx.compose.material3.BadgedBox

import androidx.compose.material3.Icon

import androidx.compose.material3.Text

import androidx.compose.material3.adaptive.navigationsuite.NavigationSuiteScaffold

import androidx.compose.runtime.Composable

import androidx.compose.runtime.getValue

import androidx.compose.ui.graphics.vector.ImageVector

import androidx.lifecycle.ViewModel

import androidx.lifecycle.compose.collectAsStateWithLifecycle

import androidx.lifecycle.viewmodel.compose.viewModel

import androidx.lifecycle.viewmodel.initializer

import androidx.lifecycle.viewmodel.viewModelFactory

import androidx.navigation.NavDestination.Companion.hasRoute

import androidx.navigation.NavDestination.Companion.hierarchy

import androidx.navigation.NavGraph.Companion.findStartDestination

import androidx.navigation.NavHostController

import androidx.navigation.compose.NavHost

import androidx.navigation.compose.composable

import androidx.navigation.compose.currentBackStackEntryAsState

import androidx.navigation.compose.rememberNavController

import androidx.navigation.toRoute

import io.oxygenhub.android.api.HubApi

import io.oxygenhub.android.auth.Session

import io.oxygenhub.android.ui.account.AccountScreen

import io.oxygenhub.android.ui.common.rememberAvatar

import androidx.compose.runtime.rememberCoroutineScope

import io.oxygenhub.android.ui.proposals.ProposalScreen

import io.oxygenhub.android.ui.proposals.ProposalViewModel

import io.oxygenhub.android.ui.proposals.ProposalsViewModel

import io.oxygenhub.android.ui.repos.RepositoryScreen

import kotlinx.coroutines.launch

import io.oxygenhub.android.ui.dashboard.DashboardScreen

import io.oxygenhub.android.ui.dashboard.DashboardViewModel

import io.oxygenhub.android.ui.inbox.InboxScreen

import io.oxygenhub.android.ui.inbox.InboxViewModel

import io.oxygenhub.android.ui.issues.IssuesViewModel

import io.oxygenhub.android.ui.repos.RepositoriesScreen

import io.oxygenhub.android.ui.repos.RepositoriesViewModel

import kotlinx.serialization.Serializable

import kotlin.reflect.KClass

// The app's routes. Top-level ones are in the navigation bar (or rail, or

// drawer, as the window allows); the rest are pushed over them. Browse

// (oxygenhub-android#3) adds a repository's overview, code and history

// under the repository's route.

@Serializable data object DashboardRoute

@Serializable data object RepositoriesRoute

@Serializable data object InboxRoute

@Serializable data object AccountRoute

/** A repository's issues, opened from outside the repositories list (the dashboard). */

@Serializable data class IssuesRoute(val owner: String, val name: String)

/** One proposal, pushed over the repository it belongs to. */

@Serializable data class ProposalRoute(val owner: String, val name: String, val number: Long)

enum class TopLevel(val label: String, val icon: ImageVector, val selectedIcon: ImageVector, val route: Any, val routeClass: KClass<*>) {

    Dashboard("Dashboard", Icons.Outlined.Dashboard, Icons.Filled.Dashboard, DashboardRoute, DashboardRoute::class),

    Repositories("Repositories", Icons.Outlined.Book, Icons.Filled.Book, RepositoriesRoute, RepositoriesRoute::class),

    Inbox("Inbox", Icons.Outlined.Inbox, Icons.Filled.Inbox, InboxRoute, InboxRoute::class),

    Account("Account", Icons.Outlined.AccountCircle, Icons.Filled.AccountCircle, AccountRoute, AccountRoute::class),

}

/** A view model made by [make], kept by the screen's back stack entry (or [key] within it). */

@Composable

inline fun <reified VM : ViewModel> rememberViewModel(key: String? = null, crossinline make: () -> VM): VM =

    viewModel(key = key, factory = viewModelFactory { initializer { make() } })

/** The signed-in app: navigation around the dashboard, repositories, inbox and account. */

@Composable

fun SignedInApp(

    session: Session,

    api: HubApi,

    nativeCore: () -> String,

    onSignOut: suspend () -> Unit,

    start: TopLevel = TopLevel.Dashboard,

    /** A repository to show beside the list from the start (`owner/name`). */

    selectedRepository: String? = null,

) {

    val nav = rememberNavController()

    // One inbox for the badge, the dashboard's count and the inbox screen.

    val inbox = rememberViewModel(key = "inbox:${session.hub}:${session.username}") { InboxViewModel(api) }

    val inboxState by inbox.state.collectAsStateWithLifecycle()

    val unread = inboxState.valueOrNull?.unread ?: 0

    val entry by nav.currentBackStackEntryAsState()

    val destination = entry?.destination

    NavigationSuiteScaffold(

        navigationSuiteItems = {

            TopLevel.entries.forEach { top ->

                val selected = destination?.hierarchy?.any { it.hasRoute(top.routeClass) } == true

                item(

                    selected = selected,

                    onClick = { nav.goTo(top) },

                    icon = {

                        val icon = if (selected) top.selectedIcon else top.icon

                        if (top == TopLevel.Inbox && unread > 0) {

                            BadgedBox(badge = { Badge { Text(if (unread > 99) "99+" else unread.toString()) } }) {

                                Icon(icon, contentDescription = "${top.label}, $unread unread")

                            }

                        } else {

                            Icon(icon, contentDescription = top.label)

                        }

                    },

                    label = { Text(top.label) },

                )

            }

        },

    ) {

        NavHost(nav, startDestination = start.route) {

            composable<DashboardRoute> {

                DashboardScreen(

                    vm = rememberViewModel { DashboardViewModel(api, session) },

                    hub = session.hub,

                    inbox = inboxState,

                    onRefreshInbox = inbox::refresh,

                    onOpenRepository = { nav.navigate(IssuesRoute(it.owner, it.name)) },

                    onAllRepositories = { nav.goTo(TopLevel.Repositories) },

                    onInbox = { nav.goTo(TopLevel.Inbox) },

                    onOpenProposal = { nav.navigate(ProposalRoute(it.owner, it.name, it.number)) },

                )

            }

            composable<RepositoriesRoute> {

                RepositoriesScreen(rememberViewModel { RepositoriesViewModel(api, session.username) }, selectedRepository) { slug, onBack ->

                    val (owner, name) = slug.split('/', limit = 2)

                    RepositoryScreen(

                        rememberViewModel(key = "issues:$slug") { IssuesViewModel(api, owner, name) },

                        rememberViewModel(key = "proposals:$slug") { ProposalsViewModel(api, owner, name) },

                        onBack,

                        onOpenProposal = { nav.navigate(ProposalRoute(owner, name, it.number)) },

                    )

                }

            }

            composable<IssuesRoute> { e ->

                val r = e.toRoute<IssuesRoute>()

                RepositoryScreen(

                    rememberViewModel { IssuesViewModel(api, r.owner, r.name) },

                    rememberViewModel { ProposalsViewModel(api, r.owner, r.name) },

                    onBack = { nav.popBackStack() },

                    onOpenProposal = { nav.navigate(ProposalRoute(r.owner, r.name, it.number)) },

                )

            }

            composable<ProposalRoute> { e ->

                val r = e.toRoute<ProposalRoute>()

                val scope = rememberCoroutineScope()

                ProposalScreen(

                    rememberViewModel { ProposalViewModel(api, r.owner, r.name, r.number) },

                    canWrite = session.canWrite,

                    onBack = { nav.popBackStack() },

                    // Signing out revokes this token; the new sign-in asks for repo:write.

                    onSignInAgain = { scope.launch { onSignOut() } },

                )

            }

            composable<InboxRoute> { InboxScreen(inbox) }

            composable<AccountRoute> { AccountScreen(session, rememberAvatar(api, session.username), api, nativeCore, onSignOut) }

        }

    }

}

/** To a top-level destination, keeping one copy of each and its state, as the bar's own taps do. */

private fun NavHostController.goTo(top: TopLevel) {

    navigate(top.route) {

        popUpTo(graph.findStartDestination().id) { saveState = true }

        launchSingleTop = true

        restoreState = true

    }

}