package uk.orllewin.sianel.ui

import android.content.res.Configuration
import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.result.contract.ActivityResultContracts
import androidx.compose.foundation.Image
import androidx.compose.foundation.isSystemInDarkTheme
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.MoreVert
import androidx.compose.material3.DropdownMenu
import androidx.compose.material3.DropdownMenuItem
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.FloatingActionButton
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.material3.TopAppBarDefaults
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.ui.input.nestedscroll.nestedScroll
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateListOf
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.platform.LocalConfiguration
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.platform.LocalWindowInfo
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.unit.dp
import androidx.lifecycle.viewmodel.compose.viewModel
import androidx.navigation3.runtime.NavEntry
import androidx.navigation3.ui.NavDisplay
import uk.orllewin.sianel.R

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun SianelRootScreen(
    externalUri: android.net.Uri? = null,
    onExternalUriConsumed: () -> Unit = {},
) {
    val viewModel: MainViewModel = viewModel()
    var showConfigDialog by remember { mutableStateOf(false) }
    var menuOpen by remember { mutableStateOf(false) }

    // First run: no credentials yet. Show the full-screen setup instead of the main
    // UI (which would otherwise render an error behind a bottom sheet).
    if (viewModel.password.isBlank()) {
        ConfigScreen(
            currentPassword = viewModel.password,
            currentBaseUrl = viewModel.baseUrl,
            verifyState = viewModel.verifyState,
            onCheck = { password, baseUrl -> viewModel.verifyCredentials(password, baseUrl) },
            onSave = { password, baseUrl -> viewModel.saveSettings(password, baseUrl) },
        )
        return
    }

    val isLandscape = LocalConfiguration.current.orientation == Configuration.ORIENTATION_LANDSCAPE
    // containerSize is in pixels; the 600 tablet breakpoint is in dp — convert before
    // comparing, otherwise every phone (~1080px wide) is wrongly treated as a tablet.
    val isTablet = with(LocalDensity.current) {
        LocalWindowInfo.current.containerSize.width.toDp() >= 600.dp
    }

    val backStack = remember { mutableStateListOf<Any>(ListRoute) }

    RequestNotificationPermissionOnce()

    // Stage videos opened from external apps (Photos share, "Open with", etc.).
    LaunchedEffect(externalUri) {
        val uri = externalUri ?: return@LaunchedEffect
        viewModel.selectVideo(uri)
        if (!isTablet && backStack.lastOrNull() !is UploadRoute) {
            backStack.add(UploadRoute)
        }
        onExternalUriConsumed()
    }

    val picker = rememberLauncherForActivityResult(
        ActivityResultContracts.GetContent()
    ) { uri ->
        uri?.let {
            viewModel.selectVideo(it)
            if (!isTablet && backStack.lastOrNull() !is UploadRoute) {
                backStack.add(UploadRoute)
            }
        }
    }
    val pickVideo: () -> Unit = { picker.launch("video/*") }

    val scrollBehavior = TopAppBarDefaults.enterAlwaysScrollBehavior()

    Scaffold(
        modifier = Modifier.nestedScroll(scrollBehavior.nestedScrollConnection),
        topBar = {
            TopAppBar(
                scrollBehavior = scrollBehavior,
                title = {
                    val logoRes = if (isSystemInDarkTheme()) {
                        R.drawable.screen_logo_dark
                    } else {
                        R.drawable.screen_logo
                    }
                    Image(
                        modifier = Modifier.height(40.dp),
                        painter = painterResource(id = logoRes),
                        contentDescription = "Sianel",
                    )
                },
                actions = {
                    IconButton(onClick = { menuOpen = true }) {
                        Icon(Icons.Default.MoreVert, contentDescription = "More")
                    }
                    DropdownMenu(
                        expanded = menuOpen,
                        onDismissRequest = { menuOpen = false },
                    ) {
                        DropdownMenuItem(
                            text = { Text("Config") },
                            onClick = {
                                menuOpen = false
                                showConfigDialog = true
                            },
                        )
                    }
                },
            )
        },
        floatingActionButton = {
            val onList = backStack.lastOrNull() is ListRoute
            if (!isTablet &&
                !isLandscape &&
                onList &&
                viewModel.password.isNotBlank() &&
                viewModel.uploadProgress == null
            ) {
                FloatingActionButton(
                    onClick = pickVideo,
                    shape = CircleShape
                ) {
                    Icon(
                        painter = painterResource(R.drawable.ic_add_video),
                        contentDescription = "Add"
                    )
                }
            }
        },
    ) { padding ->
        if (isTablet && isLandscape) {
            TwoPaneLayout(
                viewModel = viewModel,
                onPickVideo = pickVideo,
                paddingValues = padding,
            )
        } else {
            NavDisplay(
                backStack = backStack,
                onBack = {
                    if (backStack.lastOrNull() is UploadRoute) viewModel.cancelPending()
                    if (backStack.size > 1) backStack.removeLastOrNull()
                },
                entryProvider = { key ->
                    when (key) {
                        is ListRoute -> NavEntry(key) {
                            ListScreen(viewModel, padding)
                        }
                        is UploadRoute -> NavEntry(key) {
                            UploadScreen(
                                viewModel = viewModel,
                                paddingValues = padding,
                                onUpload = {
                                    viewModel.confirmUpload()
                                    if (backStack.size > 1) backStack.removeLastOrNull()
                                },
                                onCancel = {
                                    viewModel.cancelPending()
                                    if (backStack.size > 1) backStack.removeLastOrNull()
                                },
                            )
                        }
                        else -> NavEntry(key) { Text("Unknown route") }
                    }
                },
            )
        }
    }

    if (showConfigDialog) {
        ConfigDialog(
            currentPassword = viewModel.password,
            currentBaseUrl = viewModel.baseUrl,
            onSave = { password, baseUrl ->
                viewModel.saveSettings(password, baseUrl)
                showConfigDialog = false
            },
            onClear = {
                viewModel.clearPassword()
                viewModel.clearBaseUrl()
                showConfigDialog = false
            },
            onDismiss = { showConfigDialog = false },
        )
    }
}