package org.terst.feedreader.ui

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.material3.darkColorScheme
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.navigation.NavType
import androidx.navigation.compose.NavHost
import androidx.navigation.compose.composable
import androidx.navigation.compose.rememberNavController
import androidx.navigation.navArgument
import org.terst.feedreader.work.FeedFetchWorker
import java.net.URLDecoder
import java.net.URLEncoder

const val UNREAD_FEED_ID = "__unread__"
const val SAVED_FEED_ID = "__saved__"

fun encodeNavArg(value: String): String = URLEncoder.encode(value, "UTF-8")
fun decodeNavArg(value: String): String = URLDecoder.decode(value, "UTF-8")

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        FeedFetchWorker.schedulePeriodic(applicationContext)

        setContent {
            // Dark by default -- per user request, not following system light/dark for now.
            MaterialTheme(colorScheme = darkColorScheme()) {
                Surface(modifier = Modifier.fillMaxSize()) {
                    FeedReaderApp()
                }
            }
        }
    }
}

@Composable
fun FeedReaderApp() {
    val navController = rememberNavController()
    // Unread is the landing screen (per user request) -- it has no "back" affordance of its
    // own since it's the root of the back stack; ArticleListScreen instead shows a way to
    // reach the feed list from there (a forward navigation, not a pop).
    NavHost(navController = navController, startDestination = "articles/${encodeNavArg(UNREAD_FEED_ID)}") {
        composable("feeds") {
            FeedListScreen(
                onOpenFeed = { feedId -> navController.navigate("articles/${encodeNavArg(feedId)}") },
                onOpenUnread = { navController.navigate("articles/${encodeNavArg(UNREAD_FEED_ID)}") },
                onOpenSaved = { navController.navigate("articles/${encodeNavArg(SAVED_FEED_ID)}") },
                onAddFeed = { navController.navigate("addFeed") },
                onSettings = { navController.navigate("settings") }
            )
        }
        composable(
            "articles/{feedId}",
            arguments = listOf(navArgument("feedId") { type = NavType.StringType })
        ) { backStackEntry ->
            val feedId = decodeNavArg(backStackEntry.arguments?.getString("feedId") ?: UNREAD_FEED_ID)
            ArticleListScreen(
                feedId = feedId,
                onOpenArticle = { articleId -> navController.navigate("reader/${encodeNavArg(articleId)}") },
                onBack = { navController.popBackStack() },
                onOpenFeedList = { navController.navigate("feeds") }
            )
        }
        composable(
            "reader/{articleId}",
            arguments = listOf(navArgument("articleId") { type = NavType.StringType })
        ) { backStackEntry ->
            val articleId = decodeNavArg(backStackEntry.arguments?.getString("articleId") ?: "")
            ReaderScreen(articleId = articleId, onBack = { navController.popBackStack() })
        }
        composable("addFeed") {
            AddFeedScreen(onDone = { navController.popBackStack() })
        }
        composable("settings") {
            SettingsScreen(onBack = { navController.popBackStack() })
        }
    }
}