JetnewsNavGraph.kt

/*
 * Copyright 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.jetnews.ui

import androidx.compose.material.ScaffoldState
import androidx.compose.material.rememberScaffoldState
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.navigation.NavHostController
import androidx.navigation.compose.NavHost
import androidx.navigation.compose.composable
import androidx.navigation.compose.rememberNavController
import com.example.jetnews.data.AppContainer
import com.example.jetnews.ui.MainDestinations.ARTICLE_ID_KEY
import com.example.jetnews.ui.article.ArticleScreen
import com.example.jetnews.ui.home.HomeScreen
import com.example.jetnews.ui.interests.InterestsScreen
import kotlinx.coroutines.launch

/**
 * Destinations used in the ([JetnewsApp]).
 */
object MainDestinations {
    const val HOME_ROUTE = "home"
    const val INTERESTS_ROUTE = "interests"
    const val ARTICLE_ROUTE = "post"
    const val ARTICLE_ID_KEY = "postId"
}

@Composable
fun JetnewsNavGraph(
    appContainer: AppContainer,
    navController: NavHostController = rememberNavController(),
    scaffoldState: ScaffoldState = rememberScaffoldState(),
    startDestination: String = MainDestinations.HOME_ROUTE
) {
    val actions = remember(navController) { MainActions(navController) }
    val coroutineScope = rememberCoroutineScope()
    val openDrawer: () -> Unit = { coroutineScope.launch { scaffoldState.drawerState.open() } }

    NavHost(
        navController = navController,
        startDestination = startDestination
    ) {
        composable(MainDestinations.HOME_ROUTE) {
            HomeScreen(
                postsRepository = appContainer.postsRepository,
                navigateToArticle = actions.navigateToArticle,
                openDrawer = openDrawer
            )
        }
        composable(MainDestinations.INTERESTS_ROUTE) {
            InterestsScreen(
                interestsRepository = appContainer.interestsRepository,
                openDrawer = openDrawer
            )
        }
        composable("${MainDestinations.ARTICLE_ROUTE}/{$ARTICLE_ID_KEY}") { backStackEntry ->
            ArticleScreen(
                postId = backStackEntry.arguments?.getString(ARTICLE_ID_KEY),
                onBack = actions.upPress,
                postsRepository = appContainer.postsRepository
            )
        }
    }
}

/**
 * Models the navigation actions in the app.
 */
class MainActions(navController: NavHostController) {
    val navigateToArticle: (String) -> Unit = { postId: String ->
        navController.navigate("${MainDestinations.ARTICLE_ROUTE}/$postId")
    }
    val upPress: () -> Unit = {
        navController.navigateUp()
    }
}