photopicker/src/com/android/photopicker/core/PhotopickerApp.kt

/*
 * Copyright 2024 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
 *
 *      http://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.android.photopicker.core

import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.WindowInsets
import androidx.compose.foundation.layout.WindowInsetsSides
import androidx.compose.foundation.layout.fillMaxHeight
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.offset
import androidx.compose.foundation.layout.only
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.systemBars
import androidx.compose.foundation.layout.windowInsetsPadding
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.ModalBottomSheet
import androidx.compose.material3.rememberModalBottomSheetState
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.dp
import androidx.navigation.compose.rememberNavController
import com.android.photopicker.core.features.LocalFeatureManager
import com.android.photopicker.core.features.Location
import com.android.photopicker.core.features.LocationParams
import com.android.photopicker.core.navigation.LocalNavController
import com.android.photopicker.core.navigation.PhotopickerNavGraph
import com.android.photopicker.data.model.Media
import kotlinx.coroutines.CompletableDeferred
import kotlinx.coroutines.flow.Flow

private val MEASUREMENT_BOTTOM_SHEET_EDGE_PADDING = 12.dp

/**
 * This is an entrypoint of the Photopicker Compose UI. This is called from the MainActivity and is
 * the top-most [@Composable] in the activity application. This should not be called except inside
 * an Activity's [setContent] block.
 *
 * @param onDismissRequest handler for when the BottomSheet is dismissed.
 */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun PhotopickerAppWithBottomSheet(
    onDismissRequest: () -> Unit,
    onMediaSelectionConfirmed: () -> Unit,
    preloadMedia: Flow<Set<Media>>,
    obtainPreloaderDeferred: () -> CompletableDeferred<Boolean>,
) {
    // Initialize and remember the NavController. This needs to be provided before the call to
    // the NavigationGraph, so this is done at the top.
    val navController = rememberNavController()
    val state = rememberModalBottomSheetState()
    // Provide the NavController to the rest of the Compose stack.
    CompositionLocalProvider(LocalNavController provides navController) {
        Column(
            modifier =
                // Apply WindowInsets to this wrapping column to prevent the Bottom Sheet
                // from drawing over the system bars.
                Modifier.windowInsetsPadding(
                    WindowInsets.systemBars.only(WindowInsetsSides.Vertical)
                )
        ) {
            ModalBottomSheet(
                sheetState = state,
                onDismissRequest = onDismissRequest,
                scrimColor = Color.Transparent,
                containerColor = MaterialTheme.colorScheme.surfaceContainer,
                contentColor = MaterialTheme.colorScheme.onSurfaceVariant,
                contentWindowInsets = { WindowInsets.systemBars },
            ) {
                Box(
                    modifier = Modifier.fillMaxHeight(),
                    contentAlignment = Alignment.BottomCenter
                ) {
                    PhotopickerMain()
                    Column(
                        modifier =
                            // Some elements needs to be drawn over the UI inside of the
                            // BottomSheet A negative y offset will move it from the bottom of the
                            // content to the bottom of the onscreen BottomSheet.
                            Modifier.offset {
                                IntOffset(x = 0, y = -state.requireOffset().toInt())
                            },
                    ) {
                        LocalFeatureManager.current.composeLocation(
                            Location.SNACK_BAR,
                            maxSlots = 1,
                        )
                        LocalFeatureManager.current.composeLocation(
                            Location.SELECTION_BAR,
                            maxSlots = 1,
                            params = LocationParams.WithClickAction { onMediaSelectionConfirmed() }
                        )
                    }
                }
                // If a [MEDIA_PRELOADER] is configured in the current session, attach it
                // to the compose UI here, so that any dialogs it shows are drawn overtop
                // of the application.
                LocalFeatureManager.current.composeLocation(
                    Location.MEDIA_PRELOADER,
                    maxSlots = 1,
                    params =
                        object : LocationParams.WithMediaPreloader {
                            override fun obtainDeferred(): CompletableDeferred<Boolean> {
                                return obtainPreloaderDeferred()
                            }

                            override val preloadMedia = preloadMedia
                        }
                )
            }
        }
    }
}

/**
 * This is an entrypoint of the Photopicker Compose UI. This is called from a hosting View and is
 * the top-most [@Composable] in the view based application. This should not be called by any
 * Activity code, and should only be called inside of the ComposeView [setContent] block.
 */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun PhotopickerApp() {
    // Initialize and remember the NavController. This needs to be provided before the call to
    // the NavigationGraph, so this is done at the top.
    val navController = rememberNavController()

    // Provide the NavController to the rest of the Compose stack.
    CompositionLocalProvider(LocalNavController provides navController) { PhotopickerMain() }
}

/**
 * This is the shared entrypoint for the Photopicker compose-UI. Composables above this function
 * must provide the required dependencies to the compose UI before calling this entrypoint.
 *
 * It is presumed after this composable the compose UI can either be running inside of a wrapped
 * View or an Activity lifecycle.
 *
 * By this entrypoint, the expected CompositionLocals should already exist:
 * - LocalEvents
 * - LocalFeatureManager
 * - LocalNavController
 * - LocalPhotopickerConfiguration
 * - LocalSelection
 * - PhotopickerTheme
 */
@Composable
fun PhotopickerMain() {
    Box(modifier = Modifier.fillMaxSize()) {
        Column {
            // The navigation bar and profile switcher are drawn above the navigation graph
            Row(
                modifier =
                    Modifier.fillMaxWidth()
                        .padding(horizontal = MEASUREMENT_BOTTOM_SHEET_EDGE_PADDING),
                horizontalArrangement = Arrangement.SpaceBetween,
                verticalAlignment = Alignment.CenterVertically,
            ) {
                LocalFeatureManager.current.composeLocation(
                    Location.PROFILE_SELECTOR,
                    maxSlots = 1,
                    // Weight should match the overflow menu slot so they are the same size.
                    modifier = Modifier.weight(1f),
                )
                LocalFeatureManager.current.composeLocation(
                    Location.NAVIGATION_BAR,
                    maxSlots = 1,
                    modifier = Modifier,
                )
                LocalFeatureManager.current.composeLocation(
                    Location.OVERFLOW_MENU,
                    // Weight should match the profile switcher slot so they are the same size.
                    modifier = Modifier.weight(1f),
                )
            }
            // Initialize the navigation graph.
            PhotopickerNavGraph()
        }
    }
}