From 52fc21b0ad09e538243cc44f1ed6c9877512593e Mon Sep 17 00:00:00 2001
From: Satindar Dhillon <satindar@gmail.com>
Date: Fri, 9 Dec 2022 16:30:53 -0800
Subject: [PATCH] add pull to refresh mechanism on android home screen

---
 .../app/omnivore/omnivore/ui/home/HomeView.kt | 68 +++++++++++++------
 .../omnivore/ui/home/HomeViewModel.kt         | 15 ++++
 2 files changed, 61 insertions(+), 22 deletions(-)

diff --git a/android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/home/HomeView.kt b/android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/home/HomeView.kt
index 1663665b0..e3ee5d1f7 100644
--- a/android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/home/HomeView.kt
+++ b/android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/home/HomeView.kt
@@ -7,6 +7,10 @@ import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.lazy.rememberLazyListState
+import androidx.compose.material.ExperimentalMaterialApi
+import androidx.compose.material.pullrefresh.PullRefreshIndicator
+import androidx.compose.material.pullrefresh.pullRefresh
+import androidx.compose.material.pullrefresh.rememberPullRefreshState
 import androidx.compose.material3.*
 import androidx.compose.runtime.*
 import androidx.compose.runtime.livedata.observeAsState
@@ -14,6 +18,7 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.NavHostController
 import app.omnivore.omnivore.Routes
 import app.omnivore.omnivore.models.LinkedItem
@@ -50,6 +55,7 @@ fun HomeView(
   }
 }
 
+@OptIn(ExperimentalMaterialApi::class)
 @Composable
 fun HomeViewContent(
   homeViewModel: HomeViewModel,
@@ -58,35 +64,53 @@ fun HomeViewContent(
 ) {
   val context = LocalContext.current
   val listState = rememberLazyListState()
+
+  val pullRefreshState = rememberPullRefreshState(
+    refreshing = homeViewModel.isRefreshing,
+    onRefresh = { homeViewModel.refresh() }
+  )
+
   val linkedItems: List<LinkedItem> by homeViewModel.itemsLiveData.observeAsState(listOf())
 
-  LazyColumn(
-    state = listState,
-    verticalArrangement = Arrangement.Top,
-    horizontalAlignment = Alignment.CenterHorizontally,
-    modifier = modifier
-      .background(MaterialTheme.colorScheme.background)
+  Box(
+    modifier = Modifier
       .fillMaxSize()
-      .padding(horizontal = 6.dp)
+      .pullRefresh(pullRefreshState)
   ) {
-    items(linkedItems) { item ->
-      LinkedItemCard(
-        item = item,
-        onClickHandler = {
-          if (item.isPDF()) {
-            val intent = Intent(context, PDFReaderActivity::class.java)
-            intent.putExtra("LINKED_ITEM_SLUG", item.slug)
-            context.startActivity(intent)
-          } else {
-            navController.navigate("WebReader/${item.slug}")
+    LazyColumn(
+      state = listState,
+      verticalArrangement = Arrangement.Top,
+      horizontalAlignment = Alignment.CenterHorizontally,
+      modifier = modifier
+        .background(MaterialTheme.colorScheme.background)
+        .fillMaxSize()
+        .padding(horizontal = 6.dp)
+    ) {
+      items(linkedItems) { item ->
+        LinkedItemCard(
+          item = item,
+          onClickHandler = {
+            if (item.isPDF()) {
+              val intent = Intent(context, PDFReaderActivity::class.java)
+              intent.putExtra("LINKED_ITEM_SLUG", item.slug)
+              context.startActivity(intent)
+            } else {
+              navController.navigate("WebReader/${item.slug}")
+            }
           }
-        }
-      )
+        )
+      }
     }
-  }
 
-  InfiniteListHandler(listState = listState) {
-    homeViewModel.load()
+    InfiniteListHandler(listState = listState) {
+      homeViewModel.load()
+    }
+    
+    PullRefreshIndicator(
+      refreshing = homeViewModel.isRefreshing,
+      state = pullRefreshState,
+      modifier = Modifier.align(Alignment.TopCenter)
+    )
   }
 }
 
diff --git a/android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/home/HomeViewModel.kt b/android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/home/HomeViewModel.kt
index 6fc76e977..80aeb4b28 100644
--- a/android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/home/HomeViewModel.kt
+++ b/android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/home/HomeViewModel.kt
@@ -1,5 +1,8 @@
 package app.omnivore.omnivore.ui.home
 
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
@@ -7,6 +10,8 @@ import app.omnivore.omnivore.models.LinkedItem
 import app.omnivore.omnivore.networking.Networker
 import app.omnivore.omnivore.networking.search
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
@@ -26,6 +31,7 @@ class HomeViewModel @Inject constructor(
   // Live Data
   val searchTextLiveData = MutableLiveData("")
   val itemsLiveData = MutableLiveData<List<LinkedItem>>(listOf())
+  var isRefreshing by mutableStateOf(false)
 
   fun updateSearchText(text: String) {
     searchTextLiveData.value = text
@@ -37,6 +43,11 @@ class HomeViewModel @Inject constructor(
     }
   }
 
+  fun refresh() {
+    isRefreshing = true
+    load(true)
+  }
+
   fun load(clearPreviousSearch: Boolean = false) {
     if (clearPreviousSearch) {
       cursor = null
@@ -69,6 +80,10 @@ class HomeViewModel @Inject constructor(
         items = items.plus(searchResult.items)
         itemsLiveData.value = items
       }
+
+      CoroutineScope(Dispatchers.Main).launch {
+        isRefreshing = false
+      }
     }
   }