[User Availability] Update sending availability flow

app/src/main/java/com/cornellappdev/resell/android/model/api/AvailabilityApiService.kt

@@ -3,12 +3,16 @@ package com.cornellappdev.resell.android.model.api
 import retrofit2.http.Body
 import retrofit2.http.GET
 import retrofit2.http.POST
+import retrofit2.http.Path
 
 interface AvailabilityApiService {
 
     @GET("availability/")
     suspend fun getMyAvailability(): AvailabilityResponse
 
+    @GET("availability/user/{userId}")
+    suspend fun getUserAvailability(@Path("userId") userId: String): AvailabilityResponse
+
     @POST("availability/update/")
     suspend fun updateAvailability(
         @Body request: UpdateAvailabilityRequest

app/src/main/java/com/cornellappdev/resell/android/model/profile/AvailabilityRepository.kt

@@ -5,6 +5,7 @@ import com.cornellappdev.resell.android.model.api.RetrofitInstance
 import com.cornellappdev.resell.android.model.api.UpdateAvailabilityRequest
 import com.cornellappdev.resell.android.model.api.UserAvailability
 import com.cornellappdev.resell.android.ui.components.availability.helper.SLOT_DURATION_MINUTES
+import java.time.Instant
 import java.time.LocalDateTime
 import java.time.ZoneId
 import javax.inject.Inject
@@ -14,8 +15,12 @@ import javax.inject.Singleton
 class AvailabilityRepository @Inject constructor(
     private val retrofitInstance: RetrofitInstance
 ) {
-    suspend fun getMyAvailability(): UserAvailability {
-        return retrofitInstance.availabilityApi.getMyAvailability().availability
+    suspend fun getMyAvailability(): Set<LocalDateTime> {
+        return retrofitInstance.availabilityApi.getMyAvailability().availability.toLocalDateTimes()
+    }
+
+    suspend fun getUserAvailability(userId: String): Set<LocalDateTime> {
+        return retrofitInstance.availabilityApi.getUserAvailability(userId).availability.toLocalDateTimes()
     }
 
     suspend fun updateAvailability(slots: List<LocalDateTime>): UserAvailability {
@@ -40,4 +45,12 @@ class AvailabilityRepository @Inject constructor(
 // The backend stores/returns dates as UTC instants (e.g. "2026-01-23T16:00:00.000Z"), so
 // device-local wall-clock times must be converted to an instant before sending.
 private fun LocalDateTime.toUtcInstantString(): String =
-    atZone(ZoneId.systemDefault()).toInstant().toString()
+    atZone(ZoneId.systemDefault()).toInstant().toString()
+
+// The backend sends startDate as a UTC instant (e.g. "2026-01-23T16:00:00.000Z"), so it's
+// parsed as an Instant and converted to the device's local wall-clock time.
+private fun UserAvailability.toLocalDateTimes(): Set<LocalDateTime> {
+    return schedule.values.flatten().map { slot ->
+        Instant.parse(slot.startDate).atZone(ZoneId.systemDefault()).toLocalDateTime()
+    }.toSet()
+}

app/src/main/java/com/cornellappdev/resell/android/ui/components/availability/AvailabilitySheet.kt

@@ -28,6 +28,8 @@ fun AvailabilitySheet(
             title = uiState.title,
             subtitle = uiState.subtitle,
             gridSelectionType = uiState.gridSelectionType,
+            availableAvailabilities = uiState.overlapTimes,
+            onEditAvailabilityClicked = uiState.onEditAvailability,
             setProposalTime = availabilitySheetViewModel::setProposalTime
         )
 

app/src/main/java/com/cornellappdev/resell/android/ui/components/availability/AvailabilitySheetViewModel.kt

@@ -37,7 +37,9 @@ class AvailabilitySheetViewModel @Inject constructor(
         val initialAvailabilities: List<LocalDateTime>,
         val textButtonState: ResellTextButtonState = ResellTextButtonState.ENABLED,
         val gridSelectionType: GridSelectionType,
-        val proposedTime: LocalDateTime? = null
+        val proposedTime: LocalDateTime? = null,
+        val overlapTimes: List<LocalDateTime>? = null,
+        val onEditAvailability: (() -> Unit)? = null,
     )
 
     fun onAvailabilityChanged(availability: List<LocalDateTime>) {
@@ -80,7 +82,9 @@ class AvailabilitySheetViewModel @Inject constructor(
                     callback = uiEvent.payload.callback,
                     initialAvailabilities = uiEvent.payload.initialTimes,
                     textButtonState = uiEvent.payload.initialButtonState,
-                    gridSelectionType = uiEvent.payload.gridSelectionType
+                    gridSelectionType = uiEvent.payload.gridSelectionType,
+                    overlapTimes = uiEvent.payload.overlapTimes,
+                    onEditAvailability = uiEvent.payload.onEditAvailability
                 )
             }
         }

app/src/main/java/com/cornellappdev/resell/android/ui/components/availability/SelectableAvailabilityPager.kt

@@ -23,9 +23,11 @@ fun SelectableAvailabilityPager(
     title: String,
     subtitle: String,
     initialSelectedAvailabilities: List<LocalDateTime> = emptyList(),
+    availableAvailabilities: List<LocalDateTime>? = null,
     scrollRange: Pair<Int, Int> = 0 to 6,
     modifier: Modifier = Modifier,
     gridSelectionType: GridSelectionType,
+    onEditAvailabilityClicked: (() -> Unit)? = null,
     setProposalTime: (LocalDateTime) -> Unit,
     setSelectedAvailabilities: (List<LocalDateTime>) -> Unit,
 ) {
@@ -65,6 +67,7 @@ fun SelectableAvailabilityPager(
         modifier = modifier,
         title = title,
         subtitle = subtitle,
+        onEditAvailabilityClicked = onEditAvailabilityClicked,
     ) { dates, page ->
         SelectableAvailabilityGrid(
             dates = dates,
@@ -81,6 +84,7 @@ fun SelectableAvailabilityPager(
                 setSelectedAvailabilities(updatedDates.values.flatten())
             },
             gridSelectionType = gridSelectionType,
+            availableAvailabilities = availableAvailabilities,
             onProposalSelected = setProposalTime
         )
     }

app/src/main/java/com/cornellappdev/resell/android/ui/components/availability/helper/AvailabilityPagerContainer.kt

@@ -23,6 +23,7 @@ import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.unit.dp
 import com.cornellappdev.resell.android.R
+import com.cornellappdev.resell.android.ui.theme.ResellPurple
 import com.cornellappdev.resell.android.ui.theme.Secondary
 import com.cornellappdev.resell.android.ui.theme.Style
 import com.cornellappdev.resell.android.util.clickableNoIndication
@@ -45,6 +46,7 @@ fun AvailabilityPagerContainer(
     startDate: LocalDate,
     scrollRange: Pair<Int, Int>,
     modifier: Modifier = Modifier,
+    onEditAvailabilityClicked: (() -> Unit)? = null,
     availabilityGrid: @Composable (dates: List<LocalDate>, page: Int) -> Unit,
 ) {
     val state =
@@ -85,11 +87,26 @@ fun AvailabilityPagerContainer(
                 horizontalAlignment = Alignment.CenterHorizontally
             ) {
                 Text(text = title, style = Style.heading3)
-                Text(
-                    text = subtitle,
-                    style = Style.body2,
-                    color = Secondary
-                )
+                Row(verticalAlignment = Alignment.CenterVertically) {
+                    Text(
+                        text = subtitle,
+                        style = Style.body2,
+                        color = Secondary
+                    )
+                    if (onEditAvailabilityClicked != null) {
+                        Text(
+                            text = " | ",
+                            style = Style.body2,
+                            color = Secondary
+                        )
+                        Text(
+                            text = "Edit Availability",
+                            style = Style.body2,
+                            color = ResellPurple,
+                            modifier = Modifier.clickableNoIndication { onEditAvailabilityClicked() }
+                        )
+                    }
+                }
             }
             Icon(
                 painter = painterResource(R.drawable.ic_chevron_right),

app/src/main/java/com/cornellappdev/resell/android/ui/components/availability/helper/AvailabilityUtil.kt

@@ -9,6 +9,7 @@ import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import com.cornellappdev.resell.android.ui.theme.ResellPurple
 import com.cornellappdev.resell.android.ui.theme.Stroke
+import com.cornellappdev.resell.android.ui.theme.Wash
 import com.cornellappdev.resell.android.util.day
 import java.time.LocalDate
 import java.time.LocalDateTime
@@ -89,6 +90,27 @@ fun List<LocalDateTime>.mapToGrid(dates: List<LocalDate>): List<BooleanArray> {
     return grid
 }
 
+/**
+ * Greys out every cell where [unavailableGrid] is true, so only cells left white/normal
+ * represent times available to both parties.
+ */
+fun DrawScope.drawUnavailableCells(unavailableGrid: List<BooleanArray>, rectWidth: Float, rectHeight: Float) {
+    for (row in unavailableGrid.indices) {
+        for (col in unavailableGrid[row].indices) {
+            if (unavailableGrid[row][col]) {
+                val position = Offset(rectWidth * col, rectHeight * row)
+
+                drawRect(
+                    size = Size(rectWidth, rectHeight),
+                    topLeft = position,
+                    color = Wash,
+                    style = Fill
+                )
+            }
+        }
+    }
+}
+
 fun DrawScope.drawBorder(grid: List<BooleanArray>, rectWidth: Float, rectHeight: Float) {
     for (row in grid.indices.filter { it % 2 == 0 }) {
         for (col in grid[row].indices) {

app/src/main/java/com/cornellappdev/resell/android/ui/components/availability/helper/SelectableAvailabilityGrid.kt

@@ -44,6 +44,7 @@ private fun SelectableGrid(
     updateGrid: ((List<BooleanArray>) -> List<BooleanArray>) -> Unit,
     gridSelectionType: GridSelectionType,
     modifier: Modifier = Modifier,
+    unavailableGrid: List<BooleanArray>? = null,
     onProposalSelected: (Pair<Int, Int>) -> Unit
 ) {
     var isRemoving by remember { mutableStateOf(false) }
@@ -160,6 +161,9 @@ private fun SelectableGrid(
          * in.
          */
 
+        // Grey out cells not available to both parties, before the border/selection layers.
+        unavailableGrid?.let { drawUnavailableCells(it, rectWidth, rectHeight) }
+
         // Draw border
         drawBorder(grid, rectWidth, rectHeight)
 
@@ -216,9 +220,18 @@ fun SelectableAvailabilityGrid(
     setSelectedAvailabilities: (List<LocalDateTime>) -> Unit,
     gridSelectionType: GridSelectionType,
     modifier: Modifier = Modifier,
+    /**
+     * When non-null, cells NOT in this list are greyed out — e.g. the intersection of two
+     * people's saved availability, so only times that work for both are shown as normal/white.
+     * Null means the greying feature isn't used for this grid.
+     */
+    availableAvailabilities: List<LocalDateTime>? = null,
     onProposalSelected: (LocalDateTime) -> Unit,
 ) {
     val grid = selectedAvailabilities.mapToGrid(dates)
+    val unavailableGrid = availableAvailabilities?.mapToGrid(dates)?.map { row ->
+        BooleanArray(row.size) { col -> !row[col] }
+    }
 
     AvailabilityGridContainer(dates, modifier) {
         SelectableGrid(
@@ -228,6 +241,7 @@ fun SelectableAvailabilityGrid(
                 setSelectedAvailabilities(newGrid.toAvailabilities(dates))
             },
             gridSelectionType = gridSelectionType,
+            unavailableGrid = unavailableGrid,
             onProposalSelected = {
                 val (row, col) = it
                 onProposalSelected(rowColToLocalDateTime(row, col, dates))

app/src/main/java/com/cornellappdev/resell/android/ui/screens/main/AvailabilityScreen.kt

@@ -77,6 +77,7 @@ fun AvailabilityScreen(
         onSetCurrentMonth = { availabilityViewModel.setCurrentMonth(it) },
         onSetVisibleDates = { availabilityViewModel.setVisibleDates(it) },
         onSave = { availabilityViewModel.saveAvailability() },
+        onBackPressed = { availabilityViewModel.onBackPressed() },
     )
 }
 
@@ -87,6 +88,7 @@ fun AvailabilityScreenContent(
     onSetCurrentMonth: (YearMonth) -> Unit,
     onSetVisibleDates: (List<LocalDate>) -> Unit,
     onSave: () -> Unit,
+    onBackPressed: () -> Unit = {},
 ) {
     // just some UI logic to allow for smooth transitions between panels expanding on the screen.
     var activePanel by remember { mutableStateOf(AvailabilityPanel.NONE) }
@@ -110,6 +112,7 @@ fun AvailabilityScreenContent(
             ResellHeader(
                 title = "Availability",
                 leftPainter = R.drawable.ic_chevron_left,
+                onLeftClick = onBackPressed,
             )
             Column(
                 modifier = Modifier
@@ -253,5 +256,6 @@ fun AvailabilityScreenPreview() {
         onSetCurrentMonth = {},
         onSetVisibleDates = {},
         onSave = {},
+        onBackPressed = {},
     )
 }

app/src/main/java/com/cornellappdev/resell/android/ui/screens/root/RootNavigation.kt

@@ -25,6 +25,7 @@ import com.cornellappdev.resell.android.ui.components.submitted.ConfettiOverlay
 import com.cornellappdev.resell.android.ui.screens.externalprofile.ExternalProfileNavigation
 import com.cornellappdev.resell.android.ui.screens.feedback.FeedbackNavigation
 import com.cornellappdev.resell.android.ui.screens.main.AllSearchScreen
+import com.cornellappdev.resell.android.ui.screens.main.AvailabilityScreen
 import com.cornellappdev.resell.android.ui.screens.main.ChatScreen
 import com.cornellappdev.resell.android.ui.screens.main.MainTabNavigation
 import com.cornellappdev.resell.android.ui.screens.main.NotificationsHubScreen
@@ -179,6 +180,10 @@ fun RootNavigation(
         composable<ResellRootRoute.NOTIFS> {
             NotificationsHubScreen()
         }
+
+        composable<ResellRootRoute.AVAILABILITY> {
+            AvailabilityScreen()
+        }
     }
 
     RootConfirmationOverlay()
@@ -281,4 +286,7 @@ sealed class ResellRootRoute {
 
     @Serializable
     data object NOTIFS : ResellRootRoute()
+
+    @Serializable
+    data object AVAILABILITY : ResellRootRoute()
 }

app/src/main/java/com/cornellappdev/resell/android/viewmodel/main/AvailabilityViewModel.kt

@@ -2,29 +2,28 @@ package com.cornellappdev.resell.android.viewmodel.main
 
 import androidx.lifecycle.viewModelScope
 import com.cornellappdev.resell.android.model.profile.AvailabilityRepository
-import com.cornellappdev.resell.android.model.api.UserAvailability
 import com.cornellappdev.resell.android.ui.components.availability.helper.dayGroupContaining
 import com.cornellappdev.resell.android.viewmodel.ResellViewModel
+import com.cornellappdev.resell.android.viewmodel.navigation.RootNavigationRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.launch
-import java.time.Instant
 import java.time.LocalDate
 import java.time.LocalDateTime
 import java.time.YearMonth
-import java.time.ZoneId
 import javax.inject.Inject
 
 @HiltViewModel
 class AvailabilityViewModel @Inject constructor(
-    private val availabilityRepository: AvailabilityRepository
+    private val availabilityRepository: AvailabilityRepository,
+    private val rootNavigationRepository: RootNavigationRepository
 ) : ResellViewModel<AvailabilityViewModel.AvailabilityUiState>(
     initialUiState = AvailabilityUiState()
 ) {
 
     data class AvailabilityUiState(
         val selectedAvailabilities: Set<LocalDateTime> = emptySet(),
         val currentMonth: YearMonth = YearMonth.now(),
-        val visibleDates: List<LocalDate> = dayGroupContaining(YearMonth.now().atDay(1)),
+        val visibleDates: List<LocalDate> = dayGroupContaining(LocalDate.now()),
 
         // TODO: googleCalendarEnabled and availabilitySharingEnabled are not yet wired in.
         //  Need to check how/where it is in the backend
@@ -44,6 +43,10 @@ class AvailabilityViewModel @Inject constructor(
         loadAvailability()
     }
 
+    fun onBackPressed() {
+        rootNavigationRepository.popBackStack()
+    }
+
     // grid interactions
 
     /**
@@ -91,7 +94,7 @@ class AvailabilityViewModel @Inject constructor(
                 val availability = availabilityRepository.getMyAvailability()
                 applyMutation {
                     copy(
-                        selectedAvailabilities = availability.toLocalDateTimes(),
+                        selectedAvailabilities = availability,
                         isLoading = false,
                         errorMessage = null
                     )
@@ -113,18 +116,4 @@ class AvailabilityViewModel @Inject constructor(
             }
         }
     }
-}
-
-/**
- * Converts the backend schedule (Map<dateString, List<AvailabilitySlot>>) back into
- * a flat list of LocalDateTimes for the grid to consume.
- * Each slot's startDate is used as the representative time for a cell.
- *
- * The backend sends startDate as a UTC instant (e.g. "2026-01-23T16:00:00.000Z"), so it's
- * parsed as an [Instant] and converted to the device's local wall-clock time.
- */
-private fun UserAvailability.toLocalDateTimes(): Set<LocalDateTime> {
-    return schedule.values.flatten().map { slot ->
-        Instant.parse(slot.startDate).atZone(ZoneId.systemDefault()).toLocalDateTime()
-    }.toSet()
 }