feat(groups): Show Group Card on every invite link, and the host Invite sheet

apps/flipcash/core/src/androidHostTest/kotlin/com/flipcash/app/core/route/GroupCardRouteTest.kt

@@ -0,0 +1,38 @@
+package com.flipcash.app.core.route
+
+import com.flipcash.app.core.AppRoute
+import com.flipcash.services.models.chat.ChatId
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.jsonObject
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+
+/**
+ * The group card's route is saved with the back stack, and an invite link's fragment is the chat
+ * key's secret, so the link must reach the card some other way (spec group-invites.md surface 1).
+ */
+class GroupCardRouteTest {
+    private val route = AppRoute.Menu.GroupCard(
+        chatId = ChatId("aa"),
+        title = "Moony",
+        picture = null,
+        memberCount = 48,
+    )
+
+    @Test
+    fun `the saved route has no field a link could ride in`() {
+        val saved = Json.encodeToString(AppRoute.Menu.GroupCard.serializer(), route)
+
+        assertEquals(setOf("chatId", "title", "picture", "memberCount"), Json.parseToJsonElement(saved).jsonObject.keys)
+    }
+
+    @Test
+    fun `the saved route holds no link`() {
+        val saved = Json.encodeToString(AppRoute.serializer(), route)
+
+        assertFalse("http" in saved)
+        assertFalse("#s=" in saved)
+        assertFalse("flipcash.com" in saved)
+    }
+}

apps/flipcash/core/src/androidHostTest/kotlin/com/flipcash/app/core/share/groupcard/GroupCardQrTest.kt

@@ -52,6 +52,17 @@ class GroupCardQrTest {
         assertEquals(caseOneUrl, decode(bitmap))
     }
 
+    // 32 random bytes as unpadded base64url: the longest link a card encodes (spec Open 5).
+    private val inviteUrl = "https://app.flipcash.com/chat/invite#s=kQ3vR8nYw2pLx7TzA0bC9dEfGhIjKlMnOpQrStUxT9a"
+
+    @Test
+    fun `3b - an invite link fits version 6 and the styled qr with its logo decodes to it`() {
+        assertEquals(82, inviteUrl.length)
+        val matrix = QrMatrix.encodeGroupCard(inviteUrl)
+        assertEquals(41, matrix.size)
+        assertEquals(inviteUrl, decode(StyledQrBitmap.render(matrix)))
+    }
+
     @Test
     fun `4 - the qr is error correction Q, version 6, 41 modules`() {
         // encodeGroupCard checks level and version itself; this proves it ran and the size is 41.

apps/flipcash/core/src/androidMain/kotlin/com/flipcash/app/core/share/groupcard/QrMatrix.kt

@@ -1,6 +1,7 @@
 package com.flipcash.app.core.share.groupcard
 
 import com.google.zxing.EncodeHintType
+import com.google.zxing.WriterException
 import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel
 import com.google.zxing.qrcode.encoder.Encoder
 
@@ -15,28 +16,36 @@ class QrMatrix(val size: Int, private val bits: BooleanArray) {
         x in 0 until size && y in 0 until size && bits[y * size + x]
 
     companion object {
-        /** Version 6 is 41 modules: the smallest that holds the 66-byte invite URL at Q. */
+        /** Version 6 is 41 modules: the smallest that holds the 66-byte plain group URL at Q. */
         const val GroupCardVersion = 6
         const val GroupCardModules = 41
 
         /**
-         * [text] as a byte-mode, error-correction-Q, version-6 symbol. Throws when it does not fit
-         * version 6 (ZXing raises a WriterException), rather than silently moving to a version that
-         * puts an alignment pattern under the logo.
+         * [text] as a byte-mode, version-6 symbol: at error correction Q when it fits, otherwise M.
+         * An invite link (`/chat/invite#s=…`, 82 bytes) does not fit version 6 at Q, and every
+         * larger version puts an alignment pattern under the logo, so it drops to M instead.
+         * Throws when [text] does not fit version 6 at M either (ZXing raises a WriterException).
          */
         fun encodeGroupCard(text: String): QrMatrix {
-            val code = Encoder.encode(
-                text,
-                ErrorCorrectionLevel.Q,
-                mapOf(EncodeHintType.QR_VERSION to GroupCardVersion),
-            )
-            check(code.ecLevel == ErrorCorrectionLevel.Q) { "Expected error correction Q, got ${code.ecLevel}" }
+            val code = try {
+                encode(text, ErrorCorrectionLevel.Q)
+            } catch (_: WriterException) {
+                encode(text, ErrorCorrectionLevel.M)
+            }
             check(code.version.versionNumber == GroupCardVersion) { "Expected version 6, got ${code.version.versionNumber}" }
             val m = code.matrix
             check(m.width == GroupCardModules && m.height == GroupCardModules) { "Expected 41 modules, got ${m.width}" }
             val bits = BooleanArray(m.width * m.height)
             for (y in 0 until m.height) for (x in 0 until m.width) bits[y * m.width + x] = m[x, y].toInt() == 1
             return QrMatrix(m.width, bits)
         }
+
+        private fun encode(text: String, level: ErrorCorrectionLevel) = Encoder.encode(
+            text,
+            level,
+            mapOf(EncodeHintType.QR_VERSION to GroupCardVersion),
+        ).also { code ->
+            check(code.ecLevel == level) { "Expected error correction $level, got ${code.ecLevel}" }
+        }
     }
 }

apps/flipcash/core/src/androidMain/res/values/strings.xml

@@ -1583,12 +1583,16 @@
     <!-- %1$s is the group title. -->
     <string name="title_inviteToGroup">Invite to %1$s</string>
     <string name="action_shareInviteLinkLong">Share Invite Link</string>
-    <string name="subtitle_shareInviteLink">Anyone with this link joins right away</string>
-    <string name="action_shareJoinLink">Share Join Link</string>
-    <string name="subtitle_shareJoinLink">People ask to join and you approve each one</string>
     <string name="action_manageInvites">Manage Invites</string>
-    <string name="subtitle_manageInvites">See and revoke the invite links you\'ve made</string>
     <string name="label_creatingInviteLink">Creating link…</string>
+    <!-- The host sheet's link card and rows (spec group-invites.md surface 1, frame 1m). -->
+    <!-- The card's caption, joined with " · ": how many joined, then when the link ends. -->
+    <string name="label_inviteJoinedThenEnds">%1$s · %2$s</string>
+    <string name="label_joinLinkAsksToJoin">People who open this link ask to join</string>
+    <string name="label_approveNewMembers">Approve New Members</string>
+    <string name="subtitle_approveNewMembersOff">Anyone with the link joins right away</string>
+    <string name="subtitle_approveNewMembersOn">You approve each person</string>
+    <string name="subtitle_manageInvitesRow">Make more links with an expiry or a use limit</string>
     <string name="action_shareLink">Share Link</string>
     <string name="footnote_inviteLink">Anyone with this link can join and see who\'s in the group. Share it only with people you want in the group</string>
     <!-- A link's lines, joined with " · ". %1$s is a date such as "Nov 3". -->
@@ -1848,10 +1852,14 @@
     <string name="label_profileCardFileNameFallback">Profile Card</string>
     <string name="error_title_tipCardExportFailed">Couldn\'t Export</string>
     <string name="error_description_tipCardExportFailed">We were unable to export your tip code. Please try again</string>
-    <string name="action_showGroupCard">Show Group Card</string>
+    <string name="action_showGroupCard">Show QR Code</string>
     <string name="label_groupCardTitleFallback">Group Chat</string>
     <string name="label_groupCardFileName">Join %1$s</string>
     <string name="label_groupCardFileNameFallback">Group Card</string>
+    <string name="label_groupCardScanToJoin">Scan to join</string>
+    <string name="label_groupCardLinkExpires">Link expires %1$s</string>
+    <string name="label_groupCardLinkNeverExpires">Link never expires</string>
+    <string name="footnote_groupCardInviteLink">Anyone who scans this card joins without approval until the link expires or you revoke it.</string>
     <string name="error_description_groupCardExportFailed">We were unable to export your group code. Please try again</string>
 
     <!-- Bio editor. The count under the field is code points left of 160. -->

apps/flipcash/core/src/commonMain/kotlin/com/flipcash/app/core/AppRoute.kt

@@ -370,7 +370,7 @@ sealed interface AppRoute : NavKey, Parcelable {
 
         /**
          * A group's scan card: its invite link as a QR, full screen, with Download. Opened from the
-         * Show Group Card tile of the group invite sheet, which stays open beneath it. The group's
+         * Show QR Code tile of the group invite sheet, which stays open beneath it. The group's
          * identity rides on the route because the host screen already holds it and the card makes
          * no request of its own.
          */

apps/flipcash/core/src/commonMain/kotlin/com/flipcash/app/core/chat/ChatStep.kt

@@ -34,6 +34,10 @@ data class GroupInviteResult(val chatId: ChatId) : Parcelable
 @Serializable
 enum class InviteLinkAction : Parcelable { Share, Revoke }
 
+/** What the host's Invite sheet (frame 1m) hands back to the screen beneath it to open. */
+@Parcelize
+enum class InviteHostAction : Parcelable { ShareInvite, ShareJoin, ManageInvites }
+
 /**
  * What the host picked on New Invite Link (frame 2d): the preset names, not the presets, because
  * this module cannot see `shared:chat`. Presets only; never a key or link.
@@ -117,6 +121,19 @@ sealed interface ChatStep : FlowStep, Parcelable {
         Sheet,
         com.getcode.navigation.FullscreenSheet
 
+    /**
+     * Frames 1m to 1m″: a host's link card, Approve new members and Manage Invites, from the
+     * profile's share circle and Join Requests' empty state. Carries nothing: the card's link is
+     * the host's own, rebuilt from their invites, and is never on a step.
+     */
+    @Parcelize
+    @Serializable
+    data object InviteHost :
+        ChatStep,
+        NavigationRetVal<InviteHostAction>,
+        Sheet,
+        WrapContentSheet
+
     /**
      * Frame 2b: Share Link and Revoke Link for one invite on Manage Invites. Returns the pick and
      * leaves the work to Manage Invites, which is still on screen beneath it and owns the revoke

apps/flipcash/features/menu/src/main/kotlin/com/flipcash/app/menu/GroupCardScreen.kt

@@ -55,14 +55,17 @@ fun GroupCardScreen(route: AppRoute.Menu.GroupCard) {
         val textSize = with(LocalDensity.current) { (width * TextFraction).toSp() }
         val lineHeight = textSize * LineHeightRatio
 
-        Box(
+        val inviteLink = viewModel.inviteLink
+        Column(
             modifier = cardModifier
                 .align(Alignment.Center)
                 // The avatar's upper half stands outside the card, so the card sits lower by half
                 // of it and the whole group stays centred.
                 .offset(y = avatarSize / 2)
                 .width(width),
+            horizontalAlignment = Alignment.CenterHorizontally,
         ) {
+        Box(modifier = Modifier.fillMaxWidth()) {
             Column(
                 modifier = Modifier
                     .fillMaxWidth()
@@ -94,6 +97,24 @@ fun GroupCardScreen(route: AppRoute.Menu.GroupCard) {
                             .testTag("group-card-qr"),
                     )
                 }
+                // Frame 1j: an invite-link card says it joins without asking, and until when, so a
+                // saved or printed card carries its own expiry.
+                if (inviteLink != null) {
+                    Text(
+                        modifier = Modifier.padding(top = width * QrTopFraction),
+                        text = stringResource(CoreR.string.label_groupCardScanToJoin),
+                        style = CodeTheme.typography.textMedium,
+                        color = CodeTheme.colors.textMain,
+                    )
+                    Text(
+                        modifier = Modifier.padding(top = CodeTheme.dimens.grid.x1),
+                        text = inviteLink.expiresAt
+                            ?.let { stringResource(CoreR.string.label_groupCardLinkExpires, cardDate(it)) }
+                            ?: stringResource(CoreR.string.label_groupCardLinkNeverExpires),
+                        style = CodeTheme.typography.textSmall,
+                        color = CodeTheme.colors.textSecondary,
+                    )
+                }
             }
 
             // A ring in the screen colour keeps the picture from running into the card.
@@ -115,9 +136,27 @@ fun GroupCardScreen(route: AppRoute.Menu.GroupCard) {
                 )
             }
         }
+            if (inviteLink != null) {
+                Text(
+                    modifier = Modifier
+                        .padding(top = CodeTheme.dimens.grid.x4)
+                        .testTag("group-card-invite-footnote"),
+                    text = stringResource(CoreR.string.footnote_groupCardInviteLink),
+                    style = CodeTheme.typography.textSmall,
+                    color = CodeTheme.colors.textSecondary,
+                    textAlign = TextAlign.Center,
+                )
+            }
+        }
     }
 }
 
+/** "Nov 3", as the invite sheet writes a link's dates. */
+private fun cardDate(at: kotlin.time.Instant): String =
+    java.time.format.DateTimeFormatter.ofPattern("MMM d", java.util.Locale.getDefault())
+        .withZone(java.time.ZoneId.systemDefault())
+        .format(java.time.Instant.ofEpochMilli(at.toEpochMilliseconds()))
+
 private const val CardWidthFraction = 0.75f
 
 // The profile card's corner and name proportions (TipCard.kt).

apps/flipcash/features/menu/src/main/kotlin/com/flipcash/app/menu/internal/GroupCardViewModel.kt

@@ -14,6 +14,7 @@ import com.flipcash.app.core.util.Linkify
 import com.flipcash.app.shareable.ShareSheetController
 import com.flipcash.app.shareable.Shareable
 import com.flipcash.features.menu.R
+import com.flipcash.shared.chat.GroupCardLinks
 import com.getcode.manager.BottomBarManager
 import com.getcode.util.resources.ResourceHelper
 import dagger.assisted.Assisted
@@ -23,8 +24,10 @@ import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.launch
 
 /**
- * A group's scan card: the invite link as a QR, exportable as an image. The link is the one
- * [Linkify.groupChatInvite] builds, so what the card encodes is what Share and Copy hand out.
+ * A group's scan card: a link as a QR, exportable as an image. The link is the one the Invite
+ * People sheet beneath was opened for, handed over in memory through [GroupCardLinks] because the
+ * route is saved and an invite link is a key. With nothing handed over (a card restored after
+ * process death) it is the plain link [Linkify.groupChatInvite] builds.
  */
 @HiltViewModel(assistedFactory = GroupCardViewModel.Factory::class)
 internal class GroupCardViewModel @AssistedInject constructor(
@@ -33,10 +36,16 @@ internal class GroupCardViewModel @AssistedInject constructor(
     private val shareable: ShareSheetController,
     private val resources: ResourceHelper,
     private val analytics: FlipcashAnalytics,
+    links: GroupCardLinks,
 ) : ViewModel() {
 
-    /** Null only for an id with no UUID form, which no group has. */
-    val inviteUrl: String? = Linkify.groupChatInvite(group.chatId)
+    private val link: GroupCardLinks.Link? = links.cardLink(group.chatId, Linkify.groupChatInvite(group.chatId))
+
+    /** The invite link this card encodes, for the lines under the QR; null for the plain link. */
+    val inviteLink: GroupCardLinks.Link? = link?.takeIf { it.isInvite }
+
+    /** Null only for a plain link from an id with no UUID form, which no group has. */
+    val inviteUrl: String? = link?.url
 
     /** Null when [inviteUrl] is, or if the link cannot be encoded. */
     val matrix: QrMatrix? = inviteUrl?.let { runCatching { QrMatrix.encodeGroupCard(it) }.getOrNull() }