feat(chat): unlock paid messages before payment

src/lib/navigation/chat_unlock_session.ts

@@ -0,0 +1,109 @@
+"use client";
+
+const STORAGE_KEY = "cozsweet.chat.pendingUnlock";
+const MAX_AGE_MS = 30 * 60 * 1000;
+
+export type PendingChatUnlockKind = "private" | "voice" | "image";
+export type PendingChatUnlockStage = "auth" | "payment";
+
+export interface PendingChatUnlock {
+  reason: "single_message_unlock";
+  messageId: string;
+  kind: PendingChatUnlockKind;
+  returnUrl: string;
+  stage: PendingChatUnlockStage;
+  createdAt: number;
+}
+
+export function savePendingChatUnlock(input: {
+  messageId: string;
+  kind: PendingChatUnlockKind;
+  returnUrl: string;
+  stage: PendingChatUnlockStage;
+}): void {
+  if (typeof window === "undefined") return;
+  const payload: PendingChatUnlock = {
+    reason: "single_message_unlock",
+    messageId: input.messageId,
+    kind: input.kind,
+    returnUrl: input.returnUrl,
+    stage: input.stage,
+    createdAt: Date.now(),
+  };
+  window.sessionStorage.setItem(STORAGE_KEY, JSON.stringify(payload));
+}
+
+export function consumePendingChatUnlock(): PendingChatUnlock | null {
+  if (typeof window === "undefined") return null;
+
+  const raw = window.sessionStorage.getItem(STORAGE_KEY);
+  window.sessionStorage.removeItem(STORAGE_KEY);
+  if (!raw) return null;
+
+  return parsePendingChatUnlock(raw);
+}
+
+export function peekPendingChatUnlock(): PendingChatUnlock | null {
+  if (typeof window === "undefined") return null;
+
+  const raw = window.sessionStorage.getItem(STORAGE_KEY);
+  if (!raw) return null;
+
+  const value = parsePendingChatUnlock(raw);
+  if (!value) {
+    window.sessionStorage.removeItem(STORAGE_KEY);
+  }
+  return value;
+}
+
+export function hasPendingChatUnlock(): boolean {
+  return peekPendingChatUnlock() !== null;
+}
+
+export function clearPendingChatUnlock(): void {
+  if (typeof window === "undefined") return;
+  window.sessionStorage.removeItem(STORAGE_KEY);
+}
+
+function parsePendingChatUnlock(raw: string): PendingChatUnlock | null {
+  try {
+    const value = JSON.parse(raw) as Partial<PendingChatUnlock>;
+    if (value.reason !== "single_message_unlock") return null;
+    if (typeof value.messageId !== "string" || value.messageId.length === 0) {
+      return null;
+    }
+    if (!isPendingChatUnlockKind(value.kind)) return null;
+    if (!isPendingChatUnlockStage(value.stage)) return null;
+    if (typeof value.returnUrl !== "string" || value.returnUrl.length === 0) {
+      return null;
+    }
+    if (!value.returnUrl.startsWith("/") || value.returnUrl.startsWith("//")) {
+      return null;
+    }
+    if (typeof value.createdAt !== "number") return null;
+    if (Date.now() - value.createdAt > MAX_AGE_MS) return null;
+
+    return {
+      reason: value.reason,
+      messageId: value.messageId,
+      kind: value.kind,
+      returnUrl: value.returnUrl,
+      stage: value.stage,
+      createdAt: value.createdAt,
+    };
+  } catch {
+    return null;
+  }
+}
+
+function isPendingChatUnlockKind(
+  value: unknown,
+): value is PendingChatUnlockKind {
+  return value === "private" || value === "voice" || value === "image";
+}
+
+function isPendingChatUnlockStage(
+  value: unknown,
+): value is PendingChatUnlockStage {
+  return value === "auth" || value === "payment";
+}