feat(state): support full export and preferences restoration

src/client/state/export.ts

@@ -0,0 +1,121 @@
+import type { CustomEvents, CustomGames } from "../../shared/custom.ts";
+import type { DailyLogMap } from "./useDailyLog.ts";
+import type { Prefs } from "./usePrefs.ts";
+import type { ProgressMap } from "./useProgress.ts";
+
+export interface ExportData {
+  format: "gacha-tracker-export";
+  version: 1;
+  exportedAt: string;
+  progress: Record<string, unknown>;
+  daily: DailyLogMap;
+  ignored: Record<string, { at: string }>;
+  customGames: CustomGames;
+  customEvents: CustomEvents;
+  prefs?: Prefs | undefined;
+}
+
+export interface ParsedImport {
+  progress: ProgressMap | null;
+  daily: DailyLogMap | null;
+  ignored: Record<string, { at: string }> | null;
+  customGames: unknown;
+  customEvents: unknown;
+  prefs: unknown | null;
+}
+
+/**
+ * Builds the serializable JSON export object.
+ * When `prefs` is provided, includes preferences for moving hosts ("Export all").
+ * When omitted, exports progress and custom data only ("Export").
+ */
+export function buildExportData(
+  progress: Record<string, unknown>,
+  daily: DailyLogMap,
+  ignored: Record<string, { at: string }>,
+  own: { games: CustomGames; events: CustomEvents },
+  prefs?: Prefs | undefined,
+): ExportData {
+  return {
+    format: "gacha-tracker-export",
+    version: 1,
+    exportedAt: new Date().toISOString(),
+    progress,
+    daily,
+    ignored,
+    customGames: own.games,
+    customEvents: own.events,
+    ...(prefs !== undefined ? { prefs } : {}),
+  };
+}
+
+/**
+ * Validates and parses raw JSON from an import file.
+ * Returns null if the file is not a valid Event Clock export.
+ */
+export function parseImportData(parsed: unknown): ParsedImport | null {
+  if (typeof parsed !== "object" || parsed === null) return null;
+  const data = parsed as {
+    format?: string;
+    progress?: unknown;
+    completions?: unknown;
+    daily?: unknown;
+    ignored?: unknown;
+    customGames?: unknown;
+    customEvents?: unknown;
+    prefs?: unknown;
+  };
+  if (data.format !== "gacha-tracker-export") return null;
+
+  const asRecord = (v: unknown) =>
+    typeof v === "object" && v !== null
+      ? (v as Record<string, unknown>)
+      : null;
+  const asMarks = (v: unknown) =>
+    typeof v === "object" && v !== null
+      ? (v as Record<string, { at: string }>)
+      : null;
+
+  let progress: ProgressMap | null = asRecord(data.progress) as ProgressMap | null;
+  const legacy = asRecord(data.completions) as Record<string, { at: string }> | null;
+  if (progress === null && legacy !== null) {
+    progress = Object.fromEntries(
+      Object.entries(legacy).map(([id, m]) => [id, { ...m, status: "done" }]),
+    );
+  }
+
+  const daily =
+    typeof data.daily === "object" && data.daily !== null
+      ? (data.daily as DailyLogMap)
+      : null;
+  const ignored = asMarks(data.ignored);
+  const prefs =
+    typeof data.prefs === "object" && data.prefs !== null ? data.prefs : null;
+
+  return {
+    progress,
+    daily,
+    ignored,
+    customGames: data.customGames,
+    customEvents: data.customEvents,
+    prefs,
+  };
+}
+
+/**
+ * Initiates a browser download of a JSON object as a file.
+ */
+export function triggerDownload(data: unknown, filename: string): void {
+  const blob = new Blob([JSON.stringify(data, null, 2)], {
+    type: "application/json",
+  });
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement("a");
+  a.href = url;
+  a.download = filename;
+  a.style.display = "none";
+  document.body.append(a);
+  a.click();
+  a.remove();
+  setTimeout(() => URL.revokeObjectURL(url), 0);
+}