store iid in application data directory

src/app.zig

@@ -4,6 +4,8 @@ const Loop = @import("jsruntime").Loop;
 const Allocator = std.mem.Allocator;
 const Telemetry = @import("telemetry/telemetry.zig").Telemetry;
 
+const log = std.log.scoped(.app);
+
 pub const RunMode = enum {
     serve,
     fetch,
@@ -13,6 +15,7 @@ pub const RunMode = enum {
 // might need.
 pub const App = struct {
     loop: *Loop,
+    app_dir_path: ?[]const u8,
     allocator: Allocator,
     telemetry: Telemetry,
 
@@ -23,19 +26,42 @@ pub const App = struct {
         loop.* = try Loop.init(allocator);
         errdefer loop.deinit();
 
-        const telemetry = Telemetry.init(allocator, run_mode);
+        const app_dir_path = getAndMakeAppDir(allocator);
+        const telemetry = Telemetry.init(allocator, run_mode, app_dir_path);
         errdefer telemetry.deinit();
 
         return .{
             .loop = loop,
             .allocator = allocator,
             .telemetry = telemetry,
+            .app_dir_path = app_dir_path,
         };
     }
 
     pub fn deinit(self: *App) void {
+        if (self.app_dir_path) |app_dir_path| {
+            self.allocator.free(app_dir_path);
+        }
+
         self.telemetry.deinit();
         self.loop.deinit();
         self.allocator.destroy(self.loop);
     }
 };
+
+fn getAndMakeAppDir(allocator: Allocator) ?[]const u8 {
+    const app_dir_path = std.fs.getAppDataDir(allocator, "lightpanda") catch |err| {
+        log.warn("failed to get lightpanda data dir: {}", .{err});
+        return null;
+    };
+
+    std.fs.makeDirAbsolute(app_dir_path) catch |err| switch (err) {
+        error.PathAlreadyExists => return app_dir_path,
+        else => {
+            allocator.free(app_dir_path);
+            log.warn("failed to create lightpanda data dir: {}", .{err});
+            return null;
+        }
+    };
+    return app_dir_path;
+}