feat(runtime): stabilise permissions and add event target capabilities (#9573)

2 files changed, 139 insertions, 18 deletions

diff --git a/runtime/js/40_permissions.js b/runtime/js/40_permissions.js
index 2b4acb595..d7ed5a433 100644
--- a/runtime/js/40_permissions.js
+++ b/runtime/js/40_permissions.js
@@ -2,57 +2,178 @@
 "use strict";
 
 ((window) => {
-  const core = window.Deno.core;
-  const { illegalConstructorKey } = window.__bootstrap.webUtil;
+  const {
+    Event,
+    EventTarget,
+    Deno: { core },
+    __bootstrap: { webUtil: { illegalConstructorKey } },
+  } = window;
 
+  /**
+   * @typedef StatusCacheValue
+   * @property {PermissionState} state
+   * @property {PermissionStatus} status
+   */
+
+  /** @type {ReadonlyArray<"read" | "write" | "net" | "env" | "run" | "plugin" | "hrtime">} */
+  const permissionNames = [
+    "read",
+    "write",
+    "net",
+    "env",
+    "run",
+    "plugin",
+    "hrtime",
+  ];
+
+  /**
+   * @param {Deno.PermissionDescriptor} desc 
+   * @returns {Deno.PermissionState}
+   */
   function opQuery(desc) {
     return core.jsonOpSync("op_query_permission", desc).state;
   }
 
+  /**
+   * @param {Deno.PermissionDescriptor} desc 
+   * @returns {Deno.PermissionState}
+   */
   function opRevoke(desc) {
     return core.jsonOpSync("op_revoke_permission", desc).state;
   }
 
+  /**
+   * @param {Deno.PermissionDescriptor} desc 
+   * @returns {Deno.PermissionState}
+   */
   function opRequest(desc) {
     return core.jsonOpSync("op_request_permission", desc).state;
   }
 
-  class PermissionStatus {
+  class PermissionStatus extends EventTarget {
+    /** @type {{ state: Deno.PermissionState }} */
+    #state;
+
+    /** @type {((this: PermissionStatus, event: Event) => any) | null} */
+    onchange = null;
+
+    /** @returns {Deno.PermissionState} */
+    get state() {
+      return this.#state.state;
+    }
+
+    /**
+     * @param {{ state: Deno.PermissionState }} state 
+     * @param {unknown} key 
+     */
     constructor(state = null, key = null) {
       if (key != illegalConstructorKey) {
         throw new TypeError("Illegal constructor.");
       }
-      this.state = state;
+      super();
+      this.#state = state;
+    }
+
+    /**
+     * @param {Event} event 
+     * @returns {boolean}
+     */
+    dispatchEvent(event) {
+      let dispatched = super.dispatchEvent(event);
+      if (dispatched && this.onchange) {
+        this.onchange.call(this, event);
+        dispatched = !event.defaultPrevented;
+      }
+      return dispatched;
+    }
+
+    [Symbol.for("Deno.customInspect")](inspect) {
+      return `${this.constructor.name} ${
+        inspect({ state: this.state, onchange: this.onchange })
+      }`;
+    }
+  }
+
+  /** @type {Map<string, StatusCacheValue>} */
+  const statusCache = new Map();
+
+  /**
+   * 
+   * @param {Deno.PermissionDescriptor} desc 
+   * @param {Deno.PermissionState} state 
+   * @returns {PermissionStatus}
+   */
+  function cache(desc, state) {
+    let { name: key } = desc;
+    if ((desc.name === "read" || desc.name === "write") && "path" in desc) {
+      key += `-${desc.path}`;
+    } else if (desc.name === "net" && desc.host) {
+      key += `-${desc.host}`;
+    }
+    if (statusCache.has(key)) {
+      const status = statusCache.get(key);
+      if (status.state !== state) {
+        status.state = state;
+        status.status.dispatchEvent(new Event("change", { cancelable: false }));
+      }
+      return status.status;
     }
-    // TODO(kt3k): implement onchange handler
+    /** @type {{ state: Deno.PermissionState; status?: PermissionStatus }} */
+    const status = { state };
+    status.status = new PermissionStatus(status, illegalConstructorKey);
+    statusCache.set(key, status);
+    return status.status;
+  }
+
+  /**
+   * @param {unknown} desc 
+   * @returns {desc is Deno.PermissionDescriptor}
+   */
+  function isValidDescriptor(desc) {
+    return desc && desc !== null && permissionNames.includes(desc.name);
   }
 
   class Permissions {
-    constructor(key) {
+    constructor(key = null) {
       if (key != illegalConstructorKey) {
         throw new TypeError("Illegal constructor.");
       }
     }
 
     query(desc) {
+      if (!isValidDescriptor(desc)) {
+        return Promise.reject(
+          new TypeError(
+            `The provided value "${desc.name}" is not a valid permission name.`,
+          ),
+        );
+      }
       const state = opQuery(desc);
-      return Promise.resolve(
-        new PermissionStatus(state, illegalConstructorKey),
-      );
+      return Promise.resolve(cache(desc, state));
     }
 
     revoke(desc) {
+      if (!isValidDescriptor(desc)) {
+        return Promise.reject(
+          new TypeError(
+            `The provided value "${desc.name}" is not a valid permission name.`,
+          ),
+        );
+      }
       const state = opRevoke(desc);
-      return Promise.resolve(
-        new PermissionStatus(state, illegalConstructorKey),
-      );
+      return Promise.resolve(cache(desc, state));
     }
 
     request(desc) {
+      if (!isValidDescriptor(desc)) {
+        return Promise.reject(
+          new TypeError(
+            `The provided value "${desc.name}" is not a valid permission name.`,
+          ),
+        );
+      }
       const state = opRequest(desc);
-      return Promise.resolve(
-        new PermissionStatus(state, illegalConstructorKey),
-      );
+      return Promise.resolve(cache(desc, state));
     }
   }
 
diff --git a/runtime/js/90_deno_ns.js b/runtime/js/90_deno_ns.js
index 84c084062..84c6b7ade 100644
--- a/runtime/js/90_deno_ns.js
+++ b/runtime/js/90_deno_ns.js
@@ -88,6 +88,9 @@
     fsync: __bootstrap.fs.fsync,
     fdatasyncSync: __bootstrap.fs.fdatasyncSync,
     fdatasync: __bootstrap.fs.fdatasync,
+    permissions: __bootstrap.permissions.permissions,
+    Permissions: __bootstrap.permissions.Permissions,
+    PermissionStatus: __bootstrap.permissions.PermissionStatus,
   };
 
   __bootstrap.denoNsUnstable = {
@@ -96,9 +99,6 @@
     Signal: __bootstrap.signals.Signal,
     SignalStream: __bootstrap.signals.SignalStream,
     emit: __bootstrap.compilerApi.emit,
-    permissions: __bootstrap.permissions.permissions,
-    Permissions: __bootstrap.permissions.Permissions,
-    PermissionStatus: __bootstrap.permissions.PermissionStatus,
     openPlugin: __bootstrap.plugins.openPlugin,
     kill: __bootstrap.process.kill,
     setRaw: __bootstrap.tty.setRaw,