refactor kstate, add stub user syncing function

matrix/kstate.js

@@ -0,0 +1,65 @@
+// @ts-check
+
+const assert = require("assert")
+
+/** Mutates the input. */
+function kstateStripConditionals(kstate) {
+	for (const [k, content] of Object.entries(kstate)) {
+		// conditional for whether a key is even part of the kstate (doing this declaratively on json is hard, so represent it as a property instead.)
+		if ("$if" in content) {
+			if (content.$if) delete content.$if
+			else delete kstate[k]
+		}
+	}
+	return kstate
+}
+
+function kstateToState(kstate) {
+	const events = []
+	kstateStripConditionals(kstate)
+	for (const [k, content] of Object.entries(kstate)) {
+		const [type, state_key] = k.split("/")
+		assert.ok(typeof type === "string")
+		assert.ok(typeof state_key === "string")
+		events.push({type, state_key, content})
+	}
+	return events
+}
+
+/**
+ * @param {import("../types").Event.BaseStateEvent[]} events
+ * @returns {any}
+ */
+function stateToKState(events) {
+	const kstate = {}
+	for (const event of events) {
+		kstate[event.type + "/" + event.state_key] = event.content
+	}
+	return kstate
+}
+
+function diffKState(actual, target) {
+	const diff = {}
+	// go through each key that it should have
+	for (const key of Object.keys(target)) {
+		if (key in actual) {
+			// diff
+			try {
+				assert.deepEqual(actual[key], target[key])
+			} catch (e) {
+				// they differ. reassign the target
+				diff[key] = target[key]
+			}
+		} else {
+			// not present, needs to be added
+			diff[key] = target[key]
+		}
+		// keys that are missing in "actual" will not be deleted on "target" (no action)
+	}
+	return diff
+}
+
+module.exports.kstateStripConditionals = kstateStripConditionals
+module.exports.kstateToState = kstateToState
+module.exports.stateToKState = stateToKState
+module.exports.diffKState = diffKState

matrix/kstate.test.js

@@ -0,0 +1,94 @@
+const {kstateToState, stateToKState, diffKState, kstateStripConditionals} = require("./kstate")
+const {test} = require("supertape")
+
+test("kstate strip: strips false conditions", t => {
+   t.deepEqual(kstateStripConditionals({
+      a: {$if: false, value: 2},
+      b: {value: 4}
+   }), {
+      b: {value: 4}
+   })
+})
+
+test("kstate strip: keeps true conditions while removing $if", t => {
+   t.deepEqual(kstateStripConditionals({
+      a: {$if: true, value: 2},
+      b: {value: 4}
+   }), {
+      a: {value: 2},
+      b: {value: 4}
+   })
+})
+
+test("kstate2state: general", t => {
+	t.deepEqual(kstateToState({
+		"m.room.name/": {name: "test name"},
+		"m.room.member/@cadence:cadence.moe": {membership: "join"}
+	}), [
+		{
+			type: "m.room.name",
+			state_key: "",
+			content: {
+				name: "test name"
+			}
+		},
+		{
+			type: "m.room.member",
+			state_key: "@cadence:cadence.moe",
+			content: {
+				membership: "join"
+			}
+		}
+	])
+})
+
+test("state2kstate: general", t => {
+	t.deepEqual(stateToKState([
+		{
+			type: "m.room.name",
+			state_key: "",
+			content: {
+				name: "test name"
+			}
+		},
+		{
+			type: "m.room.member",
+			state_key: "@cadence:cadence.moe",
+			content: {
+				membership: "join"
+			}
+		}
+	]), {
+		"m.room.name/": {name: "test name"},
+		"m.room.member/@cadence:cadence.moe": {membership: "join"}
+	})
+})
+
+test("diffKState: detects edits", t => {
+	t.deepEqual(
+		diffKState({
+			"m.room.name/": {name: "test name"},
+			"same/": {a: 2}
+		}, {
+			"m.room.name/": {name: "edited name"},
+			"same/": {a: 2}
+		}),
+		{
+			"m.room.name/": {name: "edited name"}
+		}
+	)
+})
+
+test("diffKState: detects new properties", t => {
+	t.deepEqual(
+		diffKState({
+			"m.room.name/": {name: "test name"},
+		}, {
+			"m.room.name/": {name: "test name"},
+			"new/": {a: 2}
+		}),
+		{
+			"new/": {a: 2}
+		}
+	)
+})