import { assert, describe, it } from "@effect/vitest";
import {
  AuthSessionId,
  RpcClientId,
  type HostPowerSnapshot,
  type ClientActivityReportInput,
} from "@t3tools/contracts";
import * as DateTime from "effect/DateTime";
import * as Effect from "effect/Effect";
import * as Layer from "effect/Layer";
import * as PubSub from "effect/PubSub";
import * as Stream from "effect/Stream";

import { ServerSettingsService } from "../serverSettings.ts";
import * as BackgroundPolicy from "./BackgroundPolicy.ts";
import * as HostPowerMonitor from "./HostPowerMonitor.ts";

const TEST_NOW = DateTime.makeUnsafe("2026-05-13T00:00:00.000Z");

const nominalHostPower: HostPowerSnapshot = {
  source: "unknown",
  idle: "unknown",
  idleSeconds: null,
  locked: "unknown",
  suspended: false,
  onBattery: "unknown",
  lowPowerMode: "unknown",
  thermalState: "unknown",
  stale: true,
  updatedAt: TEST_NOW,
};

const constrainedHostPower: HostPowerSnapshot = {
  ...nominalHostPower,
  lowPowerMode: "true",
  stale: false,
};

function makeReport(overrides: Partial<ClientActivityReportInput> = {}): ClientActivityReportInput {
  return {
    clientId: "client-1",
    clientKind: "web",
    visible: true,
    focused: true,
    recentlyInteracted: true,
    scopes: [{ type: "vcs-status", cwd: "/repo" }],
    ttlMs: 45_000,
    observedAt: TEST_NOW,
    ...overrides,
  };
}

function makeLayer(
  hostPower: HostPowerSnapshot,
  settingsOverrides: Parameters<typeof ServerSettingsService.layerTest>[0] = {},
) {
  const hostLayer = Layer.effect(
    HostPowerMonitor.HostPowerMonitor,
    Effect.gen(function* () {
      const changes = yield* PubSub.sliding<HostPowerSnapshot>(1);
      let snapshot = hostPower;
      return HostPowerMonitor.HostPowerMonitor.of({
        snapshot: Effect.sync(() => snapshot),
        report: (next) =>
          Effect.sync(() => {
            snapshot = next;
          }).pipe(Effect.andThen(PubSub.publish(changes, next)), Effect.asVoid),
        setDemandActive: () => Effect.void,
        streamChanges: Stream.fromPubSub(changes),
      });
    }),
  );
  return BackgroundPolicy.layer.pipe(
    Layer.provide(Layer.merge(hostLayer, ServerSettingsService.layerTest(settingsOverrides))),
  );
}

describe("BackgroundPolicy", () => {
  it.effect("records foreground scoped client demand", () =>
    Effect.gen(function* () {
      const policy = yield* BackgroundPolicy.BackgroundPolicy;
      yield* policy.reportClientActivity(
        AuthSessionId.make("session-1"),
        RpcClientId.make(1),
        makeReport(),
      );

      const snapshot = yield* policy.snapshot;
      assert.equal(snapshot.activeForegroundLeaseCount, 1);
      assert.deepStrictEqual(snapshot.activeScopeKeys, ["vcs-status:/repo"]);
      assert.equal(snapshot.shouldRunOpportunisticWork, true);
      assert.equal(yield* policy.hasDemand({ type: "vcs-status", cwd: "/repo" }), true);
      assert.equal(yield* policy.hasDemand({ type: "vcs-status", cwd: "/other" }), false);
      assert.equal(yield* policy.shouldRunScopeWork({ type: "vcs-status", cwd: "/repo" }), true);
      assert.equal(yield* policy.shouldRunScopeWork({ type: "vcs-status", cwd: "/other" }), false);
    }).pipe(Effect.provide(makeLayer(nominalHostPower))),
  );

  it.effect("removes all leases for a disconnected websocket connection", () =>
    Effect.gen(function* () {
      const policy = yield* BackgroundPolicy.BackgroundPolicy;
      yield* policy.reportClientActivity(
        AuthSessionId.make("session-1"),
        RpcClientId.make(1),
        makeReport(),
      );
      yield* policy.removeRpcClient(RpcClientId.make(1));

      const snapshot = yield* policy.snapshot;
      assert.equal(snapshot.activeForegroundLeaseCount, 0);
      assert.deepStrictEqual(snapshot.activeScopeKeys, []);
      assert.equal(snapshot.shouldRunOpportunisticWork, false);
    }).pipe(Effect.provide(makeLayer(nominalHostPower))),
  );

  it.effect("host low power mode disables opportunistic work without dropping scoped demand", () =>
    Effect.gen(function* () {
      const policy = yield* BackgroundPolicy.BackgroundPolicy;
      yield* policy.reportClientActivity(
        AuthSessionId.make("session-1"),
        RpcClientId.make(1),
        makeReport(),
      );

      const snapshot = yield* policy.snapshot;
      assert.equal(snapshot.activeForegroundLeaseCount, 1);
      assert.deepStrictEqual(snapshot.activeScopeKeys, ["vcs-status:/repo"]);
      assert.equal(snapshot.shouldRunOpportunisticWork, false);
      assert.equal(yield* policy.hasDemand({ type: "vcs-status", cwd: "/repo" }), true);
      assert.equal(yield* policy.shouldRunScopeWork({ type: "vcs-status", cwd: "/repo" }), false);
    }).pipe(Effect.provide(makeLayer(constrainedHostPower))),
  );

  it.effect("keeps background demand visible while preventing scoped work", () =>
    Effect.gen(function* () {
      const policy = yield* BackgroundPolicy.BackgroundPolicy;
      yield* policy.reportClientActivity(
        AuthSessionId.make("session-1"),
        RpcClientId.make(1),
        makeReport({ focused: false, visible: false }),
      );

      const snapshot = yield* policy.snapshot;
      assert.equal(snapshot.activeForegroundLeaseCount, 0);
      assert.deepStrictEqual(snapshot.activeScopeKeys, ["vcs-status:/repo"]);
      assert.equal(yield* policy.hasDemand({ type: "vcs-status", cwd: "/repo" }), true);
      assert.equal(yield* policy.shouldRunScopeWork({ type: "vcs-status", cwd: "/repo" }), false);
    }).pipe(Effect.provide(makeLayer(nominalHostPower))),
  );

  it.effect(
    "performance profile allows background scoped work while a scoped lease is active",
    () =>
      Effect.gen(function* () {
        const policy = yield* BackgroundPolicy.BackgroundPolicy;
        yield* policy.reportClientActivity(
          AuthSessionId.make("session-1"),
          RpcClientId.make(1),
          makeReport({ focused: false, visible: false }),
        );

        assert.equal(yield* policy.shouldRunScopeWork({ type: "vcs-status", cwd: "/repo" }), true);
      }).pipe(
        Effect.provide(makeLayer(nominalHostPower, { backgroundActivityProfile: "performance" })),
      ),
  );

  it.effect("battery saver profile pauses scoped work on battery", () =>
    Effect.gen(function* () {
      const policy = yield* BackgroundPolicy.BackgroundPolicy;
      yield* policy.reportClientActivity(
        AuthSessionId.make("session-1"),
        RpcClientId.make(1),
        makeReport(),
      );

      assert.equal(yield* policy.shouldRunScopeWork({ type: "vcs-status", cwd: "/repo" }), false);
    }).pipe(
      Effect.provide(
        makeLayer(
          {
            ...nominalHostPower,
            onBattery: "true",
            stale: false,
          },
          { backgroundActivityProfile: "battery-saver" },
        ),
      ),
    ),
  );
});