import { describe, expect, it } from "vitest";
import { createCompletionTracker } from "../src/lib/completion-notify";
import type { ObservedSession } from "../src/lib/completion-notify";
import type { SessionStatus } from "@prismshadow/penguin-server/api";

const row = (sessionId: string, status: SessionStatus): ObservedSession => ({
  sessionId,
  status,
});

describe("createCompletionTracker", () => {
  it("fires when a known running session goes idle", () => {
    const t = createCompletionTracker();
    expect(t.observe([row("a", "running")], 0)).toEqual([]);
    expect(t.observe([row("a", "idle")], 1000)).toEqual(["a"]);
  });

  it("treats compacting as still active and fires only on the flip to idle", () => {
    const t = createCompletionTracker();
    t.observe([row("a", "running")], 0);
    expect(t.observe([row("a", "compacting")], 100)).toEqual([]);
    expect(t.observe([row("a", "idle")], 200)).toEqual(["a"]);
  });

  it("never fires on first observation, even an idle one after a running list load", () => {
    const t = createCompletionTracker();
    // A list that loads with idle sessions has witnessed nothing.
    expect(t.observe([row("a", "idle"), row("b", "idle")], 0)).toEqual([]);
    expect(t.observe([row("a", "idle"), row("b", "idle")], 100)).toEqual([]);
  });

  it("dedupes per run: repeated idle observations fire once", () => {
    const t = createCompletionTracker();
    t.observe([row("a", "running")], 0);
    expect(t.observe([row("a", "idle")], 1000)).toEqual(["a"]);
    expect(t.observe([row("a", "idle")], 2000)).toEqual([]);
    expect(t.observe([row("a", "idle")], 60_000)).toEqual([]);
  });

  it("fires again for a genuinely new run after the cooldown", () => {
    const t = createCompletionTracker(10_000);
    t.observe([row("a", "running")], 0);
    expect(t.observe([row("a", "idle")], 1000)).toEqual(["a"]);
    t.observe([row("a", "running")], 20_000);
    expect(t.observe([row("a", "idle")], 30_000)).toEqual(["a"]);
  });

  it("suppresses a stale-snapshot flap within the cooldown window", () => {
    const t = createCompletionTracker(10_000);
    t.observe([row("a", "running")], 0);
    expect(t.observe([row("a", "idle")], 1000)).toEqual(["a"]);
    // A stale reload snapshot resurrects "running", then the fresh state lands again:
    // the same finish must not notify twice.
    t.observe([row("a", "running")], 1100);
    expect(t.observe([row("a", "idle")], 1200)).toEqual([]);
  });

  it("tracks sessions independently and reports multiple completions", () => {
    const t = createCompletionTracker();
    t.observe([row("a", "running"), row("b", "running"), row("c", "idle")], 0);
    expect(t.observe([row("a", "idle"), row("b", "idle"), row("c", "idle")], 1000)).toEqual([
      "a",
      "b",
    ]);
  });

  it("prunes sessions that leave the list: reappearing is a fresh first observation", () => {
    const t = createCompletionTracker();
    t.observe([row("a", "running")], 0);
    // Project switch empties the list; the session's state is dropped.
    t.observe([], 100);
    expect(t.observe([row("a", "idle")], 200)).toEqual([]);
  });

  it("ignores duplicate ids within one observation (first occurrence wins)", () => {
    const t = createCompletionTracker();
    t.observe([row("a", "running")], 0);
    expect(t.observe([row("a", "idle"), row("a", "running")], 1000)).toEqual(["a"]);
    // The duplicate "running" row did not restart the run.
    expect(t.observe([row("a", "idle")], 60_000)).toEqual([]);
  });
});