import { describe, it, expect, beforeEach, afterEach } from "vitest";
import * as fs from "node:fs";
import * as path from "node:path";
import * as os from "node:os";
import { FlatLedger, setLedgerDir } from "./flat-ledger.js";

describe("flat ledger", () => {
  const testDir = path.join(os.tmpdir(), "fable-ledger-test");

  beforeEach(() => {
    fs.mkdirSync(testDir, { recursive: true });
    setLedgerDir(testDir);
  });

  afterEach(() => {
    fs.rmSync(testDir, { recursive: true, force: true });
  });

  it("writes and reads entries", () => {
    const ledger = new FlatLedger("test-session");
    const entry = ledger.append({
      timestamp: new Date().toISOString(),
      agent: "test-agent",
      action: "build",
      target: "src/main.ts",
      result: "ok",
      durationMs: 100,
    });
    expect(entry.step).toBe(1);
    expect(entry.result).toBe("ok");

    const state = ledger.readState();
    expect(state.length).toBe(1);
    expect(state[0].step).toBe(1);
  });

  it("returns last step", () => {
    const ledger = new FlatLedger("test-session");
    expect(ledger.lastStep()).toBeNull();

    ledger.append({ timestamp: new Date().toISOString(), agent: "a", action: "build", target: "x", result: "ok", durationMs: 10 });
    ledger.append({ timestamp: new Date().toISOString(), agent: "a", action: "test", target: "x", result: "fail", durationMs: 20 });

    const last = ledger.lastStep();
    expect(last?.step).toBe(2);
    expect(last?.result).toBe("fail");
    expect(ledger.lastActionResult()).toBe("fail");
  });

  it("produces summary", () => {
    const ledger = new FlatLedger("test-session");
    ledger.append({ timestamp: "t1", agent: "a", action: "b", target: "t", result: "ok", durationMs: 1 });
    ledger.append({ timestamp: "t2", agent: "a", action: "b", target: "t", result: "ok", durationMs: 1 });
    ledger.append({ timestamp: "t3", agent: "a", action: "b", target: "t", result: "fail", durationMs: 1 });
    ledger.append({ timestamp: "t4", agent: "a", action: "b", target: "t", result: "skip", durationMs: 1 });

    const summary = ledger.summary();
    expect(summary).toContain("4 steps");
    expect(summary).toContain("2 ok");
    expect(summary).toContain("1 fail");
    expect(summary).toContain("1 skip");
  });

  it("clear resets state", () => {
    const ledger = new FlatLedger("test-session");
    ledger.append({ timestamp: "t1", agent: "a", action: "b", target: "t", result: "ok", durationMs: 1 });
    expect(ledger.readState().length).toBe(1);
    ledger.clear();
    expect(ledger.readState().length).toBe(0);
  });

  it("sessionNameFromTask generates safe names", () => {
    const name = FlatLedger.sessionNameFromTask("Fix: broken auth on /api/v2/users");
    expect(name).toBe("fix-broken-auth-on-api-v2-users");
    expect(name.length).toBeLessThanOrEqual(40);
  });
});