/* One tutor turn, enforced — with a scripted tutor in place of a model.

   The client refuses what the prompt only asks for: an exercise built from
   a word he has not been given, an explanation written in Korean. A refused
   draft is never returned; the tutor is asked again and told why; after
   GATE_TRIES the reply is shown with its stray words named. */

import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";
import { readFileSync } from "node:fs";
import type { Db } from "@app/db/types.js";
import { GATE_TRIES } from "@lib/gate.js";
import { gateFor, metWords } from "@app/domain/gate.js";
import { noteAnswer, readProgress } from "@app/domain/progress.js";
import { applyReply, readRecent, runTurn, trimHistory } from "@app/domain/turn.js";
import type { Sample, SampleRequest } from "@app/domain/stub-tutor.js";
import { dictionaryDb } from "../helpers/dict-db.js";

const TEMPLATE = readFileSync(new URL("../../prompt/tutor-system.md", import.meta.url), "utf8");
const TODAY = 20_000;

let db: Db;
beforeEach(async () => {
  db = await dictionaryDb(1);
});
afterEach(async () => {
  vi.unstubAllGlobals();
  await db.close();
});

/** A tutor that replies from a script, and remembers what it was sent. */
function scripted(...replies: string[]) {
  const seen: SampleRequest[] = [];
  const sample: Sample = async (req) => {
    seen.push(req);
    return { text: replies[Math.min(seen.length - 1, replies.length - 1)]! };
  };
  return { sample, seen };
}

/* Unit 1.1 on a fresh install: 나무 is its own word; 마셔 belongs to 2.3. */
const CLEAN = "Read these.\n\n::task translate\n나무\n바다\n::";
const STRAY = "Read these.\n\n::task translate\n나무 마셔\n::";
const KOREAN = `${"한글은 소리를 적는 글자예요. ".repeat(4)}\n\n::task translate\n나무\n::`;

async function turn(sample: Sample, onRetry = vi.fn()) {
  const progress = await readProgress(db);
  const gate = gateFor({ progress, met: await metWords(db) });
  const result = await runTurn({
    db,
    sample,
    template: TEMPLATE,
    gate,
    progress,
    focus: "auto",
    recent: [],
    history: [],
    message: "Let's start unit 1.1.",
    strays: [],
    onRetry,
  });
  return { result, onRetry };
}

describe("the gate, enforced", () => {
  it("passes a reply built from allowed words at the first attempt", async () => {
    const { sample, seen } = scripted(CLEAN);
    const { result } = await turn(sample);
    expect(seen).toHaveLength(1);
    expect(result).toMatchObject({ text: CLEAN, findings: [], korean: false, retries: 0 });
  });

  it("refuses a draft with an ungated word, never returns it, and tells the tutor why", async () => {
    const { sample, seen } = scripted(STRAY, CLEAN);
    const { result, onRetry } = await turn(sample);

    expect(result.text).toBe(CLEAN);
    expect(result.retries).toBe(1);
    expect(onRetry).toHaveBeenCalledOnce();
    expect(seen[0]!.systemTail).not.toContain("NOT DELIVERED");
    expect(seen[1]!.systemTail).toContain("THAT MESSAGE WAS NOT DELIVERED");
    expect(seen[1]!.systemTail).toContain("마셔 (belongs to unit 2.3)");
  });

  it("gives up after GATE_TRIES retries and shows the reply with its words named", async () => {
    const { sample, seen } = scripted(STRAY);
    const { result } = await turn(sample);
    expect(seen).toHaveLength(GATE_TRIES + 1);
    expect(result.retries).toBe(GATE_TRIES);
    expect(result.findings.map((f) => f.word)).toEqual(["마셔"]);
  });

  it("sends back an explanation written in Korean", async () => {
    const { sample, seen } = scripted(KOREAN, CLEAN);
    const { result } = await turn(sample);
    expect(result.text).toBe(CLEAN);
    expect(seen[1]!.systemTail).toContain("You wrote your explanation in Korean");
  });

  it("keeps the shipped prompt stable and puts the round in the tail", async () => {
    const { sample, seen } = scripted(STRAY, CLEAN);
    await turn(sample);
    expect(seen[0]!.system).toBe(seen[1]!.system);
    expect(seen[0]!.system).toContain("WHAT HE KNOWS");
    expect(seen[0]!.systemTail).toContain("VOCABULARY DUE — WORK THESE IN");
  });
});

describe("the transcript sent", () => {
  it("keeps the newest turns that fit, and opens with the learner", () => {
    const turns = [
      { role: "assistant" as const, content: "opening" },
      { role: "user" as const, content: "a".repeat(30) },
      { role: "assistant" as const, content: "b".repeat(30) },
    ];
    expect(trimHistory(turns, 1000)[0]).toEqual({ role: "user", content: "Let's continue the lesson." });
    expect(trimHistory(turns, 65).map((t) => t.content)).toEqual(["a".repeat(30), "b".repeat(30)]);
  });
});

describe("an accepted reply", () => {
  it("applies marking, then earned progress, and remembers the exercise type", async () => {
    await noteAnswer(db, await readProgress(db), "My answers:\n나무 → tree\n바다 → sea");
    const reply = [
      "Two for two.",
      "::result",
      "나무 | ok",
      "바다 | wrong | 바지",
      "::",
      "::task recall",
      "tree",
      "::",
      "::progress 95 | good start",
    ].join("\n");
    const { parseMessage } = await import("@app/domain/gloss.js");
    const applied = await applyReply(db, parseMessage(reply), { lookups: [], today: TODAY });

    expect(applied.results?.recorded).toEqual(["나무", "바다"]);
    expect(applied.progress).toMatchObject({ stored: 25, ignored: false, clamped: true });
    expect(await readRecent(db)).toEqual(["recall"]);
    expect((await readProgress(db)).notes["1.1"]).toBe("good start");
  });
});