import test from "node:test";
import assert from "node:assert/strict";
import { buildMessages, RECENT_LIMIT } from "../src/services/ai.js";

function msg(role, i) {
  return { id: String(i), session_id: "s", role, text: `${role}-${i}`, created_at: new Date(i).toISOString() };
}

test("caps message history to the recent window", () => {
  const history = Array.from({ length: RECENT_LIMIT + 5 }, (_, i) => msg(i % 2 ? "assistant" : "user", i));
  const built = buildMessages(history, "Grade 10", "math", "c", "");
  // system + RECENT_LIMIT messages
  assert.equal(built.length, 1 + RECENT_LIMIT);
  assert.equal(built[0].role, "system");
  // the newest message is included
  assert.equal(built[built.length - 1].content, "user-" + (RECENT_LIMIT + 4));
  // the oldest message is dropped
  assert.ok(!built.some((m) => m.content === "user-0"));
});

test("injects the summary into the system prompt when present", () => {
  const history = [msg("user", 0), msg("assistant", 1)];
  const built = buildMessages(history, "Grade 6", "english", "c5", "Student is in Grade 6 English.");
  assert.equal(built[0].role, "system");
  assert.ok(built[0].content.includes("Student is in Grade 6 English."));
  // still includes the messages
  assert.equal(built.length, 3);
});

test("does not inject an empty summary", () => {
  const built = buildMessages([msg("user", 0)], "g", "s", "c", "");
  assert.ok(!built[0].content.includes("Earlier in this conversation:"));
});