import assert from "node:assert/strict";
import test from "node:test";

import {
  CONSULTATION_HISTORY_MESSAGE_CHARS,
  clipConsultationHistoryText,
  consultationHistoryFromStoredMessages,
  consultationHistoryWindow,
  consultationUserTurnContent,
  historyBudgetChars,
  isContextOverflowError,
  omissionMarker,
  SESSION_CONTEXT_SUMMARY_HEADING,
} from "../src/lib/consultation-session-history.ts";

function numberedMessages(count: number, text: (index: number) => string) {
  return Array.from({ length: count }, (_, index) => ({
    role: index % 2 === 0 ? "user" : "assistant",
    text: text(index),
    requestId: `req-${index}`,
  }));
}

test("20 unspecialized messages at 128k drop whole oldest turns to fit the budget", () => {
  const body = "x".repeat(3_000);
  const history = consultationHistoryWindow(numberedMessages(20, () => body), null, {
    contextWindow: 128_000,
  });
  const budget = historyBudgetChars(128_000);
  assert.equal(budget, 40_000);
  assert.ok(history.droppedCount > 0);
  assert.equal(history.tail.length, 20 - history.droppedCount);
  assert.equal(history.tail[0]?.text, body);
  assert.ok(history.tail.reduce((sum, message) => sum + message.text.length, 0) <= budget);
  assert.equal(history.summaryText, null);
});

test("a summary throughMessageIndex keeps only later turns in the tail", () => {
  const messages = numberedMessages(20, (index) => `keep-${index}`);
  const history = consultationHistoryWindow(messages, {
    version: 1,
    text: "先前结论",
    throughRequestId: "req-14",
    throughMessageIndex: 14,
    messageCount: 15,
    updatedAt: "2026-09-06T00:00:00.000Z",
  }, { contextWindow: 128_000 });

  assert.deepEqual(history.tail.map((message) => message.text), [
    "keep-15",
    "keep-16",
    "keep-17",
    "keep-18",
    "keep-19",
  ]);
  assert.equal(history.summaryText, "先前结论");
  assert.equal(history.droppedCount, 0);
});

test("a 20_000 character message is clipped to 12_000 with an omission count", () => {
  const text = "y".repeat(20_000);
  const clipped = clipConsultationHistoryText(text);
  assert.equal(clipped.startsWith("y".repeat(CONSULTATION_HISTORY_MESSAGE_CHARS)), true);
  assert.equal(clipped.includes(omissionMarker(8_000)), true);
  assert.equal(clipped.length, CONSULTATION_HISTORY_MESSAGE_CHARS + omissionMarker(8_000).length);

  const history = consultationHistoryWindow([
    { role: "assistant", text },
  ], null, { contextWindow: 128_000 });
  assert.equal(history.tail[0]?.text, clipped);
});

test("historyBudgetChars uses 64k, 32k, and null-as-128k windows", () => {
  assert.equal(historyBudgetChars(64_000), 6_000);
  assert.equal(historyBudgetChars(32_000), 4_000);
  assert.equal(historyBudgetChars(null), historyBudgetChars(128_000));
  assert.equal(historyBudgetChars(undefined), 40_000);
});

test("stored consultation history can skip the in-flight request id", () => {
  const history = consultationHistoryFromStoredMessages([
    { role: "user", text: "old", requestId: "keep" },
    { role: "user", text: "current", requestId: "skip" },
  ], { excludeRequestId: "skip" });

  assert.deepEqual(history, [{ role: "user", text: "old" }]);
});

test("the summary block sits after the time line and before the question", () => {
  const content = consultationUserTurnContent({
    currentTime: "当前时间：2026-09-06 14:00（中国）",
    name: "测",
    instruction: "先加载 Jyotish Skill",
    summaryText: "上次应期在 2027 年",
    question: "你前面说的应期是哪年",
  });
  const timeAt = content.indexOf("当前时间：");
  const summaryAt = content.indexOf(SESSION_CONTEXT_SUMMARY_HEADING);
  const questionAt = content.indexOf("你前面说的应期是哪年");
  assert.ok(timeAt >= 0 && summaryAt > timeAt && questionAt > summaryAt);
});

test("context overflow detection covers provider codes and related 400s", () => {
  assert.equal(isContextOverflowError({ code: "context_length_exceeded" }), true);
  assert.equal(isContextOverflowError(new Error("maximum context length exceeded")), true);
  assert.equal(isContextOverflowError({ message: "prompt is too long" }), true);
  assert.equal(isContextOverflowError({ message: "input is too long" }), true);
  assert.equal(isContextOverflowError({ message: "too many tokens in the prompt" }), true);
  assert.equal(isContextOverflowError({ status: 400, message: "max_tokens for this context" }), true);
  assert.equal(isContextOverflowError({ status: 400, message: "invalid json" }), false);
  assert.equal(isContextOverflowError(new Error("rate limit")), false);
});