/**
 * Integration test: Antigravity (AG) prompt caching behavior.
 *
 * Verifies:
 *  1. Same sessionId + repeated long prompt → cache hit (cachedContentTokenCount > 0)
 *  2. Different sessionId (same account) → cache miss
 *  3. Cross-account cache share? (call A warmup → B same prompt/session, check hit)
 *
 * Reads real OAuth refreshToken from ~/.9router/db.json.
 * Enable with: AG_CACHE_TEST=1 npm test
 */

import { describe, it, expect } from "vitest";
import fs from "node:fs";
import os from "node:os";
import path from "node:path";
import crypto from "node:crypto";
import { PROVIDERS } from "../../open-sse/config/providers.js";
import { ANTIGRAVITY_HEADERS, INTERNAL_REQUEST_HEADER } from "../../open-sse/config/appConstants.js";

const ENABLE = process.env.AG_CACHE_TEST === "1";
const DB_PATH = path.join(os.homedir(), ".9router", "db.json");
const OAUTH_TOKEN_URL = "https://oauth2.googleapis.com/token";
const MIN_CACHE_TOKENS = 100; // AG implicit cache threshold observed ~1024-2048
const LONG_TEXT = ("You are a careful assistant. Always follow these rules. ".repeat(300)).trim();

function loadAgConnections() {
  if (!fs.existsSync(DB_PATH)) return [];
  const db = JSON.parse(fs.readFileSync(DB_PATH, "utf8"));
  return (db.providerConnections || []).filter(
    c => c.provider === "antigravity" && c.isActive && c.refreshToken && c.projectId
  );
}

async function refreshAccessToken(refreshToken) {
  const { clientId, clientSecret } = PROVIDERS.antigravity;
  const res = await fetch(OAUTH_TOKEN_URL, {
    method: "POST",
    headers: { "Content-Type": "application/x-www-form-urlencoded" },
    body: new URLSearchParams({
      grant_type: "refresh_token",
      refresh_token: refreshToken,
      client_id: clientId,
      client_secret: clientSecret
    })
  });
  if (!res.ok) throw new Error(`refresh failed ${res.status}`);
  const json = await res.json();
  return json.access_token;
}

async function callAg({ accessToken, projectId, sessionId, longText, userText }) {
  const baseUrl = PROVIDERS.antigravity.baseUrls[0];
  const body = {
    project: projectId,
    model: "gemini-3-flash",
    userAgent: "antigravity",
    requestType: "agent",
    requestId: `agent-${crypto.randomUUID()}`,
    request: {
      systemInstruction: { role: "system", parts: [{ text: longText }] },
      contents: [{ role: "user", parts: [{ text: userText }] }],
      sessionId
    }
  };
  const res = await fetch(`${baseUrl}/v1internal:generateContent`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "Authorization": `Bearer ${accessToken}`,
      "User-Agent": ANTIGRAVITY_HEADERS["User-Agent"],
      [INTERNAL_REQUEST_HEADER.name]: INTERNAL_REQUEST_HEADER.value,
      "X-Machine-Session-Id": sessionId
    },
    body: JSON.stringify(body)
  });
  const json = await res.json();
  const usage = json?.response?.usageMetadata || json?.usageMetadata || {};
  return {
    status: res.status,
    promptTokens: usage.promptTokenCount || 0,
    cachedTokens: usage.cachedContentTokenCount || 0,
    totalTokens: usage.totalTokenCount || 0,
    raw: json
  };
}

describe.skipIf(!ENABLE)("Antigravity cache behavior (real API)", () => {
  const conns = loadAgConnections();

  it("has at least one active AG connection with refreshToken", () => {
    expect(conns.length).toBeGreaterThan(0);
  });

  it("same sessionId → cache hit on repeated call", async () => {
    const [acc] = conns;
    const token = await refreshAccessToken(acc.refreshToken);
    const sessionId = `test-same-${crypto.randomUUID()}`;

    const r1 = await callAg({ accessToken: token, projectId: acc.projectId, sessionId, longText: LONG_TEXT, userText: "Reply with OK only." });
    const r2 = await callAg({ accessToken: token, projectId: acc.projectId, sessionId, longText: LONG_TEXT, userText: "Reply with OK only." });

    console.log(`[same-session ${acc.email}] r1: prompt=${r1.promptTokens} cached=${r1.cachedTokens} | r2: prompt=${r2.promptTokens} cached=${r2.cachedTokens}`);

    expect(r1.status).toBe(200);
    expect(r2.status).toBe(200);
    expect(r2.cachedTokens).toBeGreaterThanOrEqual(MIN_CACHE_TOKENS);
  }, 60000);

  it("different sessionId (same account) → cache still hits (session-independent)", async () => {
    const [acc] = conns;
    const token = await refreshAccessToken(acc.refreshToken);

    const r1 = await callAg({ accessToken: token, projectId: acc.projectId, sessionId: `test-diff-a-${crypto.randomUUID()}`, longText: LONG_TEXT, userText: "Reply with OK only." });
    const r2 = await callAg({ accessToken: token, projectId: acc.projectId, sessionId: `test-diff-b-${crypto.randomUUID()}`, longText: LONG_TEXT, userText: "Reply with OK only." });

    console.log(`[diff-session ${acc.email}] r1: cached=${r1.cachedTokens} | r2: cached=${r2.cachedTokens}`);

    expect(r1.status).toBe(200);
    expect(r2.status).toBe(200);
    // AG cache is content-based, not session-based → both calls hit
    expect(r2.cachedTokens).toBeGreaterThanOrEqual(MIN_CACHE_TOKENS);
  }, 60000);

  it.skipIf(conns.length < 2)("cross-account → cache SHARED (content-based global cache)", async () => {
    const [accA, accB] = conns;
    const [tokenA, tokenB] = await Promise.all([
      refreshAccessToken(accA.refreshToken),
      refreshAccessToken(accB.refreshToken)
    ]);

    // Account A warmup with its own sessionId
    const a1 = await callAg({ accessToken: tokenA, projectId: accA.projectId, sessionId: `cross-a-${crypto.randomUUID()}`, longText: LONG_TEXT, userText: "Reply with OK only." });
    // Account B with DIFFERENT sessionId → if cache shares across accounts, it still hits
    const b1 = await callAg({ accessToken: tokenB, projectId: accB.projectId, sessionId: `cross-b-${crypto.randomUUID()}`, longText: LONG_TEXT, userText: "Reply with OK only." });

    console.log(`[cross-account] A cached=${a1.cachedTokens} | B cached=${b1.cachedTokens} (${accA.email} → ${accB.email})`);

    expect(a1.status).toBe(200);
    expect(b1.status).toBe(200);
    // Cache is shared globally across accounts (content-based)
    expect(b1.cachedTokens).toBeGreaterThanOrEqual(MIN_CACHE_TOKENS);
  }, 90000);

  // ─── Codex-style sessionId comparison ────────────────────────────────
  // Codex derives sessionId from hash(conversation history), keeping it
  // stable per-conversation. Test whether this strategy improves cache
  // hit rate vs random sessionId on AG with a fresh unique prompt.
  it("codex-style sessionId vs random sessionId on unique prompt", async () => {
    const [acc] = conns;
    const token = await refreshAccessToken(acc.refreshToken);

    // Build a unique conversation so no pre-existing cache can interfere
    const uniqueMarker = crypto.randomUUID();
    const uniqueLong = `MARKER-${uniqueMarker}. ${LONG_TEXT}`;
    const userText = "Reply with OK only.";

    // Codex-style: sess_${sha256(systemInstruction + userContent).slice(0,32)}
    const hash = crypto.createHash("sha256").update(uniqueLong + "\n" + userText).digest("hex").slice(0, 32);
    const codexStyleSessionId = `sess_${hash}`;

    const N = 4;
    const randomResults = [];
    const codexResults = [];

    // Strategy A: random sessionId each call
    for (let i = 0; i < N; i++) {
      const r = await callAg({
        accessToken: token, projectId: acc.projectId,
        sessionId: `rand-${crypto.randomUUID()}`,
        longText: uniqueLong, userText
      });
      randomResults.push(r);
      console.log(`[random   call ${i + 1}] cached=${r.cachedTokens}`);
    }

    // Strategy B: codex-style stable sessionId (same hash for every call)
    for (let i = 0; i < N; i++) {
      const r = await callAg({
        accessToken: token, projectId: acc.projectId,
        sessionId: codexStyleSessionId,
        longText: uniqueLong, userText
      });
      codexResults.push(r);
      console.log(`[codex    call ${i + 1}] cached=${r.cachedTokens}`);
    }

    const randomHitRate = randomResults.filter(r => r.cachedTokens >= MIN_CACHE_TOKENS).length / N;
    const codexHitRate = codexResults.filter(r => r.cachedTokens >= MIN_CACHE_TOKENS).length / N;
    console.log(`[summary] randomHitRate=${randomHitRate} codexHitRate=${codexHitRate}`);

    randomResults.forEach(r => expect(r.status).toBe(200));
    codexResults.forEach(r => expect(r.status).toBe(200));
    // No strict comparison — just report. AG cache is session-independent per prior tests.
  }, 180000);

  it("unique prompt (never seen) → explore when cache starts hitting", async () => {
    const [acc] = conns;
    const token = await refreshAccessToken(acc.refreshToken);
    // Unique marker to guarantee no one has cached this exact prompt before
    const uniqueLong = `UNIQUE-${crypto.randomUUID()}. ${LONG_TEXT}`;
    const sessionId = `unique-${crypto.randomUUID()}`;

    const results = [];
    for (let i = 0; i < 5; i++) {
      const r = await callAg({ accessToken: token, projectId: acc.projectId, sessionId, longText: uniqueLong, userText: "Reply with OK only." });
      results.push(r);
      console.log(`[unique-prompt call ${i + 1}] prompt=${r.promptTokens} cached=${r.cachedTokens}`);
    }

    results.forEach(r => expect(r.status).toBe(200));
    // Log whether any call ever hits cache — no strict assertion (exploratory)
    const anyHit = results.some(r => r.cachedTokens >= MIN_CACHE_TOKENS);
    console.log(`[unique-prompt] any-hit=${anyHit}`);
  }, 90000);
});