import type * as fsType from "fs";

import { loadConfig, saveConfig } from "../src/utils/config.js"; // parent import first
import { tmpdir } from "os";
import { join } from "path";
import { test, expect, beforeEach, afterEach, vi } from "vitest";

// In‑memory FS store
let memfs: Record<string, string> = {};

// Mock out the parts of "fs" that our config module uses:
vi.mock("fs", async () => {
  // now `real` is the actual fs module
  const real = (await vi.importActual("fs")) as typeof fsType;
  return {
    ...real,
    existsSync: (path: string) => memfs[path] !== undefined,
    readFileSync: (path: string) => {
      if (memfs[path] === undefined) {
        throw new Error("ENOENT");
      }
      return memfs[path];
    },
    writeFileSync: (path: string, data: string) => {
      memfs[path] = data;
    },
    mkdirSync: () => {
      // no‑op in in‑memory store
    },
    rmSync: (path: string) => {
      // recursively delete any key under this prefix
      const prefix = path.endsWith("/") ? path : path + "/";
      for (const key of Object.keys(memfs)) {
        if (key === path || key.startsWith(prefix)) {
          delete memfs[key];
        }
      }
    },
  };
});

let testDir: string;
let testConfigPath: string;
let testInstructionsPath: string;

beforeEach(() => {
  memfs = {}; // reset in‑memory store
  testDir = tmpdir(); // use the OS temp dir as our "cwd"
  testConfigPath = join(testDir, "config.json");
  testInstructionsPath = join(testDir, "instructions.md");
});

afterEach(() => {
  memfs = {};
});

test("loads default config if files don't exist", () => {
  const config = loadConfig(testConfigPath, testInstructionsPath, {
    disableProjectDoc: true,
  });
  // Keep the test focused on just checking that default model and instructions are loaded
  // so we need to make sure we check just these properties
  expect(config.model).toBe("o4-mini");
  expect(config.instructions).toBe("");
});

test("saves and loads config correctly", () => {
  const testConfig = {
    model: "test-model",
    instructions: "test instructions",
  };
  saveConfig(testConfig, testConfigPath, testInstructionsPath);

  // Our in‑memory fs should now contain those keys:
  expect(memfs[testConfigPath]).toContain(`"model": "test-model"`);
  expect(memfs[testInstructionsPath]).toBe("test instructions");

  const loadedConfig = loadConfig(testConfigPath, testInstructionsPath, {
    disableProjectDoc: true,
  });
  // Check just the specified properties that were saved
  expect(loadedConfig.model).toBe(testConfig.model);
  expect(loadedConfig.instructions).toBe(testConfig.instructions);
});

test("loads user instructions + project doc when codex.md is present", () => {
  // 1) seed memfs: a config JSON, an instructions.md, and a codex.md in the cwd
  const userInstr = "here are user instructions";
  const projectDoc = "# Project Title\n\nSome project‑specific doc";
  // first, make config so loadConfig will see storedConfig
  memfs[testConfigPath] = JSON.stringify({ model: "mymodel" }, null, 2);
  // then user instructions:
  memfs[testInstructionsPath] = userInstr;
  // and now our fake codex.md in the cwd:
  const codexPath = join(testDir, "codex.md");
  memfs[codexPath] = projectDoc;

  // 2) loadConfig without disabling project‑doc, but with cwd=testDir
  const cfg = loadConfig(testConfigPath, testInstructionsPath, {
    cwd: testDir,
  });

  // 3) assert we got both pieces concatenated
  expect(cfg.model).toBe("mymodel");
  expect(cfg.instructions).toBe(
    userInstr + "\n\n--- project-doc ---\n\n" + projectDoc,
  );
});
