import { execFile } from "node:child_process";
import { createRequire } from "node:module";
import { mkdir, mkdtemp, readFile, readdir, rm, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { dirname, join } from "node:path";
import { promisify } from "node:util";
import { expect, test } from "vitest";

const execFileAsync = promisify(execFile);
const require = createRequire(import.meta.url);
const repoRoot = join(import.meta.dirname, "../../..");
const cliEntry = join(repoRoot, "packages/cli/src/main.ts");
const tsxLoader = join(dirname(require.resolve("tsx/package.json")), "dist/loader.mjs");

test("library identity source stays private and cannot overwrite a sidecar", async () => {
  const tempRoot = process.platform === "win32" ? tmpdir() : "/tmp";
  const dir = await mkdtemp(join(tempRoot, "scriptc-cli-library-output-"));
  const cacheRoot = join(dir, "cache");
  const outDir = join(dir, ".scriptc");
  const profilePath = join(dir, "profile.json");
  try {
    await mkdir(cacheRoot, { mode: 0o700 });
    await writeFile(
      join(dir, "helper.ts"),
      ["export function initialValue(): number {", "  return 1;", "}", ""].join("\n"),
    );
    await writeFile(
      join(dir, "lib.ts"),
      [
        "export interface Model { value: number; }",
        'export type Msg = { kind: "noop" } | { kind: "set"; value: number };',
        "export function init(): Model { return { value: 1 }; }",
        "export function update(model: Model, msg: Msg): Model {",
        '  return msg.kind === "set" ? { value: msg.value } : model;',
        "}",
        "export function boot(): number { return init().value; }",
        "",
      ].join("\n"),
    );

    const writeProfile = (sidecarPath: string): Promise<void> =>
      writeFile(
        profilePath,
        `${JSON.stringify(
          {
            profile_format: 1,
            name: "cli-library-output",
            entry: "lib.ts",
            emission: "llvm",
            abi: {
              prefix: "clo_",
              init_symbol: "clo_init",
              sink_register_symbol: "clo_set_panic_sink",
              collect_symbol: null,
              result_reset_symbol: null,
            },
            exports: [{ export: "boot", symbol: "clo_boot", params: [], returns: "f64" }],
            sidecar: {
              path: sidecarPath,
              wire_version: 1,
              abi_version: 1,
              snapshot_format: 1,
              build_id_symbol: "clo_build_id",
              abi_version_symbol: "clo_abi_version",
              model: "Model",
              msg: "Msg",
            },
          },
          null,
          2,
        )}\n`,
      );
    const runBuild = async (keepLlvm = false, emitIr = false): Promise<{ stderr: string }> => {
      return execFileAsync(
        process.execPath,
        [
          "--import",
          tsxLoader,
          cliEntry,
          "build",
          "--lib",
          "--profile",
          profilePath,
          ...(keepLlvm ? [] : ["--no-keep-llvm"]),
          ...(emitIr ? ["--emit-ir"] : []),
        ],
        {
          env: {
            ...process.env,
            TMPDIR: tempRoot,
            SCRIPTC_CACHE_DIR: cacheRoot,
          },
          maxBuffer: 1024 * 1024,
        },
      );
    };

    // --no-keep-llvm removes the public program TU, and the identity source is
    // invocation-private rather than a second caller-visible LLVM artifact.
    await writeProfile("contract.json");
    await runBuild();
    expect((await readdir(outDir)).sort()).toEqual(["contract.json", "lib.lib.a"]);

    // A single-source comment-only edit takes the semantic cache path. Its
    // restored public TU must match a forced miss before --no-keep-llvm removes
    // it again.
    await writeFile(
      join(dir, "lib.ts"),
      `/* harmless rebuild comment */ ${await readFile(join(dir, "lib.ts"), "utf8")}`,
    );
    await runBuild(true);
    const semanticHitLlvm = await readFile(join(outDir, "lib.lib.ll"), "utf8");
    await rm(join(cacheRoot, "early-lib"), { recursive: true, force: true });
    await runBuild(true);
    expect(await readFile(join(outDir, "lib.lib.ll"), "utf8")).toBe(semanticHitLlvm);
    await runBuild();
    expect((await readdir(outDir)).sort()).toEqual(["contract.json", "lib.lib.a"]);

    // A line-shifting edit must preserve the same LLVM artifact as a
    // forced frontend miss.
    await writeFile(
      join(dir, "lib.ts"),
      ["// line-shifting rebuild comment", await readFile(join(dir, "lib.ts"), "utf8")].join("\n"),
    );
    await runBuild(true);
    const shiftedLlvm = await readFile(join(outDir, "lib.lib.ll"), "utf8");
    await rm(join(cacheRoot, "early-lib"), { recursive: true, force: true });
    await runBuild(true);
    expect(await readFile(join(outDir, "lib.lib.ll"), "utf8")).toBe(shiftedLlvm);

    // Imported trivia edits in a multi-source graph must also produce
    // the same LLVM artifact as a forced frontend miss.
    await writeFile(
      join(dir, "lib.ts"),
      (await readFile(join(dir, "lib.ts"), "utf8"))
        .replace(
          "export interface Model",
          'import { initialValue } from "./helper.js";\nexport interface Model',
        )
        .replace("value: 1", "value: initialValue()"),
    );
    await runBuild(true);
    await writeFile(
      join(dir, "helper.ts"),
      ["// harmless helper comment", await readFile(join(dir, "helper.ts"), "utf8")].join("\n"),
    );
    await runBuild(true);
    const savedLlvm = await readFile(join(outDir, "lib.lib.ll"), "utf8");
    await rm(join(cacheRoot, "early-lib"), { recursive: true, force: true });
    await runBuild(true);
    expect(await readFile(join(outDir, "lib.lib.ll"), "utf8")).toBe(savedLlvm);

    // This name collided with the former fixed `<stem>.lib.identity.c`
    // output. Repeat to exercise the exact early-cache-hit ordering that used
    // to restore JSON and then overwrite it with generated LLVM.
    await rm(outDir, { recursive: true, force: true });
    await writeProfile("lib.lib.identity.c");
    await runBuild();
    await runBuild();
    const sidecar = JSON.parse(await readFile(join(outDir, "lib.lib.identity.c"), "utf8")) as {
      build_id?: unknown;
    };
    expect(sidecar.build_id).toMatch(/^[0-9a-f]{16}$/);
    expect((await readdir(outDir)).sort()).toEqual(["lib.lib.a", "lib.lib.identity.c"]);

    // Library IR remains an additive option; its guidance must not recommend
    // --emit, which library mode deliberately rejects.
    const additiveIr = await runBuild(false, true);
    expect(additiveIr.stderr).not.toContain("deprecated");
    expect(additiveIr.stderr).not.toContain("use --emit=ir");
    expect(await readFile(join(outDir, "lib.lib.ir.json"), "utf8")).toContain('"irVersion"');
  } finally {
    await rm(dir, { recursive: true, force: true });
  }
});