import { afterEach, expect, test } from "bun:test";
import { mkdirSync, mkdtempSync, rmSync, symlinkSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { parse } from "@wrnexus/syntax";
import { runWithRequestContext } from "@wrnexus/core";
import { generate } from "../src/codegen.ts";

// The generated module dynamically imported below is written to an OS
// tmpdir with no node_modules of its own, so Node's bare-specifier
// resolution for "@wrnexus/core" would otherwise walk up to whatever
// (possibly stale, globally-installed) copy happens to sit outside the
// workspace. Symlink the workspace package in so it resolves to the real,
// currently-built `@wrnexus/core` — the same one every other package in
// this repo gets via its own `node_modules/@wrnexus/core` symlink.
const WORKSPACE_CORE = join(import.meta.dir, "../../core");

function linkWorkspaceCore(root: string): void {
  const scopeDir = join(root, "node_modules", "@wrnexus");
  mkdirSync(scopeDir, { recursive: true });
  symlinkSync(
    WORKSPACE_CORE,
    join(scopeDir, "core"),
    process.platform === "win32" ? "junction" : "dir",
  );
}

const ROOT_TSCONFIG = join(import.meta.dir, "../../../tsconfig.json").replace(/\\/g, "/");
// The repo's own tsc, not a `bunx`-fetched one — `bunx tsc` can resolve an
// unrelated TypeScript version that doesn't understand this repo's tsconfig
// options, unlike `bun run typecheck`, which uses this same local binary.
const LOCAL_TSC = join(import.meta.dir, "../../../node_modules/.bin/tsc").replace(/\\/g, "/");
// `types`/`typeRoots` in an extended tsconfig resolve relative to the config
// file that's actually invoked (our temp one), not the base file — so the
// ambient `bun` types need an explicit path back to the repo's node_modules.
const TYPE_ROOTS = join(import.meta.dir, "../../../node_modules/@types").replace(/\\/g, "/");

const roots: string[] = [];
afterEach(() => {
  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true });
});

/**
 * Runs the real TypeScript compiler over a generated server module. Proves
 * the emitted server `api` object (and everything else in the module)
 * actually type-checks — string-containment assertions alone can't catch a
 * declared type that omits a field every emitted object literal has.
 */
function typecheckGenerated(source: string): { ok: boolean; output: string } {
  const root = mkdtempSync(join(tmpdir(), "wrnexus-apis-server-tsc-"));
  roots.push(root);
  const file = join(root, "page.ts");
  writeFileSync(file, source);
  writeFileSync(
    join(root, "tsconfig.json"),
    JSON.stringify({
      extends: ROOT_TSCONFIG,
      compilerOptions: { noEmit: true, typeRoots: [TYPE_ROOTS] },
      include: ["page.ts"],
    }),
  );
  const result = Bun.spawnSync([LOCAL_TSC, "--project", join(root, "tsconfig.json")], {
    cwd: root,
    stdout: "pipe",
    stderr: "pipe",
  });
  const output = `${result.stdout?.toString() ?? ""}${result.stderr?.toString() ?? ""}`;
  return { ok: result.exitCode === 0, output };
}

async function importServerModule(source: string): Promise<any> {
  const root = mkdtempSync(join(tmpdir(), "wrnexus-apis-server-exec-"));
  roots.push(root);
  mkdirSync(root, { recursive: true });
  linkWorkspaceCore(root);
  const file = join(root, "page.ts");
  writeFileSync(file, source);
  return import(`${file.replace(/\\/g, "/")}?t=${Date.now()}`);
}

/**
 * Renders a page module the way the dev-server runtime does: runs the
 * generated `__wrnexusLoad` export (if any) and merges its result onto ctx
 * before calling the default render export. `callApi` fakes the transport
 * that the generated server `api` object's members call out to. The same
 * ctx object must be both the AsyncLocalStorage store (so the api member's
 * `requireRequestContext` call finds it) and the ctx passed to load/render,
 * or the fake transport is never reached.
 */
function renderPage(
  mod: any,
  callApi: (path: string, method: string, input?: unknown) => Promise<unknown>,
): Promise<string> {
  const ctx: any = {
    req: { url: "http://localhost/", headers: new Headers() },
    cookies: {},
    session: {},
    __wrnexusCallApi: callApi,
  };
  return runWithRequestContext(ctx, async () => {
    if (typeof mod.__wrnexusLoad === "function") {
      const data = await mod.__wrnexusLoad(ctx);
      if (data && typeof data === "object") Object.assign(ctx, data);
    }
    return mod.default(ctx);
  });
}

const SOURCE = `page Probe {
  apis {
    searchUsers POST /api/users {
      request { body { name?: string } }
      response { return data.users }
      error { return [] }
    }
  }

  load server directory {
    return await api.searchUsers({ name: "a" })
  }

  view { <main>x</main> }
}
`;

test("the server module declares an api object with the block's path and method", () => {
  const generated = generate(parse(SOURCE));

  expect(generated).toContain("const api =");
  expect(generated).toContain("searchUsers");
  expect(generated).toContain('"/api/users"');
  expect(generated).toContain('"POST"');
});

test("the response body is spliced in", () => {
  expect(generate(parse(SOURCE))).toContain("data.users");
});

test("a block with no error section rethrows rather than resolving undefined", () => {
  const generated = generate(
    parse(`page P {
  apis { a GET /api/a { response { return data } } }
  load server x { return await api.a() }
  view { <main>x</main> }
}
`),
  );

  expect(generated).toContain("throw");
});

// --- Execution tests --------------------------------------------------------
//
// Everything above only asserts on emitted *text*. These instead run the real
// TypeScript compiler and dynamically import + execute the generated module,
// proving the response/error sections actually run with the right bindings —
// a string-containment check cannot prove that.

function renderModule(inner: string): string {
  return generate(
    parse(`page Repro {
  apis {
${inner}
  }

  view { <main><p api="ssrUsers">loading</p></main> }
}
`),
  );
}

test("a sectioned block's response body binds the payload to data", async () => {
  const mod = await importServerModule(
    renderModule(`    ssrUsers GET /api/users {
      response {
        return data.users.length
      }
    }`),
  );

  const html = await renderPage(mod, async () => ({ users: [1, 2, 3] }));

  expect(html).toContain("3");
});

test("an error section emits the error body and binds status/message/data", async () => {
  const mod = await importServerModule(
    renderModule(`    ssrUsers GET /api/users {
      response {
        return data.users.length
      }
      error {
        return message + ":" + status + ":" + data
      }
    }`),
  );

  const html = await renderPage(mod, async () => {
    throw Object.assign(new Error("boom"), { status: 500, data: "extra" });
  });

  expect(html).toContain("boom:500:extra");
});

test("a block without an error section still propagates a genuine transport failure", async () => {
  const mod = await importServerModule(
    renderModule(`    ssrUsers GET /api/users {
      response {
        return data.users.length
      }
    }`),
  );

  await expect(
    renderPage(mod, async () => {
      throw new Error("boom");
    }),
  ).rejects.toThrow("boom");
});

test("a response body error is not swallowed by the error section", async () => {
  const mod = await importServerModule(
    renderModule(`    ssrUsers GET /api/users {
      response {
        return data.users.missing.length
      }
      error {
        return "fallback"
      }
    }`),
  );

  // The transport call itself succeeds; the bug is in the response body. That
  // must surface as a rejection, not be swallowed by the error section's own
  // fallback -- a bug in response handling is not a transport failure.
  await expect(renderPage(mod, async () => ({ users: [] }))).rejects.toThrow();
});

test("a genuine transport failure still runs the error section's fallback", async () => {
  const mod = await importServerModule(
    renderModule(`    ssrUsers GET /api/users {
      response {
        return data.users.length
      }
      error {
        return "fallback"
      }
    }`),
  );

  const html = await renderPage(mod, async () => {
    throw new Error("boom");
  });

  expect(html).toContain("fallback");
});

test("tsc: a sectioned block's generated server module has no diagnostics", () => {
  const generated = renderModule(`    ssrUsers GET /api/users {
      response {
        return data.users.length
      }
      error {
        return message + status + data
      }
    }`);

  const { ok, output } = typecheckGenerated(generated);

  expect(output.trim()).toBe("");
  expect(ok).toBe(true);
});

// {#each} iterates a plain, already-resolved value — an `await` inside the
// list expression itself is not supported (the list expression runs outside
// an async boundary). A `load server` block is the idiomatic way to resolve
// an api call before the view iterates it, and it goes through the exact
// same server `api` member (and thus the same response/error handling) as
// every other apis {} call site.
function eachModule(inner: string): string {
  return generate(
    parse(`page Repro {
  apis {
${inner}
  }

  load server users {
    return await api.ssrUsers()
  }

  view { <main>{#each users as u}<p>{u}</p>{/each}</main> }
}
`),
  );
}

test("an api block used in {#each} with an error section runs the error body on failure", async () => {
  const mod = await importServerModule(
    eachModule(`    ssrUsers GET /api/users {
      response {
        return data.users
      }
      error {
        return ["fallback"]
      }
    }`),
  );

  const html = await renderPage(mod, async () => {
    throw new Error("boom");
  });

  expect(html).toContain("fallback");
});

test("an api block used in {#each} without an error section still propagates a failure", async () => {
  const mod = await importServerModule(
    eachModule(`    ssrUsers GET /api/users {
      response {
        return data.users
      }
    }`),
  );

  await expect(
    renderPage(mod, async () => {
      throw new Error("boom");
    }),
  ).rejects.toThrow("boom");
});