// Watcher Unit Tests — exercises WorkspaceWatcher against a temp dir with
// real chokidar. We use real FS because mocking it would test the mock,
// not the actual behavior under inotify.
import { describe, it, before, after, beforeEach } from "node:test";
import * as assert from "node:assert/strict";
import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { WorkspaceWatcher, type FileEvent } from "../../src/watcher.ts";
import { pathToUri } from "../../src/root.ts";

// Wait For - Polls a predicate up to timeoutMs. Returns true if it became
// true, false if it timed out. Used to wait on async chokidar events
// without arbitrary sleeps.
async function waitFor(
  predicate: () => boolean,
  timeoutMs = 2000,
): Promise<boolean> {
  const deadline = Date.now() + timeoutMs;
  while (Date.now() < deadline) {
    if (predicate()) return true;
    await new Promise((r) => setTimeout(r, 25));
  }
  return predicate();
}

// Wait Quiet - Waits for the debounce window to elapse so any pending
// events flush. Slightly longer than DEBOUNCE_MAX_WAIT_MS.
const FLUSH_WAIT_MS = 700;

describe("WorkspaceWatcher", () => {
  let tmpDir: string;
  let received: FileEvent[][] = [];
  let watcher: WorkspaceWatcher | null = null;

  before(() => {
    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "pi-lsp-watcher-"));
  });

  after(() => {
    fs.rmSync(tmpDir, { recursive: true, force: true });
  });

  beforeEach(async () => {
    if (watcher) {
      await watcher.dispose();
      watcher = null;
    }
    received = [];
    // Reset Dir - Wipe contents between tests so file lists are predictable.
    for (const entry of fs.readdirSync(tmpDir)) {
      fs.rmSync(path.join(tmpDir, entry), { recursive: true, force: true });
    }
  });

  it("emits Created event for new file matching pattern", async () => {
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([{ globPattern: "**/*.ts" }]);
    // Settle - chokidar's `ready` is implicit; give it a moment.
    await new Promise((r) => setTimeout(r, 200));

    fs.writeFileSync(path.join(tmpDir, "foo.ts"), "x");

    const ok = await waitFor(() => received.length > 0);
    assert.ok(ok, "Expected at least one batch");
    const all = received.flat();
    const match = all.find((e) => e.uri === pathToUri(path.join(tmpDir, "foo.ts")));
    assert.ok(match, `Expected event for foo.ts, got ${JSON.stringify(all)}`);
    assert.strictEqual(match.type, 1);
  });

  it("emits Deleted event when file removed", async () => {
    const file = path.join(tmpDir, "del.ts");
    fs.writeFileSync(file, "x");
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([{ globPattern: "**/*.ts" }]);
    await new Promise((r) => setTimeout(r, 200));

    fs.unlinkSync(file);

    const ok = await waitFor(() =>
      received.flat().some((e) => e.type === 3 && e.uri === pathToUri(file)),
    );
    assert.ok(ok, `Expected delete event, got ${JSON.stringify(received)}`);
  });

  it("emits Changed event when file content changes", async () => {
    const file = path.join(tmpDir, "chg.ts");
    fs.writeFileSync(file, "x");
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([{ globPattern: "**/*.ts" }]);
    await new Promise((r) => setTimeout(r, 200));

    fs.writeFileSync(file, "y");

    const ok = await waitFor(() =>
      received.flat().some((e) => e.type === 2 && e.uri === pathToUri(file)),
    );
    assert.ok(ok, `Expected change event, got ${JSON.stringify(received)}`);
  });

  it("skips files not matching the pattern", async () => {
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([{ globPattern: "**/*.ts" }]);
    await new Promise((r) => setTimeout(r, 200));

    fs.writeFileSync(path.join(tmpDir, "ignored.txt"), "x");
    await new Promise((r) => setTimeout(r, FLUSH_WAIT_MS));

    const all = received.flat();
    assert.strictEqual(
      all.length,
      0,
      `Expected no events for .txt, got ${JSON.stringify(all)}`,
    );
  });

  it("honors .gitignore at root", async () => {
    fs.writeFileSync(path.join(tmpDir, ".gitignore"), "ignored-dir/\n");
    fs.mkdirSync(path.join(tmpDir, "ignored-dir"));
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([{ globPattern: "**/*.ts" }]);
    await new Promise((r) => setTimeout(r, 200));

    fs.writeFileSync(path.join(tmpDir, "ignored-dir", "x.ts"), "x");
    fs.writeFileSync(path.join(tmpDir, "watched.ts"), "x");

    await new Promise((r) => setTimeout(r, FLUSH_WAIT_MS));

    const all = received.flat();
    const uris = all.map((e) => e.uri);
    assert.ok(
      uris.includes(pathToUri(path.join(tmpDir, "watched.ts"))),
      "watched.ts should fire",
    );
    assert.ok(
      !uris.some((u) => u.includes("ignored-dir")),
      `ignored-dir/x.ts should be filtered, got ${JSON.stringify(uris)}`,
    );
  });

  it("respects WatchKind to filter event types", async () => {
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    // Kind 1 = Create only - delete events should be suppressed.
    watcher.setPatterns([{ globPattern: "**/*.ts", kind: 1 }]);
    await new Promise((r) => setTimeout(r, 200));

    const file = path.join(tmpDir, "only-create.ts");
    fs.writeFileSync(file, "x");
    await new Promise((r) => setTimeout(r, FLUSH_WAIT_MS));
    fs.unlinkSync(file);
    await new Promise((r) => setTimeout(r, FLUSH_WAIT_MS));

    const all = received.flat();
    assert.ok(
      all.some((e) => e.type === 1),
      "Expected create event",
    );
    assert.ok(
      !all.some((e) => e.type === 3),
      `Did not expect delete events, got ${JSON.stringify(all)}`,
    );
  });

  it("batches multiple rapid events into one onEvents call", async () => {
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([{ globPattern: "**/*.ts" }]);
    await new Promise((r) => setTimeout(r, 200));

    // Write Several Files Quickly - within the 50ms debounce window they
    // should all land in one batch, capped at 500ms max wait.
    for (let i = 0; i < 5; i++) {
      fs.writeFileSync(path.join(tmpDir, `f${i}.ts`), "x");
    }

    await new Promise((r) => setTimeout(r, FLUSH_WAIT_MS));

    const all = received.flat();
    assert.strictEqual(all.length, 5, `Expected 5 events, got ${all.length}`);
    // The batches should be << 5 (debounce coalesces). Allow up to 2 in
    // case the loop straddled a flush boundary.
    assert.ok(
      received.length <= 2,
      `Expected <=2 batches, got ${received.length}: ${JSON.stringify(received)}`,
    );
  });

  it("ignores .git/ even when not in gitignore", async () => {
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([{ globPattern: "**/*" }]);
    await new Promise((r) => setTimeout(r, 200));

    fs.mkdirSync(path.join(tmpDir, ".git"));
    fs.writeFileSync(path.join(tmpDir, ".git", "HEAD"), "ref: foo");

    await new Promise((r) => setTimeout(r, FLUSH_WAIT_MS));

    const all = received.flat();
    assert.ok(
      !all.some((e) => e.uri.includes("/.git/")),
      `.git contents should be ignored, got ${JSON.stringify(all)}`,
    );
  });

  it("stops emitting after dispose", async () => {
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([{ globPattern: "**/*.ts" }]);
    await new Promise((r) => setTimeout(r, 200));

    await watcher.dispose();
    watcher = null;

    fs.writeFileSync(path.join(tmpDir, "post-dispose.ts"), "x");
    await new Promise((r) => setTimeout(r, FLUSH_WAIT_MS));

    const all = received.flat();
    assert.strictEqual(all.length, 0, `Expected no events after dispose`);
  });

  it("matches absolute-path glob patterns (gopls-style)", async () => {
    // Regression - gopls registers e.g. `/tmp/.../**/*.{go,mod}` rather
    // than a bare relative `**/*.go`. The matcher must accept both.
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([
      { globPattern: `${tmpDir}/**/*.{go,mod}` },
    ]);
    await new Promise((r) => setTimeout(r, 200));

    fs.writeFileSync(path.join(tmpDir, "helper.go"), "package x\n");

    const ok = await waitFor(() =>
      received
        .flat()
        .some((e) => e.uri === pathToUri(path.join(tmpDir, "helper.go"))),
    );
    assert.ok(ok, `Expected event for absolute glob, got ${JSON.stringify(received)}`);
  });

  it("empty pattern set means no watching", async () => {
    watcher = new WorkspaceWatcher(tmpDir, (evs) => received.push(evs));
    watcher.setPatterns([]);
    await new Promise((r) => setTimeout(r, 200));

    fs.writeFileSync(path.join(tmpDir, "no-patterns.ts"), "x");
    await new Promise((r) => setTimeout(r, FLUSH_WAIT_MS));

    assert.strictEqual(received.length, 0);
  });
});