import { type FSWatcher, mkdtempSync, rmSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { expectDefined } from "@openclaw/normalization-core";
import { afterEach, describe, expect, it, vi } from "vitest";
import { DEFAULT_USAGE_BAR_TEMPLATE } from "./default-template.js";
import { loadUsageBarTemplate } from "./template.js";
import { clearUsageBarTemplateCacheForTest } from "./template.test-support.js";

const warnSpy = vi.hoisted(() => vi.fn());

vi.mock("../../logging/subsystem.js", () => ({
  createSubsystemLogger: () => ({ warn: warnSpy }),
}));

const capturedWatchers = vi.hoisted(() => [] as Array<ReturnType<typeof import("node:fs").watch>>);
const capturedWatchChanges = vi.hoisted(() => [] as Array<() => void>);
const watcherOperations = vi.hoisted(() => [] as Array<["watch", unknown] | ["close", FSWatcher]>);
const closedWatchers = vi.hoisted(() => new Set<FSWatcher>());

vi.mock("node:fs", async (importOriginal) => {
  const orig = await importOriginal<typeof import("node:fs")>();
  const origWatch = orig.watch;
  return {
    ...orig,
    watch: ((path: unknown, opts: unknown, cb: unknown) => {
      watcherOperations.push(["watch", path]);
      const w = origWatch(path as never, opts as never, cb as never);
      const close = w.close.bind(w);
      w.close = () => {
        close();
        watcherOperations.push(["close", w]);
      };
      w.once("close", () => {
        closedWatchers.add(w);
      });
      capturedWatchers.push(w);
      capturedWatchChanges.push(() => {
        (cb as (eventType: string, filename: null) => void)("change", null);
      });
      return w;
    }) as typeof orig.watch,
  };
});

const tplA = { segments: [{ text: "A" }] };
const tplB = { output: { default: [{ text: "B" }] } };

const cleanups: Array<() => void> = [];

afterEach(async () => {
  try {
    clearUsageBarTemplateCacheForTest();
  } finally {
    // Also close evicted watchers when a failed assertion exposes missing owner cleanup.
    for (const watcher of capturedWatchers) {
      watcher.close();
    }
    // Normal close events run on nextTick; settle them before removing watched files.
    await new Promise<void>((resolve) => {
      setImmediate(resolve);
    });
    warnSpy.mockClear();
    capturedWatchers.splice(0);
    capturedWatchChanges.splice(0);
    watcherOperations.splice(0);
    closedWatchers.clear();
    for (const fn of cleanups.splice(0)) {
      fn();
    }
  }
});

function tmpDir(): string {
  const d = mkdtempSync(join(tmpdir(), "usage-template-"));
  cleanups.push(() => rmSync(d, { recursive: true, force: true }));
  return d;
}

function tmpFile(name: string, contents: string): string {
  const d = tmpDir();
  const path = join(d, name);
  writeFileSync(path, contents);
  return path;
}

describe("loadUsageBarTemplate", () => {
  it("returns the built-in template when unset", () => {
    expect(loadUsageBarTemplate(undefined)).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
  });

  it("returns an inline template object when usable", () => {
    expect(loadUsageBarTemplate(tplA)).toBe(tplA);
  });

  it("falls back to the built-in template for an unusable inline object", () => {
    expect(loadUsageBarTemplate({ nope: true })).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).toHaveBeenCalledTimes(1);
    expect(warnSpy.mock.calls[0]).toMatchObject([
      "configured usage template could not be used; using built-in footer",
      { source: "inline", reason: "unsupported-shape" },
    ]);
  });

  it("falls back quietly for an empty inline template", () => {
    expect(loadUsageBarTemplate({ output: {} })).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(loadUsageBarTemplate({ output: { default: [] } })).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).not.toHaveBeenCalled();
  });

  it("loads and parses a template file", () => {
    const path = tmpFile("t.json", JSON.stringify(tplA));
    expect(loadUsageBarTemplate(path)).toMatchObject(tplA);
  });

  it("falls back to the built-in template for invalid JSON", () => {
    const path = tmpFile("bad.json", "{ not json");
    expect(loadUsageBarTemplate(path)).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).toHaveBeenCalledTimes(1);
    expect(warnSpy.mock.calls[0]).toMatchObject([
      "configured usage template could not be used; using built-in footer",
      { source: "file", reason: "invalid-json", path },
    ]);
  });

  it("falls back to the built-in template for an empty template file", () => {
    const path = tmpFile("empty.json", JSON.stringify({ output: { default: [] } }));
    expect(loadUsageBarTemplate(path)).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).not.toHaveBeenCalled();
  });

  it("reloads a path after an initial miss", () => {
    const dir = tmpDir();
    const missing = join(dir, "missing.json");
    expect(loadUsageBarTemplate(missing)).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).not.toHaveBeenCalled();
    writeFileSync(missing, JSON.stringify(tplB));
    expect(loadUsageBarTemplate(missing)).toMatchObject(tplB);
  });

  it("reloads a path after invalid JSON is fixed", () => {
    const path = tmpFile("bad.json", "{ not json");
    expect(loadUsageBarTemplate(path)).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).toHaveBeenCalledTimes(1);
    writeFileSync(path, JSON.stringify(tplB));
    expect(loadUsageBarTemplate(path)).toMatchObject(tplB);
  });

  it("serves the cached template without re-reading the file", () => {
    const path = tmpFile("t.json", JSON.stringify(tplA));
    expect(loadUsageBarTemplate(path)).toMatchObject(tplA);

    writeFileSync(path, JSON.stringify(tplB));
    expect(loadUsageBarTemplate(path)).toMatchObject(tplA);

    clearUsageBarTemplateCacheForTest();
    expect(loadUsageBarTemplate(path)).toMatchObject(tplB);
  });

  it("bounds invalid-template warnings by least-recently-used path", () => {
    const dir = tmpDir();
    const paths = Array.from({ length: 257 }, (_, index) => {
      const path = join(dir, `bad-${index}.json`);
      writeFileSync(path, "{ not json");
      return path;
    });

    for (const path of paths.slice(0, 256)) {
      expect(loadUsageBarTemplate(path)).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    }
    expect(warnSpy).toHaveBeenCalledTimes(256);

    // Refresh the oldest warning before overflow so the next key becomes the LRU victim.
    expect(loadUsageBarTemplate(paths[0])).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).toHaveBeenCalledTimes(256);

    expect(loadUsageBarTemplate(paths[256])).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).toHaveBeenCalledTimes(257);
    expect(loadUsageBarTemplate(paths[0])).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).toHaveBeenCalledTimes(257);

    expect(loadUsageBarTemplate(paths[1])).toBe(DEFAULT_USAGE_BAR_TEMPLATE);
    expect(warnSpy).toHaveBeenCalledTimes(258);
    expect(warnSpy).toHaveBeenLastCalledWith(
      "configured usage template could not be used; using built-in footer",
      { source: "file", reason: "invalid-json", path: paths[1] },
    );
  });

  describe("cache eviction", () => {
    it("evicts the oldest entry and closes its watcher when inserting a new key over the limit", async () => {
      const dir = tmpDir();
      const paths: string[] = [];
      // Create 65 template files — one more than MAX_CACHED_TEMPLATE_FILES (64).
      for (let i = 0; i < 65; i++) {
        const path = join(dir, `tpl-${i}.json`);
        writeFileSync(path, JSON.stringify({ segments: [{ text: `v1-${i}` }] }));
        paths.push(path);
      }

      // Load the first 64 files to fill the cache.
      for (let i = 0; i < 64; i++) {
        expect(loadUsageBarTemplate(paths[i])).toMatchObject({
          segments: [{ text: `v1-${i}` }],
        });
      }
      expect(capturedWatchers).toHaveLength(64);
      expect(watcherOperations).toHaveLength(64);
      expect(closedWatchers.size).toBe(0);
      watcherOperations.splice(0);

      // Insert the 65th file — should evict the oldest (paths[0]) and close
      // its watcher before allocating a watcher for paths[64].
      expect(loadUsageBarTemplate(paths[64])).toMatchObject({
        segments: [{ text: "v1-64" }],
      });
      expect(capturedWatchers).toHaveLength(65);
      expect(watcherOperations.map(([kind]) => kind)).toEqual(["close", "watch"]);
      expect(watcherOperations[0]?.[1]).toBe(capturedWatchers[0]);
      expect(watcherOperations[1]?.[1]).toBe(paths[64]);
      watcherOperations.splice(0);

      // Check every survivor before re-inserting the evicted path causes another eviction.
      for (let i = 1; i < 64; i++) {
        expect(loadUsageBarTemplate(paths[i])).toMatchObject({
          segments: [{ text: `v1-${i}` }],
        });
      }
      expect(capturedWatchers).toHaveLength(65);
      expect(watcherOperations).toEqual([]);

      // Re-reading changed content proves cache eviction; lifecycle assertions prove closure.
      writeFileSync(
        expectDefined(paths[0], "paths[0] test invariant"),
        JSON.stringify({ segments: [{ text: "v2-0" }] }),
      );
      expect(loadUsageBarTemplate(paths[0])).toMatchObject({
        segments: [{ text: "v2-0" }],
      });
      expect(capturedWatchers).toHaveLength(66);
      expect(watcherOperations.map(([kind]) => kind)).toEqual(["close", "watch"]);
      expect(watcherOperations[0]?.[1]).toBe(capturedWatchers[1]);
      expect(watcherOperations[1]?.[1]).toBe(paths[0]);
      watcherOperations.splice(0);

      clearUsageBarTemplateCacheForTest();
      expect(watcherOperations).toHaveLength(64);
      for (const watcher of capturedWatchers.slice(2)) {
        expect(
          watcherOperations.some(([kind, closed]) => kind === "close" && closed === watcher),
        ).toBe(true);
      }
      await new Promise<void>((resolve) => {
        setImmediate(resolve);
      });
      expect(closedWatchers.size).toBe(capturedWatchers.length);
      for (const watcher of capturedWatchers) {
        expect(closedWatchers.has(watcher)).toBe(true);
      }
    });

    it("recovers after watcher error by clearing the dead watcher reference", () => {
      const path = tmpFile("t.json", JSON.stringify(tplA));

      // Load valid template → creates a watcher in the cache.
      expect(loadUsageBarTemplate(path)).toMatchObject(tplA);
      expect(capturedWatchers.length).toBe(1);

      // Write invalid JSON to trigger the change handler, which sets
      // entry.template = undefined.
      writeFileSync(path, "{ not json");
      capturedWatchChanges[0]?.();

      // The template is now invalid — served as DEFAULT.
      expect(loadUsageBarTemplate(path)).toBe(DEFAULT_USAGE_BAR_TEMPLATE);

      // Simulate a transient watcher error.
      // Without the fix: entry.watcher stays truthy → permanent DEFAULT.
      // With the fix: entry.watcher is cleared → recovery on next access.
      capturedWatchers[0]?.emit("error", new Error("simulated watcher error"));

      // Write valid content to disk.
      writeFileSync(path, JSON.stringify(tplB));

      expect(loadUsageBarTemplate(path)).toMatchObject(tplB);
    });

    it("reloads a still-valid template after watcher error", async () => {
      const path = tmpFile("t.json", JSON.stringify(tplA));

      // Load valid template → creates a watcher in the cache.
      expect(loadUsageBarTemplate(path)).toMatchObject(tplA);
      expect(capturedWatchers.length).toBe(1);

      // Simulate a transient watcher error while the template is still valid.
      capturedWatchers[0]?.emit("error", new Error("simulated watcher error"));

      // Without the fix (entry.template cleared): the stale tplA is still
      // served from cache because entry.template is truthy.  File edits
      // are never observed because the dead watcher doesn't fire and
      // loadUsageBarTemplate never calls cacheTemplateFile() again.
      // With the fix: entry.template is also cleared, so the next load
      // re-reads from disk and creates a fresh watcher.
      writeFileSync(path, JSON.stringify(tplB));
      expect(loadUsageBarTemplate(path)).toMatchObject(tplB);
    });

    it("does not evict when retrying the same key after a prior miss", () => {
      const dir = tmpDir();
      // Fill the cache with 63 valid files plus 1 invalid file = 64 entries.
      const validPaths: string[] = [];
      for (let i = 0; i < 63; i++) {
        const path = join(dir, `good-${i}.json`);
        writeFileSync(path, JSON.stringify({ segments: [{ text: `v1-${i}` }] }));
        validPaths.push(path);
      }
      const invalidPath = join(dir, "bad.json");
      writeFileSync(invalidPath, "{ not json");

      // Load 63 valid + 1 invalid = 64 entries in cache (cache full).
      for (const p of validPaths) {
        expect(loadUsageBarTemplate(p)).toMatchObject({
          segments: [{ text: expect.any(String) }],
        });
      }
      expect(loadUsageBarTemplate(invalidPath)).toBe(DEFAULT_USAGE_BAR_TEMPLATE);

      // Fix the invalid file and retry. This is the SAME key, so it must NOT
      // evict the oldest valid entry (validPaths[0]).
      writeFileSync(invalidPath, JSON.stringify(tplB));
      expect(loadUsageBarTemplate(invalidPath)).toMatchObject(tplB);

      // validPaths[0] should still be cached — not evicted by the retry.
      writeFileSync(
        expectDefined(validPaths[0], "validPaths[0] test invariant"),
        JSON.stringify({ segments: [{ text: "changed" }] }),
      );
      expect(loadUsageBarTemplate(validPaths[0])).toMatchObject({
        segments: [{ text: `v1-0` }],
      });
    });
  });
});