import { describe, expect, test } from "bun:test"
import type { FilesAPI } from "@/lib/api/types"
import { createContentCachedFiles } from "./content-cache-owner"

const deferred = <T>() => {
  let resolve!: (value: T) => void
  const promise = new Promise<T>((res) => { resolve = res })
  return { promise, resolve }
}

describe("content cache owner", () => {
  test("reuses only strongly validated content", async () => {
    let reads = 0
    const files = {
      readFile: async (path: string) => ({ path, content: `value-${++reads}` }),
      statFile: async () => ({ isFile: true, isDirectory: false, size: 7, mtimeMs: 1 }),
    } as unknown as FilesAPI
    const owner = createContentCachedFiles(files)

    expect((await owner.files.readFile!("file.ts")).content).toBe("value-1")
    expect((await owner.files.readFile!("file.ts")).content).toBe("value-1")
    expect(reads).toBe(1)
    owner.dispose()
  })

  test("does not retain size-only reads without mtime", async () => {
    let reads = 0
    const owner = createContentCachedFiles({
      readFile: async (path: string) => ({ path, content: `value-${++reads}` }),
      statFile: async () => ({ isFile: true, isDirectory: false, size: 7 }),
    } as unknown as FilesAPI)

    await owner.files.readFile!("file.ts")
    await owner.files.readFile!("file.ts")
    expect(reads).toBe(2)
    owner.dispose()
  })

  test("retries a read that overlaps a write", async () => {
    const firstRead = deferred<{ path: string; content: string }>()
    let content = "old"
    let reads = 0
    const owner = createContentCachedFiles({
      readFile: async (path: string) => {
        reads += 1
        return reads === 1 ? firstRead.promise : { path, content }
      },
      statFile: async () => ({ isFile: true, isDirectory: false, size: content.length, mtimeMs: content === "old" ? 1 : 2 }),
      writeFile: async (_path: string, next: string) => { content = next },
    } as unknown as FilesAPI)

    const reading = owner.files.readFile!("file.ts")
    await owner.files.writeFile!("file.ts", "new")
    firstRead.resolve({ path: "file.ts", content: "old" })

    expect((await reading).content).toBe("new")
    expect(reads).toBe(2)
    owner.dispose()
  })

  test("separates identical paths by directory scope", async () => {
    let reads = 0
    const owner = createContentCachedFiles({
      readFile: async (path: string, options?: Parameters<NonNullable<FilesAPI['readFile']>>[1]) => ({ path, content: `${options?.directory}-${++reads}` }),
      statFile: async () => ({ isFile: true, isDirectory: false, size: 1, mtimeMs: 1 }),
    } as unknown as FilesAPI)

    const first = await owner.files.readFile!("file.ts", { directory: "/a" })
    const second = await owner.files.readFile!("file.ts", { directory: "/b" })
    expect(first.content).toBe("/a-1")
    expect(second.content).toBe("/b-2")
    owner.dispose()
  })

  test("disposed owners throw on subsequent reads", async () => {
    const owner = createContentCachedFiles({
      readFile: async (path: string) => ({ path, content: "value" }),
      statFile: async () => ({ isFile: true, isDirectory: false, size: 5, mtimeMs: 1 }),
    } as unknown as FilesAPI)

    owner.dispose()
    await expect(owner.files.readFile!("notes.txt", { optional: true, directory: "/tmp/project" }))
      .rejects.toThrow("File cache owner disposed")
  })

  test("runtime endpoint changes clear cache but keep serving reads", async () => {
    const originalWindow = globalThis.window
    const events = new EventTarget()
    Object.defineProperty(globalThis, "window", {
      configurable: true,
      value: {
        addEventListener: events.addEventListener.bind(events),
        removeEventListener: events.removeEventListener.bind(events),
        dispatchEvent: events.dispatchEvent.bind(events),
      },
    })

    try {
      let reads = 0
      const owner = createContentCachedFiles({
        readFile: async (path: string) => ({ path, content: `value-${++reads}` }),
        statFile: async () => ({ isFile: true, isDirectory: false, size: 7, mtimeMs: 1 }),
      } as unknown as FilesAPI)

      expect((await owner.files.readFile!("notes.txt")).content).toBe("value-1")
      window.dispatchEvent(new CustomEvent("openchamber:runtime-endpoint-will-change", {
        detail: {
          apiBaseUrl: "http://127.0.0.1:3902",
          previousApiBaseUrl: "http://127.0.0.1:3901",
          runtimeKey: "url:http://127.0.0.1:3902",
          previousRuntimeKey: "url:http://127.0.0.1:3901",
        },
      }))
      expect((await owner.files.readFile!("notes.txt")).content).toBe("value-2")
      expect(reads).toBe(2)
      owner.dispose()
    } finally {
      Object.defineProperty(globalThis, "window", {
        configurable: true,
        value: originalWindow,
      })
    }
  })
})