/**
 * write.ts — atomic disk writer (② torn-write hardening).
 *
 * The aggregator overwrites two shared files that N parallel `/ba-develop` module
 * subagents also write. Each write must be atomic (tmp + rename) so a reader — or
 * a racing aggregator — never observes a half-written file, and no temp residue is
 * left behind.
 */
import { describe, it, expect, beforeEach, afterEach } from 'vitest'
import fs from 'node:fs'
import os from 'node:os'
import path from 'node:path'
import { writeGeneratedFilesAtomic } from '../write.js'

let root: string

beforeEach(() => {
  root = fs.mkdtempSync(path.join(os.tmpdir(), 'agg-write-'))
})

afterEach(() => {
  fs.rmSync(root, { recursive: true, force: true })
})

describe('writeGeneratedFilesAtomic', () => {
  it('writes each file to its path and returns the absolute paths', () => {
    const written = writeGeneratedFilesAtomic(root, [
      { path: 'src/extensions/componentRegistry.generated.ts', content: 'A' },
      { path: 'src/extensions/moduleResources.generated.ts', content: 'B' },
    ])
    expect(written).toHaveLength(2)
    expect(fs.readFileSync(path.join(root, 'src/extensions/componentRegistry.generated.ts'), 'utf-8')).toBe('A')
    expect(fs.readFileSync(path.join(root, 'src/extensions/moduleResources.generated.ts'), 'utf-8')).toBe('B')
  })

  it('creates missing parent directories', () => {
    writeGeneratedFilesAtomic(root, [{ path: 'a/b/c/deep.ts', content: 'x' }])
    expect(fs.existsSync(path.join(root, 'a/b/c/deep.ts'))).toBe(true)
  })

  it('leaves no .tmp-* residue after writing (rename cleans up)', () => {
    writeGeneratedFilesAtomic(root, [
      { path: 'src/extensions/moduleResources.generated.ts', content: 'B' },
    ])
    const leftovers = fs
      .readdirSync(path.join(root, 'src/extensions'))
      .filter((f) => f.includes('.tmp-'))
    expect(leftovers).toEqual([])
  })

  it('overwrites an existing file in place', () => {
    writeGeneratedFilesAtomic(root, [{ path: 'src/extensions/x.ts', content: 'old' }])
    writeGeneratedFilesAtomic(root, [{ path: 'src/extensions/x.ts', content: 'new' }])
    expect(fs.readFileSync(path.join(root, 'src/extensions/x.ts'), 'utf-8')).toBe('new')
  })
})