import { mkdtemp, readFile, rm, writeFile } from 'node:fs/promises'
import { tmpdir } from 'node:os'
import { join } from 'node:path'
import { afterAll, describe, expect, it } from 'vitest'
import { runKvBackendContract } from '../../storage/tests/contract.ts'
import { JsonStorageBackend } from '../src/index.ts'

const roots: string[] = []

async function freshRoot(): Promise<string> {
  const root = await mkdtemp(join(tmpdir(), 'dsh-storage-json-'))
  roots.push(root)
  return root
}

afterAll(async () => {
  for (const root of roots) await rm(root, { recursive: true, force: true })
})

runKvBackendContract('json', async () => {
  const root = await freshRoot()
  return {
    backend: new JsonStorageBackend(root),
    reopen: async () => new JsonStorageBackend(root),
  }
})

describe('json backend specifics', () => {
  const descriptor = { name: 'shape', version: 1, tables: ['t'], hasGlobal: true }

  it('publishes a human-readable pretty-printed file', async () => {
    const root = await freshRoot()
    const backend = new JsonStorageBackend(root)
    const unit = await backend.kv.open(descriptor)
    await unit.putRecord('t', 'k', { hello: 'world' })
    const text = await readFile(join(root, 'shape.json'), 'utf8')
    expect(text).toBe(`${JSON.stringify(
      { unit: { name: 'shape', version: 1 }, global: null, tables: { t: { k: { hello: 'world' } } } },
      null,
      2,
    )}\n`)
    await backend.close()
  })

  it('defers materialization until the first write', async () => {
    const root = await freshRoot()
    const backend = new JsonStorageBackend(root)
    await backend.kv.open(descriptor)
    await expect(readFile(join(root, 'shape.json'), 'utf8')).rejects.toMatchObject({ code: 'ENOENT' })
    await backend.close()
  })

  it('rejects a malformed medium', async () => {
    const root = await freshRoot()
    await writeFile(join(root, 'shape.json'), 'not json at all', 'utf8')
    const backend = new JsonStorageBackend(root)
    await expect(backend.kv.open(descriptor)).rejects.toMatchObject({ code: 'malformed-medium' })
    await backend.close()
  })

  it('rejects a foreign unit header', async () => {
    const root = await freshRoot()
    await writeFile(
      join(root, 'shape.json'),
      JSON.stringify({ unit: { name: 'other', version: 1 }, global: null, tables: {} }),
      'utf8',
    )
    const backend = new JsonStorageBackend(root)
    await expect(backend.kv.open(descriptor)).rejects.toMatchObject({ code: 'malformed-medium' })
    await backend.close()
  })

  it('rejects double-open of one unit', async () => {
    const root = await freshRoot()
    const backend = new JsonStorageBackend(root)
    await backend.kv.open(descriptor)
    await expect(backend.kv.open(descriptor)).rejects.toMatchObject({ code: 'malformed-medium' })
    await backend.close()
  })
})