import { afterEach, describe, expect, it, vi } from 'vitest'
import { Context } from 'cordis'
import { mkdtemp, rm, writeFile } from 'node:fs/promises'
import { tmpdir } from 'node:os'
import { join } from 'node:path'
import LlmService from '@deepseek-ai/dsh-llm'
import { credentialRef } from '@deepseek-ai/dsh-credentials'
import { CredentialsLocal } from '@deepseek-ai/dsh-credentials-local'
import { settingsNamespace } from '@deepseek-ai/dsh-settings'
import { SettingsLocal } from '@deepseek-ai/dsh-settings-local'
import * as LlmDeepSeek from '@deepseek-ai/dsh-llm-deepseek'
import { assemble } from './assemble.ts'
import { closeMockServers, mockServer, textEvents } from './mock-server.ts'

const NS = settingsNamespace('llm-deepseek')
const KEY_REF = credentialRef('DEEPSEEK_API_KEY')

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

afterEach(async () => {
  while (cleanups.length > 0) await cleanups.pop()!()
  await closeMockServers()
  vi.unstubAllEnvs()
})

async function home(): Promise<string> {
  const dir = await mkdtemp(join(tmpdir(), 'dsh-llm-dynamic-'))
  cleanups.push(() => rm(dir, { recursive: true, force: true }))
  return dir
}

interface Harness {
  ctx: Context
  settingsFiber: { dispose(): Promise<void> }
}

/**
 * Real dynamic composition: llm + settings-local + credentials-local +
 * llm-deepseek over one temp harness home. `watch: false` keeps every change
 * flowing through the in-process write path, which is deterministic; external
 * file watching is the providers' own covered concern.
 */
async function boot(dir: string, config: object): Promise<Harness> {
  const ctx = new Context()
  cleanups.push(async () => {
    await ctx.fiber.dispose()
  })
  await ctx.plugin(LlmService)
  const settingsFiber = ctx.plugin(SettingsLocal, { path: join(dir, 'settings.yaml'), watch: false })
  await settingsFiber
  await ctx.plugin(CredentialsLocal, { path: join(dir, '.env'), watch: false })
  await ctx.plugin(LlmDeepSeek, config)
  return { ctx, settingsFiber }
}

function prompt(ctx: Context) {
  return assemble(ctx, { model: 'deepseek-v4-flash', messages: [] })
}

describe('request-level dynamic configuration', () => {
  it('routes the next request with the freshly resolved base URL and credential', async () => {
    vi.stubEnv('DEEPSEEK_API_KEY', '')
    const dir = await home()
    await writeFile(join(dir, '.env'), 'DEEPSEEK_API_KEY=first-key\n')
    const serverA = await mockServer([{ kind: 'sse', events: textEvents }])
    const serverB = await mockServer([{ kind: 'sse', events: textEvents }])
    const { ctx } = await boot(dir, { baseURL: serverA.url })

    await prompt(ctx)
    expect(serverA.headers[0]?.authorization).toBe('Bearer first-key')

    await ctx.settings.update(NS, { baseURL: serverB.url })
    await ctx.credentials.set(KEY_REF, 'second-key')

    await prompt(ctx)
    // No restart, no re-registration: the next request resolved both facts.
    expect(serverA.requests).toHaveLength(1)
    expect(serverB.headers[0]?.authorization).toBe('Bearer second-key')
  })

  it('prefers a literal settings apiKey over the credential layers', async () => {
    vi.stubEnv('DEEPSEEK_API_KEY', '')
    const dir = await home()
    await writeFile(join(dir, '.env'), 'DEEPSEEK_API_KEY=file-key\n')
    const server = await mockServer([{ kind: 'sse', events: textEvents }])
    const { ctx } = await boot(dir, { baseURL: server.url })

    await ctx.settings.update(NS, { apiKey: 'literal-key' })
    await prompt(ctx)
    expect(server.headers[0]?.authorization).toBe('Bearer literal-key')
  })

  it('starts keyless and serves the next request once the key arrives', async () => {
    vi.stubEnv('DEEPSEEK_API_KEY', '')
    const dir = await home()
    const server = await mockServer([{ kind: 'sse', events: textEvents }])
    const { ctx } = await boot(dir, { baseURL: server.url })

    const keyless = await prompt(ctx)
    expect(keyless.finish).toMatchObject({ kind: 'error', failure: { code: 'MISSING_CREDENTIAL' } })
    await ctx.credentials.set(KEY_REF, 'sk-arrived')
    await prompt(ctx)
    expect(server.headers[0]?.authorization).toBe('Bearer sk-arrived')
  })

  it('advertises a live settings catalog without re-registration', async () => {
    const dir = await home()
    const { ctx } = await boot(dir, { apiKey: 'k', baseURL: 'http://127.0.0.1:1' })

    await expect(ctx.llm.listModels('deepseek-official')).resolves.toHaveLength(2)
    await ctx.settings.update(NS, { models: [{ id: 'settings-model', name: 'From Settings' }] })
    await expect(ctx.llm.listModels('deepseek-official')).resolves.toEqual([
      { provider: 'deepseek-official', id: 'settings-model', name: 'From Settings' },
    ])
  })

  it('re-registers the route in place when the captured retry policy changes, without an empty-registry window', async () => {
    const dir = await home()
    const { ctx } = await boot(dir, { apiKey: 'k', baseURL: 'http://127.0.0.1:1' })

    // Observing the topology event, not just the end state: disposing and
    // re-registering also lands on the right final registry, but publishes an
    // empty route set in between, so an observer sees the provider disappear.
    const observed: string[][] = []
    ctx.on('llm/adapters-updated', () => {
      observed.push(ctx.llm.listProviders().map(provider => provider.id))
    })

    await ctx.settings.update(NS, {
      retryPolicy: { mode: 'always', backoff: { initialDelayMs: 25, maxDelayMs: 100, jitterRatio: 0.2 } },
    })
    expect(ctx.llm.providerRetryPolicy('deepseek-official')).toEqual({
      mode: 'always',
      initialDelayMs: 25,
      maxDelayMs: 100,
      jitterRatio: 0.2,
    })
    expect(ctx.llm.listProviders()).toEqual([{ id: 'deepseek-official', name: 'DeepSeek' }])
    expect(observed).toEqual([['deepseek-official']])
  })

  it('keeps the last good options when a settings snapshot fails beyond-schema validation', async () => {
    const dir = await home()
    const { ctx } = await boot(dir, { apiKey: 'k', baseURL: 'http://127.0.0.1:1' })

    // Schema-valid but resolver-invalid: duplicate catalog ids pass the array
    // schema and fail the explicit resolve step.
    await ctx.settings.update(NS, { models: [{ id: 'dup' }, { id: 'dup' }] })
    await expect(ctx.llm.listModels('deepseek-official')).resolves.toHaveLength(2)
    await ctx.settings.update(NS, { models: [{ id: 'recovered' }] })
    await expect(ctx.llm.listModels('deepseek-official')).resolves.toEqual([
      { provider: 'deepseek-official', id: 'recovered', name: 'recovered' },
    ])
  })

  it('sends the whole last-good snapshot when a rejected one changed both the key and the URL', async () => {
    vi.stubEnv('DEEPSEEK_API_KEY', '')
    const dir = await home()
    const good = await mockServer([{ kind: 'sse', events: textEvents }])
    const rejected = await mockServer([{ kind: 'sse', events: textEvents }])
    const { ctx } = await boot(dir, { apiKey: 'good-key', baseURL: good.url })

    // One snapshot moves the endpoint AND the literal key, and fails the
    // resolve step beyond the schema (duplicate catalog ids).
    await ctx.settings.update(NS, {
      apiKey: 'rejected-key',
      baseURL: rejected.url,
      models: [{ id: 'dup' }, { id: 'dup' }],
    })

    await prompt(ctx)
    // The rejected generation contributes nothing: not its endpoint, and — the
    // regression this pins — not its key either.
    expect(rejected.requests).toHaveLength(0)
    expect(good.requests).toHaveLength(1)
    expect(good.headers[0]?.authorization).toBe('Bearer good-key')
  })

  it('falls back to the composition entry when settings detach', async () => {
    vi.stubEnv('DEEPSEEK_API_KEY', '')
    const dir = await home()
    await writeFile(join(dir, '.env'), 'DEEPSEEK_API_KEY=steady-key\n')
    const serverA = await mockServer([{ kind: 'sse', events: textEvents }])
    const serverB = await mockServer([{ kind: 'sse', events: textEvents }])
    const { ctx, settingsFiber } = await boot(dir, { baseURL: serverA.url })

    await ctx.settings.update(NS, { baseURL: serverB.url })
    await prompt(ctx)
    expect(serverB.requests).toHaveLength(1)

    await settingsFiber.dispose()
    await prompt(ctx)
    expect(serverA.requests).toHaveLength(1)
    expect(serverA.headers[0]?.authorization).toBe('Bearer steady-key')
  })
})