import { mkdtempSync } from 'node:fs'
import { tmpdir } from 'node:os'
import { join } from 'node:path'
import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
import type { Context } from 'cordis'
import type { Agent } from '@deepseek-ai/dsh-agent'
import { agentEvents } from '@deepseek-ai/dsh-agent'
import type { GenerateOptions, StreamChunk } from '@deepseek-ai/dsh-llm'
import { LlmAdapter } from '@deepseek-ai/dsh-llm'
import type { SessionId } from '@deepseek-ai/dsh-session'
import type { HostFrame, MuxFrame } from '@deepseek-ai/dsh-host-apiproxy/api'
import type { RpcRequest, RpcResponse } from '@deepseek-ai/dsh-host-apiproxy/api/rpc'
import { RpcId } from '@deepseek-ai/dsh-host-apiproxy/api/rpc'
import { bootHost, startHost, type HostHandle, type RunningHost } from '../src/index.ts'

/** Scripted adapter: each model call consumes the next chunk list; 'hang' streams then waits for abort. */
class ScriptedAdapter extends LlmAdapter {
  constructor(private script: (StreamChunk[] | 'hang')[]) {
    super()
  }

  async * stream(options: GenerateOptions): AsyncIterable<StreamChunk> {
    const entry = this.script.shift()
    if (!entry) throw new Error('ScriptedAdapter: script exhausted')
    if (entry === 'hang') {
      yield { type: 'block-start', index: 0, blockType: 'text' }
      await new Promise<void>((_resolve, reject) => {
        options.signal?.addEventListener('abort', () => { reject(new Error('aborted')) }, { once: true })
      })
      return
    }
    yield * entry
  }
}

function textResponse(text: string): StreamChunk[] {
  return [
    { type: 'block-start', index: 0, blockType: 'text' },
    { type: 'text-delta', index: 0, text },
    { type: 'block-end', index: 0, block: { type: 'text', text } },
    { type: 'usage', usage: { inputTokens: 10, outputTokens: text.length } },
    { type: 'finish', reason: { kind: 'stop' } },
  ]
}

function request<P>(payload: P): RpcRequest<P> {
  return { rpcId: RpcId(`req-${String(nextRpc++)}`), payload }
}
let nextRpc = 1

function waitForIdle(ctx: Context, agent: Agent): Promise<void> {
  return new Promise((resolve) => {
    const dispose = ctx.on('agent/status', (subject: Agent, status: string) => {
      if (subject === agent && status === 'idle') {
        dispose()
        resolve()
      }
    })
  })
}

function expectOk<T>(response: RpcResponse<T>): T {
  expect(response.result.ok).toBe(true)
  if (!response.result.ok) throw new Error('unreachable')
  return response.result.value
}

let host: RunningHost | undefined

beforeEach(() => {
  vi.stubEnv('DEEPSEEK_API_KEY', 'spec-placeholder-key')
})

afterEach(async () => {
  await host?.dispose()
  host = undefined
  vi.unstubAllEnvs()
})

async function boot(script: (StreamChunk[] | 'hang')[] = []): Promise<RunningHost> {
  host = await startHost({
    boot: { persistenceRoot: mkdtempSync(join(tmpdir(), 'dsh-host-runtime-')), provider: 'scripted', model: 'test-model' },
  })
  host.ctx.llm.registerAdapter(['scripted'], new ScriptedAdapter(script))
  return host
}

describe('bootHost / startHost', () => {
  it('falls back to the deepseek defaults and disposes idempotently', async () => {
    const handle: HostHandle = await bootHost({ persistenceRoot: mkdtempSync(join(tmpdir(), 'dsh-boot-')) })
    expect(handle.defaults).toMatchObject({ provider: 'deepseek', model: 'deepseek-v4-flash' })
    expect(typeof handle.defaults.cwd).toBe('string')
    await handle.dispose()
  })

  it('startHost assembles api + handler over the same defaults and dedupes dispose', async () => {
    const running = await boot()
    expect(running.defaults).toMatchObject({ provider: 'scripted', model: 'test-model' })
    const body = JSON.stringify({ type: 'client-request', rpcId: 'r-h', method: 'host.describe', payload: {} })
    const response = await running.handler.fetch(new Request('http://x/api/host.describe', { method: 'POST', body }))
    const parsed = await response.json() as { result: { ok: boolean; value: { provider: string } } }
    expect(parsed.result.value.provider).toBe('scripted')
    const first = running.dispose()
    expect(running.dispose()).toBe(first)
    await first
    host = undefined
  })
})

describe('host.describe', () => {
  it('reports version, cwd, defaults, and the attached count', async () => {
    const { api } = await boot()
    const value = expectOk(await api.host.describe(request({})))
    expect(value).toMatchObject({ version: '0.0.1', cwd: process.cwd(), provider: 'scripted', model: 'test-model', attachedSessions: 0 })
  })
})

describe('sessions.create / list', () => {
  it('creates a session (echoing the request rpcId) and lists it newest-first', async () => {
    const { api } = await boot()
    const created = await api.sessions.create(request({ cwd: '/tmp' }))
    const { sessionId } = expectOk(created)
    expect(created.rpcId).toMatch(/^req-/)
    const second = expectOk(await api.sessions.create(request({}))).sessionId

    const { items } = expectOk(await api.sessions.list(request({})))
    expect(items.map(item => item.sessionId)).toContain(sessionId)
    expect(items.map(item => item.sessionId)).toContain(second)
    const first = items.find(item => item.sessionId === sessionId)
    expect(first?.cwd).toBe('/tmp')
    expect(first?.running).toBe(false)
    expect(first?.parentSessionId).toBeUndefined()
  })
})

describe('sessions.prompt / cancel', () => {
  it('queues a prompt whose rpcId rides into user/message, then the reply lands', async () => {
    const running = await boot([textResponse('pong')])
    const { api, ctx } = running
    const { sessionId } = expectOk(await api.sessions.create(request({})))
    const agent = ctx.agents.get(sessionId)
    expect(agent).toBeDefined()
    const idle = waitForIdle(ctx, agent as Agent)
    const promptRequest = request({ sessionId, mode: 'queue' as const, content: [{ type: 'text' as const, text: 'ping' }] })
    expectOk(await api.sessions.prompt(promptRequest))
    await idle

    const value = expectOk(await api.sessions.history(request({ sessionId })))
    const events = value.events.map(entry => entry.event)
    const userEvent = events.find(event => event.type === 'user/message') as
      | { data: { source?: { rpcId?: string } } } | undefined
    expect(userEvent?.data.source?.rpcId).toBe(promptRequest.rpcId)
    const reply = events.find(event => event.type === 'assistant/message')
    expect(reply).toBeDefined()
  })

  it('steer on an idle agent falls through to send', async () => {
    const running = await boot([textResponse('steered')])
    const { api, ctx } = running
    const { sessionId } = expectOk(await api.sessions.create(request({})))
    const idle = waitForIdle(ctx, ctx.agents.get(sessionId) as Agent)
    expectOk(await api.sessions.prompt(request({ sessionId, mode: 'steer' as const, content: [{ type: 'text' as const, text: 'now' }] })))
    await idle
  })

  it('errors session-not-found on a ghost session', async () => {
    const { api } = await boot()
    const response = await api.sessions.prompt(request({ sessionId: 'session-void' as SessionId, mode: 'queue' as const, content: [{ type: 'text' as const, text: 'x' }] }))
    expect(response.result.ok).toBe(false)
    if (!response.result.ok) expect(response.result.error.code).toBe('session-not-found')
  })

  it('maps a synchronous send throw to agent-busy', async () => {
    const { api } = await boot()
    const { sessionId } = expectOk(await api.sessions.create(request({})))
    const poisoned = [{ type: 'text', text: 'x', bad: () => 1 }] as never
    const response = await api.sessions.prompt(request({ sessionId, mode: 'queue' as const, content: poisoned }))
    expect(response.result.ok).toBe(false)
    if (!response.result.ok) expect(response.result.error.code).toBe('agent-busy')
  })

  it('cancels an attached agent and rejects an unattached one', async () => {
    const running = await boot(['hang'])
    const { api, ctx } = running
    const { sessionId } = expectOk(await api.sessions.create(request({})))
    const agent = ctx.agents.get(sessionId) as Agent
    agent.send([{ type: 'text', text: 'run forever' }])
    expectOk(await api.sessions.cancel(request({ sessionId })))

    const missing = await api.sessions.cancel(request({ sessionId: 'session-none' as SessionId }))
    expect(missing.result.ok).toBe(false)
    if (!missing.result.ok) expect(missing.result.error.code).toBe('session-not-found')
  })
})

describe('sessions.history', () => {
  it('implicitly resumes a cold session, deduplicating concurrent calls to one attach', async () => {
    const persistenceRoot = mkdtempSync(join(tmpdir(), 'dsh-host-resume-'))
    const first = await startHost({ boot: { persistenceRoot, provider: 'scripted', model: 'test-model' } })
    first.ctx.llm.registerAdapter(['scripted'], new ScriptedAdapter([textResponse('persisted')]))
    const { sessionId } = expectOk(await first.api.sessions.create(request({})))
    const agent = first.ctx.agents.get(sessionId) as Agent
    const idle = waitForIdle(first.ctx, agent)
    agent.send([{ type: 'text', text: 'save me' }])
    await idle
    await first.dispose()

    host = await startHost({ boot: { persistenceRoot, provider: 'scripted', model: 'test-model' } })
    host.ctx.llm.registerAdapter(['scripted'], new ScriptedAdapter([]))
    expect(host.ctx.agents.get(sessionId)).toBeUndefined()
    const [a, b] = await Promise.all([
      host.api.sessions.history(request({ sessionId })),
      host.api.sessions.history(request({ sessionId })),
    ])
    for (const response of [a, b]) {
      const value = expectOk(response)
      expect(value.events.some(entry => entry.event.type === 'assistant/message')).toBe(true)
    }
    expect(host.ctx.agents.get(sessionId)).toBeDefined()
    expect(host.ctx.agents.list()).toHaveLength(1)
  })

  it('errors session-not-found when resume fails, deduplicating concurrent resumes', async () => {
    const { api } = await boot()
    const ghost = 'session-ghost' as SessionId
    const [first, second] = await Promise.all([
      api.sessions.history(request({ sessionId: ghost })),
      api.sessions.history(request({ sessionId: ghost })),
    ])
    for (const response of [first, second]) {
      expect(response.result.ok).toBe(false)
      if (!response.result.ok) expect(response.result.error.code).toBe('session-not-found')
    }
  })

  it('paginates backwards on message boundaries with hasMore', async () => {
    const running = await boot([textResponse('a1'), textResponse('a2'), textResponse('a3')])
    const { api, ctx } = running
    const { sessionId } = expectOk(await api.sessions.create(request({})))
    const agent = ctx.agents.get(sessionId) as Agent
    for (const text of ['q1', 'q2', 'q3']) {
      const idle = waitForIdle(ctx, agent)
      agent.send([{ type: 'text', text }])
      await idle
    }

    const all = expectOk(await api.sessions.history(request({ sessionId })))
    expect(all.hasMore).toBe(false)
    const messageCount = all.events.filter(entry => entry.event.type === 'user/message' || entry.event.type === 'assistant/message').length
    expect(messageCount).toBe(6)

    const lastPage = expectOk(await api.sessions.history(request({ sessionId, maxMessages: 1 })))
    expect(lastPage.hasMore).toBe(true)
    expect(lastPage.events.filter(entry => entry.event.type === 'assistant/message')).toHaveLength(1)
    expect(lastPage.events.filter(entry => entry.event.type === 'user/message')).toHaveLength(0)

    const firstSeq = lastPage.events[0]?.event.seq as number
    const olderPage = expectOk(await api.sessions.history(request({ sessionId, beforeSeq: firstSeq, maxMessages: 2 })))
    expect(olderPage.events.at(-1)?.event.seq).toBeLessThan(firstSeq)
    expect(olderPage.hasMore).toBe(true)
    expect(olderPage.events.filter(entry => entry.event.type === 'user/message' || entry.event.type === 'assistant/message').length).toBe(2)
  })
})

describe('events streams', () => {
  it('mux: a pending pull wakes when a frame arrives (waiter path)', async () => {
    const running = await boot()
    const { api } = running
    const ac = new AbortController()
    const stream = api.events.mux(request({}), ac.signal)[Symbol.asyncIterator]()
    // no sessions yet: next() must pend on the queue's waiter, not the buffer
    const pending = stream.next()
    const { sessionId } = expectOk(await api.sessions.create(request({})))
    const frame = (await pending).value as RpcRequest<MuxFrame>
    expect(frame.payload).toMatchObject({ type: 'session/subscribed', sessionId })
    ac.abort()
    expect((await stream.next()).done).toBe(true)
  })

  it('lists fork lineage and announces it on the host stream', async () => {
    const running = await boot()
    const { api, ctx } = running
    const { sessionId: parent } = expectOk(await api.sessions.create(request({})))
    const ac = new AbortController()
    const stream = api.events.host(request({}), ac.signal)[Symbol.asyncIterator]()
    const child = `session-child-${String(Date.now())}` as SessionId
    const handle = await ctx.agents.create({ sessionId: child, meta: { parentSession: parent }, agentOptions: { provider: 'scripted', model: 'test-model' } })
    expect(handle.agent.id).toBe(child)
    const added = (await stream.next()).value as RpcRequest<HostFrame>
    expect(added.payload).toMatchObject({ type: 'host/session-added', sessionId: child, parentSessionId: parent })
    const { items } = expectOk(await api.sessions.list(request({})))
    expect(items.find(item => item.sessionId === child)?.parentSessionId).toBe(parent)

    await handle.dispose()
    let frame: RpcRequest<HostFrame>
    do frame = (await stream.next()).value as RpcRequest<HostFrame>
    while (frame.payload.type !== 'host/session-removed')
    expect(frame.payload).toMatchObject({ type: 'host/session-removed', sessionId: child })
    ac.abort()
  })

  it('mux: emits subscribed baselines, live session events, and new-session subscriptions until abort', async () => {
    const running = await boot([textResponse('live')])
    const { api, ctx } = running
    const { sessionId } = expectOk(await api.sessions.create(request({})))

    const ac = new AbortController()
    const stream = api.events.mux(request({}), ac.signal)[Symbol.asyncIterator]()
    const baseline = await stream.next()
    expect((baseline.value as RpcRequest<MuxFrame>).payload).toMatchObject({ type: 'session/subscribed', sessionId })

    const agent = ctx.agents.get(sessionId) as Agent
    const idle = waitForIdle(ctx, agent)
    agent.send([{ type: 'text', text: 'go' }])
    await idle
    const live = await stream.next()
    expect((live.value as RpcRequest<MuxFrame>).payload.type).toBe('session/event')

    const other = expectOk(await api.sessions.create(request({}))).sessionId
    let frame: RpcRequest<MuxFrame>
    do frame = (await stream.next()).value as RpcRequest<MuxFrame>
    while (!(frame.payload.type === 'session/subscribed' && frame.payload.sessionId === other))

    ac.abort()
    expect((await stream.next()).done).toBe(true)
  })

  it('host: session lifecycle, status flips (disposed suppressed), and agent errors', async () => {
    const running = await boot([textResponse('x')])
    const { api, ctx } = running
    const ac = new AbortController()
    const stream = api.events.host(request({}), ac.signal)[Symbol.asyncIterator]()

    const { sessionId } = expectOk(await api.sessions.create(request({})))
    const added = await stream.next()
    expect((added.value as RpcRequest<HostFrame>).payload).toMatchObject({ type: 'host/session-added', sessionId })

    const agent = ctx.agents.get(sessionId) as Agent
    const idle = waitForIdle(ctx, agent)
    agent.send([{ type: 'text', text: 'run' }])
    await idle
    const runningFrame = await stream.next()
    expect((runningFrame.value as RpcRequest<HostFrame>).payload).toMatchObject({ type: 'host/session-status', running: true })
    const idleFrame = await stream.next()
    expect((idleFrame.value as RpcRequest<HostFrame>).payload).toMatchObject({ type: 'host/session-status', running: false })

    // Raw ctx.emit lacks the scope carrier the mounted invariants plugin now
    // enforces; dispatch the way the loop does.
    agentEvents(ctx, agent).emit('agent/error', 1, 1, new Error('boom'))
    const errorFrame = await stream.next()
    expect((errorFrame.value as RpcRequest<HostFrame>).payload).toMatchObject({ type: 'host/agent-error', message: 'Error: boom' })

    ac.abort()
    // Push-after-done: an event landing between abort and generator wind-down
    // must be dropped silently, not crash the queue.
    agentEvents(ctx, agent).emit('agent/error', 1, 1, new Error('late'))
    expect((await stream.next()).done).toBe(true)
  })
})

describe('respond stub', () => {
  it('always reports not-pending (step2 registry pending)', async () => {
    const { api } = await boot()
    const receipt = await api.respond({ type: 'client-response', rpcId: RpcId('r'), result: { ok: true, value: null } })
    expect(receipt).toEqual({ accepted: false, reason: 'not-pending' })
  })
})