import { createUserMessage } from '@deepseek-ai/dsh-llm'
import { describe, expect, it } from 'vitest'
import { Context } from 'cordis'
import { type Agent, type AgentOptions } from '@deepseek-ai/dsh-agent'
import { Session, SessionId } from '@deepseek-ai/dsh-session'
import AgentLoop from '@deepseek-ai/dsh-agent-loop'
import { mountAgentLoopTestDependencies } from '@deepseek-ai/dsh-agent-loop-testkit'
import InvariantService from '@deepseek-ai/dsh-invariants'
import * as SessionInvariant from '@deepseek-ai/dsh-session/invariant'
import * as AgentInvariant from '@deepseek-ai/dsh-agent/invariant'
import * as AgentLoopInvariant from '@deepseek-ai/dsh-agent-loop/invariant'
import SubagentService, { SUBAGENT_DESCRIPTOR_VERSION, SubagentError } from '@deepseek-ai/dsh-subagent'
import { defineContentToolFixture } from '@deepseek-ai/dsh-tools'
import { maxTokensResponse, MockAdapter, textResponse, toolCallResponse } from '../../../core/agent-loop/tests/mock-adapter.ts'
import { resumeInProcessRun, startInProcessRun } from '../src/index.ts'

type Script = ConstructorParameters<typeof MockAdapter>[0]

async function mountInvariants(ctx: Context): Promise<void> {
  await ctx.plugin(InvariantService)
  await ctx.plugin(SessionInvariant)
  await ctx.plugin(AgentInvariant)
  await ctx.plugin(AgentLoopInvariant)
}

async function setup(script: Script, parentOptions: Partial<AgentOptions> = {}) {
  const ctx = new Context()
  await mountAgentLoopTestDependencies(ctx)
  await mountInvariants(ctx)
  await ctx.plugin(AgentLoop, { agents: [] })
  await ctx.plugin(SubagentService)
  const adapter = new MockAdapter(script)
  ctx.llm.registerAdapter(['mock'], adapter)
  const parent = ctx.agentLoop.create(SessionId('parent'), { provider: 'mock', model: 'mock', ...parentOptions })
  return { ctx, parent, adapter }
}

function request(parent: Agent, signal = new AbortController().signal) {
  return { prompt: [{ type: 'text' as const, text: 'child task' }], parent, signal }
}

function continuableRequest(parent: Agent) {
  const sessionId = SessionId('continuable-child')
  return {
    ...request(parent),
    continuation: {
      sessionId,
      descriptor: {
        version: SUBAGENT_DESCRIPTOR_VERSION,
        provider: 'spawn',
        agentProvider: 'mock',
        agentModel: 'mock',
      },
    },
  }
}

function text(blocks: readonly { type: string; text?: string }[]): string {
  return blocks.filter(block => block.type === 'text').map(block => block.text).join('')
}

describe('startInProcessRun', () => {
  it('returns only after publication, drives a fresh child, and disposes it', async () => {
    const { ctx, parent } = await setup([textResponse('driver answer')])
    const run = await startInProcessRun(request(parent), {})
    expect(ctx.agents.get(run.id)).toBeDefined()
    const result = await run.result
    expect(result.stopReason).toBe('completed')
    expect(text(result.output)).toBe('driver answer')
    expect(ctx.agents.get(run.id)!.options.subagentDepth).toBe(1)
    await run.dispose()
    await run.dispose()
    expect(ctx.agents.get(run.id)).toBeUndefined()
  })

  it('requires a final durability checkpoint for a continuable child', async () => {
    const { ctx, parent } = await setup([textResponse('driver answer')])
    const failure = new Error('disk full')
    let flushes = 0
    ctx.on('session/flush', (session) => {
      if (session.header.parentSession === undefined) return
      flushes++
      throw failure
    })

    const run = await startInProcessRun(continuableRequest(parent), {})
    const caught: unknown = await run.result.catch((error: unknown) => error)
    expect(caught).toBeInstanceOf(SubagentError)
    const durabilityError = caught as SubagentError
    expect(durabilityError.code).toBe('DURABILITY_FAILED')
    expect(durabilityError.cause).toBe(failure)
    expect(durabilityError.message).toContain(
      'the latest child state was not confirmed persisted and may be unavailable or stale on resume: disk full',
    )
    expect(flushes).toBe(2)
    await run.dispose()
  })

  it('completes a continuable child when the final checkpoint retries a transient flush failure', async () => {
    const { ctx, parent } = await setup([textResponse('driver answer')])
    let flushes = 0
    ctx.on('session/flush', (session) => {
      if (session.header.parentSession === undefined) return
      flushes++
      if (flushes === 1) throw new Error('temporary append failure')
    })

    const run = await startInProcessRun(continuableRequest(parent), {})
    await expect(run.result).resolves.toMatchObject({ stopReason: 'completed' })
    expect(flushes).toBe(2)
    await run.dispose()
  })

  it.each([
    { checkpoint: 'succeeds', failure: undefined },
    { checkpoint: 'fails', failure: new Error('disk full') },
  ])('lets cancellation own the result when the final durability checkpoint $checkpoint', async ({ failure }) => {
    const { ctx, parent } = await setup([textResponse('driver answer')])
    const checkpointStarted = Promise.withResolvers<undefined>()
    const releaseCheckpoint = Promise.withResolvers<undefined>()
    let flushes = 0
    ctx.on('session/flush', async (session) => {
      if (session.header.parentSession === undefined) return
      flushes++
      if (flushes !== 2) return
      checkpointStarted.resolve(undefined)
      await releaseCheckpoint.promise
      if (failure !== undefined) throw failure
    })
    const controller = new AbortController()

    const run = await startInProcessRun({
      ...continuableRequest(parent),
      signal: controller.signal,
    }, {})
    await checkpointStarted.promise
    controller.abort()
    releaseCheckpoint.resolve(undefined)

    await expect(run.result).resolves.toMatchObject({ stopReason: 'aborted' })
    expect(flushes).toBe(2)
    await run.dispose()
  })

  it('keeps foreground runs best-effort when their turn checkpoint fails', async () => {
    const { ctx, parent } = await setup([textResponse('driver answer')])
    let flushes = 0
    ctx.on('session/flush', (session) => {
      if (session.header.parentSession === undefined) return
      flushes++
      throw new Error('disk full')
    })

    const run = await startInProcessRun(request(parent), {})
    await expect(run.result).resolves.toMatchObject({ stopReason: 'completed' })
    expect(flushes).toBe(1)
    await run.dispose()
  })

  it('reports the message-turn outcome when a later non-message turn completes during flush', async () => {
    const { ctx, parent } = await setup([maxTokensResponse('partial answer')])
    let injected = false
    ctx.on('session/flush', (session) => {
      if (injected || session.header.parentSession === undefined) return
      const lastEnd = session.events.findLast(event => event.type === 'turn/end')
      if (lastEnd?.type !== 'turn/end' || lastEnd.data.reason.kind !== 'max-tokens') return
      injected = true
      const turn = lastEnd.data.turn + 1
      session.append('turn/start', {
        turn,
        trigger: { kind: 'injection', source: { kind: 'plugin', plugin: 'late-metadata' } },
      })
      session.append('user/message', createUserMessage({
        content: [{ type: 'text', text: 'late metadata' }],
        source: { kind: 'plugin', plugin: 'late-metadata' },
      }), { surfaceOp: 'append' })
      session.append('turn/end', { turn, reason: { kind: 'completed' } })
    })

    const run = await startInProcessRun(request(parent), {})
    const result = await run.result
    const child = ctx.agents.get(run.id)!

    expect(injected).toBe(true)
    expect(child.session.events.findLast(event => event.type === 'turn/end'))
      .toMatchObject({ data: { reason: { kind: 'completed' } } })
    expect(result.stopReason).toBe('max-tokens')
    await run.dispose()
  })

  it('seeds a forked child but reads only the child-owned output', async () => {
    const { ctx, parent } = await setup([textResponse('parent answer'), textResponse('child answer')])
    parent.followup(createUserMessage({ content: [{ type: 'text', text: 'parent question' }], source: { kind: 'user' } }))
    await parent.whenIdle()
    const seed = parent.session.events.slice()
    const run = await startInProcessRun(request(parent), { seed })
    const result = await run.result
    expect(text(result.output)).toBe('child answer')
    const child = ctx.agents.get(run.id)!
    expect(child.session.header.seedLength).toBe(seed.length)
    expect(child.session.events.slice(0, seed.length)).toEqual(seed)
    await run.dispose()
  })

  it('persists the child depth in its session header', async () => {
    const { ctx, parent } = await setup([textResponse('child answer')])
    const run = await startInProcessRun(request(parent), {})
    await run.result
    // The recursion budget is durable session data, not only runtime options —
    // a depth that lived only in AgentOptions would reset to 0 on resume.
    expect(ctx.agents.get(run.id)!.session.header.delegationDepth).toBe(1)
    await run.dispose()
  })

  it('inherits the parent output-token cap and accepts an explicit child override', async () => {
    const { ctx, parent, adapter } = await setup(
      [textResponse('inherited'), textResponse('overridden')],
      { maxTokens: 111 },
    )
    const inherited = await startInProcessRun(request(parent), {})
    await inherited.result
    expect(adapter.requests[0]?.maxTokens).toBe(111)
    expect(ctx.agents.get(inherited.id)?.options.maxTokens).toBe(111)
    await inherited.dispose()

    const overridden = await startInProcessRun({
      ...request(parent),
      agentOptions: { maxTokens: 222 },
    }, {})
    await overridden.result
    expect(adapter.requests[1]?.maxTokens).toBe(222)
    expect(ctx.agents.get(overridden.id)?.options.maxTokens).toBe(222)
    await overridden.dispose()
  })

  it('counts a RESUMED child by its persisted header depth, not the absent runtime depth', async () => {
    // Resume rebuilds runtime options, so the durable header must keep this
    // depth-1 child from delegating as though it were top-level.
    const { ctx } = await setup([textResponse('unused')])
    const resumed = (await ctx.agents.create({
      sessionId: SessionId('resumed-child'),
      meta: { parentSession: SessionId('root'), delegationDepth: 1 },
      agentOptions: { provider: 'mock', model: 'mock' },
      signal: new AbortController().signal,
    })).agent
    await expect(startInProcessRun({ ...request(resumed), maxDepth: 1 }, {}))
      .rejects.toMatchObject({ name: 'SubagentDepthError', attemptedDepth: 2, maxDepth: 1 })
  })

  it('lets runtime options deepen but never lower the persisted depth', async () => {
    const { ctx } = await setup([textResponse('unused')])
    const parent = (await ctx.agents.create({
      sessionId: SessionId('deep-parent'),
      meta: { delegationDepth: 2 },
      agentOptions: { provider: 'mock', model: 'mock', subagentDepth: 1 },
      signal: new AbortController().signal,
    })).agent
    // Persisted 2 vs runtime 1: the child is depth 3, so maxDepth 2 rejects.
    await expect(startInProcessRun({ ...request(parent), maxDepth: 2 }, {}))
      .rejects.toMatchObject({ name: 'SubagentDepthError', attemptedDepth: 3, maxDepth: 2 })
  })

  it('rejects invalid and exceeded depth before publication', async () => {
    const { parent } = await setup([])
    await expect(startInProcessRun({ ...request(parent), maxDepth: -1 }, {}))
      .rejects.toThrow('non-negative safe integer')
    await expect(startInProcessRun({ ...request(parent), maxDepth: 0 }, {}))
      .rejects.toMatchObject({ name: 'SubagentDepthError' })
    for (const value of [Number.NaN, 1.5, -1, -0, Number.MAX_SAFE_INTEGER + 1]) {
      const malformed = { options: { subagentDepth: value }, session: { header: {} } } as unknown as Agent
      await expect(startInProcessRun(request(malformed), {}))
        .rejects.toThrow('agent subagentDepth must be a non-negative safe integer')
    }
    const maxParent = { options: { subagentDepth: Number.MAX_SAFE_INTEGER }, session: { header: {} } } as unknown as Agent
    await expect(startInProcessRun(request(maxParent), {})).rejects.toBeInstanceOf(RangeError)
  })

  it('rejects an already-aborted request without publishing a child', async () => {
    const { ctx, parent } = await setup([])
    const beforeAgents = ctx.agents.list().length
    const beforeSessions = ctx.sessions.list().length
    const controller = new AbortController()
    controller.abort('too late')
    await expect(startInProcessRun(request(parent, controller.signal), {}))
      .rejects.toThrow('aborted before child publication')
    expect(ctx.agents.list()).toHaveLength(beforeAgents)
    expect(ctx.sessions.list()).toHaveLength(beforeSessions)
  })

  it('rejects an already-aborted resume before publication', async () => {
    const { parent } = await setup([])
    const controller = new AbortController()
    controller.abort('too late')
    await expect(resumeInProcessRun({
      sessionId: SessionId('resumed-child'),
      prompt: [{ type: 'text', text: 'continue' }],
      source: { kind: 'user' },
      parent,
      signal: controller.signal,
      descriptor: { version: SUBAGENT_DESCRIPTOR_VERSION, provider: 'spawn' },
    })).rejects.toThrow('aborted before child publication')
  })

  it('resumes without inventing undeclared agent model options', async () => {
    const childId = SessionId('resumed-child')
    let flushes = 0
    const child = {
      id: childId,
      options: {},
      session: new Session(childId),
      status: 'idle',
      acceptsNextStep: false,
      ctx: {
        sessions: {
          flush: () => {
            flushes++
            return Promise.resolve()
          },
        },
      } as unknown as Context,
      send(): void {},
      reserveTurnAdmission: () => undefined,
      updateInbox: () => 'not-found',
      followup(): void {},
      steer() { return { outcome: Promise.resolve({ status: 'rejected' as const }) } },
      inject(): void {},
      cancel(): void {},
      whenIdle: () => Promise.resolve(),
    } as Agent
    let resumedOptions: unknown
    const parent = {
      ctx: {
        agents: {
          resume: (options: { agentOptions: unknown }) => {
            resumedOptions = options.agentOptions
            return Promise.resolve({ agent: child, dispose: () => Promise.resolve() })
          },
        },
      },
    } as unknown as Agent

    const run = await resumeInProcessRun({
      sessionId: childId,
      prompt: [{ type: 'text', text: 'continue' }],
      source: { kind: 'plugin', plugin: 'test-coordinator' },
      parent,
      signal: new AbortController().signal,
      descriptor: { version: SUBAGENT_DESCRIPTOR_VERSION, provider: 'spawn' },
    })
    expect(resumedOptions).toEqual({})
    await expect(run.result).resolves.toMatchObject({ stopReason: 'error' })
    expect(flushes).toBe(1)
    await run.dispose()
  })

  it('uses the request signal after publication and dispose as cancellation paths', async () => {
    const { parent, adapter } = await setup(['hang', 'hang'])
    const controller = new AbortController()
    const signalled = await startInProcessRun(request(parent, controller.signal), {})
    await new Promise(resolve => setTimeout(resolve, 30))
    controller.abort('stop child')
    await expect(signalled.result).resolves.toMatchObject({ stopReason: 'aborted' })
    expect(adapter.requests[0]?.signal?.reason).toEqual({ kind: 'parent' })
    const child = parent.ctx.agents.get(signalled.id)
    const turnEnd = child?.session.events.findLast(event => event.type === 'turn/end')
    expect(turnEnd?.type === 'turn/end' && turnEnd.data.reason).toEqual({ kind: 'aborted' })
    await signalled.dispose()

    const disposed = await startInProcessRun(request(parent), {})
    await new Promise(resolve => setTimeout(resolve, 30))
    await disposed.dispose()
    await expect(disposed.result).resolves.toMatchObject({ stopReason: 'aborted' })
  })

  it('cleans a failed unpublished setup before rejecting', async () => {
    const { ctx, parent } = await setup([])
    const beforeAgents = ctx.agents.list().length
    const beforeSessions = ctx.sessions.list().length
    await expect(startInProcessRun({
      ...request(parent),
      toolFilter: { deny: ['unknown-tool'] },
    }, {})).rejects.toThrow('unknown global tool')
    expect(ctx.agents.list()).toHaveLength(beforeAgents)
    expect(ctx.sessions.list()).toHaveLength(beforeSessions)
  })

  it('closes the abort handoff after the factory detaches its creation listener', async () => {
    const { ctx, parent } = await setup([])
    const controller = new AbortController()
    const beforeAgents = ctx.agents.list().length
    const beforeSessions = ctx.sessions.list().length
    const parentWithAbortAtHandoff = {
      options: parent.options,
      session: parent.session,
      ctx: {
        // The driver's synchronous inheritance capture probes both policy
        // services opportunistically; this stub composes neither.
        get: () => undefined,
        agents: {
          create: async (options: Parameters<typeof ctx.agents.create>[0]) => {
            const handle = await ctx.agents.create(options)
            // `create()` has detached its creation-only listener, but the
            // provider continuation has not installed its live-run listener.
            controller.abort('handoff race')
            return handle
          },
        },
      },
    } as unknown as Agent
    await expect(startInProcessRun(request(parentWithAbortAtHandoff, controller.signal), {}))
      .rejects.toThrow('aborted before child publication')
    expect(ctx.agents.list()).toHaveLength(beforeAgents)
    expect(ctx.sessions.list()).toHaveLength(beforeSessions)
  })

  it('confirmed steering rejects a settled child instead of queueing an untracked turn', async () => {
    const { ctx, parent } = await setup([textResponse('done')])
    const run = await startInProcessRun(request(parent), {})
    await run.result
    await expect(run.steer!([{ type: 'text', text: 'late' }], { kind: 'user' }))
      .rejects.toThrow(/not running; the message was not delivered/)
    const child = ctx.agents.get(run.id)!
    expect(child.session.events.some(event => event.type === 'steering/message')).toBe(false)
    await run.dispose()
  })

  it('confirmed steering rejects when a concluding tool prevents request admission', async () => {
    const { ctx, parent } = await setup([toolCallResponse('c1', 'finalize', {})])
    const enteredTool = Promise.withResolvers<undefined>()
    const releaseTool = Promise.withResolvers<undefined>()
    ctx.tools.register(defineContentToolFixture({
      name: 'finalize',
      description: 'Finish the child run.',
      parameters: {},
      async execute(_args, exec) {
        enteredTool.resolve(undefined)
        await releaseTool.promise
        exec.concludeTurn()
        return [{ type: 'text', text: 'final' }]
      },
    }))
    const run = await startInProcessRun(request(parent), {})
    const child = ctx.agents.get(run.id)!
    await enteredTool.promise

    const delivery = run.steer!([{ type: 'text', text: 'terminal race' }], { kind: 'user' })
    releaseTool.resolve(undefined)
    await expect(delivery).rejects.toThrow(/stopped before steering admission; the message was not delivered/)
    await run.result
    expect(child.session.events.some(event => event.type === 'steering/message')).toBe(false)
    await run.dispose()
  })

  it('confirmed steering fulfills only after the next request snapshot admits it', async () => {
    const { ctx, parent, adapter } = await setup([textResponse('first'), textResponse('second')])
    const enteredStopping = Promise.withResolvers<undefined>()
    const releaseStopping = Promise.withResolvers<undefined>()
    let held = false
    ctx.on('agent/turn-stopping', (agent) => {
      if (agent.session.header.parentSession === undefined || held) return
      held = true
      enteredStopping.resolve(undefined)
      return releaseStopping.promise
    })

    const run = await startInProcessRun(request(parent), {})
    const child = ctx.agents.get(run.id)!
    await enteredStopping.promise

    let settled = false
    const delivery = run.steer!([{ type: 'text', text: 'after the first step' }], { kind: 'user' })
      .then(() => { settled = true })
    await Promise.resolve()
    expect(settled).toBe(false)
    releaseStopping.resolve(undefined)
    await delivery

    const result = await run.result
    expect(adapter.requests).toHaveLength(2)
    expect(JSON.stringify(adapter.requests[1]?.messages)).toContain('after the first step')
    expect((result.output[0] as { text?: string }).text).toBe('second')
    const steering = child.session.events.find(event => event.type === 'steering/message')
    expect(steering?.type === 'steering/message' && steering.data.message.source).toEqual({ kind: 'user' })
    await run.dispose()
  })

  it('carries steering from a non-terminal flush window into a tracked next turn', async () => {
    const { ctx, parent, adapter } = await setup([textResponse('first'), textResponse('second')])
    const enteredFlush = Promise.withResolvers<undefined>()
    const releaseFlush = Promise.withResolvers<undefined>()
    let held = false
    ctx.on('session/flush', (session) => {
      if (session.header.parentSession === undefined || held) return
      if (!session.events.some(event => event.type === 'turn/end')) return
      held = true
      enteredFlush.resolve(undefined)
      return releaseFlush.promise
    })

    const run = await startInProcessRun(request(parent), {})
    const child = ctx.agents.get(run.id)!
    await enteredFlush.promise
    expect(child.status).toBe('running')

    const delivery = run.steer!([{ type: 'text', text: 'next tracked turn' }], { kind: 'user' })
    releaseFlush.resolve(undefined)
    await delivery
    const result = await run.result
    expect(adapter.requests).toHaveLength(2)
    expect(child.session.events.filter(event => event.type === 'turn/start')).toHaveLength(2)
    expect(child.session.events.some(event => event.type === 'steering/message')).toBe(false)
    expect((result.output[0] as { text?: string }).text).toBe('second')
    await run.dispose()
  })
})