import { describe, expect, it } from 'vitest'
import { Context } from 'cordis'
import { createScope, scopeTarget } from '@deepseek-ai/dsh-scope'
import { CallId } from '@deepseek-ai/dsh-llm'
import SessionStore, { SessionId, TOOL_NOT_STARTED } from '@deepseek-ai/dsh-session'
import * as SessionInvariant from '@deepseek-ai/dsh-session/invariant'
import InvariantService, { InvariantError } from '@deepseek-ai/dsh-invariants'

async function setup(): Promise<{ ctx: Context; fiber: Awaited<ReturnType<Context['plugin']>> }> {
  const ctx = new Context()
  await ctx.plugin(SessionStore)
  await ctx.plugin(InvariantService)
  const fiber = await ctx.plugin(SessionInvariant)
  return { ctx, fiber }
}

describe('session-log invariants', () => {
  it('keeps registration global when the companion is mounted under a scope', async () => {
    const ctx = new Context()
    await ctx.plugin(SessionStore)
    await ctx.plugin(InvariantService)
    let scopedCtx!: Context
    await ctx.plugin(Object.assign((inner: Context) => {
      scopedCtx = createScope(inner, {}).ctx
    }, { inject: ['sessions', 'invariants'] }))
    await scopedCtx.plugin(SessionInvariant)
    const session = ctx.sessions.create(SessionId('global-under-scoped-invariants'))
    expect(() => {
      session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
      session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
    }).not.toThrow()
  })

  it('accepts a well-formed turn, step, and tool sequence', async () => {
    const { ctx } = await setup()
    const session = ctx.sessions.create()
    expect(() => {
      session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
      session.append('user/message', { content: [{ type: 'text', text: 'hi' }], source: { kind: 'user' } }, { surfaceOp: 'append' })
      session.append('step/start', { turn: 1, step: 1 })
      session.append('assistant/chunk', { turn: 1, step: 1, chunk: { type: 'text-delta', index: 0, text: 'h' } })
      session.append('assistant/message', {
        provenance: { provider: 'mock', model: 'mock' },
        turn: 1,
        step: 1,
        content: [{ type: 'tool-call', id: CallId('c1'), name: 'echo', arguments: '{}' }],
      }, { surfaceOp: 'append' })
      session.append('tool/call', { turn: 1, step: 1, callId: CallId('c1'), name: 'echo', arguments: '{}' })
      session.append('tool/result', { turn: 1, step: 1, callId: CallId('c1'), content: [], isError: false }, { surfaceOp: 'append' })
      session.append('step/end', { turn: 1, step: 1 })
      session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
    }).not.toThrow()
  })

  it('does not advance committed trace state when a later dispatch listener vetoes', async () => {
    const { ctx } = await setup()
    const session = ctx.sessions.create(SessionId('dispatch-veto-rollback'))
    let veto = true
    ctx.on('internal/dispatch', (_mode, name) => {
      if (name !== 'session/event' || !veto) return
      veto = false
      throw new Error('later dispatch veto')
    })
    expect(() => session.append('turn/start', {
      turn: 1,
      trigger: { kind: 'message', source: { kind: 'user' } },
    })).toThrow('later dispatch veto')
    expect(session.events).toEqual([])
    expect(() => {
      session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
      session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
    }).not.toThrow()
  })

  it('applies the committed transition after another postcommit observer throws', async () => {
    const { ctx } = await setup()
    const warnings: string[] = []
    ctx.logger.warn = ((message: unknown) => { warnings.push(String(message)) }) as typeof ctx.logger.warn
    const session = ctx.sessions.create(SessionId('postcommit-peer'))
    ctx.on('session/event', () => { throw new Error('hostile observer') }, { prepend: true })
    expect(() => {
      session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
      session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
    }).not.toThrow()
    expect(warnings).toHaveLength(2)
  })

  it('rejects non-monotonic event sequence numbers', async () => {
    const { ctx } = await setup()
    const session = ctx.sessions.create()
    ctx.emit(scopeTarget(session, undefined), 'session/event', session, {
      type: 'turn/start',
      seq: 0,
      time: 1,
      data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } },
    } as never)
    expect(() => { ctx.emit(scopeTarget(session, undefined), 'session/event', session, {
      type: 'turn/end',
      seq: 0,
      time: 2,
      data: { turn: 1, reason: { kind: 'completed' } },
    } as never) }).toThrow(/seq must strictly increase/)
  })

  it('enforces turn numbering and enclosure', async () => {
    const first = await setup()
    const open = first.ctx.sessions.create()
    open.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    expect(() => open.append('turn/start', { turn: 2, trigger: { kind: 'message', source: { kind: 'user' } } }))
      .toThrow(/turn 1 is still open/)
    expect(() => open.append('turn/end', { turn: 2, reason: { kind: 'completed' } }))
      .toThrow(/does not match open turn 1/)

    const second = (await setup()).ctx.sessions.create()
    second.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    second.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
    expect(() => second.append('turn/start', { turn: 3, trigger: { kind: 'message', source: { kind: 'user' } } }))
      .toThrow(/expected turn 2, got 3/)

    const outside = (await setup()).ctx.sessions.create()
    expect(() => outside.append('user/message', {
      content: [{ type: 'text', text: 'hi' }],
      source: { kind: 'user' },
    }, { surfaceOp: 'append' })).toThrow(/outside any open turn/)
    expect(() => outside.append('steering/message', {
      turn: 1,
      content: [{ type: 'text', text: 'go' }],
      source: { kind: 'user' },
    }, { surfaceOp: 'append' })).toThrow(/outside any open turn/)
    // Merge-extensible session events use the same default enclosure branch.
    const appendUnknown = outside.append.bind(outside) as (type: string, data: unknown) => unknown
    expect(() => { appendUnknown('plugin/marker', {}) }).toThrow(/outside any open turn/)
  })

  it('enforces open-step identity and numbering', async () => {
    const wrongTurn = (await setup()).ctx.sessions.create()
    wrongTurn.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    expect(() => wrongTurn.append('step/start', { turn: 2, step: 1 })).toThrow(/open turn is 1/)

    const nested = (await setup()).ctx.sessions.create()
    nested.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    nested.append('step/start', { turn: 1, step: 1 })
    expect(() => nested.append('step/start', { turn: 1, step: 2 })).toThrow(/while step 1 is still open/)
    expect(() => nested.append('turn/end', { turn: 1, reason: { kind: 'completed' } }))
      .toThrow(/while step 1 is still open/)
    expect(() => nested.append('step/end', { turn: 1, step: 2 })).toThrow(/open is turn 1\/step 1/)
    expect(() => nested.append('assistant/message', {
      provenance: { provider: 'mock', model: 'mock' },
      turn: 1,
      step: 2,
      content: [],
    }, { surfaceOp: 'append' })).toThrow(/open is turn 1\/step 1/)

    const skipped = (await setup()).ctx.sessions.create()
    skipped.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    skipped.append('step/start', { turn: 1, step: 1 })
    skipped.append('step/end', { turn: 1, step: 1 })
    expect(() => skipped.append('step/start', { turn: 1, step: 3 }))
      .toThrow(/expected step 2 in turn 1, got 3/)
  })

  it('requires step-scoped stream and tool events to name the open step', async () => {
    const chunk = (await setup()).ctx.sessions.create()
    chunk.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    expect(() => chunk.append('assistant/chunk', {
      turn: 1,
      step: 1,
      chunk: { type: 'text-delta', index: 0, text: 'x' },
    })).toThrow(/open is turn 1\/step null/)

    const tool = (await setup()).ctx.sessions.create()
    tool.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    tool.append('step/start', { turn: 1, step: 1 })
    expect(() => tool.append('tool/result', {
      turn: 1,
      step: 1,
      callId: CallId('ghost'),
      content: [],
      isError: false,
    }, { surfaceOp: 'append' })).toThrow(/no prior tool\/call/)
  })

  it('keeps fresh tool-result appends open-step checked', async () => {
    const { ctx } = await setup()
    const session = ctx.sessions.create()
    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    expect(() => session.append('tool/result', {
      turn: 1,
      step: 1,
      callId: CallId('closed'),
      content: [],
      isError: false,
    }, { surfaceOp: 'append' })).toThrow(/open is turn 1\/step null/)
  })

  it('treats a validated tool-result replacement as a turn-enclosed rewrite', async () => {
    const { ctx } = await setup()
    const session = ctx.sessions.create()
    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    session.append('step/start', { turn: 1, step: 1 })
    session.append('tool/call', {
      turn: 1,
      step: 1,
      callId: CallId('rewrite'),
      name: 'echo',
      arguments: '{}',
    })
    const original = session.append('tool/result', {
      turn: 1,
      step: 1,
      callId: CallId('rewrite'),
      content: [{ type: 'text', text: 'original' }],
      isError: false,
    }, { surfaceOp: 'append' })
    session.append('step/end', { turn: 1, step: 1 })
    session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })

    session.append('turn/start', { turn: 2, trigger: { kind: 'message', source: { kind: 'user' } } })
    expect(() => session.append('tool/result', {
      ...original.data,
      content: [{ type: 'text', text: 'pruned' }],
    }, {
      surfaceOp: { op: 'replace', start: original.seq, end: original.seq },
      sourceEventSeqs: [original.seq],
    })).not.toThrow()
  })

  it('rejects a tool-result replacement outside a turn', async () => {
    const { ctx } = await setup()
    const session = ctx.sessions.create()
    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    session.append('step/start', { turn: 1, step: 1 })
    session.append('tool/call', {
      turn: 1,
      step: 1,
      callId: CallId('rewrite'),
      name: 'echo',
      arguments: '{}',
    })
    const original = session.append('tool/result', {
      turn: 1,
      step: 1,
      callId: CallId('rewrite'),
      content: [{ type: 'text', text: 'original' }],
      isError: false,
    }, { surfaceOp: 'append' })
    session.append('step/end', { turn: 1, step: 1 })
    session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })

    expect(() => session.append('tool/result', {
      ...original.data,
      content: [{ type: 'text', text: 'pruned' }],
    }, {
      surfaceOp: { op: 'replace', start: original.seq, end: original.seq },
      sourceEventSeqs: [original.seq],
    })).toThrow(/outside any open turn/)
  })

  it('allows not-started repair results and unresolved calls at step end', async () => {
    const repaired = (await setup()).ctx.sessions.create()
    expect(() => {
      repaired.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
      repaired.append('step/start', { turn: 1, step: 1 })
      repaired.append('tool/result', {
        turn: 1,
        step: 1,
        callId: CallId('crashed'),
        content: [],
        isError: true,
        error: { name: 'ToolNotStartedError', code: TOOL_NOT_STARTED },
      }, { surfaceOp: 'append' })
      repaired.append('step/end', { turn: 1, step: 1 })
      repaired.append('turn/end', { turn: 1, reason: { kind: 'interrupted' } })
    }).not.toThrow()

    const unresolved = (await setup()).ctx.sessions.create()
    expect(() => {
      unresolved.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
      unresolved.append('step/start', { turn: 1, step: 1 })
      unresolved.append('tool/call', { turn: 1, step: 1, callId: CallId('c1'), name: 'echo', arguments: '{}' })
      unresolved.append('step/end', { turn: 1, step: 1 })
      unresolved.append('turn/end', { turn: 1, reason: { kind: 'error', step: 1, message: 'boom' } })
    }).not.toThrow()
  })

  it('does not let a result in a later step satisfy an earlier call', async () => {
    const { ctx } = await setup()
    const session = ctx.sessions.create()
    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    session.append('step/start', { turn: 1, step: 1 })
    session.append('tool/call', { turn: 1, step: 1, callId: CallId('c1'), name: 'echo', arguments: '{}' })
    session.append('step/end', { turn: 1, step: 1 })
    session.append('step/start', { turn: 1, step: 2 })
    expect(() => session.append('tool/result', {
      turn: 1,
      step: 2,
      callId: CallId('c1'),
      content: [],
      isError: false,
    }, { surfaceOp: 'append' })).toThrow(/no prior tool\/call in this step/)
  })

  it('replays seeded sessions and tracks each session independently', async () => {
    const { ctx } = await setup()
    const badSeed = [
      { type: 'turn/start' as const, seq: 0, time: 0, data: { turn: 1, trigger: { kind: 'message' as const, source: { kind: 'user' as const } } } },
      { type: 'turn/start' as const, seq: 1, time: 0, data: { turn: 2, trigger: { kind: 'message' as const, source: { kind: 'user' as const } } } },
    ]
    expect(() => ctx.sessions.create(undefined, { seed: badSeed })).toThrow(InvariantError)

    const a = ctx.sessions.create(SessionId('a'))
    const b = ctx.sessions.create(SessionId('b'))
    a.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    expect(() => b.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } }))
      .not.toThrow()
  })

  it('rebuilds trace state for sessions that exist when the companion reloads', async () => {
    const { ctx, fiber } = await setup()
    const session = ctx.sessions.create()
    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    session.append('step/start', { turn: 1, step: 1 })
    await fiber.dispose()
    await ctx.plugin(SessionInvariant)
    expect(() => session.append('assistant/chunk', {
      turn: 1,
      step: 1,
      chunk: { type: 'text-delta', index: 0, text: 'h' },
    })).not.toThrow()
    expect(() => session.append('turn/start', { turn: 2, trigger: { kind: 'message', source: { kind: 'user' } } }))
      .toThrow(/turn 1 is still open/)
  })

  it('removes all listeners when the companion is disposed', async () => {
    const { ctx, fiber } = await setup()
    const session = ctx.sessions.create()
    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    await fiber.dispose()
    expect(() => session.append('turn/start', {
      turn: 2,
      trigger: { kind: 'message', source: { kind: 'user' } },
    })).not.toThrow()
  })
})