import { createStep, createWorkflow } from '@mastra/core/workflows'
import { z } from 'zod'
import type { Approval, ForecastBundle, Proposal, ProposalStatus } from '@vpp/domain'
import { Approval as ApprovalSchema, ForecastBundle as ForecastBundleSchema, Proposal as ProposalSchema } from '@vpp/domain'
import { GatewayRejected, assertApproverIndependent, isStaleDenial } from '@vpp/services'
import type { RuntimeContext } from '../context.js'

/**
 * The safety chain as ONE workflow for every proposal type (ADR-0005,
 * docs/03 §2, docs/09 §2): rule check → simulation → envelope gate
 * (suspend for humans) → fresh check + permit → release. Every transition is
 * recorded through the case desk (event-sourced) so the run is replayable.
 */
export const LifecycleInput = z.object({ proposal: ProposalSchema, case_id: z.string().min(1) })

export const LifecycleOutcome = z.enum(['RELEASED', 'REJECTED', 'STALE', 'SIMULATION_ALERT'])

export const LifecycleOutput = z.object({
  outcome: LifecycleOutcome,
  proposal: ProposalSchema,
  permit_id: z.string().nullable(),
  receipt_id: z.string().nullable(),
  reasons: z.array(z.string()),
})

const Carry = z.object({
  proposal: ProposalSchema,
  case_id: z.string(),
  simulation_alert: z.boolean(),
  simulation_alerts: z.array(z.string()),
  approvals: z.array(ApprovalSchema),
  envelope_match: z.unknown().nullable(),
  done: LifecycleOutput.nullable(),
})
type Carry = z.infer<typeof Carry>

export const ResumeDecision = z.object({
  decision: z.enum(['approve', 'reject']),
  approver: z.object({ id: z.string().min(1), role: z.string().min(1) }),
  comment: z.string().optional(),
})
export type ResumeDecision = z.infer<typeof ResumeDecision>

const SuspendInfo = z.object({
  reason: z.string(),
  proposal_id: z.string(),
  required_level: z.string(),
  reasons: z.array(z.string()),
})

function transition(ctx: RuntimeContext, caseId: string, p: Proposal, status: ProposalStatus, extra: Record<string, unknown> = {}): Proposal {
  const next: Proposal = { ...p, status }
  ctx.caseDesk.recordProposal(caseId, next)
  if (Object.keys(extra).length) {
    ctx.events.append({ event_type: `Lifecycle.${status}`, payload: { proposal_id: p.id, digest: p.digest, ...extra }, correlation_id: caseId, causation_id: p.id })
  }
  return next
}

function priceForecastFromLineage(ctx: RuntimeContext, p: Proposal): ForecastBundle | null {
  for (const tc of [...p.lineage.tool_calls].reverse()) {
    if (tc.tool !== 'price-forecast') continue
    const parsed = ForecastBundleSchema.safeParse(ctx.snapshots.get(tc.outputs_ref))
    if (parsed.success) return parsed.data
  }
  return null
}

const finish = (c: Carry, outcome: z.infer<typeof LifecycleOutcome>, reasons: string[], permit_id: string | null = null, receipt_id: string | null = null): Carry => ({
  ...c,
  done: { outcome, proposal: c.proposal, permit_id, receipt_id, reasons },
})

/** One lifecycle workflow per runtime: steps close over that runtime's services. */
export function createProposalLifecycle(ctx: RuntimeContext) {
  const ruleCheck = createStep({
    id: 'rule-check',
    inputSchema: LifecycleInput,
    outputSchema: Carry,
    execute: async ({ inputData }) => {
      const pack = ctx.policy.pack(ctx.config.policyPackId, inputData.proposal.lineage.policy_pack_version)
      let p = transition(ctx, inputData.case_id, inputData.proposal, 'RULE_CHECK')
      const result = ctx.policy.check(p, { id: pack.id, version: pack.version }, { ledger: ctx.ledger.read(), ledgerService: ctx.ledger, snapshots: ctx.snapshots, now: ctx.clock() })
      const ref = ctx.snapshots.put(result)
      ctx.events.append({ event_type: 'RuleCheckCompleted', payload: { proposal_id: p.id, ok: result.ok, result_ref: ref, violations: result.violations }, correlation_id: inputData.case_id, causation_id: p.id })
      const carry: Carry = { proposal: p, case_id: inputData.case_id, simulation_alert: false, simulation_alerts: [], approvals: [], envelope_match: null, done: null }
      if (!result.ok) {
        p = transition(ctx, inputData.case_id, p, 'REJECTED', { by: 'rule-check', violations: result.violations })
        return finish({ ...carry, proposal: p }, 'REJECTED', result.violations.map((v) => `${v.rule_id}: ${v.message}`))
      }
      return carry
    },
  })

  const simulation = createStep({
    id: 'simulation',
    inputSchema: Carry,
    outputSchema: Carry,
    execute: async ({ inputData }) => {
      if (inputData.done) return inputData
      const p = transition(ctx, inputData.case_id, inputData.proposal, 'SIMULATION')
      const result = ctx.simulation.simulate(p, {
        now: ctx.clock(),
        priceForecast: priceForecastFromLineage(ctx, p),
        marginalCostYuanPerMwh: ctx.config.risk.marginal_cost_yuan_per_mwh,
        worstCaseLossBudgetYuan: ctx.config.worstCaseLossBudgetYuan,
      })
      const ref = ctx.snapshots.put(result)
      ctx.events.append({ event_type: 'SimulationCompleted', payload: { proposal_id: p.id, alert: result.alert, alerts: result.alerts, metrics: result.metrics, result_ref: ref }, correlation_id: inputData.case_id, causation_id: p.id })
      return { ...inputData, proposal: p, simulation_alert: result.alert, simulation_alerts: result.alerts }
    },
  })

  const envelopeGate = createStep({
    id: 'envelope-gate',
    inputSchema: Carry,
    outputSchema: Carry,
    suspendSchema: SuspendInfo,
    resumeSchema: ResumeDecision,
    execute: async ({ inputData, resumeData, suspend }) => {
      if (inputData.done) return inputData
      const now = ctx.clock()
      const p0 = inputData.proposal

      if (resumeData) {
        // —— Human decision path (I1/I2 enforced here; the AI has no route to APPROVED).
        try {
          assertApproverIndependent(p0, resumeData.approver, ctx.config.approverRoles)
        } catch (e) {
          ctx.events.append({ event_type: 'ApprovalRefused', payload: { proposal_id: p0.id, approver: resumeData.approver, reason: (e as Error).message }, correlation_id: inputData.case_id, causation_id: p0.id })
          return await suspend({ reason: `approval refused: ${(e as Error).message}`, proposal_id: p0.id, required_level: 'L2', reasons: [(e as Error).message] })
        }
        const approval: Approval = {
          id: ctx.newId('appr'),
          proposal_digest: p0.digest,
          decision: resumeData.decision === 'approve' ? 'APPROVE' : 'REJECT',
          approver: resumeData.approver,
          scope: { effect_type: p0.type, limits: {} },
          validity: { from: now, to: new Date(new Date(now).getTime() + ctx.config.bidPermitTtlMs).toISOString() },
          evidence_versions: { policy_pack_version: p0.lineage.policy_pack_version, ledger_version: ctx.ledger.read().version, data_snapshot_refs: p0.lineage.data_refs },
          ...(resumeData.comment ? { comment: resumeData.comment } : {}),
          decided_at: now,
        }
        ctx.caseDesk.recordApproval(inputData.case_id, approval)
        ctx.caseDesk.clearPending(p0.id)
        if (approval.decision === 'REJECT') {
          const p = transition(ctx, inputData.case_id, p0, 'REJECTED', { by: approval.approver.id, comment: resumeData.comment ?? null })
          return finish({ ...inputData, proposal: p, approvals: [approval] }, 'REJECTED', [`rejected by ${approval.approver.id}`])
        }
        const p = transition(ctx, inputData.case_id, p0, 'APPROVED', { by: approval.approver.id })
        return { ...inputData, proposal: p, approvals: [approval] }
      }

      // —— Automatic path.
      let p = transition(ctx, inputData.case_id, p0, 'ENVELOPE_CHECK')
      if (inputData.simulation_alert) {
        // One vote: any simulation alert escalates to a human, no exceptions.
        p = transition(ctx, inputData.case_id, p, 'PENDING_HUMAN', { because: 'simulation alert', alerts: inputData.simulation_alerts })
        ctx.caseDesk.requestApproval({ proposal_id: p.id, proposal_digest: p.digest, case_id: inputData.case_id, run_id: '', required_level: 'L2', reasons: inputData.simulation_alerts, since: now })
        return await suspend({ reason: 'simulation alert', proposal_id: p.id, required_level: 'L2', reasons: inputData.simulation_alerts })
      }
      const match = ctx.envelopes.match(p, { now, priceBaseline: priceForecastFromLineage(ctx, p)?.quantiles.p50 ?? null })
      ctx.snapshots.put(match)
      if (match.within) {
        p = transition(ctx, inputData.case_id, { ...p, envelope_ref: match.envelope_id }, 'AUTO_APPROVED', { envelope_id: match.envelope_id })
        return { ...inputData, proposal: p, envelope_match: match }
      }
      p = transition(ctx, inputData.case_id, p, 'PENDING_HUMAN', { because: 'outside envelope', reasons: match.reasons })
      ctx.caseDesk.requestApproval({ proposal_id: p.id, proposal_digest: p.digest, case_id: inputData.case_id, run_id: '', required_level: match.required_level, reasons: match.reasons, since: now })
      return await suspend({ reason: 'outside envelope', proposal_id: p.id, required_level: match.required_level, reasons: match.reasons })
    },
  })

  const freshCheckAndPermit = createStep({
    id: 'fresh-check',
    inputSchema: Carry,
    outputSchema: Carry,
    execute: async ({ inputData }) => {
      if (inputData.done) return inputData
      const now = ctx.clock()
      let p = transition(ctx, inputData.case_id, inputData.proposal, 'FRESH_CHECK')
      const result = ctx.authority.authorize(
        p,
        { approvals: inputData.approvals, envelopeMatch: (inputData.envelope_match as Parameters<typeof ctx.authority.authorize>[1]['envelopeMatch']) ?? null },
        { now, ledger: ctx.ledger, currentPolicyPackVersion: ctx.policy.current(ctx.config.policyPackId).version, offlineResources: [], permitTtlMs: ctx.config.bidPermitTtlMs },
      )
      if (isStaleDenial(result)) {
        p = transition(ctx, inputData.case_id, p, 'STALE', { reasons: result.reasons })
        return finish({ ...inputData, proposal: p }, 'STALE', result.reasons)
      }
      ctx.caseDesk.recordPermit(inputData.case_id, result)
      p = transition(ctx, inputData.case_id, p, 'AUTHORIZED', { permit_id: result.id, expires_at: result.expires_at })
      return { ...inputData, proposal: p, done: null, envelope_match: inputData.envelope_match, approvals: inputData.approvals, permit: result } as Carry & { permit: unknown }
    },
  })

  const release = createStep({
    id: 'release',
    inputSchema: Carry.extend({ permit: z.unknown().optional() }),
    outputSchema: LifecycleOutput,
    execute: async ({ inputData }) => {
      if (inputData.done) return inputData.done
      const now = ctx.clock()
      const permitId = (inputData.permit as { id: string } | undefined)?.id
      const permit = permitId ? ctx.authority.permits.get(permitId)?.value : undefined
      if (!permit) throw new Error('release reached without a permit — invariant I4 violated in workflow wiring')
      try {
        const receipt = ctx.gateway.dispatch(inputData.proposal, permit, now)
        const p = transition(ctx, inputData.case_id, inputData.proposal, 'RELEASED', { receipt_id: receipt.receipt_id, artifact_ref: receipt.artifact_ref })
        ctx.events.append({ event_type: 'ExecutionReceipt', payload: receipt, correlation_id: inputData.case_id, causation_id: p.id })
        ctx.ledger.append({
          id: ctx.newId('pos'),
          timescale: 'DAY_AHEAD',
          period: p.type === 'BID' ? p.payload.market_date : now.slice(0, 10),
          kind: 'BID_SUBMITTED',
          energy_mwh: p.type === 'BID' ? p.payload.quantities_mwh.values.reduce((s, v) => (Number(s) + Number(v)).toFixed(3), '0') : '0',
          curve: p.type === 'BID' ? p.payload.quantities_mwh : null,
          source_ref: p.digest,
          expected_version: ctx.ledger.read().version,
        })
        ctx.caseDesk.close(inputData.case_id, receipt.receipt_id, true)
        return { outcome: 'RELEASED' as const, proposal: p, permit_id: permit.id, receipt_id: receipt.receipt_id, reasons: [] }
      } catch (e) {
        if (e instanceof GatewayRejected) {
          const p = transition(ctx, inputData.case_id, inputData.proposal, 'STALE', { gateway_reasons: e.reasons })
          return { outcome: 'STALE' as const, proposal: p, permit_id: permit.id, receipt_id: null, reasons: e.reasons }
        }
        throw e
      }
    },
  })

  return createWorkflow({
    id: 'proposal-lifecycle',
    inputSchema: LifecycleInput,
    outputSchema: LifecycleOutput,
  })
    .then(ruleCheck)
    .then(simulation)
    .then(envelopeGate)
    .then(freshCheckAndPermit)
    .then(release)
    .commit()

}

export const ENVELOPE_GATE_STEP_ID = 'envelope-gate'