// Scope 3 Aggregator
// 원장(settlement_ledger)의 CREDIT_RETIRE + nature:* 수신자 엔트리를
// 원청 기업의 Scope 3 증빙으로 자동 집계한다.
// 특허 청구항 5 (기존 6): SME 상생 Router → Scope 3 성과 자동 기록

import { getLedgerEntries } from './ledger'
import type { LedgerEntry } from '../types'

export interface Scope3Contribution {
  /** Scope 3 인증 제출 대상 (원청 기업) — referenceData.submittedTo */
  submittedTo: string
  /** 인증서 ID — referenceData.scope3CertId */
  scope3CertId: string
  /** 기여한 SME (sender_name) */
  smeName: string
  /** 돌려준 자연 주체 (receiver_name) */
  natureBeneficiary: string
  /** 톤 */
  retiredTons: number
  /** 원장 엔트리 ID */
  ledgerEntryId: string
  /** 기록 시각 */
  retiredAt: string
}

export interface Scope3Summary {
  /** 원청 기업별 총 Scope 3 크레딧 */
  byOriginator: Record<string, {
    totalTons: number
    contributions: Scope3Contribution[]
  }>
  /** 자연 주체별 누적 회복량 */
  byNatureBeneficiary: Record<string, {
    totalTons: number
    entryCount: number
  }>
  /** 전체 Scope 3 적격 톤 합계 */
  totalScope3Tons: number
  /** 전체 적격 엔트리 수 */
  entryCount: number
}

/**
 * 원장에서 Scope 3 적격 엔트리를 추출한다.
 * 조건:
 *   1) category === 'CREDIT_RETIRE'
 *   2) receiverId가 'nature:*' 네임스페이스
 *   3) referenceData.scope3CertId 존재
 */
export function extractScope3FromLedger(entries: LedgerEntry[]): Scope3Contribution[] {
  return entries
    .filter((e) => e.category === 'CREDIT_RETIRE')
    .filter((e) => typeof e.receiverId === 'string' && e.receiverId.startsWith('nature:'))
    .filter((e) => {
      const ref = (e.referenceData ?? {}) as Record<string, unknown>
      return !(ref.is_koc_registered === true || ref.isKocRegistered === true || ref.has_koc_credits === true)
    })
    .map((e) => {
      const ref = (e.referenceData ?? {}) as Record<string, unknown>
      const certId = ref.scope3CertId ?? ref.scope3_cert_id
      if (!certId) return null
      return {
        submittedTo: (ref.submittedTo as string) ?? (ref.submitted_to as string) ?? '원청 미지정',
        scope3CertId: String(certId),
        smeName: e.senderName,
        natureBeneficiary: e.receiverName,
        retiredTons: Number(e.amount),
        ledgerEntryId: e.id ?? e.transactionId,
        retiredAt: e.createdAt,
      } satisfies Scope3Contribution
    })
    .filter((x): x is Scope3Contribution => x !== null)
}

export function summarizeScope3(entries: LedgerEntry[]): Scope3Summary {
  const contributions = extractScope3FromLedger(entries)
  const byOriginator: Scope3Summary['byOriginator'] = {}
  const byNatureBeneficiary: Scope3Summary['byNatureBeneficiary'] = {}
  let totalScope3Tons = 0

  for (const c of contributions) {
    if (!byOriginator[c.submittedTo]) {
      byOriginator[c.submittedTo] = { totalTons: 0, contributions: [] }
    }
    byOriginator[c.submittedTo].totalTons += c.retiredTons
    byOriginator[c.submittedTo].contributions.push(c)

    if (!byNatureBeneficiary[c.natureBeneficiary]) {
      byNatureBeneficiary[c.natureBeneficiary] = { totalTons: 0, entryCount: 0 }
    }
    byNatureBeneficiary[c.natureBeneficiary].totalTons += c.retiredTons
    byNatureBeneficiary[c.natureBeneficiary].entryCount += 1

    totalScope3Tons += c.retiredTons
  }

  return {
    byOriginator,
    byNatureBeneficiary,
    totalScope3Tons,
    entryCount: contributions.length,
  }
}

/**
 * Live 원장에서 Scope 3 요약을 가져온다. 실패 시 빈 요약 반환.
 */
export async function fetchScope3Summary(campaignId?: string): Promise<Scope3Summary> {
  try {
    const entries = await getLedgerEntries({ campaignId, limit: 500 })
    return summarizeScope3(entries)
  } catch {
    return {
      byOriginator: {},
      byNatureBeneficiary: {},
      totalScope3Tons: 0,
      entryCount: 0,
    }
  }
}