// Ledger Event Lifecycle Service - Event Sourcing

import { EventEmitter } from 'events';
import { ledgerService, LedgerPostingResult } from './ledger.service';
import {
  LedgerEntryType,
  LedgerEntryStatus,
  AssetType,
  MultiEntryTransaction,
} from '@/shared/types';
import prisma from '@/shared/database/prisma';
import { logger } from '@/infrastructure/monitoring/logger';


export enum LedgerEventType {
  INITIATED = 'initiated',
  VALIDATED = 'validated',
  PRE_POSTED = 'pre_posted',
  POSTED = 'posted',
  COMMITTED = 'committed',
  REPLICATED = 'replicated',
  FINALIZED = 'finalized',
  FAILED = 'failed',
}

export interface LedgerEvent {
  eventId: string;
  referenceId: string;
  eventType: LedgerEventType;
  timestamp: Date;
  data: Record<string, unknown>;
  error?: string;
}

/**
 * Ledger Event Lifecycle Service
 * Manages transaction lifecycle with event sourcing
 */
export class LedgerLifecycleService extends EventEmitter {
  /**
   * Process transaction through full lifecycle
   */
  async processTransaction(
    ledgerId: string,
    transaction: MultiEntryTransaction,
    transactionType: LedgerEntryType,
    fxRates?: Record<string, string>,
    metadata?: Record<string, unknown>
  ): Promise<LedgerPostingResult> {
    const referenceId = transaction.referenceId;
    let currentEvent: LedgerEvent | null = null;

    try {
      // 1. Initiation
      currentEvent = this.createEvent(referenceId, LedgerEventType.INITIATED, {
        ledgerId,
        transactionType,
      });
      this.emit('ledger:initiated', currentEvent);
      await this.saveEvent(currentEvent);

      // 2. Validation
      await this.validateTransaction(transaction);
      currentEvent = this.createEvent(referenceId, LedgerEventType.VALIDATED, {
        validation: 'passed',
      });
      this.emit('ledger:validated', currentEvent);
      await this.saveEvent(currentEvent);

      // 3. Pre-Posting
      currentEvent = this.createEvent(referenceId, LedgerEventType.PRE_POSTED, {
        fxRates,
        metadata,
      });
      this.emit('ledger:pre_posted', currentEvent);
      await this.saveEvent(currentEvent);

      // 4. Posting
      const postingResult = await ledgerService.postMultiEntry(
        ledgerId,
        transaction,
        transactionType,
        fxRates,
        metadata
      );
      currentEvent = this.createEvent(referenceId, LedgerEventType.POSTED, {
        entryIds: postingResult.entryIds,
        blockHash: postingResult.blockHash,
      });
      this.emit('ledger:posted', currentEvent);
      await this.saveEvent(currentEvent);

      // 5. Commitment
      currentEvent = this.createEvent(referenceId, LedgerEventType.COMMITTED, {
        blockHash: postingResult.blockHash,
      });
      this.emit('ledger:committed', currentEvent);
      await this.saveEvent(currentEvent);

      // 6. Replication (to DBIS Master Ledger)
      await this.replicateToMaster(ledgerId, postingResult);
      currentEvent = this.createEvent(referenceId, LedgerEventType.REPLICATED, {
        masterLedgerId: 'DBIS-MASTER',
      });
      this.emit('ledger:replicated', currentEvent);
      await this.saveEvent(currentEvent);

      // 7. Finalization
      currentEvent = this.createEvent(referenceId, LedgerEventType.FINALIZED, {
        status: 'settled',
      });
      this.emit('ledger:finalized', currentEvent);
      await this.saveEvent(currentEvent);

      // Update ledger entry status to settled
      await prisma.ledger_entries.updateMany({
        where: { referenceId },
        data: { status: LedgerEntryStatus.SETTLED },
      });

      return postingResult;
    } catch (error: any) {
      // Handle failure
      const errorEvent = this.createEvent(
        referenceId,
        LedgerEventType.FAILED,
        {
          error: error.message,
          previousEvent: currentEvent,
        },
        error.message
      );
      this.emit('ledger:failed', errorEvent);
      await this.saveEvent(errorEvent);

      throw error;
    }
  }

  /**
   * Validate transaction before posting
   */
  private async validateTransaction(transaction: MultiEntryTransaction): Promise<void> {
    // Validate all accounts exist
    for (const entry of transaction.entries) {
      const debitAccount = await prisma.bank_accounts.findUnique({
        where: { id: entry.debitAccountId },
      });
      const creditAccount = await prisma.bank_accounts.findUnique({
        where: { id: entry.creditAccountId },
      });

      if (!debitAccount || !creditAccount) {
        throw new Error('Account validation failed');
      }

      // Validate balance
      const amount = parseFloat(entry.amount);
      if (amount <= 0) {
        throw new Error('Invalid amount');
      }
    }

    // Validate debits equal credits
    const totalDebits = transaction.entries.reduce(
      (sum, entry) => sum + parseFloat(entry.amount),
      0
    );
    const totalCredits = transaction.entries.reduce(
      (sum, entry) => sum + parseFloat(entry.amount),
      0
    );

    if (Math.abs(totalDebits - totalCredits) > 0.00000001) {
      throw new Error('Debits and credits must balance');
    }
  }

  /**
   * Replicate to DBIS Master Ledger
   */
  private async replicateToMaster(
    sovereignLedgerId: string,
    postingResult: { entryIds: string[]; blockHash: string }
  ): Promise<void> {
    // In production, this would sync to the DBIS Master Ledger
    // For now, we'll just log the replication
    logger.info(`Replicating to DBIS Master Ledger: ${sovereignLedgerId}`, {
      entryIds: postingResult.entryIds,
      blockHash: postingResult.blockHash,
    });
  }

  /**
   * Create a ledger event
   */
  private createEvent(
    referenceId: string,
    eventType: LedgerEventType,
    data: Record<string, unknown>,
    error?: string
  ): LedgerEvent {
    return {
      eventId: `EVT-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`,
      referenceId,
      eventType,
      timestamp: new Date(),
      data,
      error,
    };
  }

  /**
   * Save event to database (event store)
   */
  private async saveEvent(event: LedgerEvent): Promise<void> {
    // In a full implementation, this would save to an event store
    // For now, we'll log it
    logger.debug('Ledger event', event);
  }

  /**
   * Get event history for a reference ID
   */
  async getEventHistory(referenceId: string): Promise<LedgerEvent[]> {
    // In production, this would query the event store
    // For now, return empty array
    return [];
  }
}

export const ledgerLifecycleService = new LedgerLifecycleService();

