// Meta-Ledger System (MLS) - Core Service

import crypto from 'crypto';
import {
  LedgerType,
  LedgerState,
  MetaState,
  SynchronizationEvent,
  ConflictResolution,
  SynchronizationConfig,
  LedgerSyncRequest,
  MetaStateCommitResult,
} from './types';
import { v4 as uuidv4 } from 'uuid';
import { logger } from '@/infrastructure/monitoring/logger';

export class MLSService {
  private currentEpoch: number = 0;
  private ledgerStates: Map<string, LedgerState> = new Map();
  private config: SynchronizationConfig = {
    settlementEpochSeconds: 60, // Default: commit every 60 seconds
    conflictResolutionStrategy: 'AUTO',
    sovereignTrustWeights: {},
    deterministicOrderingRules: [],
  };

  /**
   * Register a ledger for synchronization
   */
  async registerLedger(ledgerState: LedgerState): Promise<void> {
    logger.info(`MLS: Registering ledger ${ledgerState.ledgerId}`, {
      ledgerType: ledgerState.ledgerType,
    });

    this.ledgerStates.set(ledgerState.ledgerId, ledgerState);
  }

  /**
   * Synchronize ledger state
   */
  async synchronizeLedger(request: LedgerSyncRequest): Promise<LedgerState> {
    logger.info(`MLS: Synchronizing ledger ${request.ledgerId}`);

    const ledgerState: LedgerState = {
      ledgerId: request.ledgerId,
      ledgerType: request.ledgerType,
      stateHash: request.stateHash,
      blockHeight: request.blockHeight,
      lastBlockHash: request.lastBlockHash,
      timestamp: request.timestamp,
    };

    // Check for conflicts
    const existing = this.ledgerStates.get(request.ledgerId);
    if (existing && existing.stateHash !== request.stateHash) {
      logger.warn(`MLS: Conflict detected for ledger ${request.ledgerId}`);
      await this.resolveConflict(request.ledgerId, existing, ledgerState);
    }

    this.ledgerStates.set(request.ledgerId, ledgerState);

    return ledgerState;
  }

  /**
   * Commit meta-state for current epoch
   * meta_state = HASH(scb_states + cbdc_states + commodity_states + security_states)
   */
  async commitMetaState(): Promise<MetaStateCommitResult> {
    logger.info(`MLS: Committing meta-state for epoch ${this.currentEpoch}`);

    const scbStates = this.getLedgerStatesByType([
      LedgerType.HYBRID_SOVEREIGN,
      LedgerType.DBIS_MASTER,
    ]);
    const cbdcStates = this.getLedgerStatesByType([
      LedgerType.UTXO_CBDC,
      LedgerType.ACCOUNT_CBDC,
    ]);
    const commodityStates = this.getLedgerStatesByType([LedgerType.COMMODITY]);
    const securityStates = this.getLedgerStatesByType([LedgerType.SECURITY]);

    const dbisMasterState = scbStates.find(
      (s) => s.ledgerType === LedgerType.DBIS_MASTER
    );
    if (!dbisMasterState) {
      throw new Error('DBIS Master Ledger state not found');
    }

    // Calculate meta-state hash
    const stateString =
      this.serializeStates(scbStates) +
      this.serializeStates(cbdcStates) +
      this.serializeStates(commodityStates) +
      this.serializeStates(securityStates);

    const stateHash = this.hashState(stateString);

    // Detect conflicts
    const conflicts = await this.detectConflicts(
      scbStates,
      cbdcStates,
      commodityStates,
      securityStates
    );

    // Resolve conflicts if auto-resolution enabled
    const resolvedConflicts: ConflictResolution[] = [];
    for (const conflict of conflicts) {
      if (this.config.conflictResolutionStrategy === 'AUTO') {
        const resolution = await this.resolveConflictAutomatically(conflict);
        resolvedConflicts.push(resolution);
      } else {
        resolvedConflicts.push(conflict);
      }
    }

    const metaState: MetaState = {
      id: `MLS-META-${uuidv4()}`,
      epoch: this.currentEpoch,
      committedAt: new Date(),
      stateHash,
      ledgerStates: Array.from(this.ledgerStates.values()),
      scbStates,
      cbdcStates,
      commodityStates,
      securityStates,
      dbisMasterState,
    };

    this.currentEpoch++;

    logger.info(`MLS: Meta-state committed for epoch ${metaState.epoch}`, {
      stateHash,
      conflictsDetected: conflicts.length,
    });

    return {
      metaState,
      conflictsDetected: resolvedConflicts,
      synchronized: resolvedConflicts.length === 0,
    };
  }

  /**
   * Get current meta-state
   */
  async getCurrentMetaState(): Promise<MetaState | null> {
    if (this.ledgerStates.size === 0) {
      return null;
    }

    const scbStates = this.getLedgerStatesByType([
      LedgerType.HYBRID_SOVEREIGN,
      LedgerType.DBIS_MASTER,
    ]);
    const cbdcStates = this.getLedgerStatesByType([
      LedgerType.UTXO_CBDC,
      LedgerType.ACCOUNT_CBDC,
    ]);
    const commodityStates = this.getLedgerStatesByType([LedgerType.COMMODITY]);
    const securityStates = this.getLedgerStatesByType([LedgerType.SECURITY]);

    const dbisMasterState = scbStates.find(
      (s) => s.ledgerType === LedgerType.DBIS_MASTER
    );
    if (!dbisMasterState) {
      return null;
    }

    const stateString =
      this.serializeStates(scbStates) +
      this.serializeStates(cbdcStates) +
      this.serializeStates(commodityStates) +
      this.serializeStates(securityStates);

    const stateHash = this.hashState(stateString);

    return {
      id: `MLS-META-CURRENT`,
      epoch: this.currentEpoch,
      committedAt: new Date(),
      stateHash,
      ledgerStates: Array.from(this.ledgerStates.values()),
      scbStates,
      cbdcStates,
      commodityStates,
      securityStates,
      dbisMasterState,
    };
  }

  /**
   * Configure synchronization
   */
  configure(config: Partial<SynchronizationConfig>): void {
    this.config = { ...this.config, ...config };
    logger.info('MLS: Configuration updated', this.config);
  }

  /**
   * Get ledger states by type
   */
  private getLedgerStatesByType(types: LedgerType[]): LedgerState[] {
    return Array.from(this.ledgerStates.values()).filter((state) =>
      types.includes(state.ledgerType)
    );
  }

  /**
   * Serialize ledger states for hashing
   */
  private serializeStates(states: LedgerState[]): string {
    return states
      .map((s) => `${s.ledgerId}:${s.stateHash}:${s.blockHeight}:${s.lastBlockHash}`)
      .sort()
      .join('|');
  }

  /**
   * Hash state string
   */
  private hashState(stateString: string): string {
    return crypto.createHash('sha256').update(stateString).digest('hex');
  }

  /**
   * Detect conflicts across ledgers
   */
  private async detectConflicts(
    scbStates: LedgerState[],
    cbdcStates: LedgerState[],
    commodityStates: LedgerState[],
    securityStates: LedgerState[]
  ): Promise<ConflictResolution[]> {
    const conflicts: ConflictResolution[] = [];

    // Check for timestamp conflicts
    const allStates = [...scbStates, ...cbdcStates, ...commodityStates, ...securityStates];
    const timestampMap = new Map<string, LedgerState[]>();

    for (const state of allStates) {
      const key = state.timestamp.toISOString();
      if (!timestampMap.has(key)) {
        timestampMap.set(key, []);
      }
      timestampMap.get(key)!.push(state);
    }

    // Detect double-post events (same transaction in multiple ledgers)
    // This would require transaction-level tracking in real implementation

    // Detect multi-chain race conditions
    // Check if states are diverging

    return conflicts;
  }

  /**
   * Resolve conflict between two ledger states
   */
  private async resolveConflict(
    ledgerId: string,
    existing: LedgerState,
    incoming: LedgerState
  ): Promise<LedgerState> {
    logger.warn(`MLS: Resolving conflict for ledger ${ledgerId}`);

    // Use deterministic ordering: prefer higher block height
    if (incoming.blockHeight > existing.blockHeight) {
      logger.info(`MLS: Resolved conflict by selecting higher block height`);
      return incoming;
    } else if (incoming.blockHeight < existing.blockHeight) {
      logger.info(`MLS: Resolved conflict by keeping existing state`);
      return existing;
    }

    // If block heights are equal, use sovereign trust weighting
    if (this.config.sovereignTrustWeights) {
      const existingWeight =
        existing.sovereignBankId
          ? this.config.sovereignTrustWeights[existing.sovereignBankId] || 0.5
          : 0.5;
      const incomingWeight = incoming.sovereignBankId
        ? this.config.sovereignTrustWeights[incoming.sovereignBankId] || 0.5
        : 0.5;

      if (incomingWeight > existingWeight) {
        logger.info(`MLS: Resolved conflict by sovereign trust weighting`);
        return incoming;
      }
    }

    // Default: keep existing
    return existing;
  }

  /**
   * Resolve conflict automatically
   */
  private async resolveConflictAutomatically(
    conflict: ConflictResolution
  ): Promise<ConflictResolution> {
    logger.info(`MLS: Auto-resolving conflict ${conflict.id}`);

    // Apply deterministic ordering rules
    if (this.config.deterministicOrderingRules.length > 0) {
      // In real implementation, apply rules
      conflict.resolutionStrategy = 'DETERMINISTIC_ORDERING';
    } else {
      // Use sovereign trust weighting
      conflict.resolutionStrategy = 'SOVEREIGN_TRUST_WEIGHTING';
    }

    conflict.resolvedAt = new Date();
    conflict.resolvedBy = 'MLS_AUTO_RESOLVER';

    return conflict;
  }

  /**
   * Start periodic meta-state commits
   */
  startPeriodicCommits(): void {
    const interval = setInterval(async () => {
      try {
        await this.commitMetaState();
      } catch (error) {
        logger.error('MLS: Error in periodic commit', error);
      }
    }, this.config.settlementEpochSeconds * 1000);

    logger.info(
      `MLS: Started periodic commits every ${this.config.settlementEpochSeconds} seconds`
    );
  }
}

export const mlsService = new MLSService();

