import crypto from 'crypto';
import { IPFSService } from './IPFSService.js';

export interface EvidenceRecord {
  id: string;
  hash: string;
  caseId: string;
  documentType: string;
  ipfsHash: string;
  submittedBy: string;
  verifiedBy?: string;
  blockNumber?: number;
  chainOfCustody: CustodyRecord[];
  metadata: any;
  createdAt: Date;
  verifiedAt?: Date;
  retentionPeriod: number; // 7 years in seconds
}

export interface CustodyRecord {
  timestamp: Date;
  action: string;
  performedBy: string;
  location?: string;
  notes?: string;
  blockHash?: string;
}

export class EvidenceService {
  private ipfsService: IPFSService;
  private COOK_COUNTY_RETENTION = 7 * 365 * 24 * 60 * 60 * 1000; // 7 years in milliseconds

  constructor() {
    this.ipfsService = new IPFSService();
  }

  public async submitEvidence(
    caseId: string,
    documentType: string,
    fileBuffer: Buffer,
    submittedBy: string,
    metadata: any = {}
  ): Promise<EvidenceRecord> {
    try {
      // Calculate SHA-256 hash of the document
      const evidenceHash = crypto.createHash('sha256').update(fileBuffer).digest('hex');
      
      // Store document in IPFS
      const ipfsHash = await this.ipfsService.addFile(fileBuffer);
      
      // Create evidence record
      const evidenceRecord: EvidenceRecord = {
        id: crypto.randomUUID(),
        hash: evidenceHash,
        caseId,
        documentType,
        ipfsHash,
        submittedBy,
        chainOfCustody: [{
          timestamp: new Date(),
          action: 'Evidence Submitted',
          performedBy: submittedBy,
          notes: `Document submitted as ${documentType} for case ${caseId}`,
        }],
        metadata: {
          ...metadata,
          originalSize: fileBuffer.length,
          mimeType: this.detectMimeType(fileBuffer),
          uploadTimestamp: new Date().toISOString(),
        },
        createdAt: new Date(),
        retentionPeriod: this.COOK_COUNTY_RETENTION,
      };

      return evidenceRecord;
    } catch (error) {
      throw new Error(`Failed to submit evidence: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  public async verifyEvidence(
    evidenceId: string,
    verifiedBy: string,
    verificationNotes?: string
  ): Promise<EvidenceRecord> {
    try {
      // In a real implementation, this would update the database
      // For now, we simulate the verification process
      
      const custodyRecord: CustodyRecord = {
        timestamp: new Date(),
        action: 'Evidence Verified',
        performedBy: verifiedBy,
        notes: verificationNotes || 'Evidence verified by forensic expert',
      };

      // This would typically update an existing evidence record
      // For demonstration, we return a mock verified record
      const verifiedRecord: EvidenceRecord = {
        id: evidenceId,
        hash: 'mock_hash',
        caseId: 'mock_case',
        documentType: 'legal-document',
        ipfsHash: 'mock_ipfs_hash',
        submittedBy: 'mock_submitter',
        verifiedBy,
        chainOfCustody: [custodyRecord],
        metadata: {},
        createdAt: new Date(),
        verifiedAt: new Date(),
        retentionPeriod: this.COOK_COUNTY_RETENTION,
      };

      return verifiedRecord;
    } catch (error) {
      throw new Error(`Failed to verify evidence: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  public async updateChainOfCustody(
    evidenceId: string,
    action: string,
    performedBy: string,
    location?: string,
    notes?: string
  ): Promise<CustodyRecord> {
    try {
      const custodyRecord: CustodyRecord = {
        timestamp: new Date(),
        action,
        performedBy,
        location,
        notes,
      };

      // In a real implementation, this would update the database
      return custodyRecord;
    } catch (error) {
      throw new Error(`Failed to update chain of custody: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  public async validateEvidenceIntegrity(evidenceHash: string, fileBuffer: Buffer): Promise<boolean> {
    try {
      const calculatedHash = crypto.createHash('sha256').update(fileBuffer).digest('hex');
      return calculatedHash === evidenceHash;
    } catch (error) {
      throw new Error(`Failed to validate evidence integrity: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  public async getCookCountyComplianceReport(caseId: string): Promise<{
    totalEvidence: number;
    verifiedEvidence: number;
    withinRetention: number;
    cookCountyCompliant: boolean;
    complianceDetails: any;
  }> {
    try {
      // In a real implementation, this would query the database for case evidence
      // For now, we return mock compliance data
      
      const currentTime = new Date();
      const complianceReport = {
        totalEvidence: 5,
        verifiedEvidence: 5,
        withinRetention: 5,
        cookCountyCompliant: true,
        complianceDetails: {
          jurisdiction: 'Cook County, Illinois',
          retentionPeriod: '7 years',
          auditTrailComplete: true,
          forensicIntegrityVerified: true,
          chainOfCustodyComplete: true,
          lastAuditDate: currentTime.toISOString(),
        },
      };

      return complianceReport;
    } catch (error) {
      throw new Error(`Failed to generate compliance report: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  public async generateForensicReport(evidenceId: string): Promise<{
    evidenceId: string;
    forensicHash: string;
    integrityStatus: 'VERIFIED' | 'COMPROMISED' | 'UNKNOWN';
    chainOfCustodyComplete: boolean;
    complianceStatus: string;
    generatedAt: Date;
  }> {
    try {
      const forensicHash = crypto.createHash('sha256')
        .update(`forensic-${evidenceId}-${Date.now()}`)
        .digest('hex');

      return {
        evidenceId,
        forensicHash,
        integrityStatus: 'VERIFIED',
        chainOfCustodyComplete: true,
        complianceStatus: 'Cook County Compliant',
        generatedAt: new Date(),
      };
    } catch (error) {
      throw new Error(`Failed to generate forensic report: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  private detectMimeType(buffer: Buffer): string {
    // Simple MIME type detection based on file signatures
    if (buffer.length < 4) return 'application/octet-stream';
    
    const signature = buffer.subarray(0, 4);
    
    // PDF
    if (signature[0] === 0x25 && signature[1] === 0x50 && signature[2] === 0x44 && signature[3] === 0x46) {
      return 'application/pdf';
    }
    
    // JPEG
    if (signature[0] === 0xFF && signature[1] === 0xD8) {
      return 'image/jpeg';
    }
    
    // PNG
    if (signature[0] === 0x89 && signature[1] === 0x50 && signature[2] === 0x4E && signature[3] === 0x47) {
      return 'image/png';
    }
    
    // Default
    return 'application/octet-stream';
  }

  public async searchEvidence(query: {
    caseId?: string;
    documentType?: string;
    submittedBy?: string;
    dateRange?: { start: Date; end: Date };
    verified?: boolean;
  }): Promise<EvidenceRecord[]> {
    try {
      // In a real implementation, this would query the database
      // For now, return mock search results
      return [];
    } catch (error) {
      throw new Error(`Failed to search evidence: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }
}