// QR Generation and Trust Network Component
class QRGenerator {
    static init() {
        console.log('QRGenerator component initialized');
        this.setupQRValidation();
        this.loadTrustNetwork();
    }

    static generateTrustQR(productId, recommenderId, reason, expirationDays = 30) {
        const qrId = this.generateQRId();
        const issuedAt = new Date().toISOString();
        const expiresAt = new Date(Date.now() + expirationDays * 24 * 60 * 60 * 1000).toISOString();
        
        const payload = {
            v: 1,
            p: recommenderId,
            m: this.getMerchantId(productId),
            pr: productId,
            q: qrId,
            t: issuedAt,
            exp: expiresAt,
            r: reason
        };

        const payloadString = `TSQR:v1|p:${payload.p}|m:${payload.m}|pr:${payload.pr}|q:${payload.q}|t:${payload.t}|exp:${payload.exp}|r:${encodeURIComponent(payload.r)}`;
        
        // In a real implementation, this would be signed with the user's private key
        const signature = this.signPayload(payloadString, recommenderId);
        
        const signedPayload = `${payloadString}|sig:${signature}`;
        
        return {
            qrId,
            payload: signedPayload,
            expiresAt,
            status: 'active'
        };
    }

    static signPayload(payload, userId) {
        // In a real implementation, this would use WebCrypto API or similar
        // to sign the payload with the user's private key
        const message = `${payload}|user:${userId}|nonce:${Math.random().toString(36).substring(7)}`;
        
        // Simulate signature generation
        return btoa(message).substring(0, 44); // Base64 encoded signature
    }

    static validateQRScan(scannedPayload, scannerContext = {}) {
        try {
            // Parse the QR payload
            const parsed = this.parseQRPpayload(scannedPayload);
            
            if (!parsed) {
                return { valid: false, error: 'Invalid QR format' };
            }

            // Check expiration
            if (new Date(parsed.exp) < new Date()) {
                return { valid: false, error: 'QR code has expired' };
            }

            // Validate signature
            if (!this.validateSignature(scannedPayload, parsed)) {
                return { valid: false, error: 'Invalid signature' };
            }

            // Check usage limits
            const usageCount = this.getUsageCount(parsed.q);
            const maxUses = this.getMaxUses(parsed);
            
            if (usageCount >= maxUses) {
                return { valid: false, error: 'QR code usage limit reached' };
            }

            // Record the scan
            this.recordScan(parsed, scannerContext);

            return {
                valid: true,
                data: parsed,
                recommendation: {
                    productId: parsed.pr,
                    recommenderId: parsed.p,
                    reason: parsed.r,
                    issuedAt: parsed.t
                }
            };

        } catch (error) {
            console.error('QR validation error:', error);
            return { valid: false, error: 'Validation failed' };
        }
    }

    static parseQRPpayload(payload) {
        try {
            // Parse TSQR format
            const parts = payload.split('|');
            const data = {};
            
            parts.forEach(part => {
                const [key, value] = part.split(':');
                if (key && value) {
                    data[key] = value;
                }
            });

            // Validate required fields
            const required = ['v', 'p', 'm', 'pr', 'q', 't', 'sig'];
            const missing = required.filter(field => !data[field]);
            
            if (missing.length > 0) {
                return null;
            }

            return data;
        } catch (error) {
            return null;
        }
    }

    static validateSignature(payload, parsed) {
        // In a real implementation, this would verify the signature
        // against the user's public key
        try {
            const payloadWithoutSig = payload.split('|sig:')[0];
            const providedSig = parsed.sig;
            
            // Simulate signature validation
            const expectedSig = btoa(payloadWithoutSig).substring(0, 44);
            return providedSig === expectedSig;
        } catch (error) {
            return false;
        }
    }

    static recordScan(parsed, context) {
        // Record the QR scan for attribution tracking
        const scanRecord = {
            qrId: parsed.q,
            productId: parsed.pr,
            recommenderId: parsed.p,
            scannerUserId: context.userId || null,
            timestamp: new Date().toISOString(),
            geolocation: context.geolocation || null,
            userAgent: navigator.userAgent,
            ip: context.ip || null
        };

        // In a real implementation, this would save to the database
        console.log('QR scan recorded:', scanRecord);
        
        // Store in local storage for demo purposes
        const scans = JSON.parse(localStorage.getItem('qrScans') || '[]');
        scans.push(scanRecord);
        localStorage.setItem('qrScans', JSON.stringify(scans));
    }

    static getUsageCount(qrId) {
        // Get how many times this QR has been used
        const scans = JSON.parse(localStorage.getItem('qrScans') || '[]');
        return scans.filter(scan => scan.qrId === qrId).length;
    }

    static getMaxUses(parsed) {
        // Different products may have different usage limits
        // For now, return a default of 10 uses
        return 10;
    }

    static getMerchantId(productId) {
        // In a real implementation, this would lookup the merchant ID
        // For demo purposes, return a mock merchant ID
        return `merchant_${productId.substring(0, 8)}`;
    }

    static generateQRId() {
        return 'QR' + Date.now().toString(36) + Math.random().toString(36).substring(2, 8);
    }

    static setupQRValidation() {
        // Setup QR scanner validation handlers
        const scannerInputs = document.querySelectorAll('input[placeholder*="QR code"]');
        scannerInputs.forEach(input => {
            input.addEventListener('input', (e) => {
                if (e.target.value.trim()) {
                    this.validateManualQR(e.target.value.trim());
                }
            });
        });
    }

    static async validateManualQR(payload) {
        const result = this.validateQRScan(payload, { manualEntry: true });
        
        if (result.valid) {
            this.showValidationSuccess(result.recommendation);
        } else {
            this.showValidationError(result.error);
        }
    }

    static showValidationSuccess(recommendation) {
        // Show success message with recommendation details
        const message = `
            Valid QR from trusted recommender
            Product: ${recommendation.productId}
            Reason: ${recommendation.reason}
        `;
        
        if (window.OneSearchApp) {
            window.OneSearchApp.showNotification('Trust QR validated successfully', 'success');
        }
    }

    static showValidationError(error) {
        // Show error message
        if (window.OneSearchApp) {
            window.OneSearchApp.showNotification(`QR validation failed: ${error}`, 'error');
        }
    }

    static loadTrustNetwork() {
        // Load recent recommendations from the trust network
        const networkData = [
            {
                id: 'rec_1',
                productId: '1',
                recommenderId: 'user_123',
                recommenderName: 'Sarah M.',
                productTitle: 'Kitchen Storage Solutions',
                timestamp: new Date(Date.now() - 2 * 24 * 60 * 60 * 1000).toISOString(),
                trustLevel: 'verified',
                reason: 'Perfect for small kitchens with excellent build quality'
            },
            {
                id: 'rec_2',
                productId: '2',
                recommenderId: 'user_456',
                recommenderName: 'Mike R.',
                productTitle: 'Smart Home Automation',
                timestamp: new Date(Date.now() - 7 * 24 * 60 * 60 * 1000).toISOString(),
                trustLevel: 'high',
                reason: 'Seamless integration and reliable performance'
            },
            {
                id: 'rec_3',
                productId: '3',
                recommenderId: 'user_789',
                recommenderName: 'Lisa K.',
                productTitle: 'Space-Saving Organizer',
                timestamp: new Date(Date.now() - 1 * 24 * 60 * 60 * 1000).toISOString(),
                trustLevel: 'verified',
                reason: 'Transforms cluttered spaces into organized areas'
            }
        ];

        this.updateTrustNetworkDisplay(networkData);
    }

    static updateTrustNetworkDisplay(networkData) {
        const container = document.querySelector('#recommendations .space-y-3');
        if (!container) return;

        // Update the recent recommendations display
        networkData.forEach(rec => {
            const existingElement = Array.from(container.children).find(el => 
                el.textContent.includes(rec.productTitle)
            );
            
            if (!existingElement) {
                const newElement = this.createRecommendationElement(rec);
                container.insertBefore(newElement, container.firstChild);
            }
        });
    }

    static createRecommendationElement(recommendation) {
        const element = document.createElement('div');
        element.className = 'flex items-center space-x-3 p-3 border rounded-lg fade-in';
        
        const timeAgo = this.getTimeAgo(recommendation.timestamp);
        const trustColor = recommendation.trustLevel === 'verified' ? 'green' : 'blue';
        
        element.innerHTML = `
            <div class="w-8 h-8 bg-${trustColor}-500 rounded-full flex items-center justify-center">
                <i data-feather="check" class="h-4 w-4 text-white"></i>
            </div>
            <div class="flex-1">
                <div class="text-sm font-medium">${recommendation.productTitle}</div>
                <div class="text-xs text-gray-600">by ${recommendation.recommenderName} • ${timeAgo}</div>
            </div>
            <div class="text-xs text-${trustColor}-600 font-medium">${recommendation.trustLevel}</div>
        `;

        // Replace icons
        setTimeout(() => {
            if (window.feather) {
                window.feather.replace();
            }
        }, 0);

        return element;
    }

    static getTimeAgo(timestamp) {
        const now = new Date();
        const time = new Date(timestamp);
        const diffInMs = now - time;
        const diffInDays = Math.floor(diffInMs / (1000 * 60 * 60 * 24));
        
        if (diffInDays === 0) {
            return 'today';
        } else if (diffInDays === 1) {
            return 'yesterday';
        } else {
            return `${diffInDays} days ago`;
        }
    }

    static createQRTemplate(productId, productTitle) {
        return {
            productId,
            productTitle,
            recommendationReasons: [
                'Excellent build quality',
                'Great value for money',
                'Solved my specific problem',
                'Highly recommended by community',
                'Verified by multiple users'
            ],
            defaultExpirationDays: 30,
            maxUsages: 10
        };
    }

    static exportQRData(qrId) {
        // Export QR generation data for auditing
        const scans = JSON.parse(localStorage.getItem('qrScans') || '[]');
        const qrScans = scans.filter(scan => scan.qrId === qrId);
        
        return {
            qrId,
            generatedAt: new Date().toISOString(),
            totalScans: qrScans.length,
            scans: qrScans,
            conversions: qrScans.filter(scan => scan.conversion === true).length
        };
    }
}

// Export for use in main app
if (typeof window !== 'undefined') {
    window.QRGenerator = QRGenerator;
}

if (typeof module !== 'undefined' && module.exports) {
    module.exports = QRGenerator;
}