.env.example

# ==================== BLOCKCHAIN CONFIGURATION ====================
# Ethereum/Polygon Testnet Configuration

# Blockchain RPC endpoint
# RECOMMENDED: Polygon Mumbai (free, fast, perfect for hackathons)
# https://rpc-mumbai.maticvigil.com/ (free, no API key needed)
#
# Other options:
# - Polygon Amoy: https://rpc-amoy.maticvigil.com/
# - Ethereum Sepolia: https://sepolia.infura.io/v3/YOUR_INFURA_KEY
# - Ethereum Goerli: https://goerli.infura.io/v3/YOUR_INFURA_KEY
BLOCKCHAIN_RPC_URL=https://rpc-mumbai.maticvigil.com/

# Deployed smart contract address
# Get this after deploying CertificateRegistry.sol using Hardhat
# Leave empty to run in SIMULATION MODE (demo mode)
# Example: 0x1234567890abcdef1234567890abcdef12345678
CONTRACT_ADDRESS=

# Private key of the account that will issue certificates
# ⚠️ SECURITY: This key can issue transactions. Keep it secret!
# Never commit this file to git with a real private key
#
# How to get:
# 1. Open MetaMask wallet
# 2. Go Settings → Account Details → Export Private Key
# 3. Copy the 64-character hex string (without 0x prefix)
# 4. Paste here
#
# For hackathon demo: Create a new throwaway wallet
PRIVATE_KEY=

# ==================== GOOGLE GEMINI API CONFIGURATION ====================
# AI-powered certificate verification using Google's Gemini API

# Gemini API Key (FREE!)
# Get free API key at: https://ai.google.dev/
#
# How to get:
# 1. Go to https://ai.google.dev/
# 2. Click "Get API Key" button
# 3. Create new API key
# 4. Copy and paste here
#
# Features enabled by this key:
# - Certificate data authenticity analysis
# - Certificate image tampering detection
# - Text extraction from certificate PDFs/images
# - Confidence scoring (0-100)
#
# Leave empty to run AI in SIMULATION MODE (demo mode)
GEMINI_API_KEY=

# ==================== BACKEND SERVER CONFIGURATION ====================

# Server port (where API listens)
PORT=5000

# Node environment
# development = Full error messages, detailed logging
# production = Minimal error details
NODE_ENV=development

# Frontend URL (for CORS - cross-origin requests)
# This tells the backend which URL is allowed to access the API
FRONTEND_URL=http://localhost:5173

# ==================== OPTIONAL: PREMIUM RPC PROVIDERS ====================
# These are optional but provide better performance and reliability

# Alchemy API Key (for faster Polygon/Ethereum access)
# Get free tier at: https://alchemy.com/
# More reliable and faster than free public RPC
ALCHEMY_API_KEY=

# Infura Project ID (alternative premium RPC)
# Get free tier at: https://infura.io/
INFURA_PROJECT_ID=

# ==================== SETUP GUIDE ====================
#
# MODE 1: LOCAL DEMO (Recommended for Hackathons)
# ✅ No blockchain setup needed
# ✅ No API keys needed
# ✅ Perfect for demos and presentations
#
# Steps:
# 1. Copy this file to .env (remove .example)
# 2. Leave all values empty/default
# 3. npm install
# 4. npm run dev
# 5. Visit http://localhost:5173
#
# Features:
# - Certificates stored in simulated blockchain
# - AI analysis runs in simulation mode
# - All verification works end-to-end!
#
# ==================== SETUP GUIDE ====================
#
# MODE 2: BLOCKCHAIN ONLY
# Verify certificates on actual Polygon Mumbai testnet
#
# Prerequisites:
# - MetaMask wallet (free: https://metamask.io/)
# - Testnet MATIC tokens (free: https://faucet.polygon.technology/)
#
# Steps:
# 1. Add Polygon Mumbai to MetaMask:
#    - Network name: Polygon Mumbai
#    - RPC: https://rpc-mumbai.maticvigil.com/
#    - Chain ID: 80001
#    - Currency: MATIC
#    - Block Explorer: https://mumbai.polygonscan.com/
#
# 2. Get testnet MATIC:
#    - Go to https://faucet.polygon.technology/
#    - Enter your MetaMask address
#    - Confirm you get MATIC (usually 1 testnet MATIC)
#
# 3. Deploy smart contract:
#    - npm install --save-dev hardhat
#    - Create deployment script (in scripts/deploy.js)
#    - npx hardhat run scripts/deploy.js --network mumbai
#    - Copy output contract address
#
# 4. Set environment variables:
#    - CONTRACT_ADDRESS=<deployed address>
#    - PRIVATE_KEY=<your MetaMask private key>
#
# 5. npm run dev
#
# Testing:
# - Visit https://mumbai.polygonscan.com/
# - Paste your address to see transactions
#
# ==================== SETUP GUIDE ====================
#
# MODE 3: AI ONLY
# Use Gemini API for certificate analysis without blockchain
#
# Steps:
# 1. Get Gemini API key:
#    - Visit https://ai.google.dev/
#    - Click "Get API Key"
#    - Create new API key
#    - Copy key
#
# 2. Set in this file:
#    GEMINI_API_KEY=<your_key>
#
# 3. Leave CONTRACT_ADDRESS empty
#
# 4. npm run dev
#
# Features:
# - Certificate image analysis
# - Tampering detection
# - Text extraction from images
# - Authenticity scoring
#
# ==================== SETUP GUIDE ====================
#
# MODE 4: FULL SETUP (Blockchain + AI)
# Complete verification with both blockchain and AI
#
# Complete all steps from MODE 2 and MODE 3
# Then set all variables and run npm run dev
#
# This gives you:
# ✅ Immutable certificate storage (blockchain)
# ✅ AI tampering detection
# ✅ Hash verification
# ✅ Complete audit trail
# ✅ Enterprise-grade verification
#
# ==================== IMPORTANT SECURITY NOTES ====================
#
# 🔒 PRIVATE KEY SECURITY:
# - Never share your private key
# - Never commit .env with real keys to git
# - Use a separate private key for each environment
# - Rotate keys regularly
# - For production: use hardware wallets (Ledger, Trezor)
#
# 🔒 API KEY SECURITY:
# - Keep API keys secret
# - Set rate limits on API keys
# - Regenerate keys if compromised
# - Use different keys for different environments
#
# 🔒 GIT SAFETY:
# - Add .env to .gitignore (already done)
# - Never commit this file with real keys
# - Use .env.local for local development
# - Use CI/CD secrets for deployments
#
# ==================== TROUBLESHOOTING ====================
#
# Q: "Contract not initialized" error?
# A: CONTRACT_ADDRESS is empty - run in simulation mode or deploy contract
#
# Q: "GEMINI_API_KEY not set" warning?
# A: Normal - means AI will run in simulation mode (demo mode)
#
# Q: RPC connection timeout?
# A: Try a premium RPC (Alchemy) or different endpoint
#
# Q: MetaMask transaction reverted?
# A: Might be insufficient gas or contract error - check Mumbai explorer
#
# Q: API key invalid error?
# A: Check that key is copied correctly - no spaces or newlines
#
# ==================== USEFUL LINKS ====================
#
# 🌐 Blockchain:
# - Polygon: https://polygon.technology/
# - Mumbai Testnet: https://mumbai.polygonscan.com/
# - Faucet: https://faucet.polygon.technology/
# - ChainList: https://chainlist.org/
#
# 🤖 AI:
# - Google Gemini: https://ai.google.dev/
# - API Reference: https://ai.google.dev/docs
# - Model Info: https://ai.google.dev/models/gemini
#
# 👛 Wallet:
# - MetaMask: https://metamask.io/
# - Tutorial: https://docs.metamask.io/
#
# 🔗 Tools:
# - Hardhat: https://hardhat.org/
# - Ethers.js: https://docs.ethers.org/
# - Remix IDE: https://remix.ethereum.org/
#