┌─────────────────────────────────────────────────────────────────────────────┐
│                    SMART CONTRACT DEVELOPMENT PROCESS                       │
├─────────────────────────────────────────────────────────────────────────────┤
│                                                                             │
│  1. REQUIREMENTS ANALYSIS                                                  │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │ • Define contract functionality                                     │   │
│  │ • Identify user stories                                             │   │
│  │ • Specify interfaces                                                │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                    │                                        │
│                                    v                                        │
│  2. DESIGN                                                                 │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │ • Architecture design                                               │   │
│  │ • Data structures                                                    │   │
│  │ • Security considerations                                           │   │
│  │ • Gas optimisation planning                                         │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                    │                                        │
│                                    v                                        │
│  3. IMPLEMENTATION                                                         │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │ • Write smart contract code                                         │   │
│  │ • Use established libraries (OpenZeppelin)                         │   │
│  │ • Follow best practices                                            │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                    │                                        │
│                                    v                                        │
│  4. TESTING                                                                │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │ • Unit tests                                                         │   │
│  │ • Integration tests                                                  │   │
│  │ • Security testing                                                   │   │
│  │ • Gas analysis                                                       │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                    │                                        │
│                                    v                                        │
│  5. AUDITING                                                              │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │ • Internal review                                                   │   │
│  │ • External audit                                                    │   │
│  │ • Bug bounty (if applicable)                                        │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                    │                                        │
│                                    v                                        │
│  6. DEPLOYMENT                                                             │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │ • Deploy to testnet                                                 │   │
│  │ • Verify on explorer                                                │   │
│  │ • Deploy to mainnet                                                │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                                                             │
└─────────────────────────────────────────────────────────────────────────────┘

┌─────────────────────────────────────────────────────────────────────────────┐
│                    DAPP ARCHITECTURE                                        │
├─────────────────────────────────────────────────────────────────────────────┤
│                                                                             │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │                    FRONTEND (React/Vue)                              │   │
│  │  • User interface                                                    │   │
│  │  • Wallet integration (MetaMask)                                    │   │
│  │  • State management                                                 │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                    │                                        │
│                                    v                                        │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │                    MIDDLEWARE (Web3.js/Ethers.js)                    │   │
│  │  • Blockchain interaction                                            │   │
│  │  • Contract ABI handling                                            │   │
│  │  • Transaction signing                                               │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                    │                                        │
│                                    v                                        │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │                    BACKEND (Node.js/Python)                          │   │
│  │  • Off-chain logic                                                  │   │
│  │  • Database interaction                                              │   │
│  │  • API endpoints                                                    │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                    │                                        │
│                                    v                                        │
│  ┌──────────────────────────────────────────────────────────────────────┐   │
│  │                    BLOCKCHAIN (Ethereum, Solana, etc.)              │   │
│  │  • Smart contracts                                                  │   │
│  │  • Transaction execution                                            │   │
│  │  • State storage                                                    │   │
│  └──────────────────────────────────────────────────────────────────────┘   │
│                                                                             │
└─────────────────────────────────────────────────────────────────────────────┘

# ===================================================================
# MODULE 10, LESSON 4: DEVELOPMENT AND IMPLEMENTATION
# ===================================================================

import hashlib
import time
from typing import Dict, List
import pandas as pd
import matplotlib.pyplot as plt
import warnings
warnings.filterwarnings('ignore')

print("="*70)
print("DEVELOPMENT AND IMPLEMENTATION")
print("="*70)

# ----------------------------------------------------------------
# PART A: SMART CONTRACT SIMULATION
# ----------------------------------------------------------------

print("\n" + "-"*60)
print("PART A: Smart Contract Simulation")
print("-"*60)

class SmartContractSimulator:
    """
    Simulates a simple smart contract for demonstration.
    """
    def __init__(self, name: str):
        self.name = name
        self.owner = "Owner"
        self.balances = {}
        self.total_supply = 0
        self.is_paused = False
        self.events = []
    
    def mint(self, address: str, amount: int) -> bool:
        """Mint new tokens."""
        if self.is_paused:
            self._emit_event('MintFailed', 'Contract paused')
            return False
        if amount <= 0:
            return False
        
        self.balances[address] = self.balances.get(address, 0) + amount
        self.total_supply += amount
        self._emit_event('Mint', f'{amount} minted to {address}')
        print(f"Minted {amount} tokens to {address}")
        return True
    
    def transfer(self, from_addr: str, to_addr: str, amount: int) -> bool:
        """Transfer tokens between addresses."""
        if self.is_paused:
            return False
        if self.balances.get(from_addr, 0) < amount:
            print(f"Insufficient balance for {from_addr}")
            return False
        
        self.balances[from_addr] -= amount
        self.balances[to_addr] = self.balances.get(to_addr, 0) + amount
        self._emit_event('Transfer', f'{amount} from {from_addr} to {to_addr}')
        print(f"Transferred {amount} from {from_addr} to {to_addr}")
        return True
    
    def get_balance(self, address: str) -> int:
        return self.balances.get(address, 0)
    
    def pause(self):
        self.is_paused = True
        self._emit_event('Pause', 'Contract paused')
        print("Contract paused")
    
    def unpause(self):
        self.is_paused = False
        self._emit_event('Unpause', 'Contract unpaused')
        print("Contract unpaused")
    
    def _emit_event(self, event_type: str, data: str):
        self.events.append({
            'type': event_type,
            'data': data,
            'timestamp': time.time()
        })
    
    def get_events(self) -> List[Dict]:
        return self.events
    
    def get_state(self) -> Dict:
        return {
            'name': self.name,
            'owner': self.owner,
            'total_supply': self.total_supply,
            'is_paused': self.is_paused,
            'event_count': len(self.events)
        }

# Simulate smart contract
contract = SmartContractSimulator("TokenContract")

print("Smart Contract Simulation:")

# Mint tokens
contract.mint("Alice", 1000)
contract.mint("Bob", 500)

# Transfer tokens
contract.transfer("Alice", "Bob", 100)
contract.transfer("Alice", "Charlie", 200)

# Check balances
print("\nBalances:")
print(f"  Alice: {contract.get_balance('Alice')}")
print(f"  Bob: {contract.get_balance('Bob')}")
print(f"  Charlie: {contract.get_balance('Charlie')}")

# Pause and test
contract.pause()
contract.mint("David", 300)  # Should fail

# State
state = contract.get_state()
print(f"\nContract State:")
print(f"  Name: {state['name']}")
print(f"  Total Supply: {state['total_supply']}")
print(f"  Paused: {state['is_paused']}")
print(f"  Events: {state['event_count']}")

# ----------------------------------------------------------------
# PART B: DAPP DEVELOPMENT ROADMAP
# -----------------------------------------------------------------

print("\n" + "-"*60)
print("PART B: DApp Development Roadmap")
print("-"*60)

roadmap_data = {
    'Phase': ['Setup', 'Contracts', 'Frontend', 'Integration', 'Testing', 'Deployment'],
    'Duration': ['1 week', '2 weeks', '2 weeks', '1 week', '1 week', '1 week'],
    'Key Activities': [
        'Environment setup, tools',
        'Contract development, testing',
        'UI/UX design, implementation',
        'Wallet integration, API calls',
        'Unit, integration, security tests',
        'Testnet, mainnet deployment'
    ],
    'Deliverables': [
        'Development environment',
        'Deployed contracts (testnet)',
        'Functional UI',
        'Complete DApp',
        'Test reports',
        'Deployed DApp'
    ]
}

roadmap_df = pd.DataFrame(roadmap_data)
print(roadmap_df.to_string(index=False))

# ----------------------------------------------------------------
# PART C: DEPLOYMENT CHECKLIST
# -----------------------------------------------------------------

print("\n" + "-"*60)
print("PART C: Deployment Checklist")
print("-"*60)

deployment_checklist = {
    "Pre-Deployment": [
        "All tests passing",
        "Security audit completed",
        "Gas optimisation done",
        "Documentation complete",
        "Contract source verified"
    ],
    "Testnet Deployment": [
        "Deploy to testnet",
        "Verify on explorer",
        "Run integration tests",
        "Test all functions",
        "Monitor gas usage"
    ],
    "Mainnet Deployment": [
        "Deploy to mainnet",
        "Verify on explorer",
        "Set up monitoring",
        "Create documentation",
        "Announce launch"
    ],
    "Post-Deployment": [
        "Monitor contract activity",
        "Watch for anomalies",
        "Respond to issues",
        "Regular security reviews",
        "Plan upgrades"
    ]
}

for category, items in deployment_checklist.items():
    print(f"\n{category.upper()}:")
    for item in items:
        print(f"  □ {item}")

# ----------------------------------------------------------------
# PART D: DEVELOPMENT TOOLS
# -----------------------------------------------------------------

print("\n" + "-"*60)
print("PART D: Development Tools Overview")
print("-"*60)

tools_data = {
    'Category': ['IDE', 'Framework', 'Testing', 'Monitoring', 'Deployment'],
    'Tools': [
        'Remix, VS Code, Hardhat',
        'Hardhat, Foundry, Truffle',
        'Mocha, Chai, Echidna',
        'Tenderly, The Graph, Etherscan',
        'Infura, Alchemy, Hardhat'
    ],
    'Purpose': [
        'Code editing and compilation',
        'Smart contract development',
        'Testing and verification',
        'Monitoring and analytics',
        'Network access and deployment'
    ]
}

tools_df = pd.DataFrame(tools_data)
print(tools_df.to_string(index=False))

# ----------------------------------------------------------------
# PART E: SUMMARY AND RECOMMENDATIONS
# -----------------------------------------------------------------

print("\n" + "="*70)
print("PART E: Summary and Recommendations")
print("="*70)

print("""
Development and Implementation – Key Takeaways:

1. Smart contract process: requirements → design → implementation → testing → audit → deployment.
2. Best practices: latest Solidity, OpenZeppelin, Checks-Effects-Interactions, events, gas optimisation.
3. DApp architecture: frontend (UI) → middleware (Web3) → backend → blockchain.
4. Testing: unit, integration, security, gas analysis.
5. Deployment: local → testnet → mainnet.
6. Tools: Remix, Hardhat, Foundry, Truffle, Web3.js, Ethers.js.

Development Checklist:
  - Write and test smart contracts.
  - Build frontend with wallet integration.
  - Deploy to testnet for validation.
  - Conduct thorough testing.
  - Deploy to mainnet.
  - Monitor and maintain.

Recommendations:
  - Start with a simple contract and iterate.
  - Use established libraries and patterns.
  - Test extensively on testnet.
  - Document your code thoroughly.
  - Prepare for security audits.
  - Plan for deployment and post-deployment.
""")

print("="*70)
print("END OF LESSON 4 – MODULE 10")
print("="*70)