// Internet Computer Protocol Simplified Implementation
// This example demonstrates core ICP concepts using Rust

use std::collections::HashMap;
use ed25519_dalek::{Keypair, PublicKey, Signature};
use rand::rngs::OsRrng;

// Represents a node in the Internet Computer Network
struct Node {
    id: String,
    public_key: PublicKey,
    private_key_share: Vec<u8>,
}

// Represents a Canister - the core computational unit
struct Canister {
    id: String,
    code: Vec<u8>,
    state: HashMap<String, Vec<u8>>,
    controllers: Vec<String>,
}

// Consensus Mechanism Simulation
struct ConsensusManager {
    nodes: Vec<Node>,
    subnets: Vec<Subnet>,
}

// Subnet representation
struct Subnet {
    id: String,
    nodes: Vec<Node>,
    public_key: PublicKey,
}

impl ConsensusManager {
    // Simulate threshold cryptography
    fn create_subnet_signature(nodes: &[Node], message: &[u8]) -> Option<Signature> {
        // In real implementation, this would require multiple node collaborations
        let threshold = (nodes.len() * 2 / 3) + 1;
       
        if nodes.len() < threshold {
            return None;
        }
       
        // Simplified signature creation
        let first_node = &nodes[0];
        let keypair = Keypair::generate(&mut OsRrng);
       
        Some(keypair.sign(message))
    }
}

impl Canister {
    // Create a new canister with initial configuration
    fn new(code: Vec<u8>, controllers: Vec<String>) -> Self {
        Canister {
            id: uuid::Uuid::new_v4().to_string(),
            code,
            state: HashMap::new(),
            controllers,
        }
    }
   
    // Upgrade mechanism demonstrating flexible governance
    fn upgrade(&mut self, new_code: Vec<u8>, upgrade_type: UpgradeType) {
        match upgrade_type {
            UpgradeType::Developer => {
                // Single developer can upgrade
                self.code = new_code;
            },
            UpgradeType::Dao(vote_result) => {
                // Community vote required
                if vote_result.approved {
                    self.code = new_code;
                }
            },
            UpgradeType::Immutable => {
                // No upgrades possible
                println!("Canister is immutable, upgrade rejected");
            }
        }
    }
}

// Represents different upgrade governance models
enum UpgradeType {
    Developer,          // Single developer control
    Dao(DaoVote),       // Community governance
    Immutable,          // No upgrades possible
}

// Represents a community vote in DAO model
struct DaoVote {
    approved: bool,
    total_votes: u64,
    votes_for: u64,
}

fn main() {
    // Example usage demonstrating ICP concepts
   
    // Create a canister with initial code
    let mut social_media_canister = Canister::new(
        vec![1, 2, 3], // Placeholder for actual WebAssembly code
        vec!["founder_key".to_string()]
    );
   
    // Simulate upgrade scenarios
    let new_code = vec![4, 5, 6];
   
    // Developer-controlled upgrade
    social_media_canister.upgrade(
        new_code.clone(),
        UpgradeType::Developer
    );
   
    // DAO vote-based upgrade
    social_media_canister.upgrade(
        new_code.clone(),
        UpgradeType::Dao(DaoVote {
            approved: true,
            total_votes: 100,
            votes_for: 65
        })
    );
   
    // Immutable canister (like a traditional smart contract)
    social_media_canister.upgrade(
        new_code,
        UpgradeType::Immutable
    );
}