Millionaires' Problem Enigma Secret Contract

lib.rs

// Built-In Attributes
#![no_std]

// Imports
extern crate eng_wasm;
extern crate eng_wasm_derive;
extern crate serde;

use eng_wasm::*;
use eng_wasm_derive::pub_interface;
use serde::{Serialize, Deserialize};

// Encrypted state keys
static MILLIONAIRES: &str = "millionaires";

// Structs
#[derive(Serialize, Deserialize)]
pub struct Millionaire {
    address: H160,
    net_worth: U256,
}

// Public struct Contract which will consist of private and public-facing secret contract functions
pub struct Contract;

// Private functions accessible only by the secret contract
impl Contract {
    fn get_millionaires() -> Vec<Millionaire> {
        read_state!(MILLIONAIRES).unwrap_or_default()
    }
}

// Public trait defining public-facing secret contract functions
#[pub_interface]
pub trait ContractInterface{
    fn add_millionaire(address: H160, net_worth: U256);
    fn compute_richest() -> H160;
}

// Implementation of the public-facing secret contract functions defined in the ContractInterface
// trait implementation for the Contract struct above
impl ContractInterface for Contract {
    #[no_mangle]
    fn add_millionaire(address: H160, net_worth: U256) {
        let mut millionaires = Self::get_millionaires();
        millionaires.push(Millionaire {
            address,
            net_worth,
        });
        write_state!(MILLIONAIRES => millionaires);
    }

    #[no_mangle]
    fn compute_richest() -> H160 {
        match Self::get_millionaires().iter().max_by_key(|m| m.net_worth) {
            Some(millionaire) => {
                millionaire.address
            },
            None => H160::zero(),
        }
    }
}