//! ACC协议模块

///! # ACC-20: 可替代代币标准
///!
///! UID: nac.acc.ACC20.v1
///!
///! ACC-20是NAC的可替代代币标准，完全替代以太坊的ERC-20。

#[allow(unused_imports)]
use crate::primitives::{Address, Hash, Timestamp};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// ACC-20代币
///
/// UID: nac.acc.ACC20.v1
#[derive(Debug, Clone, Serialize, Deserialize)]
/// ACC20Token
pub struct ACC20Token {
    /// 代币名称
    pub name: String,
    
    /// 代币符号
    pub symbol: String,
    
    /// 小数位数
    pub decimals: u8,
    
    /// 总供应量
    pub total_supply: u128,
    
    /// 合约地址
    pub contract_address: Address,
    
    /// 余额映射
    pub balances: HashMap<Address, u128>,
    
    /// 授权映射 (owner -> spender -> amount)
    pub allowances: HashMap<Address, HashMap<Address, u128>>,
    
    /// 创建时间
    pub created_at: Timestamp,
}

impl ACC20Token {
    /// 创建新的ACC-20代币
    pub fn new(name: String, symbol: String, decimals: u8, total_supply: u128) -> Self {
        Self {
            name,
            symbol,
            decimals,
            total_supply,
            contract_address: Address::zero(),
            balances: HashMap::new(),
            allowances: HashMap::new(),
            created_at: Timestamp::now(),
        }
    }
    
    /// 获取余额
    pub fn balance_of(&self, owner: &Address) -> u128 {
        *self.balances.get(owner).unwrap_or(&0)
    }
    
    /// 转账
    pub fn transfer(&mut self, from: &Address, to: &Address, amount: u128) -> Result<(), String> {
        let from_balance = self.balance_of(from);
        if from_balance < amount {
            return Err("Insufficient balance".to_string());
        }
        
        self.balances.insert(*from, from_balance - amount);
        let to_balance = self.balance_of(to);
        self.balances.insert(*to, to_balance + amount);
        
        Ok(())
    }
    
    /// 授权
    pub fn approve(&mut self, owner: &Address, spender: &Address, amount: u128) {
        self.allowances
            .entry(*owner)
            .or_insert_with(HashMap::new)
            .insert(*spender, amount);
    }
    
    /// 获取授权额度
    pub fn allowance(&self, owner: &Address, spender: &Address) -> u128 {
        self.allowances
            .get(owner)
            .and_then(|spenders| spenders.get(spender))
            .copied()
            .unwrap_or(0)
    }
    
    /// 从授权额度转账
    pub fn transfer_from(
        &mut self,
        spender: &Address,
        from: &Address,
        to: &Address,
        amount: u128,
    ) -> Result<(), String> {
        let allowed = self.allowance(from, spender);
        if allowed < amount {
            return Err("Insufficient allowance".to_string());
        }
        
        self.transfer(from, to, amount)?;
        self.approve(from, spender, allowed - amount);
        
        Ok(())
    }
    
    /// 铸造代币
    pub fn mint(&mut self, to: &Address, amount: u128) -> Result<(), String> {
        let balance = self.balance_of(to);
        self.balances.insert(*to, balance + amount);
        self.total_supply += amount;
        Ok(())
    }
    
    /// 销毁代币
    pub fn burn(&mut self, from: &Address, amount: u128) -> Result<(), String> {
        let balance = self.balance_of(from);
        if balance < amount {
            return Err("Insufficient balance to burn".to_string());
        }
        
        self.balances.insert(*from, balance - amount);
        self.total_supply -= amount;
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    
    

    #[test]
    fn test_acc20_creation() {
        let token = ACC20Token::new("Test Token".to_string(), "TEST".to_string(), 18, 1_000_000);
        assert_eq!(token.name, "Test Token");
        assert_eq!(token.symbol, "TEST");
        assert_eq!(token.decimals, 18);
        assert_eq!(token.total_supply, 1_000_000);
    }

    #[test]
    fn test_acc20_transfer() {
        let mut token = ACC20Token::new("Test".to_string(), "TST".to_string(), 18, 1_000_000);
        let addr1 = Address::new([1u8; 32]);
        let addr2 = Address::new([2u8; 32]);
        
        token.mint(&addr1, 1000).expect("mainnet: handle error");
        assert_eq!(token.balance_of(&addr1), 1000);
        
        token.transfer(&addr1, &addr2, 500).expect("mainnet: handle error");
        assert_eq!(token.balance_of(&addr1), 500);
        assert_eq!(token.balance_of(&addr2), 500);
    }
}