// NAC跨链桥主合约
// 版本: v1.0.0
// 描述: 实现NAC与外部链（如以太坊）的跨链资产转移

module cross_chain_bridge;

import "acc20c/wrapped_asset.charter";
import "xtzh/governance.charter";

/// 跨链操作类型
public enum CrossChainOperation {
    Lock,      // 锁定外部链资产
    Unlock,    // 解锁外部链资产
    Mint,      // 铸造NAC包裹资产
    Burn       // 销毁NAC包裹资产
}

/// 跨链请求状态
public enum RequestStatus {
    Pending,      // 待处理
    Verified,     // 已验证
    Completed,    // 已完成
    Failed,       // 失败
    Cancelled     // 已取消
}

/// 外部链信息
public struct ExternalChain {
    chain_id: uint64,                    // 链ID（1=以太坊主网）
    chain_name: bytes32,                 // 链名称
    bridge_contract: bytes,              // 外部链桥合约地址
    enabled: bool,                       // 是否启用
    min_confirmations: uint16,           // 最小确认数
    max_lock_amount: uint128             // 单次最大锁定金额
}

/// 跨链请求
public struct CrossChainRequest {
    request_id: bytes32,                 // 请求ID
    operation: CrossChainOperation,      // 操作类型
    source_chain: uint64,                // 源链ID
    target_chain: uint64,                // 目标链ID
    source_address: bytes,               // 源地址
    target_address: [u8; 32],            // 目标地址（NAC地址）
    asset_id: bytes32,                   // 资产ID
    amount: uint128,                     // 数量
    tx_hash: bytes32,                    // 原始交易哈希
    proof: bytes,                        // SPV证明或中继签名
    status: RequestStatus,               // 状态
    created_at: uint64,                  // 创建时间
    completed_at: uint64,                // 完成时间
    relay_signatures: []bytes            // 中继节点签名
}

/// 包裹资产映射
public struct AssetMapping {
    external_chain_id: uint64,           // 外部链ID
    external_asset_address: bytes,       // 外部资产合约地址
    nac_wrapped_asset_id: bytes32,       // NAC包裹资产ID
    symbol: bytes32,                     // 符号
    decimals: uint8,                     // 小数位数
    total_locked: uint128,               // 总锁定量
    total_minted: uint128,               // 总铸造量
    enabled: bool                        // 是否启用
}

/// NAC跨链桥合约
contract CrossChainBridge {
    storage {
        // 管理员地址
        admin: [u8; 32],
        
        // 支持的外部链
        external_chains: map<uint64, ExternalChain>,
        
        // 资产映射
        asset_mappings: map<bytes32, AssetMapping>,
        
        // 跨链请求
        requests: map<bytes32, CrossChainRequest>,
        
        // 中继节点列表
        relay_nodes: []bytes48,  // BLS公钥列表
        
        // 最小中继签名数
        min_relay_signatures: uint16,
        
        // 暂停状态
        paused: bool,
        
        // 请求计数器
        request_counter: uint64
    }
    
    /// 构造函数
    constructor(
        admin_address: [u8; 32],
        min_signatures: uint16
    ) {
        self.admin = admin_address;
        self.min_relay_signatures = min_signatures;
        self.paused = false;
        self.request_counter = 0;
    }
    
    /// 添加外部链支持
    pub fn add_external_chain(
        chain_id: uint64,
        chain_name: bytes32,
        bridge_contract: bytes,
        min_confirmations: uint16,
        max_lock_amount: uint128
    ) -> bool {
        require(msg.sender == self.admin, "Only admin can add chains");
        require(!self.external_chains.contains(chain_id), "Chain already exists");
        
        self.external_chains[chain_id] = ExternalChain {
            chain_id: chain_id,
            chain_name: chain_name,
            bridge_contract: bridge_contract,
            enabled: true,
            min_confirmations: min_confirmations,
            max_lock_amount: max_lock_amount
        };
        
        true
    }
    
    /// 添加资产映射
    pub fn add_asset_mapping(
        external_chain_id: uint64,
        external_asset_address: bytes,
        nac_wrapped_asset_id: bytes32,
        symbol: bytes32,
        decimals: uint8
    ) -> bool {
        require(msg.sender == self.admin, "Only admin can add mappings");
        require(self.external_chains.contains(external_chain_id), "Chain not supported");
        
        let mapping_id = self.compute_mapping_id(external_chain_id, external_asset_address);
        
        self.asset_mappings[mapping_id] = AssetMapping {
            external_chain_id: external_chain_id,
            external_asset_address: external_asset_address,
            nac_wrapped_asset_id: nac_wrapped_asset_id,
            symbol: symbol,
            decimals: decimals,
            total_locked: 0,
            total_minted: 0,
            enabled: true
        };
        
        true
    }
    
    /// 提交跨链锁定请求（从外部链到NAC）
    /// 用户在外部链锁定资产后，中继节点调用此函数
    pub fn submit_lock_request(
        source_chain: uint64,
        source_address: bytes,
        target_address: [u8; 32],
        external_asset_address: bytes,
        amount: uint128,
        tx_hash: bytes32,
        proof: bytes,
        relay_signatures: []bytes
    ) -> bytes32 {
        require(!self.paused, "Bridge is paused");
        require(self.external_chains.contains(source_chain), "Chain not supported");
        require(relay_signatures.len() >= self.min_relay_signatures as usize, "Insufficient signatures");
        
        // 验证中继签名
        require(self.verify_relay_signatures(tx_hash, relay_signatures), "Invalid relay signatures");
        
        // 生成请求ID
        self.request_counter += 1;
        let request_id = self.compute_request_id(source_chain, tx_hash, self.request_counter);
        
        // 获取资产映射
        let mapping_id = self.compute_mapping_id(source_chain, external_asset_address);
        require(self.asset_mappings.contains(mapping_id), "Asset not supported");
        
        let mut mapping = self.asset_mappings[mapping_id];
        require(mapping.enabled, "Asset mapping disabled");
        
        // 检查10%限制
        let max_allowed = self.get_max_lockable_amount(mapping.nac_wrapped_asset_id);
        require(mapping.total_locked + amount <= max_allowed, "Exceeds 10% limit");
        
        // 创建跨链请求
        self.requests[request_id] = CrossChainRequest {
            request_id: request_id,
            operation: CrossChainOperation::Lock,
            source_chain: source_chain,
            target_chain: 0,  // NAC链ID
            source_address: source_address,
            target_address: target_address,
            asset_id: mapping.nac_wrapped_asset_id,
            amount: amount,
            tx_hash: tx_hash,
            proof: proof,
            status: RequestStatus::Verified,
            created_at: block.timestamp,
            completed_at: 0,
            relay_signatures: relay_signatures
        };
        
        // 更新锁定量
        mapping.total_locked += amount;
        mapping.total_minted += amount;
        self.asset_mappings[mapping_id] = mapping;
        
        // 铸造包裹资产
        self.mint_wrapped_asset(target_address, mapping.nac_wrapped_asset_id, amount);
        
        // 更新状态为已完成
        self.requests[request_id].status = RequestStatus::Completed;
        self.requests[request_id].completed_at = block.timestamp;
        
        request_id
    }
    
    /// 提交跨链解锁请求（从NAC到外部链）
    /// 用户在NAC销毁包裹资产后，请求解锁外部链资产
    pub fn submit_unlock_request(
        target_chain: uint64,
        target_address: bytes,
        nac_wrapped_asset_id: bytes32,
        amount: uint128
    ) -> bytes32 {
        require(!self.paused, "Bridge is paused");
        require(self.external_chains.contains(target_chain), "Chain not supported");
        
        // 查找资产映射
        let mapping_id = self.find_mapping_by_nac_asset(target_chain, nac_wrapped_asset_id);
        require(mapping_id != bytes32::zero(), "Asset mapping not found");
        
        let mut mapping = self.asset_mappings[mapping_id];
        require(mapping.enabled, "Asset mapping disabled");
        require(mapping.total_minted >= amount, "Insufficient minted supply");
        
        // 销毁NAC包裹资产
        self.burn_wrapped_asset(msg.sender, nac_wrapped_asset_id, amount);
        
        // 生成请求ID
        self.request_counter += 1;
        let request_id = self.compute_request_id(0, bytes32::zero(), self.request_counter);
        
        // 创建跨链请求
        self.requests[request_id] = CrossChainRequest {
            request_id: request_id,
            operation: CrossChainOperation::Unlock,
            source_chain: 0,  // NAC链ID
            target_chain: target_chain,
            source_address: msg.sender.to_bytes(),
            target_address: [0u8; 32],  // 不适用
            asset_id: nac_wrapped_asset_id,
            amount: amount,
            tx_hash: bytes32::zero(),
            proof: target_address,  // 目标地址作为proof
            status: RequestStatus::Pending,
            created_at: block.timestamp,
            completed_at: 0,
            relay_signatures: []
        };
        
        // 更新铸造量
        mapping.total_minted -= amount;
        self.asset_mappings[mapping_id] = mapping;
        
        // 中继节点会监听此事件并在外部链执行解锁
        
        request_id
    }
    
    /// 验证中继签名
    fn verify_relay_signatures(
        &self,
        message: bytes32,
        signatures: []bytes
    ) -> bool {
        let mut valid_count: uint16 = 0;
        
        for signature in signatures {
            // 验证BLS签名
            for relay_pubkey in self.relay_nodes {
                if self.verify_bls_signature(message, signature, relay_pubkey) {
                    valid_count += 1;
                    break;
                }
            }
        }
        
        valid_count >= self.min_relay_signatures
    }
    
    /// 验证BLS签名（简化版）
    fn verify_bls_signature(
        &self,
        message: bytes32,
        signature: bytes,
        pubkey: bytes48
    ) -> bool {
        // TODO: 实际的BLS签名验证
        // 这里需要调用NVM的BLS验证指令
        true
    }
    
    /// 计算资产映射ID
    fn compute_mapping_id(
        &self,
        chain_id: uint64,
        asset_address: bytes
    ) -> bytes32 {
        // keccak256(chain_id || asset_address)
        let mut data: bytes = [];
        data.extend(chain_id.to_bytes());
        data.extend(asset_address);
        keccak256(data)
    }
    
    /// 计算请求ID
    fn compute_request_id(
        &self,
        chain_id: uint64,
        tx_hash: bytes32,
        counter: uint64
    ) -> bytes32 {
        // keccak256(chain_id || tx_hash || counter)
        let mut data: bytes = [];
        data.extend(chain_id.to_bytes());
        data.extend(tx_hash.to_bytes());
        data.extend(counter.to_bytes());
        keccak256(data)
    }
    
    /// 查找NAC资产对应的映射ID
    fn find_mapping_by_nac_asset(
        &self,
        chain_id: uint64,
        nac_asset_id: bytes32
    ) -> bytes32 {
        // 遍历所有映射查找匹配的
        // TODO: 优化为反向索引
        for (mapping_id, mapping) in self.asset_mappings {
            if mapping.external_chain_id == chain_id && mapping.nac_wrapped_asset_id == nac_asset_id {
                return mapping_id;
            }
        }
        bytes32::zero()
    }
    
    /// 获取最大可锁定金额（10%限制）
    fn get_max_lockable_amount(&self, nac_asset_id: bytes32) -> uint128 {
        // 获取NAC资产的总供应量
        let total_supply = self.get_asset_total_supply(nac_asset_id);
        
        // 返回10%
        total_supply / 10
    }
    
    /// 获取资产总供应量
    fn get_asset_total_supply(&self, asset_id: bytes32) -> uint128 {
        // TODO: 调用ACC-20C合约查询总供应量
        1_000_000_000_000  // 占位符
    }
    
    /// 铸造包裹资产
    fn mint_wrapped_asset(
        &self,
        to: [u8; 32],
        asset_id: bytes32,
        amount: uint128
    ) {
        // TODO: 调用ACC-20C合约铸造
    }
    
    /// 销毁包裹资产
    fn burn_wrapped_asset(
        &self,
        from: [u8; 32],
        asset_id: bytes32,
        amount: uint128
    ) {
        // TODO: 调用ACC-20C合约销毁
    }
    
    /// 查询跨链请求
    pub fn get_request(request_id: bytes32) -> CrossChainRequest {
        require(self.requests.contains(request_id), "Request not found");
        self.requests[request_id]
    }
    
    /// 查询资产映射
    pub fn get_asset_mapping(
        chain_id: uint64,
        asset_address: bytes
    ) -> AssetMapping {
        let mapping_id = self.compute_mapping_id(chain_id, asset_address);
        require(self.asset_mappings.contains(mapping_id), "Mapping not found");
        self.asset_mappings[mapping_id]
    }
    
    /// 暂停桥
    pub fn pause() -> bool {
        require(msg.sender == self.admin, "Only admin can pause");
        self.paused = true;
        true
    }
    
    /// 恢复桥
    pub fn unpause() -> bool {
        require(msg.sender == self.admin, "Only admin can unpause");
        self.paused = false;
        true
    }
    
    /// 添加中继节点
    pub fn add_relay_node(pubkey: bytes48) -> bool {
        require(msg.sender == self.admin, "Only admin can add relay nodes");
        self.relay_nodes.push(pubkey);
        true
    }
    
    /// 移除中继节点
    pub fn remove_relay_node(pubkey: bytes48) -> bool {
        require(msg.sender == self.admin, "Only admin can remove relay nodes");
        
        for i in 0..self.relay_nodes.len() {
            if self.relay_nodes[i] == pubkey {
                self.relay_nodes.remove(i);
                return true;
            }
        }
        
        false
    }
}