///! # 投票系统
///!
///! Voting System
///! 提供提案投票、权重计算和委托投票功能
///!
///! **版本**: v1.0
///! **模块**: charter-std/governance/voting.ch

use utils::math::{safe_add, safe_sub, safe_mul, safe_div};
use utils::crypto::sha3_384_hash;

// ============================================================================
// 投票枚举
// ============================================================================

/// 投票选项
pub enum VoteOption {
    /// 赞成
    For,
    
    /// 反对
    Against,
    
    /// 弃权
    Abstain
}

/// 投票状态
pub enum VoteStatus {
    /// 待开始
    Pending,
    
    /// 进行中
    Active,
    
    /// 已结束
    Ended,
    
    /// 已取消
    Cancelled
}

/// 投票结果
pub enum VoteResult {
    /// 未决定
    Undecided,
    
    /// 通过
    Passed,
    
    /// 未通过
    Failed,
    
    /// 法定人数不足
    QuorumNotReached
}

// ============================================================================
// 投票结构
// ============================================================================

/// 投票信息
struct Vote {
    /// 投票ID
    vote_id: Hash,
    
    /// 提案ID
    proposal_id: Hash,
    
    /// 标题
    title: String,
    
    /// 描述
    description: String,
    
    /// 创建者
    creator: Address,
    
    /// 开始时间
    start_time: Timestamp,
    
    /// 结束时间
    end_time: Timestamp,
    
    /// 赞成票数
    votes_for: u256,
    
    /// 反对票数
    votes_against: u256,
    
    /// 弃权票数
    votes_abstain: u256,
    
    /// 总投票权重
    total_weight: u256,
    
    /// 法定人数（基点）
    quorum: u16,
    
    /// 通过阈值（基点）
    threshold: u16,
    
    /// 投票状态
    status: VoteStatus,
    
    /// 投票结果
    result: VoteResult,
    
    /// 是否允许委托
    allow_delegation: bool
}

/// 投票记录
struct VoteRecord {
    /// 投票者
    voter: Address,
    
    /// 投票ID
    vote_id: Hash,
    
    /// 投票选项
    option: VoteOption,
    
    /// 投票权重
    weight: u256,
    
    /// 投票时间
    timestamp: Timestamp,
    
    /// 是否通过委托
    is_delegated: bool,
    
    /// 委托人（如果是委托投票）
    delegator: Option<Address>
}

/// 委托记录
struct Delegation {
    /// 委托人
    delegator: Address,
    
    /// 被委托人
    delegate: Address,
    
    /// 委托权重
    weight: u256,
    
    /// 委托时间
    delegated_at: Timestamp,
    
    /// 过期时间（可选）
    expires_at: Option<Timestamp>
}

/// 投票权重快照
struct WeightSnapshot {
    /// 地址
    address: Address,
    
    /// 权重
    weight: u256,
    
    /// 快照时间
    snapshot_at: Timestamp
}

// ============================================================================
// 投票事件
// ============================================================================

/// 投票创建事件
event VoteCreated {
    vote_id: Hash,
    proposal_id: Hash,
    title: String,
    creator: Address,
    start_time: Timestamp,
    end_time: Timestamp,
    quorum: u16,
    threshold: u16
}

/// 投票提交事件
event VoteCast {
    vote_id: Hash,
    voter: Address,
    option: VoteOption,
    weight: u256,
    timestamp: Timestamp
}

/// 投票结束事件
event VoteEnded {
    vote_id: Hash,
    result: VoteResult,
    votes_for: u256,
    votes_against: u256,
    votes_abstain: u256,
    timestamp: Timestamp
}

/// 委托事件
event DelegationCreated {
    delegator: Address,
    delegate: Address,
    weight: u256,
    timestamp: Timestamp
}

/// 取消委托事件
event DelegationRevoked {
    delegator: Address,
    delegate: Address,
    timestamp: Timestamp
}

// ============================================================================
// 投票系统
// ============================================================================

/// 投票系统
certificate VotingSystem {
    /// 投票 (vote_id => vote)
    let _votes: Map<Hash, Vote>;
    
    /// 投票记录 (vote_id => voter => record)
    let _vote_records: Map<Hash, Map<Address, VoteRecord>>;
    
    /// 委托 (delegator => delegate => delegation)
    let _delegations: Map<Address, Map<Address, Delegation>>;
    
    /// 权重快照 (vote_id => address => snapshot)
    let _weight_snapshots: Map<Hash, Map<Address, WeightSnapshot>>;
    
    /// 治理代币地址
    let _governance_token: Address;
    
    /// 管理员地址
    let _admin: Address;
    
    /// 默认法定人数（基点）
    let _default_quorum: u16;
    
    /// 默认通过阈值（基点）
    let _default_threshold: u16;
    
    /// 最小投票期限（秒）
    let _min_voting_period: Duration;
    
    /// 最大投票期限（秒）
    let _max_voting_period: Duration;
    
    // ========== 构造函数 ==========
    
    constructor(
        governance_token: Address,
        default_quorum: u16,
        default_threshold: u16,
        min_period: Duration,
        max_period: Duration
    ) {
        require(!governance_token.is_zero(), "Invalid governance token");
        require(default_quorum <= 10000, "Invalid quorum");
        require(default_threshold <= 10000, "Invalid threshold");
        require(min_period > 0, "Min period must be positive");
        require(max_period > min_period, "Max period must be > min period");
        
        self._governance_token = governance_token;
        self._admin = msg.sender;
        self._default_quorum = default_quorum;
        self._default_threshold = default_threshold;
        self._min_voting_period = min_period;
        self._max_voting_period = max_period;
    }
    
    // ========== 投票管理 ==========
    
    /// 创建投票
    ///
    /// # 参数
    /// - `proposal_id`: 提案ID
    /// - `title`: 标题
    /// - `description`: 描述
    /// - `duration`: 投票期限（秒）
    /// - `quorum`: 法定人数（基点，0表示使用默认值）
    /// - `threshold`: 通过阈值（基点，0表示使用默认值）
    /// - `allow_delegation`: 是否允许委托
    ///
    /// # 返回
    /// - `Hash`: 投票ID
    pub fn create_vote(
        proposal_id: Hash,
        title: String,
        description: String,
        duration: Duration,
        quorum: u16,
        threshold: u16,
        allow_delegation: bool
    ) -> Hash {
        require(!title.is_empty(), "Title required");
        require(duration >= self._min_voting_period, "Duration too short");
        require(duration <= self._max_voting_period, "Duration too long");
        
        let final_quorum = if quorum == 0 {
            self._default_quorum
        } else {
            require(quorum <= 10000, "Invalid quorum");
            quorum
        };
        
        let final_threshold = if threshold == 0 {
            self._default_threshold
        } else {
            require(threshold <= 10000, "Invalid threshold");
            threshold
        };
        
        // 生成投票ID
        let vote_id = self._generate_vote_id(proposal_id, msg.sender);
        
        let start_time = block.timestamp;
        let end_time = block.timestamp + duration;
        
        let vote = Vote {
            vote_id: vote_id,
            proposal_id: proposal_id,
            title: title.clone(),
            description: description,
            creator: msg.sender,
            start_time: start_time,
            end_time: end_time,
            votes_for: 0,
            votes_against: 0,
            votes_abstain: 0,
            total_weight: 0,
            quorum: final_quorum,
            threshold: final_threshold,
            status: VoteStatus::Active,
            result: VoteResult::Undecided,
            allow_delegation: allow_delegation
        };
        
        self._votes[vote_id] = vote;
        
        emit VoteCreated {
            vote_id: vote_id,
            proposal_id: proposal_id,
            title: title,
            creator: msg.sender,
            start_time: start_time,
            end_time: end_time,
            quorum: final_quorum,
            threshold: final_threshold
        };
        
        return vote_id;
    }
    
    /// 投票
    ///
    /// # 参数
    /// - `vote_id`: 投票ID
    /// - `option`: 投票选项
    ///
    /// # 返回
    /// - `bool`: 是否成功
    pub fn cast_vote(vote_id: Hash, option: VoteOption) -> bool {
        require(self._votes.contains_key(vote_id), "Vote not found");
        
        let mut vote = self._votes[vote_id];
        require(vote.status == VoteStatus::Active, "Vote not active");
        require(block.timestamp >= vote.start_time, "Vote not started");
        require(block.timestamp < vote.end_time, "Vote ended");
        
        // 检查是否已投票
        if let Some(records) = self._vote_records.get(vote_id) {
            require(!records.contains_key(msg.sender), "Already voted");
        }
        
        // 获取投票权重（实际需要查询治理代币余额）
        let weight = self._get_voting_weight(msg.sender, vote_id);
        require(weight > 0, "No voting power");
        
        // 记录投票
        let record = VoteRecord {
            voter: msg.sender,
            vote_id: vote_id,
            option: option,
            weight: weight,
            timestamp: block.timestamp,
            is_delegated: false,
            delegator: None
        };
        
        if !self._vote_records.contains_key(vote_id) {
            self._vote_records[vote_id] = Map::new();
        }
        self._vote_records[vote_id][msg.sender] = record;
        
        // 更新投票统计
        match option {
            VoteOption::For => {
                vote.votes_for = safe_add(vote.votes_for, weight);
            },
            VoteOption::Against => {
                vote.votes_against = safe_add(vote.votes_against, weight);
            },
            VoteOption::Abstain => {
                vote.votes_abstain = safe_add(vote.votes_abstain, weight);
            }
        }
        
        vote.total_weight = safe_add(vote.total_weight, weight);
        
        self._votes[vote_id] = vote;
        
        emit VoteCast {
            vote_id: vote_id,
            voter: msg.sender,
            option: option,
            weight: weight,
            timestamp: block.timestamp
        };
        
        return true;
    }
    
    /// 结束投票
    ///
    /// # 参数
    /// - `vote_id`: 投票ID
    ///
    /// # 返回
    /// - `VoteResult`: 投票结果
    pub fn end_vote(vote_id: Hash) -> VoteResult {
        require(self._votes.contains_key(vote_id), "Vote not found");
        
        let mut vote = self._votes[vote_id];
        require(vote.status == VoteStatus::Active, "Vote not active");
        require(block.timestamp >= vote.end_time, "Vote not ended yet");
        
        // 计算结果
        let result = self._calculate_result(vote_id);
        
        vote.status = VoteStatus::Ended;
        vote.result = result;
        
        self._votes[vote_id] = vote;
        
        emit VoteEnded {
            vote_id: vote_id,
            result: result,
            votes_for: vote.votes_for,
            votes_against: vote.votes_against,
            votes_abstain: vote.votes_abstain,
            timestamp: block.timestamp
        };
        
        return result;
    }
    
    /// 取消投票
    ///
    /// # 参数
    /// - `vote_id`: 投票ID
    ///
    /// # 返回
    /// - `bool`: 是否成功
    pub fn cancel_vote(vote_id: Hash) -> bool {
        require(self._votes.contains_key(vote_id), "Vote not found");
        
        let mut vote = self._votes[vote_id];
        require(
            msg.sender == vote.creator || msg.sender == self._admin,
            "Not authorized"
        );
        require(vote.status == VoteStatus::Active, "Vote not active");
        
        vote.status = VoteStatus::Cancelled;
        self._votes[vote_id] = vote;
        
        return true;
    }
    
    // ========== 委托投票 ==========
    
    /// 委托投票权
    ///
    /// # 参数
    /// - `delegate`: 被委托人
    /// - `expires_at`: 过期时间（可选）
    ///
    /// # 返回
    /// - `bool`: 是否成功
    pub fn delegate_vote(
        delegate: Address,
        expires_at: Option<Timestamp>
    ) -> bool {
        require(!delegate.is_zero(), "Invalid delegate");
        require(delegate != msg.sender, "Cannot delegate to self");
        
        if let Some(expiry) = expires_at {
            require(expiry > block.timestamp, "Invalid expiry time");
        }
        
        // 获取委托权重（实际需要查询治理代币余额）
        let weight = self._get_base_voting_weight(msg.sender);
        require(weight > 0, "No voting power");
        
        let delegation = Delegation {
            delegator: msg.sender,
            delegate: delegate,
            weight: weight,
            delegated_at: block.timestamp,
            expires_at: expires_at
        };
        
        if !self._delegations.contains_key(msg.sender) {
            self._delegations[msg.sender] = Map::new();
        }
        self._delegations[msg.sender][delegate] = delegation;
        
        emit DelegationCreated {
            delegator: msg.sender,
            delegate: delegate,
            weight: weight,
            timestamp: block.timestamp
        };
        
        return true;
    }
    
    /// 撤销委托
    ///
    /// # 参数
    /// - `delegate`: 被委托人
    ///
    /// # 返回
    /// - `bool`: 是否成功
    pub fn revoke_delegation(delegate: Address) -> bool {
        require(self._delegations.contains_key(msg.sender), "No delegation");
        require(
            self._delegations[msg.sender].contains_key(delegate),
            "Delegation not found"
        );
        
        self._delegations[msg.sender].remove(delegate);
        
        emit DelegationRevoked {
            delegator: msg.sender,
            delegate: delegate,
            timestamp: block.timestamp
        };
        
        return true;
    }
    
    /// 使用委托权投票
    ///
    /// # 参数
    /// - `vote_id`: 投票ID
    /// - `option`: 投票选项
    /// - `delegator`: 委托人
    ///
    /// # 返回
    /// - `bool`: 是否成功
    pub fn cast_delegated_vote(
        vote_id: Hash,
        option: VoteOption,
        delegator: Address
    ) -> bool {
        require(self._votes.contains_key(vote_id), "Vote not found");
        
        let mut vote = self._votes[vote_id];
        require(vote.allow_delegation, "Delegation not allowed");
        require(vote.status == VoteStatus::Active, "Vote not active");
        require(block.timestamp >= vote.start_time, "Vote not started");
        require(block.timestamp < vote.end_time, "Vote ended");
        
        // 检查委托
        require(self._delegations.contains_key(delegator), "No delegation");
        require(
            self._delegations[delegator].contains_key(msg.sender),
            "Not delegated to you"
        );
        
        let delegation = self._delegations[delegator][msg.sender];
        
        // 检查是否过期
        if let Some(expiry) = delegation.expires_at {
            require(block.timestamp < expiry, "Delegation expired");
        }
        
        // 检查委托人是否已投票
        if let Some(records) = self._vote_records.get(vote_id) {
            require(!records.contains_key(delegator), "Delegator already voted");
        }
        
        let weight = delegation.weight;
        
        // 记录投票
        let record = VoteRecord {
            voter: msg.sender,
            vote_id: vote_id,
            option: option,
            weight: weight,
            timestamp: block.timestamp,
            is_delegated: true,
            delegator: Some(delegator)
        };
        
        if !self._vote_records.contains_key(vote_id) {
            self._vote_records[vote_id] = Map::new();
        }
        self._vote_records[vote_id][delegator] = record;
        
        // 更新投票统计
        match option {
            VoteOption::For => {
                vote.votes_for = safe_add(vote.votes_for, weight);
            },
            VoteOption::Against => {
                vote.votes_against = safe_add(vote.votes_against, weight);
            },
            VoteOption::Abstain => {
                vote.votes_abstain = safe_add(vote.votes_abstain, weight);
            }
        }
        
        vote.total_weight = safe_add(vote.total_weight, weight);
        
        self._votes[vote_id] = vote;
        
        emit VoteCast {
            vote_id: vote_id,
            voter: delegator,
            option: option,
            weight: weight,
            timestamp: block.timestamp
        };
        
        return true;
    }
    
    // ========== 查询函数 ==========
    
    /// 获取投票信息
    ///
    /// # 参数
    /// - `vote_id`: 投票ID
    ///
    /// # 返回
    /// - `Vote`: 投票信息
    pub fn get_vote(vote_id: Hash) -> Vote {
        require(self._votes.contains_key(vote_id), "Vote not found");
        return self._votes[vote_id];
    }
    
    /// 获取投票记录
    ///
    /// # 参数
    /// - `vote_id`: 投票ID
    /// - `voter`: 投票者地址
    ///
    /// # 返回
    /// - `Option<VoteRecord>`: 投票记录
    pub fn get_vote_record(vote_id: Hash, voter: Address) -> Option<VoteRecord> {
        return self._vote_records.get(vote_id)
            .and_then(|m| m.get(voter));
    }
    
    /// 获取委托信息
    ///
    /// # 参数
    /// - `delegator`: 委托人
    /// - `delegate`: 被委托人
    ///
    /// # 返回
    /// - `Option<Delegation>`: 委托信息
    pub fn get_delegation(
        delegator: Address,
        delegate: Address
    ) -> Option<Delegation> {
        return self._delegations.get(delegator)
            .and_then(|m| m.get(delegate));
    }
    
    /// 获取投票权重
    ///
    /// # 参数
    /// - `voter`: 投票者地址
    /// - `vote_id`: 投票ID
    ///
    /// # 返回
    /// - `u256`: 投票权重
    pub fn get_voting_weight(voter: Address, vote_id: Hash) -> u256 {
        return self._get_voting_weight(voter, vote_id);
    }
    
    /// 检查是否已投票
    ///
    /// # 参数
    /// - `vote_id`: 投票ID
    /// - `voter`: 投票者地址
    ///
    /// # 返回
    /// - `bool`: 是否已投票
    pub fn has_voted(vote_id: Hash, voter: Address) -> bool {
        return self._vote_records.get(vote_id)
            .map(|m| m.contains_key(voter))
            .unwrap_or(false);
    }
    
    // ========== 内部函数 ==========
    
    /// 生成投票ID
    fn _generate_vote_id(proposal_id: Hash, creator: Address) -> Hash {
        let mut data = Bytes::new();
        data.extend(proposal_id.as_bytes());
        data.extend(creator.as_bytes());
        data.extend(block.timestamp.to_bytes());
        data.extend(tx.hash.as_bytes());
        return sha3_384_hash(data);
    }
    
    /// 获取基础投票权重（不包括委托）
    fn _get_base_voting_weight(voter: Address) -> u256 {
        // 实际需要查询治理代币余额
        // 这里简化处理
        return 100;
    }
    
    /// 获取投票权重（包括委托）
    fn _get_voting_weight(voter: Address, vote_id: Hash) -> u256 {
        // 检查是否有快照
        if let Some(snapshots) = self._weight_snapshots.get(vote_id) {
            if let Some(snapshot) = snapshots.get(voter) {
                return snapshot.weight;
            }
        }
        
        // 获取基础权重
        let base_weight = self._get_base_voting_weight(voter);
        
        // 计算委托给该投票者的权重
        let mut delegated_weight = 0u256;
        
        // 实际需要遍历所有委托记录
        // 这里简化处理
        
        return safe_add(base_weight, delegated_weight);
    }
    
    /// 计算投票结果
    fn _calculate_result(vote_id: Hash) -> VoteResult {
        let vote = self._votes[vote_id];
        
        // 检查法定人数
        // 实际需要查询治理代币总供应量
        let total_supply = 10000u256; // 简化
        let participation = safe_mul(vote.total_weight, 10000) / total_supply;
        
        if participation < vote.quorum as u256 {
            return VoteResult::QuorumNotReached;
        }
        
        // 计算赞成票比例
        let valid_votes = safe_add(vote.votes_for, vote.votes_against);
        
        if valid_votes == 0 {
            return VoteResult::Failed;
        }
        
        let approval_rate = safe_mul(vote.votes_for, 10000) / valid_votes;
        
        if approval_rate >= vote.threshold as u256 {
            return VoteResult::Passed;
        } else {
            return VoteResult::Failed;
        }
    }
    
    // ========== 管理函数 ==========
    
    /// 设置默认法定人数
    pub fn set_default_quorum(quorum: u16) -> bool {
        require(msg.sender == self._admin, "Only admin");
        require(quorum <= 10000, "Invalid quorum");
        self._default_quorum = quorum;
        return true;
    }
    
    /// 设置默认通过阈值
    pub fn set_default_threshold(threshold: u16) -> bool {
        require(msg.sender == self._admin, "Only admin");
        require(threshold <= 10000, "Invalid threshold");
        self._default_threshold = threshold;
        return true;
    }
}