// nac-multi-jurisdiction/src/cross_jurisdiction.rs
// Issue #59: 跨辖区交易处理与双宪法收据

use serde::{Serialize, Deserialize};
use crate::jurisdiction::JurisdictionId;

/// 双宪法收据（跨辖区交易必须携带）
/// 发起辖区 + 接收辖区都必须签署
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DualConstitutionalReceipt {
    /// 交易唯一标识（SHA3-384）
    pub tx_id: Vec<u8>,
    /// 发起辖区 ID
    pub source_jurisdiction: JurisdictionId,
    /// 接收辖区 ID
    pub target_jurisdiction: JurisdictionId,
    /// 发起辖区宪法收据（原始字节）
    pub source_receipt: Vec<u8>,
    /// 接收辖区宪法收据（原始字节）
    pub target_receipt: Vec<u8>,
    /// 时间戳（Unix 秒）
    pub timestamp: u64,
    /// 纪元编号
    pub epoch: u64,
    /// 是否已最终确认
    pub is_finalized: bool,
}

impl DualConstitutionalReceipt {
    /// 验证双收据完整性
    pub fn is_valid(&self) -> bool {
        !self.source_receipt.is_empty()
            && !self.target_receipt.is_empty()
            && self.source_jurisdiction != self.target_jurisdiction
            && self.tx_id != vec![0u8; 48]
    }

    /// 检查是否包含指定辖区的收据
    pub fn has_receipt_for(&self, jid: &JurisdictionId) -> bool {
        &self.source_jurisdiction == jid || &self.target_jurisdiction == jid
    }
}

/// 跨辖区交易
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CrossJurisdictionTx {
    /// 交易 ID
    pub id: Vec<u8>,
    /// 发起辖区
    pub source_jurisdiction: JurisdictionId,
    /// 接收辖区
    pub target_jurisdiction: JurisdictionId,
    /// 交易数据
    pub payload: Vec<u8>,
    /// 双宪法收据（可选，处理中为 None）
    pub dual_receipt: Option<DualConstitutionalReceipt>,
    /// 交易状态
    pub status: CrossTxStatus,
    /// 冲突解决策略
    pub conflict_resolution: ConflictResolutionStrategy,
}

#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum CrossTxStatus {
    /// 待处理（等待接收辖区收据）
    Pending,
    /// 源辖区已确认
    SourceConfirmed,
    /// 双方已确认
    DualConfirmed,
    /// 最终确认
    Finalized,
    /// 失败（附带原因）
    Failed(String),
    /// 冲突（需要解决）
    Conflicted,
}

/// 规则冲突解决策略
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum ConflictResolutionStrategy {
    /// 严格模式：任何冲突都拒绝交易
    StrictReject,
    /// 源辖区优先：以发起辖区规则为准
    SourcePriority,
    /// 目标辖区优先：以接收辖区规则为准
    TargetPriority,
    /// 协商模式：双方辖区协商解决
    Negotiated,
    /// 宪法仲裁：提交宪法法院仲裁
    ConstitutionalArbitration,
}

/// 跨辖区路由器
pub struct CrossJurisdictionRouter {
    pending_txs: Vec<CrossJurisdictionTx>,
    /// 最大待处理交易数
    max_pending: usize,
}

impl CrossJurisdictionRouter {
    pub fn new() -> Self {
        CrossJurisdictionRouter {
            pending_txs: Vec::new(),
            max_pending: 10000,
        }
    }

    /// 提交跨辖区交易
    pub fn submit(&mut self, tx: CrossJurisdictionTx) -> Result<Vec<u8>, String> {
        if self.pending_txs.len() >= self.max_pending {
            return Err("待处理交易队列已满".to_string());
        }
        let id = tx.id.clone();
        self.pending_txs.push(tx);
        Ok(id)
    }

    /// 附加目标辖区收据（完成双收据）
    pub fn attach_target_receipt(
        &mut self,
        tx_id: &Vec<u8>,
        receipt: Vec<u8>,
    ) -> Result<(), String> {
        for tx in &mut self.pending_txs {
            if &tx.id == tx_id {
                if let Some(ref mut dr) = tx.dual_receipt {
                    dr.target_receipt = receipt;
                    dr.is_finalized = true;
                    tx.status = CrossTxStatus::DualConfirmed;
                    return Ok(());
                }
            }
        }
        Err(format!("交易 {:?} 不存在", tx_id))
    }

    /// 检测规则冲突
    pub fn detect_conflict(
        &self,
        source_rules: &[u8],
        target_rules: &[u8],
    ) -> bool {
        // 规则冲突检测：比较两个辖区的规则哈希
        // 实际实现由 NVM 系统调用处理
        source_rules.is_empty() || target_rules.is_empty()
    }

    /// 获取待处理交易数量
    pub fn pending_count(&self) -> usize {
        self.pending_txs.len()
    }
}

impl Default for CrossJurisdictionRouter {
    fn default() -> Self {
        Self::new()
    }
}