// Charter Standard Library - XTZH 汇率预言机接口
// Issue #61: 汇率数据源与验证
// 版本: 1.0

/// SDR 篮子货币枚举
public enum SdrCurrency {
    USD = 0,
    EUR = 1,
    CNY = 2,
    JPY = 3,
    GBP = 4
}

/// 预言机数据源类型
public enum OracleType {
    ZeroKnowledge = 0,    // ZK 证明预言机
    TrustedExecution = 1, // TEE 可信执行环境
    Optimistic = 2        // 乐观预言机（有挑战期）
}

/// 预言机节点信息
public struct OracleNode {
    did: DID,
    oracle_type: OracleType,
    stake: uint64,         // 质押 XIC 数量
    reputation: uint64,    // 信誉分，定点数 1e4
    is_active: bool
}

/// 汇率聚合结果
public struct RateAggregation {
    rate: XTZHRate,
    oracle_count: uint64,     // 参与聚合的预言机数量
    consensus_weight: uint64, // 加权共识比例，定点数 1e4
    is_valid: bool
}

/// 汇率预言机聚合合约
contract XTZHRateOracle {
    // 最小预言机数量（宪法要求）
    const MIN_ORACLE_COUNT: uint64 = 5;
    // 最小共识权重（宪法要求）
    const MIN_CONSENSUS_WEIGHT: uint64 = 6700; // 67.00%
    // 最大汇率偏离（触发告警）
    const MAX_DEVIATION_BPS: uint64 = 200; // 2.00%
    // AI 模型影子运行最短时长（纪元数）
    const MIN_SHADOW_RUN_EPOCHS: uint64 = 30; // 30 天

    state oracles: [OracleNode; 50];
    state oracle_count: uint64;
    state latest_rate: XTZHRate;
    state latest_aggregation: RateAggregation;
    state shadow_model_epoch: uint64; // 影子模型开始运行纪元

    /// 提交汇率报告（仅白名单预言机）
    pub fn submit_rate(
        rate_sdr: uint64,
        rate_usd: uint64,
        epoch: uint64,
        cr: ConstitutionalReceipt
    ) {
        require(xtzh::verify_rate_receipt(cr), "无效的宪法收据");
        require(epoch == self.latest_rate.epoch + 1, "纪元不连续");
        require(rate_sdr > 0, "汇率必须大于 0");

        // 检查偏离是否超标
        if self.check_deviation(rate_sdr) {
            emit XTZHRateDeviation {
                epoch: epoch,
                deviation_bps: self.calc_deviation_bps(rate_sdr),
                direction: if rate_sdr > self.latest_rate.rate_sdr { "up" } else { "down" }
            };
        }

        // 聚合逻辑由 NVM 系统调用处理
        // 当达到 MIN_ORACLE_COUNT 且 consensus_weight >= MIN_CONSENSUS_WEIGHT 时
        // 自动更新 latest_rate
    }

    /// 查询最新汇率
    @view
    pub fn get_latest() -> XTZHRate {
        return self.latest_rate;
    }

    /// 查询聚合状态
    @view
    pub fn get_aggregation() -> RateAggregation {
        return self.latest_aggregation;
    }

    /// 检查汇率偏离是否超标
    @view
    pub fn check_deviation(new_rate: uint64) -> bool {
        if self.latest_rate.rate_sdr == 0 {
            return false;
        }
        let deviation_bps = self.calc_deviation_bps(new_rate);
        return deviation_bps > MAX_DEVIATION_BPS;
    }

    /// 计算汇率偏离基点数
    @view
    pub fn calc_deviation_bps(new_rate: uint64) -> uint64 {
        if self.latest_rate.rate_sdr == 0 {
            return 0;
        }
        let diff = if new_rate > self.latest_rate.rate_sdr {
            new_rate - self.latest_rate.rate_sdr
        } else {
            self.latest_rate.rate_sdr - new_rate
        };
        return diff * 10000 / self.latest_rate.rate_sdr;
    }

    /// 激活新 AI 汇率模型（需先影子运行 30 天）
    @system
    pub fn activate_new_model(
        model_hash: hash,
        shadow_start_epoch: uint64,
        cr: ConstitutionalReceipt
    ) {
        require(xtzh::verify_rate_receipt(cr), "无效的宪法收据");
        let rate = xtzh::get_rate();
        require(
            rate.epoch >= shadow_start_epoch + MIN_SHADOW_RUN_EPOCHS,
            "影子运行时间不足 30 天"
        );
        // 激活新模型（NVM 系统处理）
    }
}