#include "altitude_calculator.hpp"
#include <cmath>
#include <iostream>
#include <limits>

// 物理常数
constexpr float STANDARD_GRAVITY = 9.80665f;        // 标准重力加速度 (m/s²)
constexpr float MOLAR_MASS_AIR = 0.0289644f;       // 空气摩尔质量 (kg/mol)
constexpr float UNIVERSAL_GAS_CONSTANT = 8.3144598f; // 通用气体常数 (J/(mol·K))
constexpr float STANDARD_TEMPERATURE = 288.15f;     // 标准温度 (K) = 15°C
constexpr float LAPSE_RATE = 0.0065f;              // 温度递减率 (K/m)

AltitudeCalculator::AltitudeCalculator(float sea_level_pressure)
    : sea_level_pressure_(sea_level_pressure) {
    // 验证输入参数
    if (!isValidPressure(sea_level_pressure)) {
        std::cerr << "警告：海平面气压值 " << sea_level_pressure 
                  << " hPa 可能超出合理范围。使用默认值 1013.25 hPa。" << std::endl;
        sea_level_pressure_ = 1013.25f;
    }
}

float AltitudeCalculator::calculateAltitude(float pressure) const {
    if (!isValidPressure(pressure)) {
        std::cerr << "错误：无效的气压值 " << pressure << " hPa" << std::endl;
        return 0.0f;
    }
    
    return barometricFormula(pressure, sea_level_pressure_);
}

float AltitudeCalculator::calculateRelativeHeight(float current_altitude, float base_altitude) {
    return current_altitude - base_altitude;
}

void AltitudeCalculator::setSeaLevelPressure(float pressure) {
    if (isValidPressure(pressure)) {
        sea_level_pressure_ = pressure;
        std::cout << "海平面气压已更新为: " << pressure << " hPa" << std::endl;
    } else {
        std::cerr << "错误：无效的海平面气压值 " << pressure << " hPa" << std::endl;
    }
}

float AltitudeCalculator::metersToFeet(float meters) {
    return meters * 3.28084f;
}

float AltitudeCalculator::feetToMeters(float feet) {
    return feet * 0.3048f;
}

bool AltitudeCalculator::isValidPressure(float pressure) {
    // 合理的气压范围：300 hPa (约9000米高度) 到 1100 hPa (海平面以下)
    return pressure >= 300.0f && pressure <= 1100.0f;
}

bool AltitudeCalculator::isValidAltitude(float altitude) {
    // 合理的高度范围：-500米 (地下) 到 9000米 (珠峰高度)
    return altitude >= -500.0f && altitude <= 9000.0f;
}

float AltitudeCalculator::barometricFormula(float pressure, float sea_level_pressure) {
    if (pressure <= 0.0f || sea_level_pressure <= 0.0f) {
        return 0.0f;
    }
    
    // 气压高度公式（国际标准大气模型）
    // h = (T0 / L) * (1 - (P / P0)^(R*L / (g*M)))
    
    // 防止除以零
    if (LAPSE_RATE == 0.0f) {
        return 0.0f;
    }
    
    // 计算压力比
    float pressure_ratio = pressure / sea_level_pressure;
    
    // 检查压力比是否合理
    if (pressure_ratio <= 0.0f) {
        return 0.0f;
    }
    
    // 计算指数部分
    float exponent = (UNIVERSAL_GAS_CONSTANT * LAPSE_RATE) / 
                     (STANDARD_GRAVITY * MOLAR_MASS_AIR);
    
    // 计算高度
    float altitude = (STANDARD_TEMPERATURE / LAPSE_RATE) * 
                     (1.0f - std::pow(pressure_ratio, exponent));
    
    // 验证计算结果
    if (!isValidAltitude(altitude)) {
        std::cerr << "警告：计算出的高度值 " << altitude 
                  << " 米可能超出合理范围。" << std::endl;
    }
    
    return altitude;
}