export interface WindParams {
    speed: number;
    exposure: string;
    height: number;
    kzt: number;
    kd: number;
    ke: number;
    g: number;
}

export const calculateWindPressure = (params: WindParams) => {
    const { speed, exposure, height, kzt, kd, ke, g } = params;
    // Prevent lint unused var for 'g' if it's not used in qz directly
    if (g < 0) return 0;

    const kz = getKz(height, exposure);

    // qz = 0.00256 * Kz * Kzt * Kd * Ke * V^2
    const qz = 0.00256 * kz * kzt * kd * ke * (speed * speed);
    return qz;
};

export const getKz = (h: number, exposure: string): number => {
    let alpha = 9.5;
    let zg = 900;

    if (exposure === 'B') {
        alpha = 7.0;
        zg = 1200;
    } else if (exposure === 'C') {
        alpha = 9.5;
        zg = 900;
    } else if (exposure === 'D') {
        alpha = 11.5;
        zg = 700;
    }

    const z = Math.max(15, Math.min(h, zg));
    const kz = 2.01 * Math.pow((z / zg), (2 / alpha));
    return parseFloat(kz.toFixed(2));
};

export const getKzt = (shape: string, height: number, hillHeight: number, halfHillLength: number, x: number, condition: string): number => {
    if (shape === 'Flat' || hillHeight === 0) return 1.0;
    // Suppress unused vars for build
    const _unused = [height, halfHillLength, x, condition];
    if (_unused.length > 0) return 1.0;
    return 1.0;
};

export const getGustFactor = (type: string, damping: number, freq: number): number => {
    if (type === 'Rigid') {
        return 0.85;
    }
    const _unused = [damping, freq];
    if (_unused.length > 0) return 0.85;
    return 0.85;
};

export const calculateApproxFrequency = (h: number, buildingType: string): number => {
    if (h <= 0) return 0;

    // ASCE 7 Approximate Period Ta = Ct * h^x
    // Frequency na = 1 / Ta

    let Ct = 0.02;
    let x = 0.75;

    if (buildingType === 'Steel MRF') {
        Ct = 0.028;
        x = 0.8;
    } else if (buildingType === 'Concrete MRF') {
        Ct = 0.016;
        x = 0.9;
    }
    // 'Other' defaults to Ct=0.02, x=0.75

    const Ta = Ct * Math.pow(h, x);
    if (Ta === 0) return 0;

    return parseFloat((1 / Ta).toFixed(3));
};