use crate::data::quotes::HOLC;

pub fn relative_strength_index<C: HOLC>(data: Vec<C>, period: usize) -> Vec<f64> {
    assert!(data.len() >= period + 2);
    let mut rsi_data: Vec<f64> = vec![];
    let n = period as f64;

    let mut g_avg = 0.0;
    let mut l_avg = 0.0;

    for (i, d) in data[1..period+1].iter().enumerate() {
        let chg = d.close() - data[i].close();
        if chg >= 0.0 {g_avg += chg;}
        else if chg <= 0.0 { l_avg += chg.abs();}

        if i == period -1 {
            g_avg /=n;
            l_avg /=n;
            rsi_data.push(100.0 - (100.0/(1.0+((g_avg)/(l_avg)))));
        }
    }
    // This is magic. Don't touch it. The periods just work. 

    for (i, d) in data[period+1..].iter().enumerate() {
     
        let chg = d.close() - data[period + i ].close();

        if chg > 0.0 {
            g_avg = (g_avg * (n - 1.0) + chg) / n;
            l_avg = (l_avg * (n - 1.0) + 0.0) / n;
        } else if chg < 0.0 {
            g_avg = (g_avg * (n - 1.0) + 0.0) / n;
            l_avg = (l_avg * (n - 1.0) + chg.abs()) / n;
        }
        else {
            g_avg = (g_avg * (n - 1.0) + 0.0) / n;
            l_avg = (l_avg * (n - 1.0) + 0.0) / n;
         }
        
        rsi_data.push(100.0 - (100.0/(1.0+((g_avg)/(l_avg)))));
        
    }
    rsi_data

}