#include "eseries.h"

#include <math.h>
#include <vector>

static const std::vector<double> E6 = {
    1.0, 1.5, 2.2, 3.3, 4.7, 6.8
};
static const std::vector<double> E12 = {
    1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2
};
static const std::vector<double> E24 = {
    1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1
};
static const std::vector<double> E48 = {
    1.00, 1.05, 1.10, 1.15, 1.21, 1.27, 1.33, 1.40, 1.47, 1.54, 1.62, 1.69, 1.78, 1.87, 1.96, 2.05, 2.15, 2.26, 2.37, 2.49, 2.61, 2.74, 2.87, 3.01, 3.16, 3.32, 3.48, 3.65, 3.83, 4.02, 4.22, 4.42, 4.64, 4.87, 5.11, 5.36, 5.62, 5.90, 6.19, 6.49, 6.81, 7.15, 7.50, 7.87, 8.25, 8.66, 9.09, 9.53
};
static const std::vector<double> E96 = {
    1.00, 1.02, 1.05, 1.07, 1.10, 1.13, 1.15, 1.18, 1.21, 1.24, 1.27, 1.30, 1.33, 1.37, 1.40, 1.43, 1.47, 1.50, 1.54, 1.58, 1.62, 1.65, 1.69, 1.74, 1.78, 1.82, 1.87, 1.91, 1.96, 2.00, 2.05, 2.10, 2.15, 2.21, 2.26, 2.32, 2.37, 2.43, 2.49, 2.55, 2.61, 2.67, 2.74, 2.80, 2.87, 2.94, 3.01, 3.09, 3.16, 3.24, 3.32, 3.40, 3.48, 3.57, 3.65, 3.74, 3.83, 3.92, 4.02, 4.12, 4.22, 4.32, 4.42, 4.53, 4.64, 4.75, 4.87, 4.99, 5.11, 5.23, 5.36, 5.49, 5.62, 5.76, 5.90, 6.04, 6.19, 6.34, 6.49, 6.65, 6.81, 6.98, 7.15, 7.32, 7.50, 7.68, 7.87, 8.06, 8.25, 8.45, 8.66, 8.87, 9.09, 9.31, 9.53, 9.76
};

double ESeries::ToESeries(double value, ESeries::Series s, ESeries::Type t)
{
    if(s == Series::Ideal || value <= 0) {
        // nothing to do
        return value;
    }
    // bring value into [1.0, 10.0) interval
    int shift10 = floor(log10(value));
    value *= pow(10.0, -shift10);
    std::vector<double> series;
    switch(s) {
    case Series::E96: series = E96; break;
    case Series::E48: series = E48; break;
    case Series::E24: series = E24; break;
    case Series::E12: series = E12; break;
    case Series::E6: series = E6; break;
    case Series::Ideal: /* already handled */ break;
    }
    unsigned int index = 1;
    while(index < 96 && series[index] <= value) {
        index++;
    }
    auto lower = series[index - 1];
    double higher = 10.0;
    if(index < series.size()) {
        higher = series[index];
    }
    double approximation = 0;
    switch(t) {
    case Type::Lower: approximation = lower; break;
    case Type::Higher: approximation = higher; break;
    case Type::BestMatch:
        if(fabs(value - lower) < fabs(value - higher)) {
            approximation = lower;
        } else {
            approximation = higher;
        }
    }
    return approximation * pow(10, shift10);
}