package com.evsuite.abrp;

/**
 * The Empire style's ages, by odometer: the Dark Age below 10,000 km, the Feudal Age below
 * 30,000, the Castle Age below 60,000 and the Imperial Age from there. Pure Java, unit-tested.
 */
final class EmpireAge {

    private static final String[] NAMES = { "Dark Age", "Feudal Age", "Castle Age", "Imperial Age" };
    /** Where each age after the first begins, in km. */
    private static final float[] STARTS = { 10_000f, 30_000f, 60_000f };

    private EmpireAge() {}

    /** 0 to 3, or -1 when the odometer is unread. */
    static int index(Float km) {
        if (km == null || Float.isNaN(km)) return -1;
        int age = 0;
        while (age < STARTS.length && km >= STARTS[age]) age++;
        return age;
    }

    /** The age's name, "—" when unread. */
    static String name(Float km) {
        int age = index(km);
        return age < 0 ? "—" : NAMES[age];
    }

    /** The next age's name, or null in the last age and when unread. */
    static String next(Float km) {
        int age = index(km);
        return age < 0 || age >= STARTS.length ? null : NAMES[age + 1];
    }

    /** Kilometres left to the next age, or null in the last age and when unread. */
    static Float toNext(Float km) {
        int age = index(km);
        return age < 0 || age >= STARTS.length ? null : STARTS[age] - km;
    }

    /** How far through the current age, 0..1; 1 in the last age, 0 when unread. */
    static float progress(Float km) {
        int age = index(km);
        if (age < 0) return 0f;
        if (age >= STARTS.length) return 1f;
        float from = age == 0 ? 0f : STARTS[age - 1];
        return Math.max(0f, Math.min(1f, (km - from) / (STARTS[age] - from)));
    }
}