package com.evsuite.abrp;

import android.content.Context;
import android.content.SharedPreferences;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
import java.util.Locale;

/**
 * Every change of the car's raw gear code with the time and speed, the last {@link #MAX_LINES},
 * shown on the Logs tab. It is how the codes for R, N and D get matched to the lever: shift
 * through them and read which code each one gave. Kept in preferences so the list survives
 * the app being closed in between. Written only when the code changes.
 */
final class GearLog {

    static final int MAX_LINES = 12;
    private static final String PREFS = "gear_log";
    private static final String KEY = "lines";

    /** The last code seen in this process; MIN_VALUE before the first reading. */
    private static int last = Integer.MIN_VALUE;

    private GearLog() {}

    /** Called with every reading; records a line when the code differs from the last one. */
    static void note(Context context, Integer raw, Float speedKmh) {
        int code = raw == null ? -1 : raw;
        synchronized (GearLog.class) {
            if (context == null || code == last) return;
            last = code;
            String line = new SimpleDateFormat("dd.MM. HH:mm:ss", Locale.US).format(new Date())
                    + "  code " + (raw == null ? "unread" : String.valueOf(raw))
                    + (raw != null && raw == Gear.PARK ? " (P)" : "")
                    + "  at " + (speedKmh == null ? "—" : String.format(Locale.US, "%.0f km/h", speedKmh));
            SharedPreferences prefs = context.getApplicationContext()
                    .getSharedPreferences(PREFS, Context.MODE_PRIVATE);
            List<String> lines = UpdateLog.append(split(prefs.getString(KEY, null)), line, MAX_LINES);
            prefs.edit().putString(KEY, String.join("\n", lines)).apply();
        }
    }

    /** The code now, null when unread or not read yet. */
    static synchronized Integer current() {
        return last < 0 ? null : last;
    }

    /** Newest first. */
    static List<String> lines(Context context) {
        SharedPreferences prefs = context.getApplicationContext()
                .getSharedPreferences(PREFS, Context.MODE_PRIVATE);
        return split(prefs.getString(KEY, null));
    }

    private static List<String> split(String stored) {
        if (stored == null || stored.isEmpty()) return new ArrayList<>();
        return new ArrayList<>(Arrays.asList(stored.split("\n")));
    }
}