package org.gingercal;

import java.io.IOException;
import java.net.ConnectException;
import java.net.SocketTimeoutException;
import java.net.URI;
import java.net.UnknownHostException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;

import javax.net.ssl.SSLException;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.AlertDialog;
import android.app.PendingIntent;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import org.gingercal.Model.Ev;

/** Shared helpers: settings, formatting, scheduling, dialogs. */
public final class App {
    private App() {}

    public static final int[] INTERVALS = {0, 1, 3, 6, 12, 24};
    public static final int[] ALARMS = {-1, 0, 5, 10, 15, 30, 60, 120, 1440};

    public static SharedPreferences prefs(Context c) {
        return c.getSharedPreferences("gingercal", 0);
    }

    public static String get(Context c, String k) {
        return prefs(c).getString(k, "");
    }

    public static boolean configured(Context c) {
        return get(c, "url").length() > 0 && get(c, "user").length() > 0;
    }

    public static int interval(Context c) {
        return prefs(c).getInt("interval", 3);
    }

    public static int remind(Context c) {
        return prefs(c).getInt("remind", 15);
    }

    public static int ahead(Context c) {
        return prefs(c).getInt("ahead", 60);
    }

    public static Dav dav(Context c) throws Exception {
        return dav(get(c, "url"), get(c, "user"), get(c, "pass"), get(c, "pin"));
    }

    public static Dav dav(String url, String user, String pass, String pin) throws Exception {
        return new Dav(new ApacheHttp(pin, 30000), url, user, pass);
    }

    public static boolean online(Context c) {
        ConnectivityManager cm = (ConnectivityManager) c.getSystemService("connectivity");
        NetworkInfo ni = cm == null ? null : cm.getActiveNetworkInfo();
        return ni != null && ni.isConnected();
    }

    public static void requestSync(Context c, boolean manual, boolean force) {
        Intent i = new Intent(c, SyncService.class);
        i.putExtra("manual", manual);
        i.putExtra("force", force);
        c.startService(i);
    }

    /** (Re)arms the periodic background sync. */
    public static void scheduleSync(Context c) {
        AlarmManager am = (AlarmManager) c.getSystemService("alarm");
        Intent i = new Intent(c, AlarmReceiver.class);
        i.setAction(AlarmReceiver.SYNC);
        PendingIntent pi = PendingIntent.getBroadcast(c, 1, i, 0);
        am.cancel(pi);
        int h = interval(c);
        if (h > 0 && configured(c)) {
            long every = h * ICal.HOUR;
            am.setInexactRepeating(1 /* RTC: don't wake the phone just to sync */,
                    System.currentTimeMillis() + every, every, pi);
        }
    }

    public static boolean isLan(String url) {
        try {
            String h = URI.create(Dav.normalize(url)).getHost();
            if (h == null) return false;
            h = h.toLowerCase(Locale.US);
            if (h.startsWith("10.") || h.startsWith("192.168.") || h.equals("localhost") || h.endsWith(".local")
                    || h.endsWith(".lan") || h.endsWith(".home.arpa")) return true;
            if (h.startsWith("172.")) {
                String[] p = h.split("\\.");
                int b = Integer.parseInt(p[1]);
                return b >= 16 && b <= 31;
            }
            if (h.startsWith("100.")) { // CGNAT / Tailscale-style ranges
                int b = Integer.parseInt(h.split("\\.")[1]);
                return b >= 64 && b <= 127;
            }
        } catch (RuntimeException ignored) {
        }
        return false;
    }

    // ------------------------------------------------------------ messages

    public static String describe(Throwable t) {
        if (t instanceof DavException || t instanceof DavException.UntrustedCert) return t.getMessage();
        if (t instanceof UnknownHostException) {
            return "Can't resolve " + t.getMessage() + ". No connection, or a typo in the server address.";
        }
        if (t instanceof ConnectException) return "Can't connect to the server (" + t.getMessage() + "). Wrong port, or the bridge is down?";
        if (t instanceof SocketTimeoutException) return "The server took too long to answer.";
        if (t instanceof SSLException) return "TLS error: " + t.getMessage();
        if (t instanceof IOException) return "Network error: " + t;
        if (t instanceof OutOfMemoryError) return "Out of memory. Lower 'Days ahead' in Settings.";
        return "Error: " + t;
    }

    public static void toast(Context c, String s) {
        Toast.makeText(c, s, 1).show();
    }

    public interface Trusted {
        void trusted(String fingerprint);
    }

    public static void askTrust(Activity a, final DavException.UntrustedCert u, final Trusted cb) {
        String msg = (u.pinMismatch
                ? "WARNING: the server certificate changed since you trusted it. That happens when you "
                + "regenerate the bridge certificate - or when someone is intercepting the connection.\n\n"
                : "This phone doesn't trust the server certificate (normal for the self-signed legacy bridge, "
                + "or for Let's Encrypt on Android 2.3).\n\n")
                + "Subject: " + u.subject + "\nIssuer: " + u.issuer + "\nExpires: " + u.expires
                + "\n\nSHA-256:\n" + u.fingerprint
                + "\n\nOnly trust it if this matches the fingerprint printed on your server.";
        new AlertDialog.Builder(a)
                .setTitle(u.pinMismatch ? "Certificate changed!" : "Trust this certificate?")
                .setMessage(msg)
                .setPositiveButton("Trust", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface d, int w) {
                        cb.trusted(u.fingerprint);
                    }
                })
                .setNegativeButton("Cancel", null)
                .show();
    }

    // ------------------------------------------------------------ formatting

    public static String time(Context c, long t) {
        String p = android.text.format.DateFormat.is24HourFormat(c) ? "HH:mm" : "h:mma";
        return new SimpleDateFormat(p, Locale.getDefault()).format(new Date(t));
    }

    public static String day(long t) {
        boolean thisYear = year(t) == year(System.currentTimeMillis());
        return new SimpleDateFormat(thisYear ? "EEE d MMM" : "EEE d MMM yyyy", Locale.getDefault()).format(new Date(t));
    }

    static int year(long t) {
        Calendar c = Calendar.getInstance();
        c.setTimeInMillis(t);
        return c.get(Calendar.YEAR);
    }

    public static String dayHeader(long dayStart) {
        long today = ICal.startOfDay(System.currentTimeMillis());
        if (dayStart == today) return "Today  ·  " + day(dayStart);
        if (dayStart == ICal.addDays(today, 1)) return "Tomorrow  ·  " + day(dayStart);
        return day(dayStart);
    }

    public static String when(Context c, Ev e) {
        if (e.allDay) {
            long lastDay = ICal.addDays(e.end, -1);
            if (lastDay <= e.start) return "All day";
            return "All day, until " + day(lastDay);
        }
        String s = time(c, e.start);
        if (e.end <= e.start) return s;
        if (ICal.startOfDay(e.end - 1) != ICal.startOfDay(e.start)) {
            return s + " – " + day(e.end) + " " + time(c, e.end);
        }
        return s + " – " + time(c, e.end);
    }

    public static String alarmLabel(int m) {
        if (m < 0) return "No reminder";
        if (m == 0) return "At start time";
        if (m < 60) return m + " min before";
        if (m < 1440) return (m / 60) + " h before";
        return (m / 1440) + " day before";
    }

    // --------------------------------------------------------------- views

    public static int dp(Context c, float v) {
        return (int) (v * c.getResources().getDisplayMetrics().density + 0.5f);
    }

    public static TextView text(Context c, String s, float sp, int color) {
        TextView t = new TextView(c);
        t.setText(s);
        t.setTextSize(sp);
        t.setTextColor(color);
        return t;
    }

    public static LinearLayout vbox(Context c) {
        LinearLayout l = new LinearLayout(c);
        l.setOrientation(LinearLayout.VERTICAL);
        return l;
    }

    public static int sysDrawable(Context c, String name) {
        return c.getResources().getIdentifier(name, "drawable", "android");
    }
}