package com.miniabs;

import java.util.UUID;

import org.json.JSONObject;

import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import android.util.Base64;

/** Settings and sign-in state. */
final class Prefs {
    static final String MODE_JWT = "jwt";       // ABS 2.26+: short access token + refresh token
    static final String MODE_LEGACY = "legacy"; // older servers: one long-lived token
    static final String MODE_KEY = "key";       // API key pasted by the user

    private static Prefs instance;
    final SharedPreferences sp;

    private Prefs(Context c) {
        sp = PreferenceManager.getDefaultSharedPreferences(c);
    }

    static synchronized Prefs get(Context c) {
        if (instance == null) instance = new Prefs(c.getApplicationContext());
        return instance;
    }

    private String s(String k) {
        return sp.getString(k, "");
    }

    String server() { return s("server"); }
    String username() { return s("username"); }
    String token() { return s("access"); }
    String refreshToken() { return s("refresh"); }
    String mode() { return s("mode"); }
    boolean wifiOnly() { return sp.getBoolean("wifi_only", true); }
    boolean covers() { return sp.getBoolean("covers", true); }
    String libraryId() { return s("library_id"); }
    String libraryName() { return s("library_name"); }

    int skipBack() { return num("skip_back", 15); }
    int skipFwd() { return num("skip_fwd", 30); }

    private int num(String k, int def) {
        try {
            return Integer.parseInt(sp.getString(k, String.valueOf(def)));
        } catch (Exception e) {
            return def;
        }
    }

    boolean loggedIn() {
        return server().length() > 0 && token().length() > 0;
    }

    boolean canRefresh() {
        return MODE_JWT.equals(mode()) && refreshToken().length() > 0;
    }

    void setServer(String server) {
        sp.edit().putString("server", server).remove("trust_all").commit();
    }

    synchronized void setAuth(String user, String mode, String access, String refresh) {
        SharedPreferences.Editor e = sp.edit()
                .putString("username", user)
                .putString("mode", mode)
                .putString("refresh", refresh == null ? "" : refresh);
        putToken(e, access);
        e.commit();
    }

    synchronized void setTokens(String access, String refresh) {
        SharedPreferences.Editor e = sp.edit();
        if (refresh != null && refresh.length() > 0) e.putString("refresh", refresh);
        putToken(e, access);
        e.commit();
    }

    /** Stores the token with its lifetime measured on this phone's clock (old phones' clocks drift). */
    private void putToken(SharedPreferences.Editor e, String access) {
        long lifetime = 0;
        try {
            String[] parts = access.split("\\.");
            if (parts.length == 3) {
                JSONObject p = new JSONObject(new String(Base64.decode(parts[1], Base64.URL_SAFE), "UTF-8"));
                long exp = p.optLong("exp", 0), iat = p.optLong("iat", 0);
                if (exp > 0 && iat > 0 && exp > iat) lifetime = exp - iat;
            }
        } catch (Exception ignored) {
            // not a JWT, or unreadable: treat as non-expiring
        }
        e.putString("access", access)
                .putLong("token_lifetime", lifetime)
                .putLong("token_obtained", System.currentTimeMillis());
    }

    /** Seconds left on the access token; Long.MAX_VALUE when it doesn't expire. */
    long tokenSecondsLeft() {
        long life = sp.getLong("token_lifetime", 0);
        if (life <= 0) return Long.MAX_VALUE;
        long age = (System.currentTimeMillis() - sp.getLong("token_obtained", 0)) / 1000;
        if (age < 0) return 0; // clock went backwards; be safe and refresh
        return life - age;
    }

    long tokenObtainedAt() {
        return sp.getLong("token_obtained", 0);
    }

    void logout() {
        sp.edit().remove("access").remove("refresh").remove("mode")
                .remove("library_id").remove("library_name").remove("last_episode").commit();
    }

    void setLibrary(String id, String name) {
        sp.edit().putString("library_id", id).putString("library_name", name).commit();
    }

    String deviceId() {
        String id = s("device_id");
        if (id.length() == 0) {
            id = UUID.randomUUID().toString();
            sp.edit().putString("device_id", id).commit();
        }
        return id;
    }

    void setLastEpisode(Episode e) {
        sp.edit().putString("last_episode", e == null ? "" : e.toJson().toString()).commit();
    }

    Episode lastEpisode() {
        String j = s("last_episode");
        if (j.length() == 0) return null;
        try {
            return Episode.fromStored(new JSONObject(j));
        } catch (Exception e) {
            return null;
        }
    }
}