package com.iamthefij.otbeta;

import android.Manifest;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.annotation.TargetApi;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.location.LocationListener;
import android.location.LocationManager;
import android.support.annotation.NonNull;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.app.LoaderManager.LoaderCallbacks;

import android.content.CursorLoader;
import android.content.Loader;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;

import android.os.Build;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.text.TextUtils;
import android.util.Log;
import android.util.SparseArray;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.inputmethod.EditorInfo;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.TextView;

import com.iamthefij.otbeta.api.Client;
import com.iamthefij.otbeta.api.Exerciser;
import com.iamthefij.otbeta.api.Location;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import static android.Manifest.permission.READ_CONTACTS;
import static android.Manifest.permission.ACCESS_FINE_LOCATION;

/**
 * A login screen that offers login via email/password.
 */
public class LoginActivity extends AppCompatActivity implements LoaderCallbacks<Cursor> {

    /**
     * Ids to identity permission requests.
     */
    private static final int REQUEST_READ_CONTACTS = 0;
    private static final int REQUEST_ACCESS_FINE_LOCATION = 1;

    /**
     * Keep track of the login task to ensure we can cancel it if requested.
     */
    private UserLoginTask mAuthTask = null;

    // UI references.
    private Spinner mLocationView;
    private AutoCompleteTextView mEmailView;
    private EditText mPasswordView;
    private View mProgressView;
    private View mLoginFormView;
    private Client mClient;
    private Exerciser mExerciser;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        // Initialize client
        mClient = new Client(this);

        // Set up the login form.
        mLocationView = (Spinner) findViewById(R.id.location);
        populateLocationList();

        mEmailView = (AutoCompleteTextView) findViewById(R.id.email);
        populateAutoComplete();

        mPasswordView = (EditText) findViewById(R.id.password);
        mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
            @Override
            public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) {
                if (id == R.id.login || id == EditorInfo.IME_NULL) {
                    attemptLogin();
                    return true;
                }
                return false;
            }
        });

        Button mEmailSignInButton = (Button) findViewById(R.id.email_sign_in_button);
        mEmailSignInButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                attemptLogin();
            }
        });

        mLoginFormView = findViewById(R.id.login_form);
        mProgressView = findViewById(R.id.login_progress);
    }

    private void populateAutoComplete() {
        if (!mayRequestContacts()) {
            return;
        }

        getLoaderManager().initLoader(0, null, this);
    }

    private void populateLocationList() {
        LocationListFetcher locationListFetcher = new LocationListFetcher();
        locationListFetcher.execute();
    }

    private void sortLocationList() {
        if (!mayRequestLocation()) {
            return;
        }
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return;
        }
        final LocationSpinnerAdapter locationSpinnerAdapter = (LocationSpinnerAdapter) mLocationView.getAdapter();
        if (locationSpinnerAdapter != null && !locationSpinnerAdapter.isEmpty() && !locationSpinnerAdapter.isSorted()) {
            final LocationManager locationManager = (LocationManager) getApplicationContext().getSystemService(LOCATION_SERVICE);
            locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, new BasicLocationListener(locationSpinnerAdapter, locationManager));
            android.location.Location currentLocation = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
            if (currentLocation != null) {
                locationSpinnerAdapter.sortByDistance(currentLocation.getLatitude(), currentLocation.getLongitude());
            }
        }
    }

    private boolean mayRequestContacts() {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            return true;
        }
        if (checkSelfPermission(READ_CONTACTS) == PackageManager.PERMISSION_GRANTED) {
            return true;
        }
        if (shouldShowRequestPermissionRationale(READ_CONTACTS)) {
            Snackbar.make(mEmailView, R.string.contact_permission_rationale, Snackbar.LENGTH_INDEFINITE)
                    .setAction(android.R.string.ok, new View.OnClickListener() {
                        @Override
                        @TargetApi(Build.VERSION_CODES.M)
                        public void onClick(View v) {
                            requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
                        }
                    });
        } else {
            requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
        }
        return false;
    }

    private boolean mayRequestLocation() {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            return true;
        }
        if (checkSelfPermission(ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
            return true;
        }
        if (shouldShowRequestPermissionRationale(ACCESS_FINE_LOCATION)) {
            Snackbar.make(mLocationView, R.string.location_permission_rationale, Snackbar.LENGTH_INDEFINITE)
                    .setAction(android.R.string.ok, new View.OnClickListener() {
                        @Override
                        @TargetApi(Build.VERSION_CODES.M)
                        public void onClick(View v) {
                            requestPermissions(new String[]{ACCESS_FINE_LOCATION}, REQUEST_ACCESS_FINE_LOCATION);
                        }
                    });
        } else {
            requestPermissions(new String[]{ACCESS_FINE_LOCATION}, REQUEST_ACCESS_FINE_LOCATION);
        }
        return false;
    }

    /**
     * Callback received when a permissions request has been completed.
     */
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                           @NonNull int[] grantResults) {
        if (requestCode == REQUEST_READ_CONTACTS) {
            if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                populateAutoComplete();
            }
        } else if (requestCode == REQUEST_ACCESS_FINE_LOCATION) {
            if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                sortLocationList();
            }
        }
    }

    /**
     * Attempts to sign in or register the account specified by the login form.
     * If there are form errors (invalid email, missing fields, etc.), the
     * errors are presented and no actual login attempt is made.
     */
    private void attemptLogin() {
        if (mAuthTask != null) {
            return;
        }

        // Reset errors.
        mEmailView.setError(null);
        mPasswordView.setError(null);

        // Store values at the time of the login attempt.
        String email = mEmailView.getText().toString();
        String password = mPasswordView.getText().toString();
        Location location = (Location) mLocationView.getSelectedItem();

        boolean cancel = false;
        View focusView = null;

        // Check for a valid password, if the user entered one.
        if (!TextUtils.isEmpty(password) && !isPasswordValid(password)) {
            mPasswordView.setError(getString(R.string.error_invalid_password));
            focusView = mPasswordView;
            cancel = true;
        }

        // Check for a valid email address.
        if (TextUtils.isEmpty(email)) {
            mEmailView.setError(getString(R.string.error_field_required));
            focusView = mEmailView;
            cancel = true;
        } else if (!isEmailValid(email)) {
            mEmailView.setError(getString(R.string.error_invalid_email));
            focusView = mEmailView;
            cancel = true;
        }

        if (cancel) {
            // There was an error; don't attempt login and focus the first
            // form field with an error.
            focusView.requestFocus();
        } else {
            // Show a progress spinner, and kick off a background task to
            // perform the user login attempt.
            showProgress(true);
            mAuthTask = new UserLoginTask(email, password, location);
            mAuthTask.execute((Void) null);
        }
    }

    private boolean isEmailValid(String email) {
        return email.contains("@");
    }

    private boolean isPasswordValid(String password) {
        return password.length() > 4;
    }

    /**
     * Shows the progress UI and hides the login form.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
    private void showProgress(final boolean show) {
        // On Honeycomb MR2 we have the ViewPropertyAnimator APIs, which allow
        // for very easy animations. If available, use these APIs to fade-in
        // the progress spinner.
        int shortAnimTime = getResources().getInteger(android.R.integer.config_shortAnimTime);

        mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
        mLoginFormView.animate().setDuration(shortAnimTime).alpha(
                show ? 0 : 1).setListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
            }
        });

        mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
        mProgressView.animate().setDuration(shortAnimTime).alpha(
                show ? 1 : 0).setListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
            }
        });
    }

    @Override
    public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
        return new CursorLoader(this,
                // Retrieve data rows for the device user's 'profile' contact.
                Uri.withAppendedPath(ContactsContract.Profile.CONTENT_URI,
                        ContactsContract.Contacts.Data.CONTENT_DIRECTORY), ProfileQuery.PROJECTION,

                // Select only email addresses.
                ContactsContract.Contacts.Data.MIMETYPE +
                        " = ?", new String[]{ContactsContract.CommonDataKinds.Email
                .CONTENT_ITEM_TYPE},

                // Show primary email addresses first. Note that there won't be
                // a primary email address if the user hasn't specified one.
                ContactsContract.Contacts.Data.IS_PRIMARY + " DESC");
    }

    @Override
    public void onLoadFinished(Loader<Cursor> cursorLoader, Cursor cursor) {
        List<String> emails = new ArrayList<>();
        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            emails.add(cursor.getString(ProfileQuery.ADDRESS));
            cursor.moveToNext();
        }

        addEmailsToAutoComplete(emails);
    }

    @Override
    public void onLoaderReset(Loader<Cursor> cursorLoader) {

    }

    private void addEmailsToAutoComplete(List<String> emailAddressCollection) {
        //Create adapter to tell the AutoCompleteTextView what to show in its dropdown list.
        ArrayAdapter<String> adapter =
                new ArrayAdapter<>(LoginActivity.this,
                        android.R.layout.simple_dropdown_item_1line, emailAddressCollection);

        mEmailView.setAdapter(adapter);
    }

    private interface ProfileQuery {
        String[] PROJECTION = {
                ContactsContract.CommonDataKinds.Email.ADDRESS,
                ContactsContract.CommonDataKinds.Email.IS_PRIMARY,
        };

        int ADDRESS = 0;
        int IS_PRIMARY = 1;
    }

    /**
     * Represents an asynchronous login/registration task used to authenticate
     * the user.
     */
    public class UserLoginTask extends AsyncTask<Void, Void, Boolean> {

        private final String mEmail;
        private final String mPassword;
        private final Location mLocation;
        private Exerciser mTempExerciser;

        UserLoginTask(String email, String password, Location location) {
            mEmail = email;
            mPassword = password;
            mLocation = location;
        }

        @Override
        protected Boolean doInBackground(Void... params) {
            mTempExerciser = mClient.login(mEmail, mPassword, mLocation);

            return (mTempExerciser != null);
        }

        @Override
        protected void onPostExecute(final Boolean success) {
            mAuthTask = null;
            showProgress(false);

            if (success) {
                mExerciser = this.mTempExerciser;
                launchMainActivity();
            } else {
                mPasswordView.setError(getString(R.string.error_incorrect_password));
                mPasswordView.requestFocus();
            }
        }

        @Override
        protected void onCancelled() {
            mAuthTask = null;
            showProgress(false);
        }
    }

    /**
     * Launches the main activity after an exerciser is retrieved
     */
    private void launchMainActivity() {
        if (mExerciser != null) {
            ExerciserStore exerciserStore = new ExerciserStore(this);
            exerciserStore.saveExerciser(mExerciser);
            Intent nextIntent = new Intent(LoginActivity.this, WorkoutListActivity.class);
            startActivity(nextIntent);
            finish();
        }
    }

    /**
     * Represents an asynchronous task to retrieve locations from the api and populate
     * the location spinner
     */
    private class LocationListFetcher extends AsyncTask<Void, Void, Boolean> {

        private final android.location.Location mCurrentLocation;
        private List<Location> mLocations;

        public LocationListFetcher() {
            mCurrentLocation = null;
            mLocations = null;
        }

        public LocationListFetcher(android.location.Location currentLocation) {
            mCurrentLocation = currentLocation;
        }

        @Override
        protected Boolean doInBackground(Void... params) {
            mLocations = mClient.getLocationsWithDetail();
            return (mLocations != null);
        }

        @Override
        protected void onPostExecute(Boolean success) {
            super.onPostExecute(success);
            if (success) {
                LocationSpinnerAdapter locationSpinnerAdapter = new LocationSpinnerAdapter(mLocations);
                mLocationView.setAdapter(locationSpinnerAdapter);

                if (mCurrentLocation != null) {
                    locationSpinnerAdapter.sortByDistance(mCurrentLocation.getLatitude(), mCurrentLocation.getLongitude());
                }

                sortLocationList();
            }
        }
    }

    /**
     * Adapter to show locations in spinner
     */
    private class LocationSpinnerAdapter extends BaseAdapter implements SpinnerAdapter {

        private final List<Location> mLocations;
        private boolean mSorted;

        public boolean isSorted() {
            return mSorted;
        }

        public LocationSpinnerAdapter(List<Location> locations) {
            mLocations = locations;
            mSorted = false;
        }

        @Override
        public int getCount() {
            return mLocations.size();
        }

        @Override
        public Object getItem(int position) {
            return mLocations.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            TextView text;
            if (convertView != null) {
                text = (TextView) convertView;
            } else {
                text = (TextView) getLayoutInflater().inflate(
                        android.R.layout.simple_dropdown_item_1line,
                        parent,
                        false
                );
            }
            text.setTextColor(Color.BLACK);
            text.setText(mLocations.get(position).getName());
            return text;
        }

        /**
         * Sorts the locations in the list by distance from a given point
         *
         * @param lat latitude of current location to calculate distance from
         * @param lon longitude of current location to calculate distance from
         */
        public void sortByDistance(double lat, double lon) {
            Collections.sort(mLocations, new LocationDistanceComparator(lat, lon));
            mSorted = true;
        }
    }

    /**
     * Comparator that allows sorting of locations by distance from a point
     */
    static class LocationDistanceComparator implements Comparator<Location> {

        private final double mLat;
        private final double mLon;
        private final SparseArray<Float> mDistances;

        public LocationDistanceComparator(double lat, double lon) {
            mLat = lat;
            mLon = lon;
            mDistances = new SparseArray<>();
        }

        private boolean locationHasCoords(Location l) {
            return (l.hasAddress() && l.getAddress().hasLatitude() && l.getAddress().hasLongitude());
        }

        private float distanceToLocation(Location l) {
            // Try to return from cache
            float distance = mDistances.get(l.getId(), -1f);
            if (distance > 0) {
                return distance;
            }

            // Calculate the distance between location and provided coordinates
            float[] results = new float[2];
            android.location.Location.distanceBetween(mLat, mLon, l.getAddress().getLatitude(), l.getAddress().getLongitude(), results);
            distance = results[0];
            // Store distance in cache
            mDistances.put(l.getId(), distance);

            return distance;
        }

        public int compare(Location l1, Location l2) {
            // TODO: Fix bug here. Getting "Comparison method violates its general contract!"
            if (locationHasCoords(l1) && !locationHasCoords(l2)) {
                return -1;
            } else if (!locationHasCoords(l1) && locationHasCoords(l2)) {
                return 1;
            } else if (locationHasCoords(l1) && locationHasCoords(l2)){
                float distance1 = distanceToLocation(l1);
                float distance2 = distanceToLocation(l2);

                if (distance1 > distance2) {
                    return 1;
                } else if (distance1 < distance2) {
                    return -1;
                }
            }

            // All else equal, let's use name
            if (l1.getName() != null && l2.getName() != null) {
                return l1.getName().compareTo(l2.getName());
            }

            return 0;
        }
    }

    private class BasicLocationListener implements LocationListener {

        private static final String TAG = "LocationListener";
        private final LocationSpinnerAdapter spinnerAdapter;
        private final LocationManager locationManager;

        public BasicLocationListener(LocationSpinnerAdapter spinnerAdapter, LocationManager locationManager) {
            this.spinnerAdapter = spinnerAdapter;
            this.locationManager = locationManager;
        }

        @Override
        public void onLocationChanged(android.location.Location location) {
            spinnerAdapter.sortByDistance(location.getLatitude(), location.getLongitude());
            locationManager.removeUpdates(this);
        }

        @Override
        public void onStatusChanged(String s, int i, Bundle bundle) {
            Log.d(TAG, "onStatusChanged: ");
        }

        @Override
        public void onProviderEnabled(String s) {
            Log.d(TAG, "onProviderEnabled: ");
        }

        @Override
        public void onProviderDisabled(String s) {
            Log.d(TAG, "onProviderDisabled: ");
        }
    }
}