/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.widget;

import android.annotation.Nullable;
import android.content.Context;
import android.content.res.ColorStateList;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.icu.text.DateFormat;
import android.icu.text.DisplayContext;
import android.icu.util.Calendar;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.util.StateSet;
import android.view.HapticFeedbackConstants;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
import android.widget.DayPickerView.OnDaySelectedListener;
import android.widget.YearPickerView.OnYearSelectedListener;

import com.android.internal.R;

import java.util.Locale;

A delegate for picking up a date (day / month / year).
/**
 * A delegate for picking up a date (day / month / year).
 */
class DatePickerCalendarDelegate extends DatePicker.AbstractDatePickerDelegate {
    private static final int USE_LOCALE = 0;

    private static final int UNINITIALIZED = -1;
    private static final int VIEW_MONTH_DAY = 0;
    private static final int VIEW_YEAR = 1;

    private static final int DEFAULT_START_YEAR = 1900;
    private static final int DEFAULT_END_YEAR = 2100;

    private static final int ANIMATION_DURATION = 300;

    private static final int[] ATTRS_TEXT_COLOR = new int[] {
            com.android.internal.R.attr.textColor};
    private static final int[] ATTRS_DISABLED_ALPHA = new int[] {
            com.android.internal.R.attr.disabledAlpha};

    private DateFormat mYearFormat;
    private DateFormat mMonthDayFormat;

    // Top-level container.
    private ViewGroup mContainer;

    // Header views.
    private TextView mHeaderYear;
    private TextView mHeaderMonthDay;

    // Picker views.
    private ViewAnimator mAnimator;
    private DayPickerView mDayPickerView;
    private YearPickerView mYearPickerView;

    // Accessibility strings.
    private String mSelectDay;
    private String mSelectYear;

    private int mCurrentView = UNINITIALIZED;

    private final Calendar mTempDate;
    private final Calendar mMinDate;
    private final Calendar mMaxDate;

    private int mFirstDayOfWeek = USE_LOCALE;

    public DatePickerCalendarDelegate(DatePicker delegator, Context context, AttributeSet attrs,
            int defStyleAttr, int defStyleRes) {
        super(delegator, context);

        final Locale locale = mCurrentLocale;
        mCurrentDate = Calendar.getInstance(locale);
        mTempDate = Calendar.getInstance(locale);
        mMinDate = Calendar.getInstance(locale);
        mMaxDate = Calendar.getInstance(locale);

        mMinDate.set(DEFAULT_START_YEAR, Calendar.JANUARY, 1);
        mMaxDate.set(DEFAULT_END_YEAR, Calendar.DECEMBER, 31);

        final Resources res = mDelegator.getResources();
        final TypedArray a = mContext.obtainStyledAttributes(attrs,
                R.styleable.DatePicker, defStyleAttr, defStyleRes);
        final LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(
                Context.LAYOUT_INFLATER_SERVICE);
        final int layoutResourceId = a.getResourceId(
                R.styleable.DatePicker_internalLayout, R.layout.date_picker_material);

        // Set up and attach container.
        mContainer = (ViewGroup) inflater.inflate(layoutResourceId, mDelegator, false);
        mContainer.setSaveFromParentEnabled(false);
        mDelegator.addView(mContainer);

        // Set up header views.
        final ViewGroup header = mContainer.findViewById(R.id.date_picker_header);
        mHeaderYear = header.findViewById(R.id.date_picker_header_year);
        mHeaderYear.setOnClickListener(mOnHeaderClickListener);
        mHeaderMonthDay = header.findViewById(R.id.date_picker_header_date);
        mHeaderMonthDay.setOnClickListener(mOnHeaderClickListener);

        // For the sake of backwards compatibility, attempt to extract the text
        // color from the header month text appearance. If it's set, we'll let
        // that override the "real" header text color.
        ColorStateList headerTextColor = null;

        @SuppressWarnings("deprecation")
        final int monthHeaderTextAppearance = a.getResourceId(
                R.styleable.DatePicker_headerMonthTextAppearance, 0);
        if (monthHeaderTextAppearance != 0) {
            final TypedArray textAppearance = mContext.obtainStyledAttributes(null,
                    ATTRS_TEXT_COLOR, 0, monthHeaderTextAppearance);
            final ColorStateList legacyHeaderTextColor = textAppearance.getColorStateList(0);
            headerTextColor = applyLegacyColorFixes(legacyHeaderTextColor);
            textAppearance.recycle();
        }

        if (headerTextColor == null) {
            headerTextColor = a.getColorStateList(R.styleable.DatePicker_headerTextColor);
        }

        if (headerTextColor != null) {
            mHeaderYear.setTextColor(headerTextColor);
            mHeaderMonthDay.setTextColor(headerTextColor);
        }

        // Set up header background, if available.
        if (a.hasValueOrEmpty(R.styleable.DatePicker_headerBackground)) {
            header.setBackground(a.getDrawable(R.styleable.DatePicker_headerBackground));
        }

        a.recycle();

        // Set up picker container.
        mAnimator = mContainer.findViewById(R.id.animator);

        // Set up day picker view.
        mDayPickerView = mAnimator.findViewById(R.id.date_picker_day_picker);
        mDayPickerView.setFirstDayOfWeek(mFirstDayOfWeek);
        mDayPickerView.setMinDate(mMinDate.getTimeInMillis());
        mDayPickerView.setMaxDate(mMaxDate.getTimeInMillis());
        mDayPickerView.setDate(mCurrentDate.getTimeInMillis());
        mDayPickerView.setOnDaySelectedListener(mOnDaySelectedListener);

        // Set up year picker view.
        mYearPickerView = mAnimator.findViewById(R.id.date_picker_year_picker);
        mYearPickerView.setRange(mMinDate, mMaxDate);
        mYearPickerView.setYear(mCurrentDate.get(Calendar.YEAR));
        mYearPickerView.setOnYearSelectedListener(mOnYearSelectedListener);

        // Set up content descriptions.
        mSelectDay = res.getString(R.string.select_day);
        mSelectYear = res.getString(R.string.select_year);

        // Initialize for current locale. This also initializes the date, so no
        // need to call onDateChanged.
        onLocaleChanged(mCurrentLocale);

        setCurrentView(VIEW_MONTH_DAY);
    }

    
The legacy text color might have been poorly defined. Ensures that it
has an appropriate activated state, using the selected state if one
exists or modifying the default text color otherwise.
Params:
color – a legacy text color, or null
Returns:
a color state list with an appropriate activated state, or null if a valid activated state could not be generated/**
     * The legacy text color might have been poorly defined. Ensures that it
     * has an appropriate activated state, using the selected state if one
     * exists or modifying the default text color otherwise.
     *
     * @param color a legacy text color, or {@code null}
     * @return a color state list with an appropriate activated state, or
     *         {@code null} if a valid activated state could not be generated
     */
    @Nullable
    private ColorStateList applyLegacyColorFixes(@Nullable ColorStateList color) {
        if (color == null || color.hasState(R.attr.state_activated)) {
            return color;
        }

        final int activatedColor;
        final int defaultColor;
        if (color.hasState(R.attr.state_selected)) {
            activatedColor = color.getColorForState(StateSet.get(
                    StateSet.VIEW_STATE_ENABLED | StateSet.VIEW_STATE_SELECTED), 0);
            defaultColor = color.getColorForState(StateSet.get(
                    StateSet.VIEW_STATE_ENABLED), 0);
        } else {
            activatedColor = color.getDefaultColor();

            // Generate a non-activated color using the disabled alpha.
            final TypedArray ta = mContext.obtainStyledAttributes(ATTRS_DISABLED_ALPHA);
            final float disabledAlpha = ta.getFloat(0, 0.30f);
            defaultColor = multiplyAlphaComponent(activatedColor, disabledAlpha);
        }

        if (activatedColor == 0 || defaultColor == 0) {
            // We somehow failed to obtain the colors.
            return null;
        }

        final int[][] stateSet = new int[][] {{ R.attr.state_activated }, {}};
        final int[] colors = new int[] { activatedColor, defaultColor };
        return new ColorStateList(stateSet, colors);
    }

    private int multiplyAlphaComponent(int color, float alphaMod) {
        final int srcRgb = color & 0xFFFFFF;
        final int srcAlpha = (color >> 24) & 0xFF;
        final int dstAlpha = (int) (srcAlpha * alphaMod + 0.5f);
        return srcRgb | (dstAlpha << 24);
    }

    
Listener called when the user selects a day in the day picker view.
/**
     * Listener called when the user selects a day in the day picker view.
     */
    private final OnDaySelectedListener mOnDaySelectedListener = new OnDaySelectedListener() {
        @Override
        public void onDaySelected(DayPickerView view, Calendar day) {
            mCurrentDate.setTimeInMillis(day.getTimeInMillis());
            onDateChanged(true, true);
        }
    };

    
Listener called when the user selects a year in the year picker view.
/**
     * Listener called when the user selects a year in the year picker view.
     */
    private final OnYearSelectedListener mOnYearSelectedListener = new OnYearSelectedListener() {
        @Override
        public void onYearChanged(YearPickerView view, int year) {
            // If the newly selected month / year does not contain the
            // currently selected day number, change the selected day number
            // to the last day of the selected month or year.
            // e.g. Switching from Mar to Apr when Mar 31 is selected -> Apr 30
            // e.g. Switching from 2012 to 2013 when Feb 29, 2012 is selected -> Feb 28, 2013
            final int day = mCurrentDate.get(Calendar.DAY_OF_MONTH);
            final int month = mCurrentDate.get(Calendar.MONTH);
            final int daysInMonth = getDaysInMonth(month, year);
            if (day > daysInMonth) {
                mCurrentDate.set(Calendar.DAY_OF_MONTH, daysInMonth);
            }

            mCurrentDate.set(Calendar.YEAR, year);
            onDateChanged(true, true);

            // Automatically switch to day picker.
            setCurrentView(VIEW_MONTH_DAY);

            // Switch focus back to the year text.
            mHeaderYear.requestFocus();
        }
    };

    
Listener called when the user clicks on a header item.
/**
     * Listener called when the user clicks on a header item.
     */
    private final OnClickListener mOnHeaderClickListener = v -> {
        tryVibrate();

        switch (v.getId()) {
            case R.id.date_picker_header_year:
                setCurrentView(VIEW_YEAR);
                break;
            case R.id.date_picker_header_date:
                setCurrentView(VIEW_MONTH_DAY);
                break;
        }
    };

    @Override
    protected void onLocaleChanged(Locale locale) {
        final TextView headerYear = mHeaderYear;
        if (headerYear == null) {
            // Abort, we haven't initialized yet. This method will get called
            // again later after everything has been set up.
            return;
        }

        // Update the date formatter.
        mMonthDayFormat = DateFormat.getInstanceForSkeleton("EMMMd", locale);
        mMonthDayFormat.setContext(DisplayContext.CAPITALIZATION_FOR_STANDALONE);
        mYearFormat = DateFormat.getInstanceForSkeleton("y", locale);

        // Update the header text.
        onCurrentDateChanged(false);
    }

    private void onCurrentDateChanged(boolean announce) {
        if (mHeaderYear == null) {
            // Abort, we haven't initialized yet. This method will get called
            // again later after everything has been set up.
            return;
        }

        final String year = mYearFormat.format(mCurrentDate.getTime());
        mHeaderYear.setText(year);

        final String monthDay = mMonthDayFormat.format(mCurrentDate.getTime());
        mHeaderMonthDay.setText(monthDay);

        // TODO: This should use live regions.
        if (announce) {
            mAnimator.announceForAccessibility(getFormattedCurrentDate());
        }
    }

    private void setCurrentView(final int viewIndex) {
        switch (viewIndex) {
            case VIEW_MONTH_DAY:
                mDayPickerView.setDate(mCurrentDate.getTimeInMillis());

                if (mCurrentView != viewIndex) {
                    mHeaderMonthDay.setActivated(true);
                    mHeaderYear.setActivated(false);
                    mAnimator.setDisplayedChild(VIEW_MONTH_DAY);
                    mCurrentView = viewIndex;
                }

                mAnimator.announceForAccessibility(mSelectDay);
                break;
            case VIEW_YEAR:
                final int year = mCurrentDate.get(Calendar.YEAR);
                mYearPickerView.setYear(year);
                mYearPickerView.post(() -> {
                    mYearPickerView.requestFocus();
                    final View selected = mYearPickerView.getSelectedView();
                    if (selected != null) {
                        selected.requestFocus();
                    }
                });

                if (mCurrentView != viewIndex) {
                    mHeaderMonthDay.setActivated(false);
                    mHeaderYear.setActivated(true);
                    mAnimator.setDisplayedChild(VIEW_YEAR);
                    mCurrentView = viewIndex;
                }

                mAnimator.announceForAccessibility(mSelectYear);
                break;
        }
    }

    @Override
    public void init(int year, int month, int dayOfMonth,
            DatePicker.OnDateChangedListener callBack) {
        setDate(year, month, dayOfMonth);
        onDateChanged(false, false);

        mOnDateChangedListener = callBack;
    }

    @Override
    public void updateDate(int year, int month, int dayOfMonth) {
        setDate(year, month, dayOfMonth);
        onDateChanged(false, true);
    }

    private void setDate(int year, int month, int dayOfMonth) {
        mCurrentDate.set(Calendar.YEAR, year);
        mCurrentDate.set(Calendar.MONTH, month);
        mCurrentDate.set(Calendar.DAY_OF_MONTH, dayOfMonth);
        resetAutofilledValue();
    }

    private void onDateChanged(boolean fromUser, boolean callbackToClient) {
        final int year = mCurrentDate.get(Calendar.YEAR);

        if (callbackToClient
                && (mOnDateChangedListener != null || mAutoFillChangeListener != null)) {
            final int monthOfYear = mCurrentDate.get(Calendar.MONTH);
            final int dayOfMonth = mCurrentDate.get(Calendar.DAY_OF_MONTH);
            if (mOnDateChangedListener != null) {
                mOnDateChangedListener.onDateChanged(mDelegator, year, monthOfYear, dayOfMonth);
            }
            if (mAutoFillChangeListener != null) {
                mAutoFillChangeListener.onDateChanged(mDelegator, year, monthOfYear, dayOfMonth);
            }
        }

        mDayPickerView.setDate(mCurrentDate.getTimeInMillis());
        mYearPickerView.setYear(year);

        onCurrentDateChanged(fromUser);

        if (fromUser) {
            tryVibrate();
        }
    }

    @Override
    public int getYear() {
        return mCurrentDate.get(Calendar.YEAR);
    }

    @Override
    public int getMonth() {
        return mCurrentDate.get(Calendar.MONTH);
    }

    @Override
    public int getDayOfMonth() {
        return mCurrentDate.get(Calendar.DAY_OF_MONTH);
    }

    @Override
    public void setMinDate(long minDate) {
        mTempDate.setTimeInMillis(minDate);
        if (mTempDate.get(Calendar.YEAR) == mMinDate.get(Calendar.YEAR)
                && mTempDate.get(Calendar.DAY_OF_YEAR) == mMinDate.get(Calendar.DAY_OF_YEAR)) {
            // Same day, no-op.
            return;
        }
        if (mCurrentDate.before(mTempDate)) {
            mCurrentDate.setTimeInMillis(minDate);
            onDateChanged(false, true);
        }
        mMinDate.setTimeInMillis(minDate);
        mDayPickerView.setMinDate(minDate);
        mYearPickerView.setRange(mMinDate, mMaxDate);
    }

    @Override
    public Calendar getMinDate() {
        return mMinDate;
    }

    @Override
    public void setMaxDate(long maxDate) {
        mTempDate.setTimeInMillis(maxDate);
        if (mTempDate.get(Calendar.YEAR) == mMaxDate.get(Calendar.YEAR)
                && mTempDate.get(Calendar.DAY_OF_YEAR) == mMaxDate.get(Calendar.DAY_OF_YEAR)) {
            // Same day, no-op.
            return;
        }
        if (mCurrentDate.after(mTempDate)) {
            mCurrentDate.setTimeInMillis(maxDate);
            onDateChanged(false, true);
        }
        mMaxDate.setTimeInMillis(maxDate);
        mDayPickerView.setMaxDate(maxDate);
        mYearPickerView.setRange(mMinDate, mMaxDate);
    }

    @Override
    public Calendar getMaxDate() {
        return mMaxDate;
    }

    @Override
    public void setFirstDayOfWeek(int firstDayOfWeek) {
        mFirstDayOfWeek = firstDayOfWeek;

        mDayPickerView.setFirstDayOfWeek(firstDayOfWeek);
    }

    @Override
    public int getFirstDayOfWeek() {
        if (mFirstDayOfWeek != USE_LOCALE) {
            return mFirstDayOfWeek;
        }
        return mCurrentDate.getFirstDayOfWeek();
    }

    @Override
    public void setEnabled(boolean enabled) {
        mContainer.setEnabled(enabled);
        mDayPickerView.setEnabled(enabled);
        mYearPickerView.setEnabled(enabled);
        mHeaderYear.setEnabled(enabled);
        mHeaderMonthDay.setEnabled(enabled);
    }

    @Override
    public boolean isEnabled() {
        return mContainer.isEnabled();
    }

    @Override
    public CalendarView getCalendarView() {
        throw new UnsupportedOperationException("Not supported by calendar-mode DatePicker");
    }

    @Override
    public void setCalendarViewShown(boolean shown) {
        // No-op for compatibility with the old DatePicker.
    }

    @Override
    public boolean getCalendarViewShown() {
        return false;
    }

    @Override
    public void setSpinnersShown(boolean shown) {
        // No-op for compatibility with the old DatePicker.
    }

    @Override
    public boolean getSpinnersShown() {
        return false;
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        setCurrentLocale(newConfig.locale);
    }

    @Override
    public Parcelable onSaveInstanceState(Parcelable superState) {
        final int year = mCurrentDate.get(Calendar.YEAR);
        final int month = mCurrentDate.get(Calendar.MONTH);
        final int day = mCurrentDate.get(Calendar.DAY_OF_MONTH);

        int listPosition = -1;
        int listPositionOffset = -1;

        if (mCurrentView == VIEW_MONTH_DAY) {
            listPosition = mDayPickerView.getMostVisiblePosition();
        } else if (mCurrentView == VIEW_YEAR) {
            listPosition = mYearPickerView.getFirstVisiblePosition();
            listPositionOffset = mYearPickerView.getFirstPositionOffset();
        }

        return new SavedState(superState, year, month, day, mMinDate.getTimeInMillis(),
                mMaxDate.getTimeInMillis(), mCurrentView, listPosition, listPositionOffset);
    }

    @Override
    public void onRestoreInstanceState(Parcelable state) {
        if (state instanceof SavedState) {
            final SavedState ss = (SavedState) state;

            // TODO: Move instance state into DayPickerView, YearPickerView.
            mCurrentDate.set(ss.getSelectedYear(), ss.getSelectedMonth(), ss.getSelectedDay());
            mMinDate.setTimeInMillis(ss.getMinDate());
            mMaxDate.setTimeInMillis(ss.getMaxDate());

            onCurrentDateChanged(false);

            final int currentView = ss.getCurrentView();
            setCurrentView(currentView);

            final int listPosition = ss.getListPosition();
            if (listPosition != -1) {
                if (currentView == VIEW_MONTH_DAY) {
                    mDayPickerView.setPosition(listPosition);
                } else if (currentView == VIEW_YEAR) {
                    final int listPositionOffset = ss.getListPositionOffset();
                    mYearPickerView.setSelectionFromTop(listPosition, listPositionOffset);
                }
            }
        }
    }

    @Override
    public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
        onPopulateAccessibilityEvent(event);
        return true;
    }

    public CharSequence getAccessibilityClassName() {
        return DatePicker.class.getName();
    }

    public static int getDaysInMonth(int month, int year) {
        switch (month) {
            case Calendar.JANUARY:
            case Calendar.MARCH:
            case Calendar.MAY:
            case Calendar.JULY:
            case Calendar.AUGUST:
            case Calendar.OCTOBER:
            case Calendar.DECEMBER:
                return 31;
            case Calendar.APRIL:
            case Calendar.JUNE:
            case Calendar.SEPTEMBER:
            case Calendar.NOVEMBER:
                return 30;
            case Calendar.FEBRUARY:
                return (year % 4 == 0) ? 29 : 28;
            default:
                throw new IllegalArgumentException("Invalid Month");
        }
    }

    private void tryVibrate() {
        mDelegator.performHapticFeedback(HapticFeedbackConstants.CALENDAR_DATE);
    }
}