/*
 * Copyright (C) 2015 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 com.android.internal.widget.PagerAdapter;

import android.annotation.IdRes;
import android.annotation.LayoutRes;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.Context;
import android.content.res.ColorStateList;
import android.content.res.TypedArray;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.SimpleMonthView.OnDayClickListener;

import java.util.Calendar;

/**
 * An adapter for a list of {@link android.widget.SimpleMonthView} items.
 */
class DayPickerPagerAdapter extends PagerAdapter {
    private static final int MONTHS_IN_YEAR = 12;

    private final Calendar mMinDate = Calendar.getInstance();
    private final Calendar mMaxDate = Calendar.getInstance();

    private final SparseArray<ViewHolder> mItems = new SparseArray<>();

    private final LayoutInflater mInflater;
    private final int mLayoutResId;
    private final int mCalendarViewId;

    private Calendar mSelectedDay = null;

    private int mMonthTextAppearance;
    private int mDayOfWeekTextAppearance;
    private int mDayTextAppearance;

    private ColorStateList mCalendarTextColor;
    private ColorStateList mDaySelectorColor;
    private ColorStateList mDayHighlightColor;

    private OnDaySelectedListener mOnDaySelectedListener;

    private int mCount;
    private int mFirstDayOfWeek;

    public DayPickerPagerAdapter(@NonNull Context context, @LayoutRes int layoutResId,
            @IdRes int calendarViewId) {
        mInflater = LayoutInflater.from(context);
        mLayoutResId = layoutResId;
        mCalendarViewId = calendarViewId;

        final TypedArray ta = context.obtainStyledAttributes(new int[] {
                com.android.internal.R.attr.colorControlHighlight});
        mDayHighlightColor = ta.getColorStateList(0);
        ta.recycle();
    }

    public void setRange(@NonNull Calendar min, @NonNull Calendar max) {
        mMinDate.setTimeInMillis(min.getTimeInMillis());
        mMaxDate.setTimeInMillis(max.getTimeInMillis());

        final int diffYear = mMaxDate.get(Calendar.YEAR) - mMinDate.get(Calendar.YEAR);
        final int diffMonth = mMaxDate.get(Calendar.MONTH) - mMinDate.get(Calendar.MONTH);
        mCount = diffMonth + MONTHS_IN_YEAR * diffYear + 1;

        // Positions are now invalid, clear everything and start over.
        notifyDataSetChanged();
    }

    /**
     * Sets the first day of the week.
     *
     * @param weekStart which day the week should start on, valid values are
     *                  {@link Calendar#SUNDAY} through {@link Calendar#SATURDAY}
     */
    public void setFirstDayOfWeek(int weekStart) {
        mFirstDayOfWeek = weekStart;

        // Update displayed views.
        final int count = mItems.size();
        for (int i = 0; i < count; i++) {
            final SimpleMonthView monthView = mItems.valueAt(i).calendar;
            monthView.setFirstDayOfWeek(weekStart);
        }
    }

    public int getFirstDayOfWeek() {
        return mFirstDayOfWeek;
    }

    /**
     * Sets the selected day.
     *
     * @param day the selected day
     */
    public void setSelectedDay(@Nullable Calendar day) {
        final int oldPosition = getPositionForDay(mSelectedDay);
        final int newPosition = getPositionForDay(day);

        // Clear the old position if necessary.
        if (oldPosition != newPosition && oldPosition >= 0) {
            final ViewHolder oldMonthView = mItems.get(oldPosition, null);
            if (oldMonthView != null) {
                oldMonthView.calendar.setSelectedDay(-1);
            }
        }

        // Set the new position.
        if (newPosition >= 0) {
            final ViewHolder newMonthView = mItems.get(newPosition, null);
            if (newMonthView != null) {
                final int dayOfMonth = day.get(Calendar.DAY_OF_MONTH);
                newMonthView.calendar.setSelectedDay(dayOfMonth);
            }
        }

        mSelectedDay = day;
    }

    /**
     * Sets the listener to call when the user selects a day.
     *
     * @param listener The listener to call.
     */
    public void setOnDaySelectedListener(OnDaySelectedListener listener) {
        mOnDaySelectedListener = listener;
    }

    void setCalendarTextColor(ColorStateList calendarTextColor) {
        mCalendarTextColor = calendarTextColor;
    }

    void setDaySelectorColor(ColorStateList selectorColor) {
        mDaySelectorColor = selectorColor;
    }

    void setMonthTextAppearance(int resId) {
        mMonthTextAppearance = resId;
    }

    void setDayOfWeekTextAppearance(int resId) {
        mDayOfWeekTextAppearance = resId;
    }

    int getDayOfWeekTextAppearance() {
        return mDayOfWeekTextAppearance;
    }

    void setDayTextAppearance(int resId) {
        mDayTextAppearance = resId;
    }

    int getDayTextAppearance() {
        return mDayTextAppearance;
    }

    @Override
    public int getCount() {
        return mCount;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        final ViewHolder holder = (ViewHolder) object;
        return view == holder.container;
    }

    private int getMonthForPosition(int position) {
        return position % MONTHS_IN_YEAR + mMinDate.get(Calendar.MONTH);
    }

    private int getYearForPosition(int position) {
        return position / MONTHS_IN_YEAR + mMinDate.get(Calendar.YEAR);
    }

    private int getPositionForDay(@Nullable Calendar day) {
        if (day == null) {
            return -1;
        }

        final int yearOffset = (day.get(Calendar.YEAR) - mMinDate.get(Calendar.YEAR));
        final int monthOffset = (day.get(Calendar.MONTH) - mMinDate.get(Calendar.MONTH));
        final int position = yearOffset * MONTHS_IN_YEAR + monthOffset;
        return position;
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        final View itemView = mInflater.inflate(mLayoutResId, container, false);

        final SimpleMonthView v = (SimpleMonthView) itemView.findViewById(mCalendarViewId);
        v.setOnDayClickListener(mOnDayClickListener);
        v.setMonthTextAppearance(mMonthTextAppearance);
        v.setDayOfWeekTextAppearance(mDayOfWeekTextAppearance);
        v.setDayTextAppearance(mDayTextAppearance);

        if (mDaySelectorColor != null) {
            v.setDaySelectorColor(mDaySelectorColor);
        }

        if (mDayHighlightColor != null) {
            v.setDayHighlightColor(mDayHighlightColor);
        }

        if (mCalendarTextColor != null) {
            v.setMonthTextColor(mCalendarTextColor);
            v.setDayOfWeekTextColor(mCalendarTextColor);
            v.setDayTextColor(mCalendarTextColor);
        }

        final int month = getMonthForPosition(position);
        final int year = getYearForPosition(position);

        final int selectedDay;
        if (mSelectedDay != null && mSelectedDay.get(Calendar.MONTH) == month) {
            selectedDay = mSelectedDay.get(Calendar.DAY_OF_MONTH);
        } else {
            selectedDay = -1;
        }

        final int enabledDayRangeStart;
        if (mMinDate.get(Calendar.MONTH) == month && mMinDate.get(Calendar.YEAR) == year) {
            enabledDayRangeStart = mMinDate.get(Calendar.DAY_OF_MONTH);
        } else {
            enabledDayRangeStart = 1;
        }

        final int enabledDayRangeEnd;
        if (mMaxDate.get(Calendar.MONTH) == month && mMaxDate.get(Calendar.YEAR) == year) {
            enabledDayRangeEnd = mMaxDate.get(Calendar.DAY_OF_MONTH);
        } else {
            enabledDayRangeEnd = 31;
        }

        v.setMonthParams(selectedDay, month, year, mFirstDayOfWeek,
                enabledDayRangeStart, enabledDayRangeEnd);

        final ViewHolder holder = new ViewHolder(position, itemView, v);
        mItems.put(position, holder);

        container.addView(itemView);

        return holder;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        final ViewHolder holder = (ViewHolder) object;
        container.removeView(holder.container);

        mItems.remove(position);
    }

    @Override
    public int getItemPosition(Object object) {
        final ViewHolder holder = (ViewHolder) object;
        return holder.position;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        final SimpleMonthView v = mItems.get(position).calendar;
        if (v != null) {
            return v.getTitle();
        }
        return null;
    }

    private boolean isCalendarInRange(Calendar value) {
        return value.compareTo(mMinDate) >= 0 && value.compareTo(mMaxDate) <= 0;
    }

    private final OnDayClickListener mOnDayClickListener = new OnDayClickListener() {
        @Override
        public void onDayClick(SimpleMonthView view, Calendar day) {
            if (day != null && isCalendarInRange(day)) {
                setSelectedDay(day);

                if (mOnDaySelectedListener != null) {
                    mOnDaySelectedListener.onDaySelected(DayPickerPagerAdapter.this, day);
                }
            }
        }
    };

    private static class ViewHolder {
        public final int position;
        public final View container;
        public final SimpleMonthView calendar;

        public ViewHolder(int position, View container, SimpleMonthView calendar) {
            this.position = position;
            this.container = container;
            this.calendar = calendar;
        }
    }

    public interface OnDaySelectedListener {
        public void onDaySelected(DayPickerPagerAdapter view, Calendar day);
    }
}