/*
 * Copyright (C) 2017 wangchenyan
 *
 * 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 code.name.monkey.retromusic.lyrics;

import android.animation.ValueAnimator;
import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.os.Looper;
import android.text.Layout;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.text.TextUtils;
import android.text.format.DateUtils;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.LinearInterpolator;
import android.widget.Scroller;

import java.io.File;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import code.name.monkey.retromusic.BuildConfig;
import code.name.monkey.retromusic.R;

/**
 * 歌词 Created by wcy on 2015/11/9.
 */
@SuppressLint("StaticFieldLeak")
public class LrcView extends View {
  private static final long ADJUST_DURATION = 100;
  private static final long TIMELINE_KEEP_TIME = 4 * DateUtils.SECOND_IN_MILLIS;

  private final List<LrcEntry> mLrcEntryList = new ArrayList<>();
  private final TextPaint mLrcPaint = new TextPaint();
  private final TextPaint mTimePaint = new TextPaint();
  private Paint.FontMetrics mTimeFontMetrics;
  private Drawable mPlayDrawable;
  private float mDividerHeight;
  private long mAnimationDuration;
  private int mNormalTextColor;
  private float mNormalTextSize;
  private int mCurrentTextColor;
  private float mCurrentTextSize;
  private int mTimelineTextColor;
  private int mTimelineColor;
  private int mTimeTextColor;
  private int mDrawableWidth;
  private int mTimeTextWidth;
  private String mDefaultLabel;
  private float mLrcPadding;
  private OnPlayClickListener mOnPlayClickListener;
  private ValueAnimator mAnimator;
  private GestureDetector mGestureDetector;
  private Scroller mScroller;
  private float mOffset;
  private int mCurrentLine;
  private Object mFlag;
  private boolean isShowTimeline;
  private boolean isTouching;
  private boolean isFling;
  private int mTextGravity; // 歌词显示位置，靠左/居中/靠右
  private final Runnable hideTimelineRunnable =
          new Runnable() {
            @Override
            public void run() {
              if (hasLrc() && isShowTimeline) {
                isShowTimeline = false;
                smoothScrollTo(mCurrentLine);
              }
            }
          };
  /**
   * 手势监听器
   */
  private final GestureDetector.SimpleOnGestureListener mSimpleOnGestureListener =
          new GestureDetector.SimpleOnGestureListener() {
            @Override
            public boolean onDown(MotionEvent e) {
              if (hasLrc() && mOnPlayClickListener != null) {
                mScroller.forceFinished(true);
                removeCallbacks(hideTimelineRunnable);
                isTouching = true;
                isShowTimeline = true;
                invalidate();
                return true;
          }
          return super.onDown(e);
        }

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
          if (hasLrc()) {
            mOffset += -distanceY;
            mOffset = Math.min(mOffset, getOffset(0));
            mOffset = Math.max(mOffset, getOffset(mLrcEntryList.size() - 1));
            invalidate();
            getParent().requestDisallowInterceptTouchEvent(true);
            return true;
          }
          return super.onScroll(e1, e2, distanceX, distanceY);
        }

        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
          if (hasLrc()) {
            mScroller.fling(
                0,
                (int) mOffset,
                0,
                (int) velocityY,
                0,
                0,
                (int) getOffset(mLrcEntryList.size() - 1),
                (int) getOffset(0));
            isFling = true;
            return true;
          }
          return super.onFling(e1, e2, velocityX, velocityY);
        }

        @Override
        public boolean onSingleTapConfirmed(MotionEvent e) {
          if (hasLrc()
              && isShowTimeline
              && mPlayDrawable.getBounds().contains((int) e.getX(), (int) e.getY())) {
            int centerLine = getCenterLine();
            long centerLineTime = mLrcEntryList.get(centerLine).getTime();
            // onPlayClick 消费了才更新 UI
            if (mOnPlayClickListener != null && mOnPlayClickListener.onPlayClick(centerLineTime)) {
              isShowTimeline = false;
              removeCallbacks(hideTimelineRunnable);
              mCurrentLine = centerLine;
              invalidate();
              return true;
            }
          }
          return super.onSingleTapConfirmed(e);
        }
      };

  public LrcView(Context context) {
    this(context, null);
  }

  public LrcView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public LrcView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(attrs);
  }

  private void init(AttributeSet attrs) {
    TypedArray ta = getContext().obtainStyledAttributes(attrs, R.styleable.LrcView);
    mCurrentTextSize =
        ta.getDimension(
            R.styleable.LrcView_lrcTextSize, getResources().getDimension(R.dimen.lrc_text_size));
    mNormalTextSize =
        ta.getDimension(
            R.styleable.LrcView_lrcNormalTextSize,
            getResources().getDimension(R.dimen.lrc_text_size));
    if (mNormalTextSize == 0) {
      mNormalTextSize = mCurrentTextSize;
    }

    mDividerHeight =
        ta.getDimension(
            R.styleable.LrcView_lrcDividerHeight,
            getResources().getDimension(R.dimen.lrc_divider_height));
    int defDuration = getResources().getInteger(R.integer.lrc_animation_duration);
    mAnimationDuration = ta.getInt(R.styleable.LrcView_lrcAnimationDuration, defDuration);
    mAnimationDuration = (mAnimationDuration < 0) ? defDuration : mAnimationDuration;
    mNormalTextColor =
        ta.getColor(
            R.styleable.LrcView_lrcNormalTextColor,
            getResources().getColor(R.color.lrc_normal_text_color));
    mCurrentTextColor =
        ta.getColor(
            R.styleable.LrcView_lrcCurrentTextColor,
            getResources().getColor(R.color.lrc_current_text_color));
    mTimelineTextColor =
        ta.getColor(
            R.styleable.LrcView_lrcTimelineTextColor,
            getResources().getColor(R.color.lrc_timeline_text_color));
    mDefaultLabel = ta.getString(R.styleable.LrcView_lrcLabel);
    mDefaultLabel =
        TextUtils.isEmpty(mDefaultLabel) ? getContext().getString(R.string.empty) : mDefaultLabel;
    mLrcPadding = ta.getDimension(R.styleable.LrcView_lrcPadding, 0);
    mTimelineColor =
        ta.getColor(
            R.styleable.LrcView_lrcTimelineColor,
            getResources().getColor(R.color.lrc_timeline_color));
    float timelineHeight =
        ta.getDimension(
            R.styleable.LrcView_lrcTimelineHeight,
            getResources().getDimension(R.dimen.lrc_timeline_height));
    mPlayDrawable = ta.getDrawable(R.styleable.LrcView_lrcPlayDrawable);
    mPlayDrawable =
        (mPlayDrawable == null)
            ? getResources().getDrawable(R.drawable.ic_play_arrow)
            : mPlayDrawable;
    mTimeTextColor =
        ta.getColor(
            R.styleable.LrcView_lrcTimeTextColor,
            getResources().getColor(R.color.lrc_time_text_color));
    float timeTextSize =
        ta.getDimension(
            R.styleable.LrcView_lrcTimeTextSize,
            getResources().getDimension(R.dimen.lrc_time_text_size));
    mTextGravity = ta.getInteger(R.styleable.LrcView_lrcTextGravity, LrcEntry.GRAVITY_CENTER);

    ta.recycle();

    mDrawableWidth = (int) getResources().getDimension(R.dimen.lrc_drawable_width);
    mTimeTextWidth = (int) getResources().getDimension(R.dimen.lrc_time_width);

    mLrcPaint.setAntiAlias(true);
    mLrcPaint.setTextSize(mCurrentTextSize);
    mLrcPaint.setTextAlign(Paint.Align.LEFT);
    mTimePaint.setAntiAlias(true);
    mTimePaint.setTextSize(timeTextSize);
    mTimePaint.setTextAlign(Paint.Align.CENTER);
    //noinspection SuspiciousNameCombination
    mTimePaint.setStrokeWidth(timelineHeight);
    mTimePaint.setStrokeCap(Paint.Cap.ROUND);
    mTimeFontMetrics = mTimePaint.getFontMetrics();

    mGestureDetector = new GestureDetector(getContext(), mSimpleOnGestureListener);
    mGestureDetector.setIsLongpressEnabled(false);
    mScroller = new Scroller(getContext());
  }

  /** 设置非当前行歌词字体颜色 */
  public void setNormalColor(int normalColor) {
    mNormalTextColor = normalColor;
    postInvalidate();
  }

  /** 普通歌词文本字体大小 */
  public void setNormalTextSize(float size) {
    mNormalTextSize = size;
  }

  /** 当前歌词文本字体大小 */
  public void setCurrentTextSize(float size) {
    mCurrentTextSize = size;
  }

  /** 设置当前行歌词的字体颜色 */
  public void setCurrentColor(int currentColor) {
    mCurrentTextColor = currentColor;
    postInvalidate();
  }

  /** 设置拖动歌词时选中歌词的字体颜色 */
  public void setTimelineTextColor(int timelineTextColor) {
    mTimelineTextColor = timelineTextColor;
    postInvalidate();
  }

  /** 设置拖动歌词时时间线的颜色 */
  public void setTimelineColor(int timelineColor) {
    mTimelineColor = timelineColor;
    postInvalidate();
  }

  /** 设置拖动歌词时右侧时间字体颜色 */
  public void setTimeTextColor(int timeTextColor) {
    mTimeTextColor = timeTextColor;
    postInvalidate();
  }

  /**
   * 设置歌词是否允许拖动
   *
   * @param draggable 是否允许拖动
   * @param onPlayClickListener 设置歌词拖动后播放按钮点击监听器，如果允许拖动，则不能为 null
   */
  public void setDraggable(boolean draggable, OnPlayClickListener onPlayClickListener) {
    if (draggable) {
      if (onPlayClickListener == null) {
        throw new IllegalArgumentException(
            "if draggable == true, onPlayClickListener must not be null");
      }
      mOnPlayClickListener = onPlayClickListener;
    } else {
      mOnPlayClickListener = null;
    }
  }

  /**
   * 设置播放按钮点击监听器
   *
   * @param onPlayClickListener 如果为非 null ，则激活歌词拖动功能，否则将将禁用歌词拖动功能
   * @deprecated use {@link #setDraggable(boolean, OnPlayClickListener)} instead
   */
  @Deprecated
  public void setOnPlayClickListener(OnPlayClickListener onPlayClickListener) {
    mOnPlayClickListener = onPlayClickListener;
  }

  /** 设置歌词为空时屏幕中央显示的文字，如“暂无歌词” */
  public void setLabel(String label) {
    runOnUi(
        () -> {
          mDefaultLabel = label;
          invalidate();
        });
  }

  /**
   * 加载歌词文件
   *
   * @param lrcFile 歌词文件
   */
  public void loadLrc(File lrcFile) {
    loadLrc(lrcFile, null);
  }

  /**
   * 加载双语歌词文件，两种语言的歌词时间戳需要一致
   *
   * @param mainLrcFile 第一种语言歌词文件
   * @param secondLrcFile 第二种语言歌词文件
   */
  public void loadLrc(File mainLrcFile, File secondLrcFile) {
    runOnUi(
        () -> {
          reset();

          StringBuilder sb = new StringBuilder("file://");
          sb.append(mainLrcFile.getPath());
          if (secondLrcFile != null) {
            sb.append("#").append(secondLrcFile.getPath());
          }
          String flag = sb.toString();
          setFlag(flag);
          new AsyncTask<File, Integer, List<LrcEntry>>() {
            @Override
            protected List<LrcEntry> doInBackground(File... params) {
              return LrcUtils.parseLrc(params);
            }

            @Override
            protected void onPostExecute(List<LrcEntry> lrcEntries) {
              if (getFlag() == flag) {
                onLrcLoaded(lrcEntries);
                setFlag(null);
              }
            }
          }.execute(mainLrcFile, secondLrcFile);
        });
  }

  /**
   * 加载歌词文本
   *
   * @param lrcText 歌词文本
   */
  public void loadLrc(String lrcText) {
    loadLrc(lrcText, null);
  }

  /**
   * 加载双语歌词文本，两种语言的歌词时间戳需要一致
   *
   * @param mainLrcText 第一种语言歌词文本
   * @param secondLrcText 第二种语言歌词文本
   */
  public void loadLrc(String mainLrcText, String secondLrcText) {
    runOnUi(
        () -> {
          reset();

          StringBuilder sb = new StringBuilder("file://");
          sb.append(mainLrcText);
          if (secondLrcText != null) {
            sb.append("#").append(secondLrcText);
          }
          String flag = sb.toString();
          setFlag(flag);
          new AsyncTask<String, Integer, List<LrcEntry>>() {
            @Override
            protected List<LrcEntry> doInBackground(String... params) {
              return LrcUtils.parseLrc(params);
            }

            @Override
            protected void onPostExecute(List<LrcEntry> lrcEntries) {
              if (getFlag() == flag) {
                onLrcLoaded(lrcEntries);
                setFlag(null);
              }
            }
          }.execute(mainLrcText, secondLrcText);
        });
  }

  /**
   * 加载在线歌词，默认使用 utf-8 编码
   *
   * @param lrcUrl 歌词文件的网络地址
   */
  public void loadLrcByUrl(String lrcUrl) {
    loadLrcByUrl(lrcUrl, "utf-8");
  }

  /**
   * 加载在线歌词
   *
   * @param lrcUrl 歌词文件的网络地址
   * @param charset 编码格式
   */
  public void loadLrcByUrl(String lrcUrl, String charset) {
    String flag = "url://" + lrcUrl;
    setFlag(flag);
    new AsyncTask<String, Integer, String>() {
      @Override
      protected String doInBackground(String... params) {
        return LrcUtils.getContentFromNetwork(params[0], params[1]);
      }

      @Override
      protected void onPostExecute(String lrcText) {
        if (getFlag() == flag) {
          loadLrc(lrcText);
        }
      }
    }.execute(lrcUrl, charset);
  }

  /**
   * 歌词是否有效
   *
   * @return true，如果歌词有效，否则false
   */
  public boolean hasLrc() {
    return !mLrcEntryList.isEmpty();
  }

  /**
   * 刷新歌词
   *
   * @param time 当前播放时间
   */
  public void updateTime(long time) {
    runOnUi(
        () -> {
          if (!hasLrc()) {
            return;
          }

          int line = findShowLine(time);
          if (line != mCurrentLine) {
            mCurrentLine = line;
            if (!isShowTimeline) {
              smoothScrollTo(line);
            } else {
              invalidate();
            }
          }
        });
  }

  /**
   * 将歌词滚动到指定时间
   *
   * @param time 指定的时间
   * @deprecated 请使用 {@link #updateTime(long)} 代替
   */
  @Deprecated
  public void onDrag(long time) {
    updateTime(time);
  }

  @Override
  protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
    super.onLayout(changed, left, top, right, bottom);
    if (changed) {
      initPlayDrawable();
      initEntryList();
      if (hasLrc()) {
        smoothScrollTo(mCurrentLine, 0L);
      }
    }
  }

  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    int centerY = getHeight() / 2;

    // 无歌词文件
    if (!hasLrc()) {
      mLrcPaint.setColor(mCurrentTextColor);
      @SuppressLint("DrawAllocation")
      StaticLayout staticLayout =
          new StaticLayout(
              mDefaultLabel,
              mLrcPaint,
              (int) getLrcWidth(),
              Layout.Alignment.ALIGN_CENTER,
              1f,
              0f,
              false);
      drawText(canvas, staticLayout, centerY);
      return;
    }

    int centerLine = getCenterLine();

    if (isShowTimeline) {
      mPlayDrawable.draw(canvas);

      mTimePaint.setColor(mTimelineColor);
      canvas.drawLine(mTimeTextWidth, centerY, getWidth() - mTimeTextWidth, centerY, mTimePaint);

      mTimePaint.setColor(mTimeTextColor);
      String timeText = LrcUtils.formatTime(mLrcEntryList.get(centerLine).getTime());
      float timeX = getWidth() - mTimeTextWidth / 2;
      float timeY = centerY - (mTimeFontMetrics.descent + mTimeFontMetrics.ascent) / 2;
      canvas.drawText(timeText, timeX, timeY, mTimePaint);
    }

    canvas.translate(0, mOffset);

    float y = 0;
    for (int i = 0; i < mLrcEntryList.size(); i++) {
      if (i > 0) {
        y +=
            ((mLrcEntryList.get(i - 1).getHeight() + mLrcEntryList.get(i).getHeight()) >> 1)
                + mDividerHeight;
      }
      if (BuildConfig.DEBUG) {
        // mLrcPaint.setTypeface(ResourcesCompat.getFont(getContext(), R.font.sans));
      }
      if (i == mCurrentLine) {
        mLrcPaint.setTextSize(mCurrentTextSize);
        mLrcPaint.setColor(mCurrentTextColor);
      } else if (isShowTimeline && i == centerLine) {
        mLrcPaint.setColor(mTimelineTextColor);
      } else {
        mLrcPaint.setTextSize(mNormalTextSize);
        mLrcPaint.setColor(mNormalTextColor);
      }
      drawText(canvas, mLrcEntryList.get(i).getStaticLayout(), y);
    }
  }

  /**
   * 画一行歌词
   *
   * @param y 歌词中心 Y 坐标
   */
  private void drawText(Canvas canvas, StaticLayout staticLayout, float y) {
    canvas.save();
    canvas.translate(mLrcPadding, y - (staticLayout.getHeight() >> 1));
    staticLayout.draw(canvas);
    canvas.restore();
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {
    if (event.getAction() == MotionEvent.ACTION_UP
        || event.getAction() == MotionEvent.ACTION_CANCEL) {
      isTouching = false;
      if (hasLrc() && !isFling) {
        adjustCenter();
        postDelayed(hideTimelineRunnable, TIMELINE_KEEP_TIME);
      }
    }
    return mGestureDetector.onTouchEvent(event);
  }

  @Override
  public void computeScroll() {
    if (mScroller.computeScrollOffset()) {
      mOffset = mScroller.getCurrY();
      invalidate();
    }

    if (isFling && mScroller.isFinished()) {
      isFling = false;
      if (hasLrc() && !isTouching) {
        adjustCenter();
        postDelayed(hideTimelineRunnable, TIMELINE_KEEP_TIME);
      }
    }
  }

  @Override
  protected void onDetachedFromWindow() {
    removeCallbacks(hideTimelineRunnable);
    super.onDetachedFromWindow();
  }

  private void onLrcLoaded(List<LrcEntry> entryList) {
    if (entryList != null && !entryList.isEmpty()) {
      mLrcEntryList.addAll(entryList);
    }

    Collections.sort(mLrcEntryList);

    initEntryList();
    invalidate();
  }

  private void initPlayDrawable() {
    int l = (mTimeTextWidth - mDrawableWidth) / 2;
    int t = getHeight() / 2 - mDrawableWidth / 2;
    int r = l + mDrawableWidth;
    int b = t + mDrawableWidth;
    mPlayDrawable.setBounds(l, t, r, b);
  }

  private void initEntryList() {
    if (!hasLrc() || getWidth() == 0) {
      return;
    }

    for (LrcEntry lrcEntry : mLrcEntryList) {
      lrcEntry.init(mLrcPaint, (int) getLrcWidth(), mTextGravity);
    }

    mOffset = getHeight() / 2;
  }

  private void reset() {
    endAnimation();
    mScroller.forceFinished(true);
    isShowTimeline = false;
    isTouching = false;
    isFling = false;
    removeCallbacks(hideTimelineRunnable);
    mLrcEntryList.clear();
    mOffset = 0;
    mCurrentLine = 0;
    invalidate();
  }

  /** 将中心行微调至正中心 */
  private void adjustCenter() {
    smoothScrollTo(getCenterLine(), ADJUST_DURATION);
  }

  /** 滚动到某一行 */
  private void smoothScrollTo(int line) {
    smoothScrollTo(line, mAnimationDuration);
  }

  /** 滚动到某一行 */
  private void smoothScrollTo(int line, long duration) {
    float offset = getOffset(line);
    endAnimation();

    mAnimator = ValueAnimator.ofFloat(mOffset, offset);
    mAnimator.setDuration(duration);
    mAnimator.setInterpolator(new LinearInterpolator());
    mAnimator.addUpdateListener(
        animation -> {
          mOffset = (float) animation.getAnimatedValue();
          invalidate();
        });
    LrcUtils.resetDurationScale();
    mAnimator.start();
  }

  /** 结束滚动动画 */
  private void endAnimation() {
    if (mAnimator != null && mAnimator.isRunning()) {
      mAnimator.end();
    }
  }

  /** 二分法查找当前时间应该显示的行数（最后一个 <= time 的行数） */
  private int findShowLine(long time) {
    int left = 0;
    int right = mLrcEntryList.size();
    while (left <= right) {
      int middle = (left + right) / 2;
      long middleTime = mLrcEntryList.get(middle).getTime();

      if (time < middleTime) {
        right = middle - 1;
      } else {
        if (middle + 1 >= mLrcEntryList.size() || time < mLrcEntryList.get(middle + 1).getTime()) {
          return middle;
        }

        left = middle + 1;
      }
    }

    return 0;
  }

  /** 获取当前在视图中央的行数 */
  private int getCenterLine() {
    int centerLine = 0;
    float minDistance = Float.MAX_VALUE;
    for (int i = 0; i < mLrcEntryList.size(); i++) {
      if (Math.abs(mOffset - getOffset(i)) < minDistance) {
        minDistance = Math.abs(mOffset - getOffset(i));
        centerLine = i;
      }
    }
    return centerLine;
  }

  /** 获取歌词距离视图顶部的距离 采用懒加载方式 */
  private float getOffset(int line) {
    if (mLrcEntryList.get(line).getOffset() == Float.MIN_VALUE) {
      float offset = getHeight() / 2;
      for (int i = 1; i <= line; i++) {
        offset -=
            ((mLrcEntryList.get(i - 1).getHeight() + mLrcEntryList.get(i).getHeight()) >> 1)
                + mDividerHeight;
      }
      mLrcEntryList.get(line).setOffset(offset);
    }

    return mLrcEntryList.get(line).getOffset();
  }

  /** 获取歌词宽度 */
  private float getLrcWidth() {
    return getWidth() - mLrcPadding * 2;
  }

  /** 在主线程中运行 */
  private void runOnUi(Runnable r) {
    if (Looper.myLooper() == Looper.getMainLooper()) {
      r.run();
    } else {
      post(r);
    }
  }

  private Object getFlag() {
    return mFlag;
  }

  private void setFlag(Object flag) {
    this.mFlag = flag;
  }

  /** 播放按钮点击监听器，点击后应该跳转到指定播放位置 */
  public interface OnPlayClickListener {
    /**
     * 播放按钮被点击，应该跳转到指定播放位置
     *
     * @return 是否成功消费该事件，如果成功消费，则会更新UI
     */
    boolean onPlayClick(long time);
  }
}