/*
 * Copyright (c) 2017, Daniel Gultsch All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation and/or
 * other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package de.pixart.messenger.utils;

import android.content.Context;
import android.graphics.Color;
import android.graphics.Typeface;
import android.support.annotation.ColorInt;
import android.support.v4.content.ContextCompat;
import android.text.Editable;
import android.text.ParcelableSpan;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.TextWatcher;
import android.text.style.BackgroundColorSpan;
import android.text.style.ForegroundColorSpan;
import android.text.style.StrikethroughSpan;
import android.text.style.StyleSpan;
import android.text.style.TypefaceSpan;
import android.widget.EditText;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import de.pixart.messenger.R;
import de.pixart.messenger.entities.Message;
import de.pixart.messenger.ui.text.QuoteSpan;

public class StylingHelper {

    private static List<? extends Class<? extends ParcelableSpan>> SPAN_CLASSES = Arrays.asList(
            StyleSpan.class,
            StrikethroughSpan.class,
            TypefaceSpan.class,
            ForegroundColorSpan.class
    );

    public static void clear(final Editable editable) {
        final int end = editable.length() - 1;
        for (Class<? extends ParcelableSpan> clazz : SPAN_CLASSES) {
            for (ParcelableSpan span : editable.getSpans(0, end, clazz)) {
                editable.removeSpan(span);
            }
        }
    }

    public static void format(final Editable editable, int start, int end, @ColorInt int textColor) {
        for (ImStyleParser.Style style : ImStyleParser.parse(editable, start, end)) {
            final int keywordLength = style.getKeyword().length();
            editable.setSpan(createSpanForStyle(style), style.getStart() + keywordLength, style.getEnd() - keywordLength + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
            makeKeywordOpaque(editable, style.getStart(), style.getStart() + keywordLength, textColor);
            makeKeywordOpaque(editable, style.getEnd() - keywordLength + 1, style.getEnd() + 1, textColor);
        }
    }

    public static void format(final Editable editable, @ColorInt int textColor) {
        int end = 0;
        Message.MergeSeparator[] spans = editable.getSpans(0, editable.length() - 1, Message.MergeSeparator.class);
        for (Message.MergeSeparator span : spans) {
            format(editable, end, editable.getSpanStart(span), textColor);
            end = editable.getSpanEnd(span);
        }
        format(editable, end, editable.length() - 1, textColor);
    }

    public static void highlight(final Context context, final Editable editable, List<String> needles, boolean dark) {
        for (String needle : needles) {
            if (!FtsUtils.isKeyword(needle)) {
                highlight(context, editable, needle, dark);
            }
        }
    }

    public static List<String> filterHighlightedWords(List<String> terms) {
        List<String> words = new ArrayList<>();
        for (String term : terms) {
            if (!FtsUtils.isKeyword(term)) {
                StringBuilder builder = new StringBuilder();
                for (int codepoint, i = 0; i < term.length(); i += Character.charCount(codepoint)) {
                    codepoint = term.codePointAt(i);
                    if (Character.isLetterOrDigit(codepoint)) {
                        builder.append(Character.toChars(codepoint));
                    } else if (builder.length() > 0) {
                        words.add(builder.toString());
                        builder.delete(0, builder.length());
                    }
                }
                if (builder.length() > 0) {
                    words.add(builder.toString());
                }
            }
        }
        return words;
    }

    private static void highlight(final Context context, final Editable editable, String needle, boolean dark) {
        final int length = needle.length();
        String string = editable.toString();
        int start = indexOfIgnoreCase(string, needle, 0);
        while (start != -1) {
            int end = start + length;
            editable.setSpan(new BackgroundColorSpan(ContextCompat.getColor(context, dark ? R.color.deep_purple_a100 : R.color.deep_purple_a200)), start, end, SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
            editable.setSpan(new ForegroundColorSpan(ContextCompat.getColor(context, dark ? R.color.black87 : R.color.white)), start, end, SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
            start = indexOfIgnoreCase(string, needle, start + length);
        }

    }

    static CharSequence subSequence(CharSequence charSequence, int start, int end) {
        if (start == 0 && charSequence.length() + 1 == end) {
            return charSequence;
        }
        if (charSequence instanceof Spannable) {
            Spannable spannable = (Spannable) charSequence;
            Spannable sub = (Spannable) spannable.subSequence(start, end);
            for (Class<? extends ParcelableSpan> clazz : SPAN_CLASSES) {
                ParcelableSpan[] spannables = spannable.getSpans(start, end, clazz);
                for (ParcelableSpan parcelableSpan : spannables) {
                    int beginSpan = spannable.getSpanStart(parcelableSpan);
                    int endSpan = spannable.getSpanEnd(parcelableSpan);
                    if (beginSpan >= start && endSpan <= end) {
                        continue;
                    }
                    sub.setSpan(clone(parcelableSpan), Math.max(beginSpan - start, 0), Math.min(sub.length() - 1, endSpan), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
                }
            }
            return sub;
        } else {
            return charSequence.subSequence(start, end);
        }
    }

    private static ParcelableSpan clone(ParcelableSpan span) {
        if (span instanceof ForegroundColorSpan) {
            return new ForegroundColorSpan(((ForegroundColorSpan) span).getForegroundColor());
        } else if (span instanceof TypefaceSpan) {
            return new TypefaceSpan(((TypefaceSpan) span).getFamily());
        } else if (span instanceof StyleSpan) {
            return new StyleSpan(((StyleSpan) span).getStyle());
        } else if (span instanceof StrikethroughSpan) {
            return new StrikethroughSpan();
        } else {
            throw new AssertionError("Unknown Span");
        }
    }

    public static boolean isDarkText(TextView textView) {
        int argb = textView.getCurrentTextColor();
        return Color.red(argb) + Color.green(argb) + Color.blue(argb) == 0;
    }

    private static ParcelableSpan createSpanForStyle(ImStyleParser.Style style) {
        switch (style.getKeyword()) {
            case "*":
                return new StyleSpan(Typeface.BOLD);
            case "_":
                return new StyleSpan(Typeface.ITALIC);
            case "~":
                return new StrikethroughSpan();
            case "`":
            case "```":
                return new TypefaceSpan("monospace");
            default:
                throw new AssertionError("Unknown Style");
        }
    }

    private static void makeKeywordOpaque(final Editable editable, int start, int end, @ColorInt int fallbackTextColor) {
        QuoteSpan[] quoteSpans = editable.getSpans(start, end, QuoteSpan.class);
        @ColorInt int textColor = quoteSpans.length > 0 ? quoteSpans[0].getColor() : fallbackTextColor;
        @ColorInt int keywordColor = transformColor(textColor);
        editable.setSpan(new ForegroundColorSpan(keywordColor), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    }

    private static
    @ColorInt
    int transformColor(@ColorInt int c) {
        return Color.argb(Math.round(Color.alpha(c) * 0.45f), Color.red(c), Color.green(c), Color.blue(c));
    }

    private static int indexOfIgnoreCase(final String haystack, final String needle, final int start) {
        if (haystack == null || needle == null) {
            return -1;
        }
        final int endLimit = haystack.length() - needle.length() + 1;
        if (start > endLimit) {
            return -1;
        }
        if (needle.length() == 0) {
            return start;
        }
        for (int i = start; i < endLimit; i++) {
            if (haystack.regionMatches(true, i, needle, 0, needle.length())) {
                return i;
            }
        }
        return -1;
    }

    public static class MessageEditorStyler implements TextWatcher {

        private final EditText mEditText;

        public MessageEditorStyler(EditText editText) {
            this.mEditText = editText;
        }

        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void afterTextChanged(Editable editable) {
            clear(editable);
            format(editable, mEditText.getCurrentTextColor());
        }
    }
}