/*
 * 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 eu.siacs.conversations.utils;

import android.graphics.Color;
import android.graphics.Typeface;
import android.preference.PreferenceManager;
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.RelativeSizeSpan;
import android.text.style.StrikethroughSpan;
import android.text.style.StyleSpan;
import android.text.style.TypefaceSpan;
import android.widget.EditText;
import android.widget.TextView;
import androidx.annotation.ColorInt;
import com.google.android.material.color.MaterialColors;
import eu.siacs.conversations.ui.text.QuoteSpan;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import eu.siacs.conversations.R;
import eu.siacs.conversations.entities.Message;
import eu.siacs.conversations.ui.adapter.MessageAdapter;
import eu.siacs.conversations.ui.text.QuoteSpan;

public class StylingHelper {

    public static final int XHTML_IGNORE = 1;
    public static final int XHTML_REMOVE = 2;
    public static final int XHTML_EMPHASIS = 3;
    public static final int XHTML_CODE = 4;
    public static final int NOLINKIFY = 0xf0;

    private static final List<? extends Class<? extends ParcelableSpan>> SPAN_CLASSES =
            Arrays.asList(
                    StyleSpan.class,
                    StrikethroughSpan.class,
                    TypefaceSpan.class,
                    RelativeSizeSpan.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 Spannable editable, int start, int end, @ColorInt int textColor, final boolean composing) {
        for (ImStyleParser.Style style : ImStyleParser.parse(editable, start, end)) {
            final int keywordLength = style.getKeyword().length();
            int keywordLengthStart = keywordLength;
            if ("```".equals(style.getKeyword())) {
                int i;
                for (i = style.getStart(); i < editable.length(); i++) {
                    if (editable.charAt(i) == '\n') break;
                }
                keywordLengthStart = i - style.getStart() + 1;
            }

            editable.setSpan(
                createSpanForStyle(style),
                style.getStart() + keywordLengthStart,
                style.getEnd() - keywordLength + 1,
                Spanned.SPAN_EXCLUSIVE_EXCLUSIVE |
                    ("*".equals(style.getKeyword()) || "_".equals(style.getKeyword()) ? XHTML_EMPHASIS << Spanned.SPAN_USER_SHIFT : 0) |
                    ("```".equals(style.getKeyword()) && keywordLengthStart > 4 ? XHTML_CODE << Spanned.SPAN_USER_SHIFT : 0) |
                    ("`".equals(style.getKeyword()) || "```".equals(style.getKeyword()) ? NOLINKIFY << Spanned.SPAN_USER_SHIFT : 0)
            );
            makeKeywordOpaque(editable, style.getStart(), style.getStart() + keywordLengthStart, textColor, composing);
            makeKeywordOpaque(editable, style.getEnd() - keywordLength + 1, style.getEnd() + 1, textColor, composing);
        }
    }

    public static void format(final Spannable editable, @ColorInt int textColor) {
        format(editable, textColor, false);
    }

    public static void format(final Spannable editable, @ColorInt int textColor, final boolean composing) {
        format(editable, 0, editable.length() - 1, textColor, composing);
    }

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

    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 TextView view, final Spannable editable, final String needle) {
        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(
                            MaterialColors.getColor(
                                    view, com.google.android.material.R.attr.colorPrimaryFixedDim)),
                    start,
                    end,
                    SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
            editable.setSpan(
                    new ForegroundColorSpan(
                            MaterialColors.getColor(
                                    view, com.google.android.material.R.attr.colorOnPrimaryFixed)),
                    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 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");
        }
    }

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

    private static void makeKeywordOpaque(final Spannable editable, int start, int end, @ColorInt int fallbackTextColor, final boolean composing) {
        QuoteSpan[] quoteSpans = editable.getSpans(start, end, QuoteSpan.class);
        @ColorInt int textColor = quoteSpans.length > 0 ? quoteSpans[0].getColor() : fallbackTextColor;
        @ColorInt int keywordColor = transformColor(textColor);
        if (composing) {
            if (end-start > 1) {
                editable.setSpan(new ForegroundColorSpan(keywordColor), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE | XHTML_REMOVE << Spanned.SPAN_USER_SHIFT);
            } else {
                editable.setSpan(new RelativeSizeSpan(0), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE | XHTML_REMOVE << Spanned.SPAN_USER_SHIFT);
            }
        } else {
            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;
        private final MessageAdapter mAdapter;

        public MessageEditorStyler(EditText editText, MessageAdapter adapter) {
            this.mEditText = editText;
            this.mAdapter = adapter;
        }

        @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);
            final var p = PreferenceManager.getDefaultSharedPreferences(mEditText.getContext());
            if (!p.getBoolean("compose_rich_text", mEditText.getContext().getResources().getBoolean(R.bool.compose_rich_text))) return;
            for (final var span : editable.getSpans(0, editable.length() - 1, QuoteSpan.class)) {
                editable.removeSpan(span);
            }
            format(editable, mEditText.getCurrentTextColor(), true);
            mAdapter.handleTextQuotes(mEditText, editable, false);
        }
    }
}