/*
 * Jexer - Java Text User Interface
 *
 * The MIT License (MIT)
 *
 * Copyright (C) 2019 Kevin Lamonte
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * @author Kevin Lamonte [kevin.lamonte@gmail.com]
 * @version 1
 */
package jexer.teditor;

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

import jexer.bits.CellAttributes;
import jexer.bits.StringUtils;

/**
 * A Line represents a single line of text on the screen, as a collection of
 * words.
 */
public class Line {

    // ------------------------------------------------------------------------
    // Variables --------------------------------------------------------------
    // ------------------------------------------------------------------------

    /**
     * The list of words.
     */
    private ArrayList<Word> words = new ArrayList<Word>();

    /**
     * The default color for the TEditor class.
     */
    private CellAttributes defaultColor = null;

    /**
     * The text highlighter to use.
     */
    private Highlighter highlighter = null;

    /**
     * The current edition position on this line.
     */
    private int position = 0;

    /**
     * The current editing position screen column number.
     */
    private int screenPosition = 0;

    /**
     * The raw text of this line, what is passed to Word to determine
     * highlighting behavior.
     */
    private StringBuilder rawText;

    // ------------------------------------------------------------------------
    // Constructors -----------------------------------------------------------
    // ------------------------------------------------------------------------

    /**
     * Construct a new Line from an existing text string, and highlight
     * certain strings.
     *
     * @param str the text string
     * @param defaultColor the color for unhighlighted text
     * @param highlighter the highlighter to use
     */
    public Line(final String str, final CellAttributes defaultColor,
        final Highlighter highlighter) {

        this.defaultColor = defaultColor;
        this.highlighter = highlighter;
        this.rawText = new StringBuilder(str);

        scanLine();
    }

    /**
     * Construct a new Line from an existing text string.
     *
     * @param str the text string
     * @param defaultColor the color for unhighlighted text
     */
    public Line(final String str, final CellAttributes defaultColor) {
        this(str, defaultColor, null);
    }

    // ------------------------------------------------------------------------
    // Line -------------------------------------------------------------------
    // ------------------------------------------------------------------------

    /**
     * Get a (shallow) copy of the words in this line.
     *
     * @return a copy of the word list
     */
    public List<Word> getWords() {
        return new ArrayList<Word>(words);
    }

    /**
     * Get the current cursor position in the text.
     *
     * @return the cursor position
     */
    public int getRawCursor() {
        return position;
    }

    /**
     * Get the current cursor position on screen.
     *
     * @return the cursor position
     */
    public int getCursor() {
        return screenPosition;
    }

    /**
     * Set the current cursor position.
     *
     * @param cursor the new cursor position
     */
    public void setCursor(final int cursor) {
        if ((cursor < 0)
            || ((cursor >= getDisplayLength())
                && (getDisplayLength() > 0))
        ) {
            throw new IndexOutOfBoundsException("Max length is " +
                getDisplayLength() + ", requested position " + cursor);
        }
        screenPosition = cursor;
        position = screenToTextPosition(screenPosition);
    }

    /**
     * Get the character at the current cursor position in the text.
     *
     * @return the character, or -1 if the cursor is at the end of the line
     */
    public int getChar() {
        if (position == rawText.length()) {
            return -1;
        }
        return rawText.codePointAt(position);
    }

    /**
     * Get the on-screen display length.
     *
     * @return the number of cells needed to display this line
     */
    public int getDisplayLength() {
        int n = StringUtils.width(rawText.toString());

        if (n > 0) {
            // If we have any visible characters, add one to the display so
            // that the position is immediately after the data.
            return n + 1;
        }
        return n;
    }

    /**
     * Get the raw string that matches this line.
     *
     * @return the string
     */
    public String getRawString() {
        return rawText.toString();
    }

    /**
     * Scan rawText and make words out of it.
     */
    private void scanLine() {
        words.clear();
        Word word = new Word(this.defaultColor, this.highlighter);
        words.add(word);
        for (int i = 0; i < rawText.length();) {
            int ch = rawText.codePointAt(i);
            i += Character.charCount(ch);
            Word newWord = word.addChar(ch);
            if (newWord != word) {
                words.add(newWord);
                word = newWord;
            }
        }
        for (Word w: words) {
            w.applyHighlight();
        }
    }

    /**
     * Decrement the cursor by one.  If at the first column, do nothing.
     *
     * @return true if the cursor position changed
     */
    public boolean left() {
        if (position == 0) {
            return false;
        }
        screenPosition -= StringUtils.width(rawText.codePointBefore(position));
        position -= Character.charCount(rawText.codePointBefore(position));
        return true;
    }

    /**
     * Increment the cursor by one.  If at the last column, do nothing.
     *
     * @return true if the cursor position changed
     */
    public boolean right() {
        if (getDisplayLength() == 0) {
            return false;
        }
        if (position == getDisplayLength() - 1) {
            return false;
        }
        if (position < rawText.length()) {
            screenPosition += StringUtils.width(rawText.codePointAt(position));
            position += Character.charCount(rawText.codePointAt(position));
        }
        assert (position <= rawText.length());
        return true;
    }

    /**
     * Go to the first column of this line.
     *
     * @return true if the cursor position changed
     */
    public boolean home() {
        if (position > 0) {
            position = 0;
            screenPosition = 0;
            return true;
        }
        return false;
    }

    /**
     * Go to the last column of this line.
     *
     * @return true if the cursor position changed
     */
    public boolean end() {
        if (position != getDisplayLength() - 1) {
            position = rawText.length();
            screenPosition = StringUtils.width(rawText.toString());
            return true;
        }
        return false;
    }

    /**
     * Delete the character under the cursor.
     */
    public void del() {
        assert (words.size() > 0);

        if (position < getDisplayLength()) {
            int n = Character.charCount(rawText.codePointAt(position));
            for (int i = 0; i < n; i++) {
                rawText.deleteCharAt(position);
            }
        }

        // Re-scan the line to determine the new word boundaries.
        scanLine();
    }

    /**
     * Delete the character immediately preceeding the cursor.
     */
    public void backspace() {
        if (left()) {
            del();
        }
    }

    /**
     * Insert a character at the cursor.
     *
     * @param ch the character to insert
     */
    public void addChar(final int ch) {
        if (position < getDisplayLength() - 1) {
            rawText.insert(position, Character.toChars(ch));
        } else {
            rawText.append(Character.toChars(ch));
        }
        position += Character.charCount(ch);
        screenPosition += StringUtils.width(ch);
        scanLine();
    }

    /**
     * Replace a character at the cursor.
     *
     * @param ch the character to replace
     */
    public void replaceChar(final int ch) {
        if (position < getDisplayLength() - 1) {
            // Replace character
            String oldText = rawText.toString();
            rawText = new StringBuilder(oldText.substring(0, position));
            rawText.append(Character.toChars(ch));
            rawText.append(oldText.substring(position + 1));
            screenPosition += StringUtils.width(rawText.codePointAt(position));
            position += Character.charCount(ch);
        } else {
            rawText.append(Character.toChars(ch));
            position += Character.charCount(ch);
            screenPosition += StringUtils.width(ch);
        }
        scanLine();
    }

    /**
     * Determine string position from screen position.
     *
     * @param screenPosition the position on screen
     * @return the equivalent position in text
     */
    protected int screenToTextPosition(final int screenPosition) {
        if (screenPosition == 0) {
            return 0;
        }

        int n = 0;
        for (int i = 0; i < rawText.length(); i++) {
            n += StringUtils.width(rawText.codePointAt(i));
            if (n >= screenPosition) {
                return i + 1;
            }
        }
        // screenPosition exceeds the available text length.
        throw new IndexOutOfBoundsException("screenPosition " + screenPosition +
            " exceeds available text length " + rawText.length());
    }

}