package com.jayway.jsonpath.internal;

import com.jayway.jsonpath.InvalidPathException;

public class CharacterIndex {

    private static final char OPEN_PARENTHESIS = '(';
    private static final char CLOSE_PARENTHESIS = ')';
    private static final char CLOSE_SQUARE_BRACKET = ']';
    private static final char SPACE = ' ';
    private static final char ESCAPE = '\\';
    private static final char SINGLE_QUOTE = '\'';
    private static final char MINUS = '-';
    private static final char PERIOD = '.';
    private static final char REGEX = '/';

    private final CharSequence charSequence;
    private int position;

    public CharacterIndex(CharSequence charSequence) {
        this.charSequence = charSequence;
        this.position = 0;
    }

    public int length() {
        return charSequence.length();
    }

    public char charAt(int idx) {
        return charSequence.charAt(idx);
    }

    public char currentChar() {
        return charSequence.charAt(position);
    }

    public boolean currentCharIs(char c) {
        return (charSequence.charAt(position) == c);
    }

    public boolean nextCharIs(char c) {
        return inBounds(position + 1) && (charSequence.charAt(position + 1) == c);
    }

    public int incrementPosition(int charCount) {
        return setPosition(position + charCount);
    }

    public int setPosition(int newPosition) {
        //position = min(newPosition, charSequence.length() - 1);
        position = newPosition;
        return position;
    }

    public int position(){
        return position;
    }

    public int indexOfClosingSquareBracket(int startPosition) {
        int readPosition = startPosition;
        while (inBounds(readPosition)) {
            if(charAt(readPosition) == CLOSE_SQUARE_BRACKET){
                return readPosition;
            }
            readPosition++;
        }
        return -1;
    }
    public int indexOfMatchingCloseChar(int startPosition, char openChar, char closeChar, boolean skipStrings, boolean skipRegex) {
        if(charAt(startPosition) != openChar){
            throw new InvalidPathException("Expected " + openChar + " but found " + charAt(startPosition));
        }

        int opened = 1;
        int readPosition = startPosition + 1;
        while (inBounds(readPosition)) {
            if (skipStrings) {
                if (charAt(readPosition) == SINGLE_QUOTE) {
                    boolean escaped = false;
                    while (inBounds(readPosition)) {
                        readPosition++;
                        if (escaped) {
                            escaped = false;
                            continue;
                        }
                        if (charAt(readPosition) == ESCAPE) {
                            escaped = true;
                            continue;
                        }
                        if (charAt(readPosition) == SINGLE_QUOTE) {
                            readPosition++;
                            break;
                        }
                    }
                }
            }
            if (skipRegex) {
                if (charAt(readPosition) == REGEX) {
                    while (inBounds(readPosition)) {
                        readPosition++;
                        if (charAt(readPosition) == REGEX) {
                            readPosition++;
                            break;
                        }
                    }
                }
            }
            if (charAt(readPosition) == openChar) {
                opened++;
            }
            if (charAt(readPosition) == closeChar) {
                opened--;
                if (opened == 0) {
                    return readPosition;
                }
            }
            readPosition++;
        }
        return -1;
    }
    public int indexOfClosingBracket(int startPosition, boolean skipStrings, boolean skipRegex) {
        return indexOfMatchingCloseChar(startPosition, OPEN_PARENTHESIS, CLOSE_PARENTHESIS, skipStrings, skipRegex);
    }

    public int indexOfNextSignificantChar(char c) {
        return indexOfNextSignificantChar(position, c);
    }

    public int indexOfNextSignificantChar(int startPosition, char c) {
        int readPosition = startPosition + 1;
        while (!isOutOfBounds(readPosition) && charAt(readPosition) == SPACE) {
            readPosition++;
        }
        if (charAt(readPosition) == c) {
            return readPosition;
        } else {
            return -1;
        }
    }

    public int nextIndexOf(char c) {
        return nextIndexOf(position + 1, c);
    }

    public int nextIndexOf(int startPosition, char c) {
        int readPosition = startPosition;
        while (!isOutOfBounds(readPosition)) {
            if (charAt(readPosition) == c) {
                return readPosition;
            }
            readPosition++;
        }
        return -1;
    }

    public int nextIndexOfUnescaped(char c) {
        return nextIndexOfUnescaped(position + 1, c);
    }

    public int nextIndexOfUnescaped(int startPosition, char c) {
        int readPosition = startPosition;
        char prev1;
        char prev2;
        while (!isOutOfBounds(readPosition)) {
            prev1 = charAtOr(readPosition - 1, ' ');
            prev2 = charAtOr(readPosition - 2, ' ');
            boolean ignore = (prev1 == '\\' && prev2 == '\\');
            boolean escaped = (prev1 == '\\' && !ignore);

            if (charAt(readPosition) == c && !escaped) {
                return readPosition;
            }
            readPosition++;
        }
        return -1;
    }

    public char charAtOr(int postition, char defaultChar){
        if(!inBounds(postition)) return defaultChar;
        else return charAt(postition);
    }

    public boolean nextSignificantCharIs(int startPosition, char c) {
        int readPosition = startPosition + 1;
        while (!isOutOfBounds(readPosition) && charAt(readPosition) == SPACE) {
            readPosition++;
        }
        return !isOutOfBounds(readPosition) && charAt(readPosition) == c;
    }

    public boolean nextSignificantCharIs(char c) {
        return nextSignificantCharIs(position, c);
    }

    public char nextSignificantChar() {
        return nextSignificantChar(position);
    }

    public char nextSignificantChar(int startPosition) {
        int readPosition = startPosition + 1;
        while (!isOutOfBounds(readPosition) && charAt(readPosition) == SPACE) {
            readPosition++;
        }
        if (!isOutOfBounds(readPosition)) {
            return charAt(readPosition);
        } else {
            return ' ';
        }
    }

    public int indexOfPreviousSignificantChar(int startPosition){
        int readPosition = startPosition - 1;
        while (!isOutOfBounds(readPosition) && charAt(readPosition) == SPACE) {
            readPosition--;
        }
        if (!isOutOfBounds(readPosition)) {
            return readPosition;
        } else {
            return -1;
        }
    }

    public int indexOfPreviousSignificantChar(){
        return indexOfPreviousSignificantChar(position);
    }

    public char previousSignificantChar(int startPosition) {
        int previousSignificantCharIndex = indexOfPreviousSignificantChar(startPosition);
        if(previousSignificantCharIndex == -1) return ' ';
        else return charAt(previousSignificantCharIndex);
    }

    public char previousSignificantChar() {
        return previousSignificantChar(position);
    }

    public boolean currentIsTail() {
        return isOutOfBounds(position + 1);
    }

    public boolean hasMoreCharacters() {
        return inBounds(position + 1);
    }

    public boolean inBounds(int idx) {
        return (idx >= 0) && (idx < charSequence.length());
    }
    public boolean inBounds() {
        return inBounds(position);
    }

    public boolean isOutOfBounds(int idx) {
        return !inBounds(idx);
    }

    public CharSequence subSequence(int start, int end) {
        return charSequence.subSequence(start, end);
    }

    public CharSequence charSequence() {
        return charSequence;
    }

    @Override
    public String toString() {
        return charSequence.toString();
    }

    public boolean isNumberCharacter(int readPosition) {
        char c = charAt(readPosition);
        return Character.isDigit(c) || c == MINUS  || c == PERIOD;
    }

    public CharacterIndex skipBlanks() {
        while (inBounds() && currentChar() == SPACE){
            incrementPosition(1);
        }
        return this;
    }
}