/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 * 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 io.appium.uiautomator2.utils;

import android.support.test.uiautomator.UiSelector;

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

import io.appium.uiautomator2.common.exceptions.UiSelectorSyntaxException;


/**
 * For parsing strings passed in for the "-android uiautomator" locator strategy
 */
public class UiAutomatorParser {

    private String text;
    private List<UiSelector> selectors;
    private UiScrollableParser scrollableParser = new UiScrollableParser();
    private UiSelectorParser selectorParser = new UiSelectorParser();

    public List<UiSelector> parse(String textToParse) throws UiSelectorSyntaxException {
        if (textToParse.isEmpty()) {
            throw new UiSelectorSyntaxException("Tried to parse an empty string. Expected to see a string consisting of text to be interpreted as UiAutomator java code.");
        }
        selectors = new ArrayList<UiSelector>();
        text = textToParse.trim();
        removeTailingSemicolon();
        trimWhitespace();

        consumeStatement();
        while (text.length() > 0) {
            trimWhitespace();
            consumeSemicolon();
            trimWhitespace();
            consumeStatement();
        }

        return selectors;
    }

    private void trimWhitespace() {
        text = text.trim();
    }

    private void removeTailingSemicolon() {
        if (text.charAt(text.length() - 1) == ';') {
            text = text.substring(0, text.length() - 1);
        }
    }

    private void consumeSemicolon() throws UiSelectorSyntaxException {
        if (text.charAt(0) != ';') {
            throw new UiSelectorSyntaxException("Expected ';' but saw '" + text.charAt(0) + "'");
        }

        text = text.substring(1);
    }

    private void consumeStatement() throws UiSelectorSyntaxException {
        String statement;
        int index = 0;
        int parenCount = -1; // semicolons could appear inside String arguments, so we make sure we only count occurrences outside of a parenthesis pair
        while (index < text.length()) {
            if (text.charAt(index) == ';' && parenCount == 0) {
                break;
            }
            if (text.charAt(index) == '(') {
                if (parenCount < 0) {
                    parenCount = 1;
                } else {
                    parenCount++;
                }
            }
            if (text.charAt(index) == ')') {
                parenCount--;
            }
            index++;
        }

        statement = text.substring(0, index);
        if (UiScrollableParser.isUiScrollable(statement)) {
            Logger.debug("Parsing scrollable: " + statement);
            selectors.add(scrollableParser.parse(statement));
        } else {
            Logger.debug("Parsing selector: " + statement);
            selectors.add(selectorParser.parse(statement));
        }

        text = text.substring(index);
    }

}