/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  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 org.codehaus.groovy.tools.shell.util

import groovy.transform.CompileStatic

@CompileStatic
class CommandArgumentParser {

    /**
     * takes a String and tokenizes it according to posix-shell-like rules, meaning
     * arguments are separated by non-escaped blanks or hyphens, and hyphens wrap tokens regardless
     * of blanks, other hyphens or escaped hyphens within the wrapping hyphens.
     *
     * Example: "foo bar 123'456' 'abc\'def\\' ''"  has 6 tokens:
     * ["foo", "bar", "123", "456", "abc'def\", ""]
     *
     * @param untrimmedLine
     * @param numTokensToCollect stop processing after so many tokens, negative means unlimited
     * @return
     */
    static List<String> parseLine(final String untrimmedLine, final int numTokensToCollect = -1) {
        assert untrimmedLine != null

        final String line = untrimmedLine.trim()
        List<String> tokens = []
        String currentToken = ''
        // state machine being either in neutral state, in singleHyphenOpen state, or in doubleHyphenOpen State.
        boolean singleHyphenOpen = false
        boolean doubleHyphenOpen = false
        int index = 0
        for (; index < line.length(); index++) {
            if (tokens.size() == numTokensToCollect) {
                break
            }
            String ch = line.charAt(index)
            // escaped char? -> maybe unescape
            if (ch == '\\') {
                if (index >= line.length() - 1) {
                    // end reached
                    currentToken += ch
                    continue
                }
                if (singleHyphenOpen || doubleHyphenOpen) {
                    // add escaped, no other parsing action
                    currentToken += ch
                    index++
                    currentToken += line.charAt(index)
                    continue
                } else {
                    // unescape, only add char after, no parsing action
                    index++
                    currentToken += line.charAt(index)
                    continue
                }
            }

            if (ch == '"' && !singleHyphenOpen) {
                if (doubleHyphenOpen) {
                    tokens.add(currentToken)
                    currentToken = ''
                    doubleHyphenOpen = false
                } else {
                    if (currentToken.size() > 0) {
                        tokens.add(currentToken)
                        currentToken = ''
                    }
                    doubleHyphenOpen = true
                }
                continue
            }
            if (ch == '\'' && !doubleHyphenOpen) {
                if (singleHyphenOpen) {
                    tokens.add(currentToken)
                    currentToken = ''
                    singleHyphenOpen = false
                } else {
                    if (currentToken.size() > 0) {
                        tokens.add(currentToken)
                        currentToken = ''
                    }
                    singleHyphenOpen = true
                }
                continue
            }
            if (ch == ' ' && !doubleHyphenOpen && !singleHyphenOpen) {
                if (currentToken.size() > 0) {
                    tokens.add(currentToken)
                    currentToken = ''
                }
                continue
            }
            currentToken += ch
        } // end for char in line
        if (index == line.length() && doubleHyphenOpen) {
            throw new IllegalArgumentException('Missing closing " in ' + line + ' -- ' + tokens)
        }
        if (index == line.length() && singleHyphenOpen) {
            throw new IllegalArgumentException('Missing closing \' in ' + line  + ' -- ' + tokens)
        }
        if (currentToken.size() > 0) {
            tokens.add(currentToken)
        }
        return tokens
    }
}
