/*
  ==============================================================================

   This file is part of the juce_core module of the JUCE library.
   Copyright (c) 2013 - Raw Material Software Ltd.

   Permission to use, copy, modify, and/or distribute this software for any purpose with
   or without fee is hereby granted, provided that the above copyright notice and this
   permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN
   NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
   DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
   IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
   CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

   ------------------------------------------------------------------------------

   NOTE! This permissive ISC license applies ONLY to files within the juce_core module!
   All other JUCE modules are covered by a dual GPL/commercial license, so if you are
   using any other modules, be sure to check that you also comply with their license.

   For more details, visit www.juce.com

  ==============================================================================
*/

XmlDocument::XmlDocument (const String& documentText)
    : originalText (documentText),
      input (nullptr),
      outOfData (false),
      errorOccurred (false),
      needToLoadDTD (false),
      ignoreEmptyTextElements (true)
{
}

XmlDocument::XmlDocument (const File& file)
    : input (nullptr),
      outOfData (false),
      errorOccurred (false),
      needToLoadDTD (false),
      ignoreEmptyTextElements (true),
      inputSource (new FileInputSource (file))
{
}

XmlDocument::~XmlDocument()
{
}

XmlElement* XmlDocument::parse (const File& file)
{
    XmlDocument doc (file);
    return doc.getDocumentElement();
}

XmlElement* XmlDocument::parse (const String& xmlData)
{
    XmlDocument doc (xmlData);
    return doc.getDocumentElement();
}

void XmlDocument::setInputSource (InputSource* const newSource) noexcept
{
    inputSource = newSource;
}

void XmlDocument::setEmptyTextElementsIgnored (const bool shouldBeIgnored) noexcept
{
    ignoreEmptyTextElements = shouldBeIgnored;
}

namespace XmlIdentifierChars
{
    static bool isIdentifierCharSlow (const juce_wchar c) noexcept
    {
        return CharacterFunctions::isLetterOrDigit (c)
                 || c == '_' || c == '-' || c == ':' || c == '.';
    }

    static bool isIdentifierChar (const juce_wchar c) noexcept
    {
        static const uint32 legalChars[] = { 0, 0x7ff6000, 0x87fffffe, 0x7fffffe, 0 };

        return ((int) c < (int) numElementsInArray (legalChars) * 32) ? ((legalChars [c >> 5] & (1 << (c & 31))) != 0)
                                                                      : isIdentifierCharSlow (c);
    }

    /*static void generateIdentifierCharConstants()
    {
        uint32 n[8] = { 0 };
        for (int i = 0; i < 256; ++i)
            if (isIdentifierCharSlow (i))
                n[i >> 5] |= (1 << (i & 31));

        String s;
        for (int i = 0; i < 8; ++i)
            s << "0x" << String::toHexString ((int) n[i]) << ", ";

        DBG (s);
    }*/
}

XmlElement* XmlDocument::getDocumentElement (const bool onlyReadOuterDocumentElement)
{
    String textToParse (originalText);

    if (textToParse.isEmpty() && inputSource != nullptr)
    {
        ScopedPointer <InputStream> in (inputSource->createInputStream());

        if (in != nullptr)
        {
            MemoryOutputStream data;
            data.writeFromInputStream (*in, onlyReadOuterDocumentElement ? 8192 : -1);
            textToParse = data.toString();

            if (! onlyReadOuterDocumentElement)
                originalText = textToParse;
        }
    }

    input = textToParse.getCharPointer();
    lastError = String::empty;
    errorOccurred = false;
    outOfData = false;
    needToLoadDTD = true;

    if (textToParse.isEmpty())
    {
        lastError = "not enough input";
    }
    else
    {
        skipHeader();

        if (input.getAddress() != nullptr)
        {
            ScopedPointer <XmlElement> result (readNextElement (! onlyReadOuterDocumentElement));

            if (! errorOccurred)
                return result.release();
        }
        else
        {
            lastError = "incorrect xml header";
        }
    }

    return nullptr;
}

const String& XmlDocument::getLastParseError() const noexcept
{
    return lastError;
}

void XmlDocument::setLastError (const String& desc, const bool carryOn)
{
    lastError = desc;
    errorOccurred = ! carryOn;
}

String XmlDocument::getFileContents (const String& filename) const
{
    if (inputSource != nullptr)
    {
        const ScopedPointer <InputStream> in (inputSource->createInputStreamFor (filename.trim().unquoted()));

        if (in != nullptr)
            return in->readEntireStreamAsString();
    }

    return String::empty;
}

juce_wchar XmlDocument::readNextChar() noexcept
{
    const juce_wchar c = input.getAndAdvance();

    if (c == 0)
    {
        outOfData = true;
        --input;
    }

    return c;
}

int XmlDocument::findNextTokenLength() noexcept
{
    int len = 0;
    juce_wchar c = *input;

    while (XmlIdentifierChars::isIdentifierChar (c))
        c = input [++len];

    return len;
}

void XmlDocument::skipHeader()
{
    const int headerStart = input.indexOf (CharPointer_UTF8 ("<?xml"));

    if (headerStart >= 0)
    {
        const int headerEnd = (input + headerStart).indexOf (CharPointer_UTF8 ("?>"));
        if (headerEnd < 0)
            return;

       #if JUCE_DEBUG
        const String header (input + headerStart, (size_t) (headerEnd - headerStart));
        const String encoding (header.fromFirstOccurrenceOf ("encoding", false, true)
                                     .fromFirstOccurrenceOf ("=", false, false)
                                     .fromFirstOccurrenceOf ("\"", false, false)
                                     .upToFirstOccurrenceOf ("\"", false, false).trim());

        /* If you load an XML document with a non-UTF encoding type, it may have been
           loaded wrongly.. Since all the files are read via the normal juce file streams,
           they're treated as UTF-8, so by the time it gets to the parser, the encoding will
           have been lost. Best plan is to stick to utf-8 or if you have specific files to
           read, use your own code to convert them to a unicode String, and pass that to the
           XML parser.
        */
        jassert (encoding.isEmpty() || encoding.startsWithIgnoreCase ("utf-"));
       #endif

        input += headerEnd + 2;
    }

    skipNextWhiteSpace();

    const int docTypeIndex = input.indexOf (CharPointer_UTF8 ("<!DOCTYPE"));
    if (docTypeIndex < 0)
        return;

    input += docTypeIndex + 9;
    const String::CharPointerType docType (input);

    int n = 1;

    while (n > 0)
    {
        const juce_wchar c = readNextChar();

        if (outOfData)
            return;

        if (c == '<')
            ++n;
        else if (c == '>')
            --n;
    }

    dtdText = String (docType, (size_t) (input.getAddress() - (docType.getAddress() + 1))).trim();
}

void XmlDocument::skipNextWhiteSpace()
{
    for (;;)
    {
        juce_wchar c = *input;

        while (CharacterFunctions::isWhitespace (c))
            c = *++input;

        if (c == 0)
        {
            outOfData = true;
            break;
        }
        else if (c == '<')
        {
            if (input[1] == '!'
                 && input[2] == '-'
                 && input[3] == '-')
            {
                input += 4;
                const int closeComment = input.indexOf (CharPointer_UTF8 ("-->"));

                if (closeComment < 0)
                {
                    outOfData = true;
                    break;
                }

                input += closeComment + 3;
                continue;
            }
            else if (input[1] == '?')
            {
                input += 2;
                const int closeBracket = input.indexOf (CharPointer_UTF8 ("?>"));

                if (closeBracket < 0)
                {
                    outOfData = true;
                    break;
                }

                input += closeBracket + 2;
                continue;
            }
        }

        break;
    }
}

void XmlDocument::readQuotedString (String& result)
{
    const juce_wchar quote = readNextChar();

    while (! outOfData)
    {
        const juce_wchar c = readNextChar();

        if (c == quote)
            break;

        --input;

        if (c == '&')
        {
            readEntity (result);
        }
        else
        {
            const String::CharPointerType start (input);
            size_t numChars = 0;

            for (;;)
            {
                const juce_wchar character = *input;

                if (character == quote)
                {
                    result.appendCharPointer (start, numChars);
                    ++input;
                    return;
                }
                else if (character == '&')
                {
                    result.appendCharPointer (start, numChars);
                    break;
                }
                else if (character == 0)
                {
                    outOfData = true;
                    setLastError ("unmatched quotes", false);
                    break;
                }

                ++input;
                ++numChars;
            }
        }
    }
}

XmlElement* XmlDocument::readNextElement (const bool alsoParseSubElements)
{
    XmlElement* node = nullptr;

    skipNextWhiteSpace();
    if (outOfData)
        return nullptr;

    const int openBracket = input.indexOf ((juce_wchar) '<');

    if (openBracket >= 0)
    {
        input += openBracket + 1;
        int tagLen = findNextTokenLength();

        if (tagLen == 0)
        {
            // no tag name - but allow for a gap after the '<' before giving an error
            skipNextWhiteSpace();
            tagLen = findNextTokenLength();

            if (tagLen == 0)
            {
                setLastError ("tag name missing", false);
                return node;
            }
        }

        node = new XmlElement (String (input, (size_t) tagLen));
        input += tagLen;
        LinkedListPointer<XmlElement::XmlAttributeNode>::Appender attributeAppender (node->attributes);

        // look for attributes
        for (;;)
        {
            skipNextWhiteSpace();

            const juce_wchar c = *input;

            // empty tag..
            if (c == '/' && input[1] == '>')
            {
                input += 2;
                break;
            }

            // parse the guts of the element..
            if (c == '>')
            {
                ++input;

                if (alsoParseSubElements)
                    readChildElements (node);

                break;
            }

            // get an attribute..
            if (XmlIdentifierChars::isIdentifierChar (c))
            {
                const int attNameLen = findNextTokenLength();

                if (attNameLen > 0)
                {
                    const String::CharPointerType attNameStart (input);
                    input += attNameLen;

                    skipNextWhiteSpace();

                    if (readNextChar() == '=')
                    {
                        skipNextWhiteSpace();

                        const juce_wchar nextChar = *input;

                        if (nextChar == '"' || nextChar == '\'')
                        {
                            XmlElement::XmlAttributeNode* const newAtt
                                = new XmlElement::XmlAttributeNode (String (attNameStart, (size_t) attNameLen),
                                                                    String::empty);

                            readQuotedString (newAtt->value);
                            attributeAppender.append (newAtt);
                            continue;
                        }
                    }
                }
            }
            else
            {
                if (! outOfData)
                    setLastError ("illegal character found in " + node->getTagName() + ": '" + c + "'", false);
            }

            break;
        }
    }

    return node;
}

void XmlDocument::readChildElements (XmlElement* parent)
{
    LinkedListPointer<XmlElement>::Appender childAppender (parent->firstChildElement);

    for (;;)
    {
        const String::CharPointerType preWhitespaceInput (input);
        skipNextWhiteSpace();

        if (outOfData)
        {
            setLastError ("unmatched tags", false);
            break;
        }

        if (*input == '<')
        {
            if (input[1] == '/')
            {
                // our close tag..
                const int closeTag = input.indexOf ((juce_wchar) '>');

                if (closeTag >= 0)
                    input += closeTag + 1;

                break;
            }
            else if (input[1] == '!'
                  && input[2] == '['
                  && input[3] == 'C'
                  && input[4] == 'D'
                  && input[5] == 'A'
                  && input[6] == 'T'
                  && input[7] == 'A'
                  && input[8] == '[')
            {
                input += 9;
                const String::CharPointerType inputStart (input);

                size_t len = 0;

                for (;;)
                {
                    if (*input == 0)
                    {
                        setLastError ("unterminated CDATA section", false);
                        outOfData = true;
                        break;
                    }
                    else if (input[0] == ']'
                              && input[1] == ']'
                              && input[2] == '>')
                    {
                        input += 3;
                        break;
                    }

                    ++input;
                    ++len;
                }

                childAppender.append (XmlElement::createTextElement (String (inputStart, len)));
            }
            else
            {
                // this is some other element, so parse and add it..
                if (XmlElement* const n = readNextElement (true))
                    childAppender.append (n);
                else
                    break;
            }
        }
        else  // must be a character block
        {
            input = preWhitespaceInput; // roll back to include the leading whitespace
            String textElementContent;

            for (;;)
            {
                const juce_wchar c = *input;

                if (c == '<')
                    break;

                if (c == 0)
                {
                    setLastError ("unmatched tags", false);
                    outOfData = true;
                    return;
                }

                if (c == '&')
                {
                    String entity;
                    readEntity (entity);

                    if (entity.startsWithChar ('<') && entity [1] != 0)
                    {
                        const String::CharPointerType oldInput (input);
                        const bool oldOutOfData = outOfData;

                        input = entity.getCharPointer();
                        outOfData = false;

                        for (;;)
                        {
                            XmlElement* const n = readNextElement (true);

                            if (n == nullptr)
                                break;

                            childAppender.append (n);
                        }

                        input = oldInput;
                        outOfData = oldOutOfData;
                    }
                    else
                    {
                        textElementContent += entity;
                    }
                }
                else
                {
                    const String::CharPointerType start (input);
                    size_t len = 0;

                    for (;;)
                    {
                        const juce_wchar nextChar = *input;

                        if (nextChar == '<' || nextChar == '&')
                        {
                            break;
                        }
                        else if (nextChar == 0)
                        {
                            setLastError ("unmatched tags", false);
                            outOfData = true;
                            return;
                        }

                        ++input;
                        ++len;
                    }

                    textElementContent.appendCharPointer (start, len);
                }
            }

            if ((! ignoreEmptyTextElements) || textElementContent.containsNonWhitespaceChars())
            {
                childAppender.append (XmlElement::createTextElement (textElementContent));
            }
        }
    }
}

void XmlDocument::readEntity (String& result)
{
    // skip over the ampersand
    ++input;

    if (input.compareIgnoreCaseUpTo (CharPointer_UTF8 ("amp;"), 4) == 0)
    {
        input += 4;
        result += '&';
    }
    else if (input.compareIgnoreCaseUpTo (CharPointer_UTF8 ("quot;"), 5) == 0)
    {
        input += 5;
        result += '"';
    }
    else if (input.compareIgnoreCaseUpTo (CharPointer_UTF8 ("apos;"), 5) == 0)
    {
        input += 5;
        result += '\'';
    }
    else if (input.compareIgnoreCaseUpTo (CharPointer_UTF8 ("lt;"), 3) == 0)
    {
        input += 3;
        result += '<';
    }
    else if (input.compareIgnoreCaseUpTo (CharPointer_UTF8 ("gt;"), 3) == 0)
    {
        input += 3;
        result += '>';
    }
    else if (*input == '#')
    {
        int charCode = 0;
        ++input;

        if (*input == 'x' || *input == 'X')
        {
            ++input;
            int numChars = 0;

            while (input[0] != ';')
            {
                const int hexValue = CharacterFunctions::getHexDigitValue (input[0]);

                if (hexValue < 0 || ++numChars > 8)
                {
                    setLastError ("illegal escape sequence", true);
                    break;
                }

                charCode = (charCode << 4) | hexValue;
                ++input;
            }

            ++input;
        }
        else if (input[0] >= '0' && input[0] <= '9')
        {
            int numChars = 0;

            while (input[0] != ';')
            {
                if (++numChars > 12)
                {
                    setLastError ("illegal escape sequence", true);
                    break;
                }

                charCode = charCode * 10 + ((int) input[0] - '0');
                ++input;
            }

            ++input;
        }
        else
        {
            setLastError ("illegal escape sequence", true);
            result += '&';
            return;
        }

        result << (juce_wchar) charCode;
    }
    else
    {
        const String::CharPointerType entityNameStart (input);
        const int closingSemiColon = input.indexOf ((juce_wchar) ';');

        if (closingSemiColon < 0)
        {
            outOfData = true;
            result += '&';
        }
        else
        {
            input += closingSemiColon + 1;

            result += expandExternalEntity (String (entityNameStart, (size_t) closingSemiColon));
        }
    }
}

String XmlDocument::expandEntity (const String& ent)
{
    if (ent.equalsIgnoreCase ("amp"))   return String::charToString ('&');
    if (ent.equalsIgnoreCase ("quot"))  return String::charToString ('"');
    if (ent.equalsIgnoreCase ("apos"))  return String::charToString ('\'');
    if (ent.equalsIgnoreCase ("lt"))    return String::charToString ('<');
    if (ent.equalsIgnoreCase ("gt"))    return String::charToString ('>');

    if (ent[0] == '#')
    {
        const juce_wchar char1 = ent[1];

        if (char1 == 'x' || char1 == 'X')
            return String::charToString (static_cast <juce_wchar> (ent.substring (2).getHexValue32()));

        if (char1 >= '0' && char1 <= '9')
            return String::charToString (static_cast <juce_wchar> (ent.substring (1).getIntValue()));

        setLastError ("illegal escape sequence", false);
        return String::charToString ('&');
    }

    return expandExternalEntity (ent);
}

String XmlDocument::expandExternalEntity (const String& entity)
{
    if (needToLoadDTD)
    {
        if (dtdText.isNotEmpty())
        {
            dtdText = dtdText.trimCharactersAtEnd (">");
            tokenisedDTD.addTokens (dtdText, true);

            if (tokenisedDTD [tokenisedDTD.size() - 2].equalsIgnoreCase ("system")
                 && tokenisedDTD [tokenisedDTD.size() - 1].isQuotedString())
            {
                const String fn (tokenisedDTD [tokenisedDTD.size() - 1]);

                tokenisedDTD.clear();
                tokenisedDTD.addTokens (getFileContents (fn), true);
            }
            else
            {
                tokenisedDTD.clear();
                const int openBracket = dtdText.indexOfChar ('[');

                if (openBracket > 0)
                {
                    const int closeBracket = dtdText.lastIndexOfChar (']');

                    if (closeBracket > openBracket)
                        tokenisedDTD.addTokens (dtdText.substring (openBracket + 1,
                                                                   closeBracket), true);
                }
            }

            for (int i = tokenisedDTD.size(); --i >= 0;)
            {
                if (tokenisedDTD[i].startsWithChar ('%')
                     && tokenisedDTD[i].endsWithChar (';'))
                {
                    const String parsed (getParameterEntity (tokenisedDTD[i].substring (1, tokenisedDTD[i].length() - 1)));
                    StringArray newToks;
                    newToks.addTokens (parsed, true);

                    tokenisedDTD.remove (i);

                    for (int j = newToks.size(); --j >= 0;)
                        tokenisedDTD.insert (i, newToks[j]);
                }
            }
        }

        needToLoadDTD = false;
    }

    for (int i = 0; i < tokenisedDTD.size(); ++i)
    {
        if (tokenisedDTD[i] == entity)
        {
            if (tokenisedDTD[i - 1].equalsIgnoreCase ("<!entity"))
            {
                String ent (tokenisedDTD [i + 1].trimCharactersAtEnd (">").trim().unquoted());

                // check for sub-entities..
                int ampersand = ent.indexOfChar ('&');

                while (ampersand >= 0)
                {
                    const int semiColon = ent.indexOf (i + 1, ";");

                    if (semiColon < 0)
                    {
                        setLastError ("entity without terminating semi-colon", false);
                        break;
                    }

                    const String resolved (expandEntity (ent.substring (i + 1, semiColon)));

                    ent = ent.substring (0, ampersand)
                           + resolved
                           + ent.substring (semiColon + 1);

                    ampersand = ent.indexOfChar (semiColon + 1, '&');
                }

                return ent;
            }
        }
    }

    setLastError ("unknown entity", true);

    return entity;
}

String XmlDocument::getParameterEntity (const String& entity)
{
    for (int i = 0; i < tokenisedDTD.size(); ++i)
    {
        if (tokenisedDTD[i] == entity
             && tokenisedDTD [i - 1] == "%"
             && tokenisedDTD [i - 2].equalsIgnoreCase ("<!entity"))
        {
            const String ent (tokenisedDTD [i + 1].trimCharactersAtEnd (">"));

            if (ent.equalsIgnoreCase ("system"))
                return getFileContents (tokenisedDTD [i + 2].trimCharactersAtEnd (">"));

            return ent.trim().unquoted();
        }
    }

    return entity;
}