/**
 * Inspired by: http://dbus-cplusplus.sourceforge.net/
 */

#include "xml.h"

#include <expat.h>

using namespace sdbuscpp::xml;

std::istream &operator >> (std::istream& in, Document& doc)
{
    std::stringbuf xmlbuf;
    in.get(xmlbuf, '\0');
    doc.from_xml(xmlbuf.str());

    return in;
}

std::ostream &operator << (std::ostream& out, const Document& doc)
{
    return out << doc.to_xml();
}


Error::Error(const char *error, int line, int column)
{
    std::ostringstream estream;

    estream << "line " << line << ", column " << column << ": " << error;

    m_error = estream.str();
}

Node::Node(const char *n, const char **a)
: name(n)
{
    if (a)
    {
        for (int i = 0; a[i]; i += 2)
        {
            m_attrs[a[i]] = a[i + 1];
        }
    }
}

Nodes Nodes::operator[](const std::string& key) const
{
    Nodes result;

    for (auto it = begin(), endIt = end(); it != endIt; ++it)
    {
        Nodes part = (**it)[key];

        result.insert(result.end(), part.begin(), part.end());
    }
    return result;
}

Nodes Nodes::select(const std::string& attr, const std::string& value) const
{
    Nodes result;

    for (auto it = begin(), itEnd = end(); it != itEnd; ++it)
    {
        if ((*it)->get(attr) == value)
        {
            result.insert(result.end(), *it);
        }
    }
    return result;
}

Nodes Node::operator[](const std::string& key)
{
    Nodes result;

    if (key.length() == 0)
    {
        return result;
    }

    for (auto it = children.begin(), itEnd = children.end(); it != itEnd; ++it)
    {
        if (it->name == key)
        {
            result.push_back(&(*it));
        }
    }
    return result;
}

std::string Node::get(const std::string& attribute) const
{
    const auto it = m_attrs.find(attribute);
    if (it != m_attrs.end())
    {
        return it->second;
    }

    return "";
}

void Node::set(const std::string& attribute, std::string value)
{
    if (value.length())
    {
        m_attrs[attribute] = value;
    }
    else
    {
        m_attrs.erase(value);
    }
}

std::string Node::to_xml() const
{
    std::string xml;
    int depth = 0;

    _raw_xml(xml, depth);

    return xml;
}

void Node::_raw_xml(std::string& xml, int& depth) const
{
    xml.append(depth * 2, ' ');
    xml.append("<" + name);

    for (auto it = m_attrs.begin(), itEnd = m_attrs.end(); it != itEnd; ++it)
    {
        xml.append(" " + it->first + "=\"" + it->second + "\"");
    }

    if (cdata.length() == 0 && children.size() == 0)
    {
        xml.append("/>\n");
    }
    else
    {
        xml.append(">");

        if (cdata.length())
        {
            xml.append(cdata);
        }

        if (children.size())
        {
            xml.append("\n");
            ++depth;

            for (auto it = children.begin(), itEnd = children.end(); it != itEnd; ++it)
            {
                it->_raw_xml(xml, depth);
            }

            --depth;
            xml.append(depth * 2, ' ');
        }

        xml.append("</" + name + ">\n");
    }
}

Document::Document() :
        root(nullptr),
        m_depth(0)
{
}

Document::Document(const std::string &xml) :
        root(nullptr),
        m_depth(0)
{
    from_xml(xml);
}

Document::~Document()
{
    delete root;
}

struct Document::Expat
{
        static void start_doctype_decl_handler(
                void *data, const XML_Char *name, const XML_Char *sysid, const XML_Char *pubid, int has_internal_subset
        );
        static void end_doctype_decl_handler(void *data);
        static void start_element_handler(void *data, const XML_Char *name, const XML_Char **atts);
        static void character_data_handler(void *data, const XML_Char *chars, int len);
        static void end_element_handler(void *data, const XML_Char *name);
};

void Document::from_xml(const std::string& xml)
{
    m_depth = 0;
    if (root)
    {
        delete root;
    }
    root = nullptr;

    XML_Parser parser = XML_ParserCreate("UTF-8");

    XML_SetUserData(parser, this);

    XML_SetDoctypeDeclHandler(
            parser,
            Document::Expat::start_doctype_decl_handler,
            Document::Expat::end_doctype_decl_handler
    );

    XML_SetElementHandler(
            parser,
            Document::Expat::start_element_handler,
            Document::Expat::end_element_handler
    );

    XML_SetCharacterDataHandler(
            parser,
            Document::Expat::character_data_handler
    );

    XML_Status status = XML_Parse(parser, xml.c_str(), xml.length(), true);

    if (status == XML_STATUS_ERROR)
    {
        const char* error = XML_ErrorString(XML_GetErrorCode(parser));
        int line = XML_GetCurrentLineNumber(parser);
        int column = XML_GetCurrentColumnNumber(parser);

        XML_ParserFree(parser);

        throw Error(error, line, column);
    }
    else
    {
        XML_ParserFree(parser);
    }
}

std::string Document::to_xml() const
{
    return root->to_xml();
}

void Document::Expat::start_doctype_decl_handler(
        void* /*data*/,
        const XML_Char* /*name*/,
        const XML_Char* /*sysid*/,
        const XML_Char */*pubid*/,
        int /*has_internal_subset*/)
{
}

void Document::Expat::end_doctype_decl_handler(void* /*data*/)
{
}

void Document::Expat::start_element_handler(void* data, const XML_Char* name, const XML_Char** atts)
{
    Document* doc = static_cast<Document*>(data);

    if (!doc->root)
    {
        doc->root = new Node(name, atts);
    }
    else
    {
        Node::Children* cld = &(doc->root->children);

        for (int i = 1; i < doc->m_depth; ++i)
        {
            cld = &(cld->back().children);
        }
        cld->push_back(Node(name, atts));

    }
    doc->m_depth++;
}

void Document::Expat::character_data_handler(void* data, const XML_Char* chars, int len)
{
    Document* doc = static_cast<Document*>(data);

    Node* nod = doc->root;

    for (int i = 1; i < doc->m_depth; ++i)
    {
        nod = &(nod->children.back());
    }

    int offset = 0, count = len;

    while (count > 0 && isspace(chars[count - 1])) --count;
    while (offset < count && isspace(chars[offset])) { ++offset; --count; }

    nod->cdata = std::string{chars + offset, static_cast<std::string::size_type>(count)};
}

void Document::Expat::end_element_handler(void* data, const XML_Char* /*name*/)
{
    Document* doc = static_cast<Document*>(data);

    doc->m_depth--;
}