/************************************************************************
 *
 * Copyright (C) 2009-2021 IRCAD France
 * Copyright (C) 2012-2020 IHU Strasbourg
 *
 * This file is part of Sight.
 *
 * Sight is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Sight is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Sight. If not, see <https://www.gnu.org/licenses/>.
 *
 ***********************************************************************/

//#include <ios_base.h> not necessary on win32
#include <filesystem>
#include <libxml/xmlversion.h>
#ifndef LIBXML_SCHEMAS_ENABLED
    #warning "Error libxml schemas disabled"
#endif
#include <libxml/tree.h>
#include <libxml/parser.h>
#include <libxml/xinclude.h>
#include <libxml/xmlschemas.h>
#include <libxml/xmlschemastypes.h>

#include "core/runtime/RuntimeException.hpp"
#include "core/runtime/detail/io/Validator.hpp"

#include <core/base.hpp>

namespace sight::core::runtime
{

namespace detail
{

namespace io
{

//------------------------------------------------------------------------------

Validator::Validator(const Validator& validator)
{
    m_xsd_content         = validator.m_xsd_content;
    m_schemaParserContext = validator.m_schemaParserContext;
    m_schema              = validator.m_schema;
}

//------------------------------------------------------------------------------

Validator::Validator(const std::string& buffer)
{
    m_xsd_content = buffer;
}

//------------------------------------------------------------------------------

Validator::Validator(const std::filesystem::path& path)
{
    std::string strPath(path.string());
    // Checks the path validity.
    if(std::filesystem::exists(path) == false || std::filesystem::is_directory(path))
    {
        throw RuntimeException(strPath + ": is not a valid path to an xml schema file.");
    }

    m_xsd_content = strPath;
}

//------------------------------------------------------------------------------

Validator::~Validator()
{
}

//------------------------------------------------------------------------------

void Validator::clearErrorLog()
{
    m_errorLog.str(std::string());
}

//------------------------------------------------------------------------------

const std::string Validator::getErrorLog() const
{
    return m_errorLog.str();
}

//------------------------------------------------------------------------------

void Validator::initializeContext()
{
    if(m_schemaValidContext)
    {
        return;
    }

    if(!m_schemaParserContext)
    {
        if(!(m_schemaParserContext = SchemaParserCtxtSptr(
                 xmlSchemaNewParserCtxt(m_xsd_content.c_str()),
                 xmlSchemaFreeParserCtxt
        )))
        {
            return;
        }

        // Set the structured error callback
        xmlSchemaSetParserStructuredErrors(m_schemaParserContext.get(), Validator::ErrorHandler, this);
    }

    // Load XML schema content
    if(!m_schema)
    {
        m_schema = SchemaSptr(xmlSchemaParse(m_schemaParserContext.get()), xmlSchemaFree);
    }

    if(!m_schema)
    {
        return;
    }

    // Create XML schemas validation context
    if((m_schemaValidContext = SchemaValidCtxtSptr(xmlSchemaNewValidCtxt(m_schema.get()), xmlSchemaFreeValidCtxt)))
    {
        // Set the structured error callback
        xmlSchemaSetValidStructuredErrors(m_schemaValidContext.get(), Validator::ErrorHandler, this);
    }
}

//------------------------------------------------------------------------------

bool Validator::validate(const std::filesystem::path& xmlFile)
{
    int result;

    initializeContext();

    xmlDocPtr xmlDoc = xmlParseFile(xmlFile.string().c_str());
    if(xmlDoc == NULL)
    {
        throw std::ios_base::failure("Unable to parse the XML file " + xmlFile.string());
    }

    xmlNodePtr xmlRoot = xmlDocGetRootElement(xmlDoc);
    if(xmlXIncludeProcessTreeFlags(xmlRoot, XML_PARSE_NOBASEFIX) == -1)
    {
        xmlFreeDoc(xmlDoc);
        throw std::ios_base::failure(std::string("Unable to manage xinclude !"));
    }

    if(!m_schemaValidContext)
    {
        return false;
    }

    result = xmlSchemaValidateDoc(m_schemaValidContext.get(), xmlDoc);

    xmlFreeDoc(xmlDoc);

    if(result != 0)
    {
        SIGHT_WARN("Validator::validation NOK, xml = " << xmlFile.string());
        SIGHT_WARN("Validator::validation NOK, xsd = " << getXsdContent());
        SIGHT_ERROR("Validator::validation NOK, error log = " << getErrorLog());
    }

    return result == 0;
}

//------------------------------------------------------------------------------

bool Validator::validate(xmlNodePtr node)
{
    int result;

    initializeContext();

    if(!m_schemaValidContext)
    {
        return false;
    }

    result = xmlSchemaValidateOneElement(m_schemaValidContext.get(), node);

    if(result != 0)
    {
        xmlBufferPtr buffer = xmlBufferCreate();
        xmlNodeDump(buffer, node->doc, node, 1, 1);
        SIGHT_WARN("Validator::validation NOK, node :\n " << buffer->content);
        xmlBufferFree(buffer);
        SIGHT_WARN("Validator::validation NOK, xsd = " << getXsdContent());
        SIGHT_ERROR("Validator::validation NOK, error log = " << getErrorLog());
    }

    return result == 0;
}

//------------------------------------------------------------------------------

void Validator::ErrorHandler(void* userData, xmlErrorPtr error)
{
    Validator* validator = (Validator*) userData;

    validator->m_errorLog << "At line " << error->line << ": " << error->message;
}

//------------------------------------------------------------------------------

std::string Validator::getXsdContent()
{
    return m_xsd_content;
}

//------------------------------------------------------------------------------

} // namespace io

} // namespace detail

} // namespace sight::core::runtime
