//=-------------------------------------------------------------------------=//
//  XML parsing module                                                       //
//                                                                           //
//  Copyright © 2021 The Gem-graph Project                                   //
//                                                                           //
//  This file is part of gem-graph.                                          //
//                                                                           //
//  This program is free software: you can redistribute it and/or modify     //
//  it under the terms of the GNU Affero General Public License as           //
//  published by the Free Software Foundation, either version 3 of the       //
//  License, or (at your option) any later version.                          //
//                                                                           //
//  This program 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 Affero General Public License for more details.                      //
//                                                                           //
//  You should have received a copy of the GNU Affero General Public License //
//  along with this program.  If not, see <https://www.gnu.org/licenses/>.   //
//=-------------------------------------------------------------------------=//

#include "../include/base.h"
#include "../include/model.h"

#include <string.h>
#include <stdlib.h>
#include <libxml/parser.h>

/* -------------------------------------------------------------------------- */

#define NO_DESTINATION NULL

/* -------------------------------------------------------------------------- */

struct ModelParserTableXML_t;

struct ParserTableXML_t
{
    const xmlChar *tag;
    int (*parse) (xmlDoc*,
                  struct ModelParserTableXML_t*,
                  int currentParser,
                  xmlNode*);
    void *destination;
} typedef ParserTableXML_t;

struct ModelParserTableXML_t
{
    size_t len;
    ParserTableXML_t *table;
} typedef ModelParserTableXML_t;

/* -------------------------------------------------------------------------- */

int parseParentFieldXML(xmlDocPtr,
                        ModelParserTableXML_t*,
                        int,
                        xmlNodePtr);

int parseTextField(xmlDocPtr,
                   ModelParserTableXML_t*,
                   int,
                   xmlNodePtr);

/* -------------------------------------------------------------------------- */

// -------------------------------------------------------------------------- //
// Parsing NOTHING                                                            //
// -------------------------------------------------------------------------- //
int parseStubFieldXML (xmlDocPtr doc,
                       ModelParserTableXML_t *ModelTable,
                       int currentParser,
                       xmlNodePtr currentNode)
{
    xmlChar *content;
    content = xmlNodeListGetString(doc, currentNode->xmlChildrenNode, 1);

    printLog("%s (stub): %s\n",
              ModelTable->table[currentParser].tag,
              content);

    xmlFree(content);
    return 0;
}

// -------------------------------------------------------------------------- //
// Parsing a text field                                                       //
// -------------------------------------------------------------------------- //
int parseTextFieldXML (xmlDocPtr doc,
                       ModelParserTableXML_t *ModelTable,
                       int currentParser,
                       xmlNodePtr currentNode)
{
    xmlChar *content;
    content = xmlNodeListGetString(doc, currentNode->xmlChildrenNode, 1);

    printLog("%s: %s\n", ModelTable->table[currentParser].tag,
                         content);

    strncpy((char *)ModelTable->table[currentParser].destination,
           (char *)content, MODEL_STRING_SIZE);
    xmlFree(content);
    return 0;
}

// -------------------------------------------------------------------------- //
// Parsing a field that contains children fields                              //
// -------------------------------------------------------------------------- //
int parseParentFieldXML (xmlDocPtr doc,
                         ModelParserTableXML_t *ModelTable,
                         int currentParser,
                         xmlNodePtr currentNode)
{
    currentNode = currentNode->xmlChildrenNode;
    while (currentNode != NULL) {
        for (int i = 0; i < ModelTable->len; i++) {
            if ((!xmlStrcmp(currentNode->name,
                            ModelTable->table[i].tag))) {
                ModelTable->table[i].parse(doc,
                                           ModelTable,
                                           i,
                                           currentNode);
            }
        }
    currentNode = currentNode->next;
    }
    return 0;
}

// -------------------------------------------------------------------------- //
// Parsing a model file                                                       //
// -------------------------------------------------------------------------- //
int ParseModelXML(Model_t *model)
{
    ParserTableXML_t table[] =
    {
        {(const xmlChar *)"identity",   parseParentFieldXML,  model},
        {(const xmlChar *)"name",       parseTextFieldXML, model->name},
        {(const xmlChar *)"owner",      parseTextFieldXML, model->owner},
        {(const xmlChar *)"owner_id",   parseStubFieldXML, model->owner_id},
        {(const xmlChar *)"date",       parseStubFieldXML, &model->date},
        {(const xmlChar *)"version",    parseTextFieldXML, model->version},
    };

    ModelParserTableXML_t modelParserTable =
    {
        LEN(table),
        &table[0]
    };

    printLog("Parsing model %s\n", model->name);
    xmlDocPtr xmlDocument;
    xmlNodePtr currentNode;

    xmlDocument = xmlParseFile(model->filename);

    if (xmlDocument == NULL) {
        printLog("Can't parse model file at '%s'.\n", model->filename);
        return -1;
    }

    currentNode = xmlDocGetRootElement(xmlDocument);

    if (currentNode == NULL) {
        printLog("Invalid model file at '%s', document empty !\n",
                 model->filename);
        xmlFreeDoc(xmlDocument);
        return -2;
    }

    if (xmlStrcmp(currentNode->name, (const xmlChar *) "gem-graph-model")) {
        printLog("Invalid model file at '%s', "
                 "root node is not <gem-graph-model> !\n",
                 model->filename);
        xmlFreeDoc(xmlDocument);
        return -3;
    }

    currentNode = currentNode->xmlChildrenNode;
    while (currentNode != NULL) {
        for (int i = 0; i < modelParserTable.len; i++) {
            if ((!xmlStrcmp(currentNode->name,
                            modelParserTable.table[i].tag))) {
                modelParserTable.table[i].parse(xmlDocument,
                                                &modelParserTable,
                                                i,
                                                currentNode);
            }
        }

    currentNode = currentNode->next;
    }

    xmlFreeDoc(xmlDocument);

    // Interpret what needs to be
    //model->date = strtol(date, NULL, 0);

    // validate when we're finished
    // model->validated = true;
    return 0;
}