import ErrorBuilder from "./ErrorBuilder";

/**
 * Classe permettant de gérer les tables simples
 */
class QueryBuilder {
  /**
   * Initialisation de la classe
   * @param {Object} params
   * @param {Object} models
   */
  constructor(params, models) {
    this.params = params;
    this.models = models;
    this.includes = [];
  }

  /**
   * Méthode permettant de générer le lien vers une ressource
   * @param  {String} href
   * @param  {Number} currentPage
   * @param  {Number} maxPage
   * @param  {String} page
   */
  static _createLink(href, currentPage, maxPage, page) {
    if (
      (page === "first" && currentPage > 1) ||
      (page === "last" && currentPage < maxPage) ||
      (page === "prev" && currentPage > 1) ||
      (page === "next" && currentPage < maxPage)
    ) {
      let newIndex = 0;
      switch (page) {
        case "first":
          newIndex = 1;
          break;
        case "last":
          newIndex = maxPage;
          break;
        case "prev":
          newIndex = currentPage - 1;
          break;
        case "next":
          newIndex = currentPage + 1;
          break;
        default:
          newIndex = currentPage;
          break;
      }
      return {
        href: href.replace(`page=${currentPage}`, `page=${newIndex}`),
        methdod: "GET"
      };
    }
    return undefined;
  }

  /**
   * Méthde permettant de générer les élements de pagination
   * @param  {Object} req
   * @param  {Number} total
   * @param  {Number} limit
   * @param  {Number} skip
   * @return {Object}
   */
  static _createPagination(req, total, limit, skip) {
    const maxPage = Math.ceil(total / limit); // Nombre total de pages
    const currentPage = Math.ceil(skip / limit) + 1; // Numéro de la page courante
    const href = `${req.protocol}://${req.get("host")}${req.originalUrl}`; // Lien vers la page actuelle

    return {
      paging: {
        first: QueryBuilder._createLink(href, currentPage, maxPage, "first"),
        prev: QueryBuilder._createLink(href, currentPage, maxPage, "prev"),
        next: QueryBuilder._createLink(href, currentPage, maxPage, "next"),
        last: QueryBuilder._createLink(href, currentPage, maxPage, "last")
      },
      total,
      maxPage
    };
  }

  /**
   * Fonction permettant de remplacer les attributs du genre $lte pat Op.lte
   * @param  {Object} obj
   * @return {Object}
   */
  _replaceKeys(obj) {
    const { Op } = this.models.Sequelize;
    let newObject = {};

    if (Array.isArray(obj)) {
      newObject = [];
      for (let i = 0; i < obj.length; i += 1) {
        const value =
          typeof obj[i] === "object" ? this._replaceKeys(obj[i]) : obj[i];
        newObject.push(value);
      }
    } else {
      Object.keys(obj).map(key => {
        const value =
          typeof obj[key] === "object" ? this._replaceKeys(obj[key]) : obj[key];
        if (key.indexOf("$") === 0 && key.slice(-1) !== "$") {
          switch (key) {
            case "$or":
              newObject[Op.or] = value;
              break;
            case "$lte":
              newObject[Op.lte] = value;
              break;
            case "$gte":
              newObject[Op.gte] = value;
              break;
            case "$contains":
              newObject[Op.contains] = [value];
              break;
            case "$in":
              newObject[Op.in] = value.split(",");
              break;
            default:
              newObject[key] = [value];
              break;
          }
        } else {
          newObject[key] = value;
        }
        return true;
      });
    }

    return newObject;
  }

  /**
   * Fonction permettant de savoir si un utilisateur a assez de droit pour effectuer une action
   * @param {Object} req
   * @return {Boolean}
   */
  _haveRight(req) {
    let allowedRole = "all";

    // eslint-disable-next-line default-case
    switch (req.method) {
      case "POST":
        allowedRole = this.params.crud.write;
        break;
      case "PATCH":
      case "PUT":
        allowedRole = this.params.crud.edit;
        break;
      case "GET":
        allowedRole = this.params.crud.read;
        break;
      case "DELETE":
        allowedRole = this.params.crud.delete;
        break;
    }

    return allowedRole === "all" || allowedRole.indexOf(req.user.role) !== -1;
  }

  /**
   * Fonction permettant d'ajouter des restructions sur un get
   * @param {Object} req
   * @return {Object}
   */
  _restrictOn(req) {
    const where = {};
    if (!this.params || !this.params.restrictOn) {
      return where;
    }

    const _overrideWhere = restrictions => {
      if (!restrictions) {
        return false;
      }
      for (let i = 0; i < restrictions.length; i += 1) {
        const restrict = restrictions[i];

        const value =
          restrict.type === "raw"
            ? restrict.value
            : req[restrict.type][restrict.value];

        if (restrict.roles.indexOf(req.user.role) !== -1) {
          where[restrict.field] = value;
        }
      }
      return true;
    };

    _overrideWhere(this.params.restrictOn[req.getType]);

    switch (req.method) {
      case "PATCH":
        _overrideWhere(this.params.restrictOn.update);
        break;
      case "DELETE":
        _overrideWhere(this.params.restrictOn.delete);
        break;
      default:
      // Do nothing
    }

    return where;
  }

  /**
   * Fonction permettant de surcharger des valeurs
   * @param {Object} req
   * @param {String} method
   * @return {Object}
   */
  _override(req, method) {
    let override = {};
    const params = this.params.override ? this.params.override[method] : {};
    if (!this.params.override) {
      return override;
    }

    if (!params) {
      return override;
    }

    // On surcharge certains paramètres passé en query
    if (params.filters) {
      Object.keys(params.filters).map(column => {
        if (req.query[column]) {
          const value = req.query[column];

          const query = JSON.parse(
            JSON.stringify(params.filters[column]).replace(
              new RegExp("_TERM_", "g"),
              value
            )
          );
          override = Object.assign(override, this._replaceKeys(query));
        }
        return true;
      });
    }

    // On rajoute des paramètres à la requête
    if (params.params) {
      for (let i = 0; i < params.params.length; i += 1) {
        const currentParam = params.params[i];
        override[currentParam.append] =
          req[currentParam.from][currentParam.value];
      }
    }

    return override;
  }

  /**
   * Fonction permettant de charger la liste des relations à inclures lors d'un get
   * @param {Object} req
   * @param {Array} include
   * @return {Mixed}
   */
  _setInclusions(req, include) {
    const includes = [];

    const listOfIncludes = include || this.params.includes;

    for (let i = 0; i < listOfIncludes.length; i += 1) {
      const current = listOfIncludes[i];
      // const include = current.collection;

      if (
        !current.requiredRole ||
        current.requiredRole.indexOf(req.user.role) !== -1
      ) {
        let currentInclude = null;

        if (!current.model) {
          currentInclude = current.collection;
        } else {
          currentInclude = {
            as: current.collection,
            model: current.model,
            required: current.required || false
          };

          // Pour cette inclusion il y a des filtres à appliquer
          if (current.restrictOn || current.include) {
            currentInclude.where = {};

            if (current.include) {
              currentInclude.include = this._setInclusions(
                req,
                current.include
              );
            }

            // On parcours la liste des règles d'inclusion pour ce modèle
            if (current.restrictOn) {
              for (let j = 0; j < current.restrictOn.length; j += 1) {
                const currentRestriction = current.restrictOn[j];
                // Cette restriction s'applique à tout le monde (pas de field roles)
                // ou alors elle s'applique juste sur une liste de groupes
                if (
                  !currentRestriction.roles ||
                  currentRestriction.roles.indexOf(req.user.role) !== -1
                ) {
                  if (currentRestriction.type === "raw") {
                    currentInclude.where[currentRestriction.field] =
                      currentRestriction.value;
                  }
                }
              }
            }
          }
        }

        includes.push(currentInclude);
      }
    }

    // Mode reccursif
    if (include) {
      return includes;
    }

    this.includes = includes;
    return true;
  }

  /**
   * Méthode interne permettant de créer un item
   * @param {Object} req
   * @param {Object} value
   * @param {Function} callback
   */
  _insertItem(req, value, callback) {
    const values = {};
    // On converti les 'null' en null (formData par exemple)
    Object.keys(value).map(key => {
      if (value[key] === "null") {
        values[key] = null;
      } else {
        values[key] = value[key];
      }
      return true;
    });

    // Création de l'élément
    this.models[this.params.model]
      .create(values)
      .then(item => {
        let createdItem = item;
        if (this.params.format) {
          const formatRules = req.user
            ? this.params.format[req.user.role]
            : null;

          if (formatRules) {
            createdItem = this._formatItem(item, formatRules);
          }
        }
        callback(null, createdItem);
      })
      .catch(err => {
        if (err.name === "SequelizeUniqueConstraintError") {
          callback(new ErrorBuilder(409, "Duplicate item"));
          return false;
        }
        callback(err);
        return false;
      });
  }

  /**
   * Fonction permettant de formater un item en fonction du user
   * @param  {Object} item
   * @param  {Object} formatRule
   * @return {Object}
   */
  _formatItem(item, formatRule) {
    const formated = {};
    Object.keys(formatRule).map(key => {
      switch (typeof formatRule[key]) {
        case "string":
          formated[key] = item[key] || null;
          break;
        case "object":
          if (Array.isArray(item[key])) {
            formated[key] = [];
            for (let i = 0; i < item[key].length; i += 1) {
              formated[key].push(
                this._formatItem(item[key][i], formatRule[key])
              );
            }
          } else {
            formated[key] = this._formatItem(item[key], formatRule[key]);
          }
          break;
        default:
        // Do nothing
      }
      return true;
    });

    return formated;
  }

  /**
   * Fonction permettant de formater une liste d'items en fonction du user
   * @param  {Object} req
   * @param  {Object} items
   * @return {Object}
   */
  _formatItems(req, items) {
    if (!this.params.format) {
      return items;
    }

    const formatRules = this.params.format[req.user.role];

    if (!formatRules) {
      return items;
    }

    const formated = [];
    for (let i = 0; i < items.length; i += 1) {
      formated.push(this._formatItem(items[i], formatRules));
    }

    return formated;
  }

  /**
   * Méthode permettant de vérifier que les valeurs reçues dans le body sont valides
   * @param  {Object} req
   * @param  {Function} callback
   */
  _checkCreateOneValues(req, callback) {
    // On regarde s'il faut surcharger les valeurs du body avec des valeurs dérivées (req.user, req.params...)
    if (this.params.override && this.params.override.create) {
      if (this.params.override.create.body) {
        for (let i = 0; i < this.params.override.create.body.length; i += 1) {
          const override = this.params.override.create.body[i];
          req.body[override.append] = req[override.from][override.value];
        }
      }
    }

    // On teste le body
    const { error, value } = this.params.validate.create.validate(req.body, {
      abortEarly: false
    });

    if (error) {
      callback(new ErrorBuilder(406, error));
    } else {
      callback(null, value);
    }
  }

  /**
   * Fonction permettant de vérifier et de surcharger des valeurs lors d'un get
   * @param  {Object} req
   * @param  {Function} callback
   * @return {Boolean}
   */
  _createQuery(req, callback) {
    this._setInclusions(req);
    const query = {};
    let where = {};
    let order = [];

    // On test les droits
    if (!this._haveRight(req)) {
      callback(new ErrorBuilder(401, "You're not allowed"));
      return false;
    }

    // On teste la query (ou les params)
    const toValidate = req.getType === "list" ? req.query : req.params;
    const { error, value } = this.params.validate[
      req.getType
    ].validate(toValidate, { abortEarly: false });

    // On vire, pour le moment la liste des filtres un peu particuliers
    let listOfIgnoredFilters = [
      "limit",
      "page",
      "sort",
      "order",
      this.params.itemId
    ];
    if (this.params.removeKeys && this.params.removeKeys[req.getType]) {
      listOfIgnoredFilters = listOfIgnoredFilters.concat(
        this.params.removeKeys[req.getType]
      );
    }
    if (
      this.params.override &&
      this.params.override[req.getType] &&
      this.params.override[req.getType].filters
    ) {
      Object.keys(this.params.override[req.getType].filters).map(key => {
        listOfIgnoredFilters.push(key);
        return true;
      });
    }
    // On rajoute les filtres autorisés
    Object.keys(value).map(key => {
      if (listOfIgnoredFilters.indexOf(key) === -1) {
        where[key] = value[key];
      }
      return true;
    });

    // Un paramètre n'est pas bon dans la query
    if (error) {
      callback(new ErrorBuilder(406, error));
      return false;
    }

    if (req.getType === "list") {
      // Aucune pagination n'est passée, on set celle par défaut
      if (!value.page || !value.limit) {
        value.page = 1;
        value.limit = 20;
      }

      // Un tri est spécifié
      if (value.order && value.sort) {
        order = [[value.sort, value.order.toUpperCase()]];
      }
    } else {
      // On get un item. on set son id
      where.id = value[this.params.itemId];
    }

    // S'il y a des restrictions (genre un utilisateur n'a le droit de voir que tel ou tel items)
    const restrict = this._restrictOn(req);
    where = Object.assign(where, restrict);

    // On regarde s'il n'y a pas des valeurs à overrider
    const override = this._override(req, req.getType);
    where = Object.assign(where, override);

    // if ( value.page) {
    //   query.offset = ( value.page - 1 ) * value.limit;
    //   query.limit = value.limit;
    // }

    if (order) {
      query.order = order;
    }

    query.distinct = true; // On supprime les id en double (jointure de type hasmany)
    query.where = where; // On rajoute des filtres
    if (this.includes) {
      query.include = this.includes; // On set la liste des modèles à inclure
    }

    // Hack pour faire un recherche dans les nested de type hasMany
    query.subQuery = false;

    if (!value.page || !value.limit) {
      value.page = 1;
      value.limit = 50;
    }

    callback(null, query, {
      start: value.page * value.limit - value.limit,
      limit: value.limit
    });
    return true;
  }
}

module.exports = QueryBuilder;