const DateString = Match.Where(function (dateAsString) {
  check(dateAsString, String);
  return moment(dateAsString, moment.ISO_8601).isValid();
});

export class WekanCreator {
  constructor(data) {
    // we log current date, to use the same timestamp for all our actions.
    // this helps to retrieve all elements performed by the same import.
    this._nowDate = new Date();
    // The object creation dates, indexed by Wekan id
    // (so we only parse actions once!)
    this.createdAt = {
      board: null,
      cards: {},
      lists: {},
    };
    // The object creator Wekan Id, indexed by the object Wekan id
    // (so we only parse actions once!)
    this.createdBy = {
      cards: {}, // only cards have a field for that
    };

    // Map of labels Wekan ID => Wekan ID
    this.labels = {};
    // Map of lists Wekan ID => Wekan ID
    this.lists = {};
    // Map of cards Wekan ID => Wekan ID
    this.cards = {};
    // The comments, indexed by Wekan card id (to map when importing cards)
    this.comments = {};
    // the members, indexed by Wekan member id => Wekan user ID
    this.members = data.membersMapping ? data.membersMapping : {};

    // maps a wekanCardId to an array of wekanAttachments
    this.attachments = {};
  }

  /**
   * If dateString is provided,
   * return the Date it represents.
   * If not, will return the date when it was first called.
   * This is useful for us, as we want all import operations to
   * have the exact same date for easier later retrieval.
   *
   * @param {String} dateString a properly formatted Date
   */
  _now(dateString) {
    if(dateString) {
      return new Date(dateString);
    }
    if(!this._nowDate) {
      this._nowDate = new Date();
    }
    return this._nowDate;
  }

  /**
   * if wekanUserId is provided and we have a mapping,
   * return it.
   * Otherwise return current logged user.
   * @param wekanUserId
   * @private
     */
  _user(wekanUserId) {
    if(wekanUserId && this.members[wekanUserId]) {
      return this.members[wekanUserId];
    }
    return Meteor.userId();
  }

  checkActivities(wekanActivities) {
    check(wekanActivities, [Match.ObjectIncluding({
      userId: String,
      activityType: String,
      createdAt: DateString,
    })]);
    // XXX we could perform more thorough checks based on action type
  }

  checkBoard(wekanBoard) {
    check(wekanBoard, Match.ObjectIncluding({
      archived: Boolean,
      title: String,
      // XXX refine control by validating 'color' against a list of
      // allowed values (is it worth the maintenance?)
      color: String,
      permission: Match.Where((value) => {
        return ['private', 'public'].indexOf(value)>= 0;
      }),
    }));
  }

  checkCards(wekanCards) {
    check(wekanCards, [Match.ObjectIncluding({
      archived: Boolean,
      dateLastActivity: DateString,
      labelIds: [String],
      title: String,
      sort: Number,
    })]);
  }

  checkLabels(wekanLabels) {
    check(wekanLabels, [Match.ObjectIncluding({
      // XXX refine control by validating 'color' against a list of allowed
      // values (is it worth the maintenance?)
      color: String,
    })]);
  }

  checkLists(wekanLists) {
    check(wekanLists, [Match.ObjectIncluding({
      archived: Boolean,
      title: String,
    })]);
  }

  checkChecklists(wekanChecklists) {
    check(wekanChecklists, [Match.ObjectIncluding({
      cardId: String,
      title: String,
      items: [Match.ObjectIncluding({
        isFinished: Boolean,
        title: String,
      })],
    })]);
  }

  // You must call parseActions before calling this one.
  createBoardAndLabels(wekanBoard) {
    const boardToCreate = {
      archived: wekanBoard.archived,
      color: wekanBoard.color,
      // very old boards won't have a creation activity so no creation date
      createdAt: this._now(wekanBoard.createdAt),
      labels: [],
      members: [{
        userId: Meteor.userId(),
        isAdmin: true,
        isActive: true,
        isCommentOnly: false,
      }],
      permission: wekanBoard.permission,
      slug: getSlug(wekanBoard.title) || 'board',
      stars: 0,
      title: wekanBoard.title,
    };
    // now add other members
    if(wekanBoard.members) {
      wekanBoard.members.forEach((wekanMember) => {
        const wekanId = wekanMember.userId;
        // do we have a mapping?
        if(this.members[wekanId]) {
          const wekanId = this.members[wekanId];
          // do we already have it in our list?
          const wekanMember = boardToCreate.members.find((wekanMember) => wekanMember.userId === wekanId);
          if(!wekanMember) {
            boardToCreate.members.push({
              userId: wekanId,
              isAdmin: wekanMember.isAdmin,
              isActive: true,
              isCommentOnly: false,
            });
          }
        }
      });
    }
    wekanBoard.labels.forEach((label) => {
      const labelToCreate = {
        _id: Random.id(6),
        color: label.color,
        name: label.name,
      };
      // We need to remember them by Wekan ID, as this is the only ref we have
      // when importing cards.
      this.labels[label._id] = labelToCreate._id;
      boardToCreate.labels.push(labelToCreate);
    });
    const boardId = Boards.direct.insert(boardToCreate);
    Boards.direct.update(boardId, {$set: {modifiedAt: this._now()}});
    // log activity
    Activities.direct.insert({
      activityType: 'importBoard',
      boardId,
      createdAt: this._now(),
      source: {
        id: wekanBoard.id,
        system: 'Wekan',
      },
      // We attribute the import to current user,
      // not the author from the original object.
      userId: this._user(),
    });
    return boardId;
  }

  /**
   * Create the Wekan cards corresponding to the supplied Wekan cards,
   * as well as all linked data: activities, comments, and attachments
   * @param wekanCards
   * @param boardId
   * @returns {Array}
   */
  createCards(wekanCards, boardId) {
    const result = [];
    wekanCards.forEach((card) => {
      const cardToCreate = {
        archived: card.archived,
        boardId,
        // very old boards won't have a creation activity so no creation date
        createdAt: this._now(this.createdAt.cards[card._id]),
        dateLastActivity: this._now(),
        description: card.description,
        listId: this.lists[card.listId],
        sort: card.sort,
        title: card.title,
        // we attribute the card to its creator if available
        userId: this._user(this.createdBy.cards[card._id]),
        dueAt: card.dueAt ? this._now(card.dueAt) : null,
      };
      // add labels
      if (card.labelIds) {
        cardToCreate.labelIds = card.labelIds.map((wekanId) => {
          return this.labels[wekanId];
        });
      }
      // add members {
      if(card.members) {
        const wekanMembers = [];
        // we can't just map, as some members may not have been mapped
        card.members.forEach((sourceMemberId) => {
          if(this.members[sourceMemberId]) {
            const wekanId = this.members[sourceMemberId];
            // we may map multiple Wekan members to the same wekan user
            // in which case we risk adding the same user multiple times
            if(!wekanMembers.find((wId) => wId === wekanId)){
              wekanMembers.push(wekanId);
            }
          }
          return true;
        });
        if(wekanMembers.length>0) {
          cardToCreate.members = wekanMembers;
        }
      }
      // insert card
      const cardId = Cards.direct.insert(cardToCreate);
      // keep track of Wekan id => WeKan id
      this.cards[card._id] = cardId;
      // log activity
      Activities.direct.insert({
        activityType: 'importCard',
        boardId,
        cardId,
        createdAt: this._now(),
        listId: cardToCreate.listId,
        source: {
          id: card._id,
          system: 'Wekan',
        },
        // we attribute the import to current user,
        // not the author of the original card
        userId: this._user(),
      });
      // add comments
      const comments = this.comments[card._id];
      if (comments) {
        comments.forEach((comment) => {
          const commentToCreate = {
            boardId,
            cardId,
            createdAt: this._now(comment.date),
            text: comment.text,
            // we attribute the comment to the original author, default to current user
            userId: this._user(comment.userId),
          };
          // dateLastActivity will be set from activity insert, no need to
          // update it ourselves
          const commentId = CardComments.direct.insert(commentToCreate);
          Activities.direct.insert({
            activityType: 'addComment',
            boardId: commentToCreate.boardId,
            cardId: commentToCreate.cardId,
            commentId,
            createdAt: this._now(commentToCreate.createdAt),
            // we attribute the addComment (not the import)
            // to the original author - it is needed by some UI elements.
            userId: commentToCreate.userId,
          });
        });
      }
      const attachments = this.attachments[card._id];
      const wekanCoverId = card.coverId;
      if (attachments) {
        attachments.forEach((att) => {
          const file = new FS.File();
          // Simulating file.attachData on the client generates multiple errors
          // - HEAD returns null, which causes exception down the line
          // - the template then tries to display the url to the attachment which causes other errors
          // so we make it server only, and let UI catch up once it is done, forget about latency comp.
          if(Meteor.isServer) {
            if (att.url) {
              file.attachData(att.url, function (error) {
                file.boardId = boardId;
                file.cardId = cardId;
                if (error) {
                  throw(error);
                } else {
                  const wekanAtt = Attachments.insert(file, () => {
                    // we do nothing
                  });
                  //
                  if(wekanCoverId === att._id) {
                    Cards.direct.update(cardId, { $set: {coverId: wekanAtt._id}});
                  }
                }
              });
            } else if (att.file) {
              file.attachData(new Buffer(att.file, 'base64'), {type: att.type}, (error) => {
                file.name(att.name);
                file.boardId = boardId;
                file.cardId = cardId;
                if (error) {
                  throw(error);
                } else {
                  const wekanAtt = Attachments.insert(file, () => {
                    // we do nothing
                  });
                  //
                  if(wekanCoverId === att._id) {
                    Cards.direct.update(cardId, { $set: {coverId: wekanAtt._id}});
                  }
                }
              });
            }
          }
          // todo XXX set cover - if need be
        });
      }
      result.push(cardId);
    });
    return result;
  }

  // Create labels if they do not exist and load this.labels.
  createLabels(wekanLabels, board) {
    wekanLabels.forEach((label) => {
      const color = label.color;
      const name = label.name;
      const existingLabel = board.getLabel(name, color);
      if (existingLabel) {
        this.labels[label.id] = existingLabel._id;
      } else {
        const idLabelCreated = board.pushLabel(name, color);
        this.labels[label.id] = idLabelCreated;
      }
    });
  }

  createLists(wekanLists, boardId) {
    wekanLists.forEach((list) => {
      const listToCreate = {
        archived: list.archived,
        boardId,
        // We are being defensing here by providing a default date (now) if the
        // creation date wasn't found on the action log. This happen on old
        // Wekan boards (eg from 2013) that didn't log the 'createList' action
        // we require.
        createdAt: this._now(this.createdAt.lists[list.id]),
        title: list.title,
      };
      const listId = Lists.direct.insert(listToCreate);
      Lists.direct.update(listId, {$set: {'updatedAt': this._now()}});
      this.lists[list._id] = listId;
      // log activity
      Activities.direct.insert({
        activityType: 'importList',
        boardId,
        createdAt: this._now(),
        listId,
        source: {
          id: list._id,
          system: 'Wekan',
        },
        // We attribute the import to current user,
        // not the creator of the original object
        userId: this._user(),
      });
    });
  }

  createChecklists(wekanChecklists) {
    wekanChecklists.forEach((checklist) => {
      // Create the checklist
      const checklistToCreate = {
        cardId: this.cards[checklist.cardId],
        title: checklist.title,
        createdAt: checklist.createdAt,
      };
      const checklistId = Checklists.direct.insert(checklistToCreate);
      // Now add the items to the checklist
      const itemsToCreate = [];
      checklist.items.forEach((item) => {
        itemsToCreate.push({
          _id: checklistId + itemsToCreate.length,
          title: item.title,
          isFinished: item.isFinished,
        });
      });
      Checklists.direct.update(checklistId, {$set: {items: itemsToCreate}});
    });
  }

  parseActivities(wekanBoard) {
    wekanBoard.activities.forEach((activity) => {
      switch (activity.activityType) {
      case 'addAttachment': {
        // We have to be cautious, because the attachment could have been removed later.
        // In that case Wekan still reports its addition, but removes its 'url' field.
        // So we test for that
        const wekanAttachment = wekanBoard.attachments.filter((attachment) => {
          return attachment._id === activity.attachmentId;
        })[0];
        if(wekanAttachment.url || wekanAttachment.file) {
          // we cannot actually create the Wekan attachment, because we don't yet
          // have the cards to attach it to, so we store it in the instance variable.
          const wekanCardId = activity.cardId;
          if(!this.attachments[wekanCardId]) {
            this.attachments[wekanCardId] = [];
          }
          this.attachments[wekanCardId].push(wekanAttachment);
        }
        break;
      }
      case 'addComment': {
        const wekanComment = wekanBoard.comments.filter((comment) => {
          return comment._id === activity.commentId;
        })[0];
        const id = activity.cardId;
        if (!this.comments[id]) {
          this.comments[id] = [];
        }
        this.comments[id].push(wekanComment);
        break;
      }
      case 'createBoard': {
        this.createdAt.board = activity.createdAt;
        break;
      }
      case 'createCard': {
        const cardId = activity.cardId;
        this.createdAt.cards[cardId] = activity.createdAt;
        this.createdBy.cards[cardId] = activity.userId;
        break;
      }
      case 'createList': {
        const listId = activity.listId;
        this.createdAt.lists[listId] = activity.createdAt;
        break;
      }}
    });
  }

  check(board) {
    try {
      // check(data, {
      //   membersMapping: Match.Optional(Object),
      // });
      this.checkActivities(board.activities);
      this.checkBoard(board);
      this.checkLabels(board.labels);
      this.checkLists(board.lists);
      this.checkCards(board.cards);
      this.checkChecklists(board.checklists);
    } catch (e) {
      throw new Meteor.Error('error-json-schema');
    }
  }

  create(board) {
    this.parseActivities(board);
    const boardId = this.createBoardAndLabels(board);
    this.createLists(board.lists, boardId);
    this.createCards(board.cards, boardId);
    this.createChecklists(board.checklists);
    // XXX add members
    return boardId;
  }
}