// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

import FauxtonAPI from '../../../../core/api';
import SidebarActions from '../../sidebar/actions';
import Constants from '../../constants';
import { errorReason } from '../helpers/shared-helpers';
import * as IndexResultsAPI from '../api';
import { nowLoading, newResultsAvailable, newSelectedDocs,
  changeLayout, resetState, partitionParamNotSupported, partitionParamIsMandatory } from './base';

const maxDocLimit = 10000;

// This is a helper function to determine what params need to be sent to couch based
// on what the user entered (i.e. queryOptionsParams) and what fauxton is using to
// emulate pagination (i.e. fetchParams).
export const mergeParams = (fetchParams, queryOptionsParams) => {
  const params = {};

  // determine the final "index" or "position" in the total result list based on the
  // user's skip and limit inputs.  If queryOptionsParams.limit is empty,
  // finalDocPosition will be NaN.  That's ok.
  const finalDocPosition = (queryOptionsParams.skip || 0) + queryOptionsParams.limit;

  // The skip value sent to couch will be the max of our current pagination skip
  // (i.e. fetchParams.skip) and the user's original skip input (i.e. queryOptionsParams.skip).
  // The limit will continue to be our pagination limit.
  params.skip = Math.max(fetchParams.skip, queryOptionsParams.skip || 0);
  params.limit = fetchParams.limit;
  if (fetchParams.conflicts) {
    params.conflicts = true;
  }

  // Determine the total number of documents remaining based on the user's skip and
  // limit inputs.  Again, note that this will be NaN if queryOptionsParams.limit is
  // empty.  That's ok.
  const totalDocsRemaining = finalDocPosition - params.skip;

  // return the merged params to send to couch and the num docs remaining.
  return {
    params: Object.assign({}, queryOptionsParams, params),
    totalDocsRemaining: totalDocsRemaining
  };
};

export const removeOverflowDocsAndCalculateHasNext = (docs, totalDocsRemaining, fetchLimit) => {
  // Now is the time to determine if we have another page of results
  // after this set of documents.  We also want to manipulate the array
  // of docs because we always search with a limit larger than the desired
  // number of results.  This is necessaary to emulate pagination.
  let canShowNext = false;
  if (totalDocsRemaining && docs.length > totalDocsRemaining) {
    // We know the user manually entered a limit and we've reached the
    // end of their desired results.  We need to remove any extra results
    // that were returned because of our pagination emulation logic.
    docs.splice(totalDocsRemaining);
  } else if (docs.length === fetchLimit) {
    // The number of docs returned is equal to our params.limit, which is
    // one more than our perPage size.  We know that there is another
    // page of results after this.
    docs.splice(fetchLimit - 1);
    canShowNext = true;
  }

  return {
    finalDocList: docs,
    canShowNext
  };
};

// All the business logic for fetching docs from couch.
// Arguments:
// - queryDocs -> a function that fetches the docs. Accepts fetch params and returns a Promise of {docs[], docType}.
// - fetchParams -> the internal params fauxton uses to emulate pagination
// - queryOptionsParams -> manual query params entered by user
export const fetchDocs = (queryDocs, fetchParams, queryOptionsParams) => {
  const { params, totalDocsRemaining } = mergeParams(fetchParams, queryOptionsParams);
  params.limit = Math.min(params.limit, maxDocLimit);

  return (dispatch) => {
    // first, tell app state that we're loading
    dispatch(nowLoading());

    // now fetch the results
    return queryDocs(params).then(({ docs, docType, executionStats, warning, layout }) => {
      const {
        finalDocList,
        canShowNext
      } = removeOverflowDocsAndCalculateHasNext(docs, totalDocsRemaining, params.limit);

      if (layout) {
        dispatch(changeLayout(layout));
      }
      // dispatch that we're all done
      dispatch(newResultsAvailable(finalDocList, params, canShowNext, docType, executionStats, warning));
    }).catch((error) => {
      if (error && error.message.includes('`partition` parameter is not supported')) {
        dispatch(partitionParamNotSupported());
      } else if (error && error.message.includes('`partition` parameter is mandatory')) {
        dispatch(partitionParamIsMandatory());
      } else {
        FauxtonAPI.addNotification({
          msg: 'Error running query. ' + errorReason(error),
          type: 'error',
          clear: true
        });
      }
      dispatch(resetState());
    });
  };
};


export const deleteErrorMessage = (ids) => {
  let msg = 'Failed to delete your document!';

  if (ids) {
    msg = 'Failed to delete: ' + ids.join(', ');
  }

  FauxtonAPI.addNotification({
    msg: msg,
    type: 'error',
    clear:  true
  });
};

export const validateBulkDelete = (docs) => {
  const itemsLength = docs.length;

  const msg = (itemsLength === 1) ? 'Are you sure you want to delete this doc?' :
    'Are you sure you want to delete these ' + itemsLength + ' docs?';

  if (itemsLength === 0) {
    window.alert('Please select the document rows you want to delete.');
    return false;
  }

  if (!window.confirm(msg)) {
    return false;
  }

  return true;
};

export const bulkDeleteDocs = (databaseName, queryDocs, docs, designDocs, fetchParams, queryOptionsParams, docType) => {
  if (!validateBulkDelete(docs)) {
    return false;
  }

  return (dispatch) => {
    let postPromise, payload;
    if (docType === Constants.INDEX_RESULTS_DOC_TYPE.MANGO_INDEX) {
      payload = { docids: docs.map(doc => doc._id) };
      postPromise = IndexResultsAPI.postToIndexBulkDelete(databaseName, payload);
    } else if (docType === Constants.INDEX_RESULTS_DOC_TYPE.VIEW
        || docType === Constants.INDEX_RESULTS_DOC_TYPE.MANGO_QUERY) {
      payload = { docs: docs };
      postPromise = IndexResultsAPI.postToBulkDocs(databaseName, payload);
    } else {
      throw new Error('Invalid document type: ' + docType);
    }
    return postPromise.then((res) => {
      if (res.error) {
        deleteErrorMessage();
        return;
      }
      processBulkDeleteResponse(res, docs, designDocs, docType);
      dispatch(newSelectedDocs());
      dispatch(fetchDocs(queryDocs, fetchParams, queryOptionsParams));
    });
  };
};

export const processBulkDeleteResponse = (res, deletedDocs, designDocs, docType) => {
  FauxtonAPI.addNotification({
    msg: 'Successfully deleted your docs',
    clear:  true
  });

  let failedDocs = [];
  if (docType === Constants.INDEX_RESULTS_DOC_TYPE.MANGO_INDEX) {
    if (res.fail) {
      failedDocs = res.fail.map(doc => doc.id);
    }
  } else {
    failedDocs = res.filter(doc => !!doc.error).map(doc => doc.id);
  }

  const hasDesignDocs = !!deletedDocs.map(d => d._id).find((_id) => /_design/.test(_id));

  if (failedDocs.length > 0) {
    deleteErrorMessage(failedDocs);
  }

  if (designDocs && hasDesignDocs) {
    SidebarActions.dispatchUpdateDesignDocs(designDocs);
  }
};