import produce from 'immer';
import VueApollo from 'vue-apollo';
import { defaultDataIdFromObject } from '@apollo/client/core';
import { concatPagination } from '@apollo/client/utilities';
import getIssueStateQuery from '~/issues/show/queries/get_issue_state.query.graphql';
import createDefaultClient from '~/lib/graphql';
import typeDefs from '~/work_items/graphql/typedefs.graphql';
import { WIDGET_TYPE_NOTES } from '~/work_items/constants';
import getWorkItemLinksQuery from '~/work_items/graphql/work_item_links.query.graphql';
import { findHierarchyWidgetChildren } from '~/work_items/utils';

export const config = {
  typeDefs,
  cacheConfig: {
    // included temporarily until Vuex is removed from boards app
    dataIdFromObject: (object) => {
      // eslint-disable-next-line no-underscore-dangle
      return object.__typename === 'BoardList' && !window.gon?.features?.apolloBoards
        ? object.iid
        : defaultDataIdFromObject(object);
    },
    typePolicies: {
      Project: {
        fields: {
          projectMembers: {
            keyArgs: ['fullPath', 'search', 'relations', 'first'],
          },
        },
      },
      WorkItemWidgetNotes: {
        fields: {
          // If we add any key args, the discussions field becomes discussions({"filter":"ONLY_ACTIVITY","first":10}) and
          // kills any possibility to handle it on the widget level without hardcoding a string.
          discussions: {
            keyArgs: false,
          },
        },
      },
      WorkItemWidgetProgress: {
        fields: {
          progress: {
            // We want to show null progress as 0 as per https://gitlab.com/gitlab-org/gitlab/-/issues/386117
            read(existing) {
              return existing === null ? 0 : existing;
            },
          },
        },
      },
      WorkItem: {
        fields: {
          // widgets policy because otherwise the subscriptions invalidate the cache
          widgets: {
            merge(existing = [], incoming, context) {
              if (existing.length === 0) {
                return incoming;
              }
              return existing.map((existingWidget) => {
                const incomingWidget = incoming.find(
                  (w) => w.type && w.type === existingWidget.type,
                );
                // We don't want to override existing notes with empty widget on work item updates
                if (incomingWidget?.type === WIDGET_TYPE_NOTES && !context.variables.pageSize) {
                  return existingWidget;
                }
                // we want to concat next page of discussions to the existing ones
                if (incomingWidget?.type === WIDGET_TYPE_NOTES && context.variables.after) {
                  // concatPagination won't work because we were placing new widget here so we have to do this manually
                  return {
                    ...incomingWidget,
                    discussions: {
                      ...incomingWidget.discussions,
                      nodes: [
                        ...existingWidget.discussions.nodes,
                        ...incomingWidget.discussions.nodes,
                      ],
                    },
                  };
                }

                return incomingWidget || existingWidget;
              });
            },
          },
        },
      },
      MemberInterfaceConnection: {
        fields: {
          nodes: concatPagination(),
        },
      },
      ...(window.gon?.features?.apolloBoards
        ? {
            BoardList: {
              fields: {
                issues: {
                  keyArgs: ['filters'],
                },
              },
            },
            IssueConnection: {
              merge(existing = { nodes: [] }, incoming, { args }) {
                if (!args.after) {
                  return incoming;
                }
                return {
                  ...incoming,
                  nodes: [...existing.nodes, ...incoming.nodes],
                };
              },
            },
            EpicList: {
              fields: {
                epics: {
                  keyArgs: ['filters'],
                },
              },
            },
            EpicConnection: {
              merge(existing = { nodes: [] }, incoming, { args }) {
                if (!args.after) {
                  return incoming;
                }
                return {
                  ...incoming,
                  nodes: [...existing.nodes, ...incoming.nodes],
                };
              },
            },
            BoardEpicConnection: {
              merge(existing = { nodes: [] }, incoming, { args }) {
                if (!args.after) {
                  return incoming;
                }
                return {
                  ...incoming,
                  nodes: [...existing.nodes, ...incoming.nodes],
                };
              },
            },
          }
        : {}),
    },
  },
};

export const resolvers = {
  Mutation: {
    addHierarchyChild: (_, { id, workItem }, { cache }) => {
      const queryArgs = { query: getWorkItemLinksQuery, variables: { id } };
      const sourceData = cache.readQuery(queryArgs);

      const data = produce(sourceData, (draftState) => {
        findHierarchyWidgetChildren(draftState.workItem).push(workItem);
      });

      cache.writeQuery({ ...queryArgs, data });
    },
    removeHierarchyChild: (_, { id, workItem }, { cache }) => {
      const queryArgs = { query: getWorkItemLinksQuery, variables: { id } };
      const sourceData = cache.readQuery(queryArgs);

      const data = produce(sourceData, (draftState) => {
        const hierarchyChildren = findHierarchyWidgetChildren(draftState.workItem);
        const index = hierarchyChildren.findIndex((child) => child.id === workItem.id);
        hierarchyChildren.splice(index, 1);
      });

      cache.writeQuery({ ...queryArgs, data });
    },
    updateIssueState: (_, { issueType = undefined, isDirty = false }, { cache }) => {
      const sourceData = cache.readQuery({ query: getIssueStateQuery });
      const data = produce(sourceData, (draftData) => {
        draftData.issueState = { issueType, isDirty };
      });
      cache.writeQuery({ query: getIssueStateQuery, data });
    },
  },
};

export const defaultClient = createDefaultClient(resolvers, config);

export const apolloProvider = new VueApollo({
  defaultClient,
});