import { DocumentNode } from "graphql";
import gql from "graphql-tag";
import React from "react";
import { Query, QueryResult } from "react-apollo";

import { ApolloQueryResult } from "apollo-client";
import AppProgress from "./components/AppProgress";
import ErrorPage from "./components/ErrorPage/ErrorPage";
import useNavigator from "./hooks/useNavigator";
import useNotifier from "./hooks/useNotifier";
import i18n from "./i18n";
import { RequireAtLeastOne } from "./misc";

export interface LoadMore<TData, TVariables> {
  loadMore: (
    mergeFunc: (prev: TData, next: TData) => TData,
    extraVariables: RequireAtLeastOne<TVariables>
  ) => Promise<ApolloQueryResult<TData>>;
}

export type TypedQueryResult<TData, TVariables> = QueryResult<
  TData,
  TVariables
> &
  LoadMore<TData, TVariables>;

export interface TypedQueryInnerProps<TData, TVariables> {
  children: (result: TypedQueryResult<TData, TVariables>) => React.ReactNode;
  displayLoader?: boolean;
  skip?: boolean;
  variables?: TVariables;
  require?: Array<keyof TData>;
}

interface QueryProgressProps {
  loading: boolean;
  onLoading: () => void;
  onCompleted: () => void;
}

class QueryProgress extends React.Component<QueryProgressProps, {}> {
  componentDidMount() {
    const { loading, onLoading } = this.props;
    if (loading) {
      onLoading();
    }
  }

  componentDidUpdate(prevProps) {
    const { loading, onLoading, onCompleted } = this.props;
    if (prevProps.loading !== loading) {
      if (loading) {
        onLoading();
      } else {
        onCompleted();
      }
    }
  }

  render() {
    return this.props.children;
  }
}

export function TypedQuery<TData, TVariables>(
  query: DocumentNode
): React.FC<TypedQueryInnerProps<TData, TVariables>> {
  class StrictTypedQuery extends Query<TData, TVariables> {}
  return props => {
    const navigate = useNavigator();
    const pushMessage = useNotifier();

    return (
      <AppProgress>
        {({ setProgressState }) => {
          // Obviously, this is workaround to the problem described here:
          // https://github.com/DefinitelyTyped/DefinitelyTyped/issues/32588
          const {
            children,
            displayLoader,
            skip,
            variables,
            require
          } = props as JSX.LibraryManagedAttributes<
            typeof StrictTypedQuery,
            typeof props
          >;
          return (
            <StrictTypedQuery
              fetchPolicy="cache-and-network"
              query={query}
              variables={variables}
              skip={skip}
              context={{ useBatching: true }}
            >
              {queryData => {
                if (queryData.error) {
                  const msg = i18n.t("Something went wrong: {{ message }}", {
                    message: queryData.error.message
                  });
                  pushMessage({ text: msg });
                }

                const loadMore = (
                  mergeFunc: (
                    previousResults: TData,
                    fetchMoreResult: TData
                  ) => TData,
                  extraVariables: RequireAtLeastOne<TVariables>
                ) =>
                  queryData.fetchMore({
                    query,
                    updateQuery: (previousResults, { fetchMoreResult }) => {
                      if (!fetchMoreResult) {
                        return previousResults;
                      }
                      return mergeFunc(previousResults, fetchMoreResult);
                    },
                    variables: { ...variables, ...extraVariables }
                  });

                let childrenOrNotFound = children({
                  ...queryData,
                  loadMore
                });
                if (
                  !queryData.loading &&
                  require &&
                  queryData.data &&
                  !require.reduce(
                    (acc, key) => acc && queryData.data[key] !== null,
                    true
                  )
                ) {
                  childrenOrNotFound = (
                    <ErrorPage onBack={() => navigate("/")} />
                  );
                }

                if (displayLoader) {
                  return (
                    <QueryProgress
                      loading={queryData.loading}
                      onCompleted={() => setProgressState(false)}
                      onLoading={() => setProgressState(true)}
                    >
                      {childrenOrNotFound}
                    </QueryProgress>
                  );
                }

                return childrenOrNotFound;
              }}
            </StrictTypedQuery>
          );
        }}
      </AppProgress>
    );
  };
}

export const pageInfoFragment = gql`
  fragment PageInfoFragment on PageInfo {
    endCursor
    hasNextPage
    hasPreviousPage
    startCursor
  }
`;