import { Subscription } from 'rxjs';

import { DataSourceRef } from '@grafana/data';
import { getDataSourceSrv, toDataQueryError } from '@grafana/runtime';

import { ThunkResult } from '../../../types';
import { getVariableQueryEditor } from '../editor/getVariableQueryEditor';
import { addVariableEditorError, changeVariableEditorExtended, removeVariableEditorError } from '../editor/reducer';
import { getQueryVariableEditorState } from '../editor/selectors';
import { updateOptions } from '../state/actions';
import { toKeyedAction } from '../state/keyedVariablesReducer';
import { getVariable, getVariablesState } from '../state/selectors';
import { changeVariableProp } from '../state/sharedReducer';
import { KeyedVariableIdentifier } from '../state/types';
import { hasOngoingTransaction, toKeyedVariableIdentifier, toVariablePayload } from '../utils';

import { getVariableQueryRunner } from './VariableQueryRunner';
import { variableQueryObserver } from './variableQueryObserver';

export const updateQueryVariableOptions = (
  identifier: KeyedVariableIdentifier,
  searchFilter?: string
): ThunkResult<void> => {
  return async (dispatch, getState) => {
    try {
      const { rootStateKey } = identifier;
      if (!hasOngoingTransaction(rootStateKey, getState())) {
        // we might have cancelled a batch so then variable state is removed
        return;
      }

      const variableInState = getVariable(identifier, getState());
      if (variableInState.type !== 'query') {
        return;
      }

      if (getVariablesState(rootStateKey, getState()).editor.id === variableInState.id) {
        dispatch(toKeyedAction(rootStateKey, removeVariableEditorError({ errorProp: 'update' })));
      }
      const datasource = await getDataSourceSrv().get(variableInState.datasource ?? '');

      // We need to await the result from variableQueryRunner before moving on otherwise variables dependent on this
      // variable will have the wrong current value as input
      await new Promise((resolve, reject) => {
        const subscription: Subscription = new Subscription();
        const observer = variableQueryObserver(resolve, reject, subscription);
        const responseSubscription = getVariableQueryRunner().getResponse(identifier).subscribe(observer);
        subscription.add(responseSubscription);

        getVariableQueryRunner().queueRequest({ identifier, datasource, searchFilter });
      });
    } catch (err) {
      if (err instanceof Error) {
        const error = toDataQueryError(err);
        const { rootStateKey } = identifier;
        if (getVariablesState(rootStateKey, getState()).editor.id === identifier.id) {
          dispatch(
            toKeyedAction(rootStateKey, addVariableEditorError({ errorProp: 'update', errorText: error.message }))
          );
        }

        throw error;
      }
    }
  };
};

export const initQueryVariableEditor =
  (identifier: KeyedVariableIdentifier): ThunkResult<void> =>
  async (dispatch, getState) => {
    const variable = getVariable(identifier, getState());
    if (variable.type !== 'query') {
      return;
    }

    await dispatch(changeQueryVariableDataSource(toKeyedVariableIdentifier(variable), variable.datasource));
  };

export const changeQueryVariableDataSource = (
  identifier: KeyedVariableIdentifier,
  name: DataSourceRef | null
): ThunkResult<void> => {
  return async (dispatch, getState) => {
    try {
      const { rootStateKey } = identifier;
      const { editor } = getVariablesState(rootStateKey, getState());
      const extendedEditorState = getQueryVariableEditorState(editor);
      const previousDatasource = extendedEditorState?.dataSource;
      const dataSource = await getDataSourceSrv().get(name ?? '');

      if (previousDatasource && previousDatasource.type !== dataSource?.type) {
        dispatch(
          toKeyedAction(
            rootStateKey,
            changeVariableProp(toVariablePayload(identifier, { propName: 'query', propValue: '' }))
          )
        );
      }

      const VariableQueryEditor = await getVariableQueryEditor(dataSource);

      dispatch(
        toKeyedAction(
          rootStateKey,
          changeVariableEditorExtended({
            dataSource,
            VariableQueryEditor,
          })
        )
      );
    } catch (err) {
      console.error(err);
    }
  };
};

export const changeQueryVariableQuery =
  (identifier: KeyedVariableIdentifier, query: any, definition?: string): ThunkResult<void> =>
  async (dispatch, getState) => {
    const { rootStateKey } = identifier;
    const variableInState = getVariable(identifier, getState());
    if (variableInState.type !== 'query') {
      return;
    }

    if (hasSelfReferencingQuery(variableInState.name, query)) {
      const errorText = 'Query cannot contain a reference to itself. Variable: $' + variableInState.name;
      dispatch(toKeyedAction(rootStateKey, addVariableEditorError({ errorProp: 'query', errorText })));
      return;
    }

    dispatch(toKeyedAction(rootStateKey, removeVariableEditorError({ errorProp: 'query' })));
    dispatch(
      toKeyedAction(
        rootStateKey,
        changeVariableProp(toVariablePayload(identifier, { propName: 'query', propValue: query }))
      )
    );

    if (definition !== undefined) {
      dispatch(
        toKeyedAction(
          rootStateKey,
          changeVariableProp(toVariablePayload(identifier, { propName: 'definition', propValue: definition }))
        )
      );
    } else if (typeof query === 'string') {
      dispatch(
        toKeyedAction(
          rootStateKey,
          changeVariableProp(toVariablePayload(identifier, { propName: 'definition', propValue: query }))
        )
      );
    }

    await dispatch(updateOptions(identifier));
  };

export function hasSelfReferencingQuery(name: string, query: any): boolean {
  if (typeof query === 'string' && query.match(new RegExp('\\$' + name + '(/| |$)'))) {
    return true;
  }

  const flattened = flattenQuery(query);

  for (let prop in flattened) {
    if (flattened.hasOwnProperty(prop)) {
      const value = flattened[prop];
      if (typeof value === 'string' && value.match(new RegExp('\\$' + name + '(/| |$)'))) {
        return true;
      }
    }
  }

  return false;
}

/*
 * Function that takes any object and flattens all props into one level deep object
 * */
export function flattenQuery(query: any): any {
  if (typeof query !== 'object' || query === null) {
    return { query };
  }

  const keys = Object.keys(query);
  const flattened = keys.reduce<Record<string, any>>((all, key) => {
    const value = query[key];
    if (typeof value !== 'object' || value === null) {
      all[key] = value;
      return all;
    }

    const result = flattenQuery(value);
    for (let childProp in result) {
      if (result.hasOwnProperty(childProp)) {
        all[`${key}_${childProp}`] = result[childProp];
      }
    }

    return all;
  }, {});

  return flattened;
}