import _ from 'lodash';
import { getNextRefIdChar } from './utils';
import { getDefaultTarget } from './triggers_panel_ctrl';

// Actual schema version
export const CURRENT_SCHEMA_VERSION = 7;

export function migratePanelSchema(panel) {
  if (isEmptyPanel(panel)) {
    delete panel.targets;
    return panel;
  }

  const schemaVersion = getSchemaVersion(panel);
  panel.schemaVersion = CURRENT_SCHEMA_VERSION;

  if (schemaVersion < 2) {
    panel.datasources = [panel.datasource];
    panel.targets = {};
    panel.targets[panel.datasources[0]] = panel.triggers;

    // delete old props
    delete panel.triggers;
    delete panel.datasource;
  }

  if (schemaVersion < 3) {
    // delete old props
    delete panel.lastChangeField;
    delete panel.infoField;
    delete panel.scroll;
    delete panel.hideHostsInMaintenance;
  }

  if (schemaVersion < 5) {
    if (panel.targets && !_.isEmpty(panel.targets)) {
      _.each(panel.targets, (target) => {
        _.defaultsDeep(target, getDefaultTarget());
      });
    }
  }

  if (schemaVersion < 6) {
    if (panel.showEvents && panel.showEvents.value === '1') {
      panel.showEvents.value = 1;
    }
  }

  if (schemaVersion < 7) {
    const updatedTargets = [];
    for (const targetKey in panel.targets) {
      const target = panel.targets[targetKey];
      if (!isEmptyTarget(target) && !isInvalidTarget(target, targetKey)) {
        updatedTargets.push({
          ...target,
          datasource: targetKey,
        });
      }
    }
    for (const target of updatedTargets) {
      if (!target.refId) {
        target.refId = getNextRefIdChar(updatedTargets);
      }
    }
    panel.targets = updatedTargets;
    delete panel.datasources;
  }

  return panel;
}

function getSchemaVersion(panel) {
  return panel.schemaVersion || 1;
}

function isEmptyPanel(panel) {
  return !panel.datasource && !panel.datasources && !panel.triggers && isEmptyTargets(panel.targets);
}

function isEmptyTargets(targets) {
  return !targets || (_.isArray(targets) && (targets.length === 0 || targets.length === 1 && _.isEmpty(targets[0])));
}

function isEmptyTarget(target) {
  return !target || !(target.group && target.host && target.application && target.trigger);
}

function isInvalidTarget(target, targetKey) {
  return target && target.refId === 'A' && targetKey === '0';
}