import {state} from 'lstream';

export function activate(context) {
  let {services} = context;

  context.streams.operation = {
    registry: state({})
  };
  
  let registry$ = context.streams.operation.registry;
  
  function addOperation(descriptor, actions) {
    let {id, label, info, icon, actionParams} = descriptor;
    let appearance = {
      label,
        info,
        icon32: icon + '32.png',
        icon96: icon + '96.png',
    };
    let opAction = {
      id: id,
      appearance,
      invoke: () => services.wizard.open({type: id}),
      ...actionParams
    };
    actions.push(opAction);

    registry$.mutate(registry => registry[id] = Object.assign({appearance}, descriptor, {
      run: (request, services) => runOperation(request, descriptor, services)
    }));
  }

  function registerOperations(operations) {
    let actions = [];
    for (let op of operations) {
      addOperation(op, actions);
    }
    services.action.registerActions(actions);
  }

  function get(id) {
    let op = registry$.value[id];
    if (!op) {
      throw `operation ${id} is not registered`;
    }
    return op;
  }

  services.operation = {
    registerOperations,
    get
  };
}

function runOperation(request, descriptor, services) {
  for (let engine of services.craftEngines.getRegisteredEngines()) {
    let result = engine.handler(descriptor.id, request, services);
    if (result) {
      return result;
    }
  }
  return descriptor.run(request, services);
}