import { TypeState } from 'typestate';

import {
  ProjectStageApplicantStatus,
  ProjectStageStatus,
} from './model/projectStage';

// State machine that defines how project stage status can change
export function getProjectStageFsm(initState : ProjectStageStatus)
: TypeState.FiniteStateMachine<ProjectStageStatus> {
  const stageFsm = new TypeState.FiniteStateMachine<ProjectStageStatus>(initState);

  stageFsm.from(ProjectStageStatus.created).to(ProjectStageStatus.queue);
  stageFsm.from(ProjectStageStatus.queue).to(ProjectStageStatus.inprogress);
  stageFsm.from(ProjectStageStatus.inprogress).to(ProjectStageStatus.pmcheck);
  stageFsm.from(ProjectStageStatus.pmcheck).to(ProjectStageStatus.techeck);
  stageFsm.from(ProjectStageStatus.pmcheck).to(ProjectStageStatus.inprogress);
  stageFsm.from(ProjectStageStatus.techeck).to(ProjectStageStatus.pmcheck);
  stageFsm.from(ProjectStageStatus.techeck).to(ProjectStageStatus.completed);

  return stageFsm;
}

export const checkProjectStageStatus = (
  stageId: number,
  currentStatus: ProjectStageStatus,
  nextStatus: ProjectStageStatus)
  : void => {
  const stageFsm = getProjectStageFsm(currentStatus);

  if (!stageFsm.canGo(nextStatus)) {
    throw new Error(`Project stage ${stageId} is in status ${currentStatus}
    and connot be moved to status ${nextStatus}`);
  }
};

// State machine that defines how project stage application status can change
export function getProjectStageApplicationFsm(initState : ProjectStageApplicantStatus)
: TypeState.FiniteStateMachine<ProjectStageApplicantStatus> {
  const stageFsm = new TypeState.FiniteStateMachine<ProjectStageApplicantStatus>(initState);

  stageFsm.from(ProjectStageApplicantStatus.invited).to(ProjectStageApplicantStatus.active);
  // TODO: remove next two transitions later
  stageFsm.from(ProjectStageApplicantStatus.cancelled).to(ProjectStageApplicantStatus.active);
  stageFsm.from(ProjectStageApplicantStatus.declined).to(ProjectStageApplicantStatus.active);
  stageFsm.from(ProjectStageApplicantStatus.invited).to(ProjectStageApplicantStatus.cancelled);
  stageFsm.from(ProjectStageApplicantStatus.invited).to(ProjectStageApplicantStatus.declined);
  stageFsm.from(ProjectStageApplicantStatus.invited).to(ProjectStageApplicantStatus.invited);
  stageFsm.from(ProjectStageApplicantStatus.active).to(ProjectStageApplicantStatus.cancelled);
  stageFsm.from(ProjectStageApplicantStatus.active).to(ProjectStageApplicantStatus.approved);
  stageFsm.from(ProjectStageApplicantStatus.active).to(ProjectStageApplicantStatus.declined);
  stageFsm.from(ProjectStageApplicantStatus.cancelled).to(ProjectStageApplicantStatus.cancelled);
  stageFsm.from(ProjectStageApplicantStatus.cancelled).to(ProjectStageApplicantStatus.active);
  stageFsm.from(ProjectStageApplicantStatus.declined).to(ProjectStageApplicantStatus.declined);
  stageFsm.from(ProjectStageApplicantStatus.declined).to(ProjectStageApplicantStatus.invited);

  return stageFsm;
}

export const checkProjectStageApplicantStatus = (
  applicantId: string,
  currentStatus: ProjectStageApplicantStatus,
  nextStatus: ProjectStageApplicantStatus)
  : void => {
  const stageFsm = getProjectStageApplicationFsm(currentStatus);

  if (!stageFsm.canGo(nextStatus)) {
    throw new Error(`Project stage applicant ${applicantId} 
    is in status ${currentStatus} and cannot be moved to status ${nextStatus}`);
  }
};