import { defaults } from "./params";

export type TaskID = string

export enum EstimationConfidence {
  Optimistic = "optimistic",
  Likely = "likely",
  Pessimistic = "pessimistic"
}

export interface Task {
  id: TaskID
  label: string
  category: TaskCategoryID
  estimations: { [confidence in EstimationConfidence]: number }
}

export type TaskCategoryID = string

export interface TaskCategory {
  id: TaskCategoryID
  label: string
  costPerTimeUnit: number
}

export function newTask(label: string, category: TaskCategoryID): Task {
  return {
    id: '',
    label,
    category,
    estimations: {
      [EstimationConfidence.Optimistic]: 0,
      [EstimationConfidence.Likely]: 0,
      [EstimationConfidence.Pessimistic]: 0,
    }
  };
}

export function createTaskCategory(): TaskCategory {
  return {
    id: '',
    costPerTimeUnit: defaults.costPerTimeUnit,
    label: ""
  };
}

export function getTaskWeightedMean(t: Task): number {
  return (t.estimations.optimistic + (4*t.estimations.likely) + t.estimations.pessimistic) / 6;
}

export function getTaskStandardDeviation(t: Task): number {
  return (t.estimations.pessimistic - t.estimations.optimistic) / 6;
}