import * as _ from 'lodash'

import type { CircleCompletion, LearningContent, LearningPathChild, CourseWagtailPage, Topic } from '@/types'
import { Circle } from '@/services/circle'

function getLastCompleted(learningPathKey: string, completionData: CircleCompletion[]) {
  return _.orderBy(completionData, ['updated_at'], 'desc').find((c: CircleCompletion) => {
    return c.completed && c.learning_path_key === learningPathKey && c.page_type === 'learnpath.LearningContent'
  })
}

export class LearningPath implements CourseWagtailPage {
  readonly type = 'learnpath.LearningPath'
  public topics: Topic[]
  public circles: Circle[]
  public nextLearningContent?: LearningContent

  public static fromJson(json: any, completionData: CircleCompletion[]): LearningPath {
    return new LearningPath(json.id, json.slug, json.title, json.translation_key, json.children, completionData)
  }

  constructor(
    public readonly id: number,
    public readonly slug: string,
    public readonly title: string,
    public readonly translation_key: string,
    public children: LearningPathChild[],
    completionData?: any
  ) {
    // parse children
    this.topics = []
    this.circles = []

    let topic: Topic | undefined

    this.children.forEach((page) => {
      if (page.type === 'learnpath.Topic') {
        if (topic) {
          this.topics.push(topic)
        }
        topic = Object.assign(page, { circles: [] })
      }
      if (page.type === 'learnpath.Circle') {
        const circle = Circle.fromJson(page, this)
        circle.parseCompletionData(completionData)
        if (topic) {
          topic.circles.push(circle)
        }

        circle.previousCircle = this.circles[this.circles.length - 1]
        if (circle.previousCircle) {
          circle.previousCircle.nextCircle = circle
        }
        this.circles.push(circle)
      }
    })

    if (topic) {
      this.topics.push(topic)
    }

    this.calcNextLearningContent(completionData)
  }

  public calcNextLearningContent(completionData: CircleCompletion[]): void {
    this.nextLearningContent = undefined

    const lastCompletedLearningContent = getLastCompleted(this.translation_key, completionData)

    if (lastCompletedLearningContent) {
      const lastCircle = this.circles.find(
        (circle) => circle.translation_key === lastCompletedLearningContent.circle_key
      )
      if (lastCircle) {
        const lastLearningContent = lastCircle.flatLearningContents.find(
          (learningContent) => learningContent.translation_key === lastCompletedLearningContent.page_key
        )
        if (lastLearningContent && lastLearningContent.nextLearningContent) {
          this.nextLearningContent = lastLearningContent.nextLearningContent
        } else {
          if (lastCircle.nextCircle) {
            this.nextLearningContent = lastCircle.nextCircle.flatLearningContents[0]
          }
        }
      }
    } else {
      if (this.circles[0]) {
        this.nextLearningContent = this.circles[0].flatLearningContents[0]
      }
    }
  }
}