const m = require('mithril')
const api = require('./api')

const Tree = []
const Articles = []

exports.Tree = Tree
exports.Articles = Articles

exports.loading = false
exports.error = ''
exports.year = null
exports.month = null

const matcher = /\/(\d+)(\/\d+)?/

function calculateActiveBranches() {
  let path = matcher.exec(m.route.get())
  if (path && path[1] !== exports.year?.title) {
    for (let year of Tree) {
      if (year.title === path[1]) {
        exports.year = year
        break
      }
    }
  } else if (!path && m.route.get() === '/') {
    exports.year = Tree[Tree.length - 1]
  } else if (!path) {
    exports.year = null
  }
  if (path && exports.year && path[2]) {
    exports.month = exports.year.branches[Number(path[2].slice(1)) - 1] || null
  } else if (!path?.[2]) {
    exports.month = null
  }
}

function rebuildTree() {
  Tree.splice(0, Tree.length)

  if (!Articles.length) return

  let startYear = Articles[0].publish_at
  let target = new Date()
  let articleIndex = 0

  for (let year = startYear.getFullYear(); year <= target.getFullYear(); year++) {
    let branchYear = {
      title: year.toString(),
      type: 'year',
      branches: [],
      videos: []
    }
    Tree.push(branchYear)
    let lastMonth = year === target.getFullYear() ? target.getMonth() + 1 : 12

    for (let month = 1; month <= lastMonth; month++) {
      let branchMonth = {
        title: month.toString(),
        type: 'month',
        branches: [],
        videos: []
      }
      branchYear.branches.push(branchMonth)

      let start = new Date(year, month - 1)
      let end = new Date(year, month)

      for (; Articles[articleIndex] && Articles[articleIndex].publish_at >= start && Articles[articleIndex].publish_at < end; articleIndex++) {
        branchYear.videos.push(Articles[articleIndex])
        branchMonth.videos.push(Articles[articleIndex])
      }
    }
  }
}

function removeArticle(id) {
  let index = Articles.findIndex(article => article.id === id)
  if (index >= 0) {
    Articles.splice(index, 1)
    rebuildTree()
  }
}

function refreshTree() {
  exports.error = ''

  if (exports.loading) return Promise.resolve()

  exports.loading = true

  m.redraw()

  return api.sendRequest({
    method: 'GET',
    url: '/api/articles',
  })
  .then(result => {
    result.videos.forEach(video => {
      video.publish_at = new Date(video.publish_at)
      video.path_short = video.path.split('-')[2]
    })

    Articles.splice(0, Articles.length)
    Articles.push.apply(Articles, result.videos)

    rebuildTree()
  }, err => {
    exports.error = 'Error fetching videos: ' + err.message
  })
  .then(() => {
    exports.loading = false
    m.redraw()
  })
}

exports.removeArticle = removeArticle
exports.rebuildTree = rebuildTree
exports.refreshTree = refreshTree
exports.calculateActiveBranches = calculateActiveBranches