const moment = require("moment")

const {postApi} = require("../../../../../rpdata/api/Post")
const {logsApi} = require("../../../../../rpdata/api/Log")

module.exports = class {
  onCreate(input) {
    this.state = {
      log: input.log,
      modal: null,
      removed: false,
    }
  }  
  
  onMount() {
    this.sub = logsApi.subscribeChanges(this.state.log.id)

    this.sub.on("data", data => {
      this.handleChange(data.changes)
    })

    this.sub.connect()
  }

  onUnmount() {
    if (this.sub != null) {
      this.sub.disconnect()
    }
  }

  open(modal) {
    this.state.modal = modal
  }

  close() {
    this.state.modal = null
  }

  /**
   * Patch the posts
   * 
   * @param {{id:string, [x:string]: any}[]} patches 
   */
  patch(patches) {
    const posts = this.state.log.posts.slice()

    for (const patch of patches) {
      const index = posts.findIndex(p => p.id === patch.id)
      if (index == -1) {
        continue
      }

      posts[index] = Object.assign(Object.assign({}, posts[index]), patch)
    }

    // Sort posts and look for continuity issues (duplicate or skipped positions)
    posts.sort((a, b) => a.position - b.position)
    for (let i = 1; i < posts.length; ++i) {
      if (posts[i].position !== posts[i - 1].position + 1) {
        console.warn("Discontinuity detected:", i, posts)
      }
    }

    this.state.log.posts = posts
    this.state.log = Object.assign({}, this.state.log)
  }

  movePost(post, toPosition, relative) {
    if (relative) {
      toPosition = post.position + toPosition
    }

    postApi.move({id: post.id, toPosition}).then(patches => {
      this.patch(patches)
    }).catch(err => {
      console.warn(err)
    })
  }

  removePost(post) {
    postApi.remove({id: post.id}).then(() => {
      this.postRemoved(post)
    }).catch(errs => {
      console.warn("Failed to delete:", errs)
      this.state.error = "Failed to delete: " + (errs.message || errs[0].message)
    })
  }

  postEdited(patch) {
    this.patch([patch])
  }

  logEdited(patch) {
    this.state.log = Object.assign(Object.assign({}, this.state.log), patch)
  }

  postRemoved(post) {
    if (this.state.log.posts.find(p => p.id === post.id) == null) {
      return
    }

    const posts = this.state.log.posts.filter(p => p.id !== post.id).map(p => {
      if (p.position > post.position) {
        return Object.assign({}, p, {position: p.position - 1})
      }

      return p
    })

    this.state.log = Object.assign({}, this.state.log, {posts: posts})
  }

  postAdded(post) {
    // Stop duplicates in case of race condition.
    if (this.state.log.posts.find(p => p.id === post.id)) {
      return
    }

    this.state.log.posts = this.state.log.posts.concat([post])
    this.state.log = Object.assign({}, this.state.log)    
  }

  handleChange(change) {
    switch (`${change.model}.${change.op}`) {
      case "Post.add": {
        for (const post of change.objects.filter(o => o.type === "Post")) {
          this.postAdded(post)
        }

        break
      }

      case "Post.move":
      case "Post.edit": {
        this.patch(change.objects.filter(o => o.type === "Post"))

        break
      }

      case "Post.remove": {
        for (const post of change.objects.filter(o => o.type === "Post")) {
          this.postRemoved(post)
        }
      }

      case "Log.edit": {
        const patch = change.objects.find(o => o.type === "Log")
        if (patch == null) {
          break
        }

        this.logEdited(patch)

        break
      }

      case "Log.remove": {
        this.logRemoved()

        break
      }
    }
  }

  logRemoved() {
    this.state.removed = true
  }

  get title() {
    if (this.state.log.title) {
      return this.state.log.title
    }

    return `${this.state.log.channel.name} – ${moment(this.state.log.date).format("MMMM D, YYYY")}`
  }
}