import { kebabCase } from './helpers'
import { DataArray, DataArrayPartial, Optgroup, OptgroupOptional, Option } from './store'

export default class Select {
  public select: HTMLSelectElement

  // Mutation observer fields
  public onValueChange?: (value: Option[]) => void
  public onClassChange?: (classes: string[]) => void
  public onDisabledChange?: (disabled: boolean) => void
  public onOptionsChange?: (data: DataArrayPartial) => void

  // Change observers
  public listen: boolean = false
  private observer: MutationObserver | null = null

  constructor(select: HTMLSelectElement) {
    this.select = select

    this.valueChange = this.valueChange.bind(this)
    // Add change event listener
    this.select.addEventListener('change', this.valueChange, {
      // allow bubbling of event
      passive: true
    })

    // Initiate mutation observer
    this.observer = new MutationObserver(this.observeCall.bind(this))

    // Start listening for changes
    this.changeListen(true)
  }

  public enable(): void {
    this.select.disabled = false
  }

  public disable(): void {
    this.select.disabled = true
  }

  public hideUI(): void {
    this.select.tabIndex = -1
    this.select.style.display = 'none'
    this.select.setAttribute('aria-hidden', 'true')
  }

  public showUI(): void {
    this.select.removeAttribute('tabindex')
    this.select.style.display = ''
    this.select.removeAttribute('aria-hidden')
  }

  public changeListen(listen: boolean) {
    this.listen = listen

    // Start listening for changes
    if (listen) {
      if (this.observer) {
        this.observer.observe(this.select, {
          subtree: true, // subtree for optgroups options
          childList: true, // children changes
          attributes: true // attributes changes
        })
      }
    }

    // Stop listening for changes
    if (!listen) {
      if (this.observer) {
        this.observer.disconnect()
      }
    }
  }

  // This function get triggers when the select value changes
  // and will call the onValueChange function if it exists
  public valueChange(ev: Event): boolean {
    if (this.listen && this.onValueChange) {
      this.onValueChange(this.getSelectedOptions())
    }

    // Allow bubbling back to other change event listeners
    return true
  }

  private observeCall(mutations: MutationRecord[]): void {
    // If we are not listening, do nothing.
    if (!this.listen) {
      return
    }

    let classChanged = false
    let disabledChanged = false
    let optgroupOptionChanged = false

    // Loop through mutations and check various things
    for (const m of mutations) {
      // Check if its the select
      if (m.target === this.select) {
        // Check if disabled has changed
        if (m.attributeName === 'disabled') {
          disabledChanged = true
        }

        // Check if class has changed
        if (m.attributeName === 'class') {
          classChanged = true
        }

        if (m.type === 'childList') {
          for (const n of m.addedNodes) {
            if (n.nodeName === 'OPTION' && (<HTMLOptionElement>n).value === this.select.value) {
              // we added a new option that's now the select value
              this.select.dispatchEvent(new Event('change'))
              break
            }
          }

          // options changed, so we need the optionsChange event to fire
          optgroupOptionChanged = true
        }
      }

      // Check if its an optgroup or option
      if (m.target.nodeName === 'OPTGROUP' || m.target.nodeName === 'OPTION') {
        optgroupOptionChanged = true
      }
    }

    // If class has changed then call the class change function
    if (classChanged && this.onClassChange) {
      this.onClassChange(this.select.className.split(' '))
    }

    // If disabled has changed then call the disabled change function
    if (disabledChanged && this.onDisabledChange) {
      this.changeListen(false)
      this.onDisabledChange(this.select.disabled)
      this.changeListen(true)
    }

    // If optgroup or option has changed then call the select change function
    if (optgroupOptionChanged && this.onOptionsChange) {
      this.changeListen(false)
      this.onOptionsChange(this.getData())
      this.changeListen(true)
    }
  }

  // From the select element pull optgroup and options into data
  public getData(): DataArrayPartial {
    let data = [] as DataArrayPartial

    // Loop through nodes and get data
    const nodes = this.select.childNodes as any as HTMLOptGroupElement[] | HTMLOptionElement[]
    for (const n of nodes) {
      // Optgroup
      if (n.nodeName === 'OPTGROUP') {
        data.push(this.getDataFromOptgroup(n as HTMLOptGroupElement))
      }

      // Option
      if (n.nodeName === 'OPTION') {
        data.push(this.getDataFromOption(n as HTMLOptionElement))
      }
    }

    return data
  }

  public getDataFromOptgroup(optgroup: HTMLOptGroupElement): OptgroupOptional {
    let data = {
      id: optgroup.id,
      label: optgroup.label,
      selectAll: optgroup.dataset ? optgroup.dataset.selectall === 'true' : false,
      selectAllText: optgroup.dataset ? optgroup.dataset.selectalltext : 'Select all',
      closable: optgroup.dataset ? optgroup.dataset.closable : 'off',
      options: []
    } as OptgroupOptional

    const options = optgroup.childNodes as any as HTMLOptionElement[]
    for (const o of options) {
      if (o.nodeName === 'OPTION') {
        data.options!.push(this.getDataFromOption(o as HTMLOptionElement))
      }
    }

    return data
  }

  // From passed in option pull pieces of usable information
  public getDataFromOption(option: HTMLOptionElement): Option {
    return {
      id: option.id,
      value: option.value,
      text: option.text,
      html: option.dataset && option.dataset.html ? option.dataset.html : '',
      selected: option.selected,
      display: option.style.display !== 'none',
      disabled: option.disabled,
      mandatory: option.dataset ? option.dataset.mandatory === 'true' : false,
      placeholder: option.dataset.placeholder === 'true',
      class: option.className,
      style: option.style.cssText,
      data: option.dataset
    } as Option
  }

  public getSelectedOptions(): Option[] {
    let options = []

    // Loop through options and set selected
    const opts = this.select.childNodes as any as (HTMLOptGroupElement | HTMLOptionElement)[]
    for (const o of opts) {
      if (o.nodeName === 'OPTGROUP') {
        const optgroupOptions = o.childNodes as any as HTMLOptionElement[]
        for (const oo of optgroupOptions) {
          if (oo.nodeName === 'OPTION') {
            const option = oo as HTMLOptionElement
            if (option.selected) {
              options.push(this.getDataFromOption(option))
            }
          }
        }
      }

      if (o.nodeName === 'OPTION') {
        const option = o as HTMLOptionElement
        if (option.selected) {
          options.push(this.getDataFromOption(option))
        }
      }
    }

    return options
  }

  public getSelectedValues(): string[] {
    return this.getSelectedOptions().map((option) => option.value)
  }

  public setSelected(ids: string[]): void {
    // Stop listening to changes
    this.changeListen(false)

    // Loop through options and set selected
    const options = this.select.childNodes as any as (HTMLOptGroupElement | HTMLOptionElement)[]
    for (const o of options) {
      if (o.nodeName === 'OPTGROUP') {
        const optgroup = o as HTMLOptGroupElement
        const optgroupOptions = optgroup.childNodes as any as HTMLOptionElement[]
        for (const oo of optgroupOptions) {
          if (oo.nodeName === 'OPTION') {
            const option = oo as HTMLOptionElement
            option.selected = ids.includes(option.id)
          }
        }
      }

      if (o.nodeName === 'OPTION') {
        const option = o as HTMLOptionElement
        option.selected = ids.includes(option.id)
      }
    }

    // Stop listening to changes
    this.changeListen(true)
  }

  // Set selected options by value instead of id
  // This is useful when the id is not known
  // and only the value is known
  // but the value is not unique and can be duplicated
  public setSelectedByValue(values: string[]): void {
    // Stop listening to changes
    this.changeListen(false)

    // Loop through options and set selected
    const options = this.select.childNodes as any as (HTMLOptGroupElement | HTMLOptionElement)[]
    for (const o of options) {
      if (o.nodeName === 'OPTGROUP') {
        const optgroup = o as HTMLOptGroupElement
        const optgroupOptions = optgroup.childNodes as any as HTMLOptionElement[]
        for (const oo of optgroupOptions) {
          if (oo.nodeName === 'OPTION') {
            const option = oo as HTMLOptionElement
            option.selected = values.includes(option.value)
          }
        }
      }

      if (o.nodeName === 'OPTION') {
        const option = o as HTMLOptionElement
        option.selected = values.includes(option.value)
      }
    }

    // Stop listening to changes
    this.changeListen(true)
  }

  public updateSelect(id?: string, style?: string, classes?: string[]): void {
    // Stop listening to changes
    this.changeListen(false)

    // Update id, only if the id isnt already set
    if (id) {
      this.select.dataset.id = id
    }

    // Update style
    if (style) {
      this.select.style.cssText = style
    }

    // Update classes
    if (classes) {
      this.select.className = ''
      classes.forEach((c) => {
        if (c.trim() !== '') {
          this.select.classList.add(c.trim())
        }
      })
    }

    // Start listening to changes
    this.changeListen(true)
  }

  public updateOptions(data: DataArray): void {
    // Stop listening to changes
    this.changeListen(false)

    // Clear out select
    this.select.innerHTML = ''

    for (const d of data) {
      if (d instanceof Optgroup) {
        this.select.appendChild(this.createOptgroup(d))
      }

      if (d instanceof Option) {
        this.select.appendChild(this.createOption(d))
      }
    }

    // Trigger change event on original select
    this.select.dispatchEvent(new Event('change', { bubbles: true }))

    // Start listening to changes
    this.changeListen(true)
  }

  public createOptgroup(optgroup: Optgroup): HTMLOptGroupElement {
    const optgroupEl = document.createElement('optgroup')
    optgroupEl.id = optgroup.id
    optgroupEl.label = optgroup.label
    if (optgroup.selectAll) {
      optgroupEl.dataset.selectAll = 'true'
    }
    if (optgroup.closable !== 'off') {
      optgroupEl.dataset.closable = optgroup.closable
    }
    if (optgroup.options) {
      for (const o of optgroup.options) {
        optgroupEl.appendChild(this.createOption(o))
      }
    }
    return optgroupEl
  }

  public createOption(info: Option): HTMLOptionElement {
    const optionEl = document.createElement('option')
    optionEl.id = info.id
    optionEl.value = info.value
    optionEl.textContent = info.text
    if (info.html !== '') {
      optionEl.setAttribute('data-html', info.html)
    }
    if (info.selected) {
      optionEl.selected = info.selected
    }
    if (info.disabled) {
      optionEl.disabled = true
    }
    if (!info.display) {
      optionEl.style.display = 'none'
    }
    if (info.placeholder) {
      optionEl.setAttribute('data-placeholder', 'true')
    }
    if (info.mandatory) {
      optionEl.setAttribute('data-mandatory', 'true')
    }
    if (info.class) {
      info.class.split(' ').forEach((optionClass: string) => {
        optionEl.classList.add(optionClass)
      })
    }
    if (info.data && typeof info.data === 'object') {
      Object.keys(info.data).forEach((key) => {
        optionEl.setAttribute('data-' + kebabCase(key), info.data[key])
      })
    }

    return optionEl
  }

  public destroy() {
    this.changeListen(false)

    // Remove event change listener
    this.select.removeEventListener('change', this.valueChange)

    // Disconnect observer and null
    if (this.observer) {
      this.observer.disconnect()
      this.observer = null
    }

    // Remove dataset id from original select
    delete this.select.dataset.id

    // Show the original select
    this.showUI()
  }
}