fizzy/app/javascript/controllers/navigable_list_controller.js

import { Controller } from "@hotwired/stimulus"
import { nextFrame } from "helpers/timing_helpers"

export default class extends Controller {
  static targets = [ "item", "input" ]
  static values = {
    reverseOrder: { type: Boolean, default: false },
    selectionAttribute: { type: String, default: "aria-selected" },
    focusOnSelection: { type: Boolean, default: true },
    actionableItems: { type: Boolean, default: false },
    reverseNavigation: { type: Boolean, default: false },
    supportsHorizontalNavigation: { type: Boolean, default: true },
    supportsVerticalNavigation: { type: Boolean, default: true },
    hasNestedNavigation: { type: Boolean, default: false },
    preventHandledKeys: { type: Boolean, default: false },
    autoSelect: { type: Boolean, default: true },
    onlyActOnFocusedItems: { type: Boolean, default: false }
  }

  connect() {
    if (this.autoSelectValue) {
      this.reset()
    } else {
      this.#activateManualSelection()
    }
  }

  // Actions

  reset(event) {
    if (this.reverseOrderValue) {
      this.selectLast()
    } else {
      this.selectFirst()
    }
  }

  navigate(event) {
    this.#keyHandlers[event.key]?.call(this, event)
    this.#relayNavigationToParentNavigableList(event)
  }

  select({ target }) {
    this.selectItem(target, true)
  }

  selectCurrentOrReset(event) {
    if (this.currentItem) {
      this.#setCurrentFrom(this.currentItem)
    } else {
      this.reset()
    }
  }

  selectFirst() {
    this.#setCurrentFrom(this.#visibleItems[0])
  }

  selectLast() {
    this.#setCurrentFrom(this.#visibleItems[this.#visibleItems.length - 1])
  }

  deselectWhenClickingOutside(event) {
    if (this.element.contains(event.target)) {
      return
    }

    this.#clearSelection()
  }

  // Public

  async selectItem(item, skipFocus = false) {
    await this.#selectCurrentElementInParent()

    this.#clearSelection()
    item.setAttribute(this.selectionAttributeValue, "true")
    this.currentItem = item
    this.#refreshActiveDescendant()

    await nextFrame()

    this.currentItem.scrollIntoView({ block: "nearest", inline: "nearest" })
    if (this.hasNestedNavigationValue) { this.#activateNestedNavigableList() }

    if (!skipFocus && this.focusOnSelectionValue) { this.currentItem.focus() }
  }

  isSelected(item) {
    return item === this.currentItem
  }

  // Private

  async #setCurrentFrom(element) {
    const selectedItem = this.#visibleItems.find(item => item.contains(element))

    if (selectedItem) {
      await this.selectItem(selectedItem)
    }
  }

  get #parentNavigableListController() {
    const parentNavigableList = this.element.parentElement?.closest("[data-controller~='navigable-list']")
    if (parentNavigableList) {
      return this.application.getControllerForElementAndIdentifier(parentNavigableList, "navigable-list")
    }
    return null
  }

  async #selectCurrentElementInParent() {
    const parentController = this.#parentNavigableListController
    if (parentController) {
      const parentItem = this.element.closest("[data-navigable-list-target~='item']")
      const isAlreadySelected = parentController.isSelected(parentItem)
      if (!isAlreadySelected) {
        await parentController.selectItem(parentItem, true)
      }
    }
  }

  #clearSelection() {
    for (const item of this.itemTargets) {
      item.removeAttribute(this.selectionAttributeValue)
    }
  }

  #refreshActiveDescendant() {
    const id = this.currentItem?.getAttribute("id")
    if (this.hasInputTarget && id) {
      this.inputTarget.setAttribute("aria-activedescendant", id)
    }
  }

  #activateNestedNavigableList() {
    const nestedController = this.#nestedNavigableListController()
    if (nestedController) {
      nestedController.selectCurrentOrReset()
      return true
    }
    return false
  }

  #nestedNavigableListController() {
    const nestedElement = this.currentItem?.querySelector('[data-controller~="navigable-list"]')
    if (nestedElement) {
      return this.application.getControllerForElementAndIdentifier(nestedElement, "navigable-list")
    }
    return null
  }

  #activateManualSelection() {
    const preselectedItem = this.itemTargets.find(item => item.hasAttribute(this.selectionAttributeValue))
    if (preselectedItem) {
      this.#setCurrentFrom(preselectedItem)
    }
  }

  // Stimulus won't let you handle keydown events with different handlers for the same (nested) stimulus controllers.
  #relayNavigationToParentNavigableList(event) {
    const parentController = this.#parentNavigableListController
    if (parentController) {
      parentController.element.focus()
      parentController.navigate(event)
    }
  }

  #selectPrevious() {
    const index = this.#visibleItems.indexOf(this.currentItem)
    if (index > 0) {
      this.#setCurrentFrom(this.#visibleItems[index - 1])
    }
  }

  #selectNext() {
    const index = this.#visibleItems.indexOf(this.currentItem)
    if (index >= 0 && index < this.#visibleItems.length - 1) {
      this.#setCurrentFrom(this.#visibleItems[index + 1])
    }
  }

  #handleArrowKey(event, fn) {
    if (event.shiftKey || event.metaKey || event.ctrlKey) { return }
    fn.call()
    if (this.preventHandledKeysValue) {
      event.preventDefault()
    }
  }

  #clickCurrentItem(event) {
    if (this.actionableItemsValue && this.currentItem && this.#visibleItems.length && this.#isFocusContainedOnNavigableItem) {
      const clickableElement = this.currentItem.querySelector("a,button") || this.currentItem
      clickableElement.click()
      event.preventDefault()
    }
  }

  get #isFocusContainedOnNavigableItem() {
    return !this.onlyActOnFocusedItemsValue || this.itemTargets.some(item => item === document.activeElement || item.contains(document.activeElement))
  }

  #toggleCurrentItem(event) {
    if (this.actionableItemsValue && this.currentItem && this.#visibleItems.length) {
      const toggleable = this.currentItem.querySelector("input[type=checkbox]")
      const isDisabled = toggleable.hasAttribute("disabled")

      if (toggleable) {
        if (!isDisabled) {
          toggleable.checked = !toggleable.checked
          toggleable.dispatchEvent(new Event('change', { bubbles: true }))
        }
        event.preventDefault()
      }
    }
  }

  get #visibleItems() {
    return this.itemTargets.filter(item => {
      return item.checkVisibility() && !item.hidden
    })
  }

  #keyHandlers = {
    ArrowDown(event) {
      if (this.supportsVerticalNavigationValue) {
        const selectMethod = this.reverseNavigationValue ? this.#selectPrevious.bind(this) : this.#selectNext.bind(this)
        this.#handleArrowKey(event, selectMethod)
      }
    },
    ArrowUp(event) {
      if (this.supportsVerticalNavigationValue) {
        const selectMethod = this.reverseNavigationValue ? this.#selectNext.bind(this) : this.#selectPrevious.bind(this)
        this.#handleArrowKey(event, selectMethod)
      }
    },
    ArrowRight(event) {
      if (this.supportsHorizontalNavigationValue) {
        this.#handleArrowKey(event, this.#selectNext.bind(this))
      }
    },
    ArrowLeft(event) {
      if (this.supportsHorizontalNavigationValue) {
        this.#handleArrowKey(event, this.#selectPrevious.bind(this))
      }
    },
    Enter(event) {
      if (event.shiftKey) {
        this.#toggleCurrentItem(event)
      } else {
        this.#clickCurrentItem(event)
      }
    },
  }
}