"use client"

import { useCallback, useEffect, useState } from "react"
import { type Editor } from "@tiptap/react"
import { NodeSelection, TextSelection } from "@tiptap/pm/state"

// --- Hooks ---
import { useTiptapEditor } from "@/hooks/use-tiptap-editor"

// --- Lib ---
import {
  findNodePosition,
  getSelectedBlockNodes,
  isNodeInSchema,
  isNodeTypeSelected,
  isValidPosition,
  selectionWithinConvertibleTypes,
} from "@/lib/tiptap-utils"

// --- Icons ---
import { HeadingOneIcon } from "@/components/tiptap-icons/heading-one-icon"
import { HeadingTwoIcon } from "@/components/tiptap-icons/heading-two-icon"
import { HeadingThreeIcon } from "@/components/tiptap-icons/heading-three-icon"
import { HeadingFourIcon } from "@/components/tiptap-icons/heading-four-icon"
import { HeadingFiveIcon } from "@/components/tiptap-icons/heading-five-icon"
import { HeadingSixIcon } from "@/components/tiptap-icons/heading-six-icon"

export type Level = 1 | 2 | 3 | 4 | 5 | 6

/**
 * Configuration for the heading functionality
 */
export interface UseHeadingConfig {
  /**
   * The Tiptap editor instance.
   */
  editor?: Editor | null
  /**
   * The heading level.
   */
  level: Level
  /**
   * Whether the button should hide when heading is not available.
   * @default false
   */
  hideWhenUnavailable?: boolean
  /**
   * Callback function called after a successful heading toggle.
   */
  onToggled?: () => void
}

export const headingIcons = {
  1: HeadingOneIcon,
  2: HeadingTwoIcon,
  3: HeadingThreeIcon,
  4: HeadingFourIcon,
  5: HeadingFiveIcon,
  6: HeadingSixIcon,
}

export const HEADING_SHORTCUT_KEYS: Record<Level, string> = {
  1: "ctrl+alt+1",
  2: "ctrl+alt+2",
  3: "ctrl+alt+3",
  4: "ctrl+alt+4",
  5: "ctrl+alt+5",
  6: "ctrl+alt+6",
}

/**
 * Checks if heading can be toggled in the current editor state
 */
export function canToggle(
  editor: Editor | null,
  level?: Level,
  turnInto: boolean = true
): boolean {
  if (!editor || !editor.isEditable) return false
  if (
    !isNodeInSchema("heading", editor) ||
    isNodeTypeSelected(editor, ["image"])
  )
    return false

  if (!turnInto) {
    return level
      ? editor.can().setNode("heading", { level })
      : editor.can().setNode("heading")
  }

  // Ensure selection is in nodes we're allowed to convert
  if (
    !selectionWithinConvertibleTypes(editor, [
      "paragraph",
      "heading",
      "bulletList",
      "orderedList",
      "taskList",
      "blockquote",
      "codeBlock",
    ])
  )
    return false

  // Either we can set heading directly on the selection,
  // or we can clear formatting/nodes to arrive at a heading.
  return level
    ? editor.can().setNode("heading", { level }) || editor.can().clearNodes()
    : editor.can().setNode("heading") || editor.can().clearNodes()
}

/**
 * Checks if heading is currently active
 */
export function isHeadingActive(
  editor: Editor | null,
  level?: Level | Level[]
): boolean {
  if (!editor || !editor.isEditable) return false

  if (Array.isArray(level)) {
    return level.some((l) => editor.isActive("heading", { level: l }))
  }

  return level
    ? editor.isActive("heading", { level })
    : editor.isActive("heading")
}

/**
 * Toggles heading in the editor
 */
export function toggleHeading(
  editor: Editor | null,
  level: Level | Level[]
): boolean {
  if (!editor || !editor.isEditable) return false

  const levels = Array.isArray(level) ? level : [level]
  const toggleLevel = levels.find((l) => canToggle(editor, l))

  if (!toggleLevel) return false

  try {
    const view = editor.view
    let state = view.state
    let tr = state.tr

    const blocks = getSelectedBlockNodes(editor)

    // In case a selection contains multiple blocks, we only allow
    // toggling to nide if there's exactly one block selected
    // we also dont block the canToggle since it will fall back to the bottom logic
    const isPossibleToTurnInto =
      selectionWithinConvertibleTypes(editor, [
        "paragraph",
        "heading",
        "bulletList",
        "orderedList",
        "taskList",
        "blockquote",
        "codeBlock",
      ]) && blocks.length === 1

    // No selection, find the the cursor position
    if (
      (state.selection.empty || state.selection instanceof TextSelection) &&
      isPossibleToTurnInto
    ) {
      const pos = findNodePosition({
        editor,
        node: state.selection.$anchor.node(1),
      })?.pos
      if (!isValidPosition(pos)) return false

      tr = tr.setSelection(NodeSelection.create(state.doc, pos))
      view.dispatch(tr)
      state = view.state
    }

    const selection = state.selection
    let chain = editor.chain().focus()

    // Handle NodeSelection
    if (selection instanceof NodeSelection) {
      const firstChild = selection.node.firstChild?.firstChild
      const lastChild = selection.node.lastChild?.lastChild

      const from = firstChild
        ? selection.from + firstChild.nodeSize
        : selection.from + 1

      const to = lastChild
        ? selection.to - lastChild.nodeSize
        : selection.to - 1

      const resolvedFrom = state.doc.resolve(from)
      const resolvedTo = state.doc.resolve(to)

      chain = chain
        .setTextSelection(TextSelection.between(resolvedFrom, resolvedTo))
        .clearNodes()
    }

    const isActive = levels.some((l) =>
      editor.isActive("heading", { level: l })
    )

    const toggle = isActive
      ? chain.setNode("paragraph")
      : chain.setNode("heading", { level: toggleLevel })

    toggle.run()

    editor.chain().focus().selectTextblockEnd().run()

    return true
  } catch {
    return false
  }
}

/**
 * Determines if the heading button should be shown
 */
export function shouldShowButton(props: {
  editor: Editor | null
  level?: Level | Level[]
  hideWhenUnavailable: boolean
}): boolean {
  const { editor, level, hideWhenUnavailable } = props

  if (!editor) return false

  if (!hideWhenUnavailable) {
    return true
  }

  if (!editor.isEditable) return false

  if (!isNodeInSchema("heading", editor)) return false

  if (!editor.isActive("code")) {
    if (Array.isArray(level)) {
      return level.some((l) => canToggle(editor, l))
    }
    return canToggle(editor, level)
  }

  return true
}

/**
 * Custom hook that provides heading functionality for Tiptap editor
 *
 * @example
 * ```tsx
 * // Simple usage
 * function MySimpleHeadingButton() {
 *   const { isVisible, isActive, handleToggle, Icon } = useHeading({ level: 1 })
 *
 *   if (!isVisible) return null
 *
 *   return (
 *     <button
 *       onClick={handleToggle}
 *       aria-pressed={isActive}
 *     >
 *       <Icon />
 *       Heading 1
 *     </button>
 *   )
 * }
 *
 * // Advanced usage with configuration
 * function MyAdvancedHeadingButton() {
 *   const { isVisible, isActive, handleToggle, label, Icon } = useHeading({
 *     level: 2,
 *     editor: myEditor,
 *     hideWhenUnavailable: true,
 *     onToggled: (isActive) => console.log('Heading toggled:', isActive)
 *   })
 *
 *   if (!isVisible) return null
 *
 *   return (
 *     <MyButton
 *       onClick={handleToggle}
 *       aria-label={label}
 *       aria-pressed={isActive}
 *     >
 *       <Icon />
 *       Toggle Heading 2
 *     </MyButton>
 *   )
 * }
 * ```
 */
export function useHeading(config: UseHeadingConfig) {
  const {
    editor: providedEditor,
    level,
    hideWhenUnavailable = false,
    onToggled,
  } = config

  const { editor } = useTiptapEditor(providedEditor)
  const [isVisible, setIsVisible] = useState<boolean>(true)
  const canToggleState = canToggle(editor, level)
  const isActive = isHeadingActive(editor, level)

  useEffect(() => {
    if (!editor) return

    const handleSelectionUpdate = () => {
      setIsVisible(shouldShowButton({ editor, level, hideWhenUnavailable }))
    }

    handleSelectionUpdate()

    editor.on("selectionUpdate", handleSelectionUpdate)

    return () => {
      editor.off("selectionUpdate", handleSelectionUpdate)
    }
  }, [editor, level, hideWhenUnavailable])

  const handleToggle = useCallback(() => {
    if (!editor) return false

    const success = toggleHeading(editor, level)
    if (success) {
      onToggled?.()
    }
    return success
  }, [editor, level, onToggled])

  return {
    isVisible,
    isActive,
    handleToggle,
    canToggle: canToggleState,
    label: `Heading ${level}`,
    shortcutKeys: HEADING_SHORTCUT_KEYS[level],
    Icon: headingIcons[level],
  }
}