"use client";

import * as React from "react";
import { NodeSelection, TextSelection } from "@tiptap/pm/state";
import { type Editor } from "@tiptap/react";

// --- Lib ---
import {
  findNodePosition,
  isNodeInSchema,
  isNodeTypeSelected,
  isValidPosition,
} from "@/lib/tiptap-utils";
// --- Hooks ---
import { useTiptapEditor } from "@/hooks/use-tiptap-editor";
import { HeadingFiveIcon } from "@/components/shared/tiptap/tiptap-icons/heading-five-icon";
import { HeadingFourIcon } from "@/components/shared/tiptap/tiptap-icons/heading-four-icon";
// --- Icons ---
import { HeadingOneIcon } from "@/components/shared/tiptap/tiptap-icons/heading-one-icon";
import { HeadingSixIcon } from "@/components/shared/tiptap/tiptap-icons/heading-six-icon";
import { HeadingThreeIcon } from "@/components/shared/tiptap/tiptap-icons/heading-three-icon";
import { HeadingTwoIcon } from "@/components/shared/tiptap/tiptap-icons/heading-two-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");
  }

  try {
    const view = editor.view;
    const state = view.state;
    const selection = state.selection;

    if (selection.empty || selection instanceof TextSelection) {
      const pos = findNodePosition({
        editor,
        node: state.selection.$anchor.node(1),
      })?.pos;
      if (!isValidPosition(pos)) return false;
    }

    return true;
  } catch {
    return false;
  }
}

/**
 * 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;

    // No selection, find the cursor position
    if (state.selection.empty || state.selection instanceof TextSelection) {
      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;

      chain = chain.setTextSelection({ from, to }).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 || !editor.isEditable) return false;
  if (!isNodeInSchema("heading", editor)) return false;

  if (hideWhenUnavailable && !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] = React.useState<boolean>(true);
  const canToggleState = canToggle(editor, level);
  const isActive = isHeadingActive(editor, level);

  React.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 = React.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],
  };
}
