import { Button, Card, Stack, Text, Wrap } from '@chakra-ui/react';
import isHotkey from 'is-hotkey';
import React, { KeyboardEvent, MouseEvent, useCallback, useEffect, useMemo } from 'react';
import { createEditor, Descendant, Editor, Element as SlateElement, Transforms } from 'slate';
import { withHistory } from 'slate-history';
import {
  Editable,
  RenderElementProps,
  RenderLeafProps,
  Slate,
  useSlate,
  withReact
} from 'slate-react';
import {
  CustomEditor,
  CustomElement,
  CustomElementType,
  CustomElementWithAlign,
  CustomTextKey
} from '../types';
import { Prose } from './ui/prose';

export function EditorSlate({
  initialValue,
  onChange,
  readOnly
}: {
  readonly initialValue?: Descendant[];
  readonly onChange?: (values: Descendant[]) => void;
  readonly readOnly?: boolean;
}) {
  return (
    <>
      <Card.Root
        variant={'subtle'}
        width="100%"
        flex={1}
        justifyContent="center"
        alignItems="center"
        background={readOnly ? 'none' : undefined}
      >
        <Card.Body
          width="100%"
          css={{
            '& *': {
              fontSize: 'revert',
              fontWeight: 'revert'
            }
          }}
        >
          <EditorViewport
            initialValue={
              initialValue ?? [
                {
                  type: 'paragraph',
                  children: [{ text: '' }]
                }
              ]
            }
            onChange={values => {
              if (onChange != null) onChange(values);
            }}
            readOnly={readOnly}
          />
        </Card.Body>
      </Card.Root>
    </>
  );
}

const HOTKEYS: Record<string, CustomTextKey> = {
  'mod+b': 'bold',
  'mod+i': 'italic',
  'mod+u': 'underline',
  'mod+`': 'code'
};

const LIST_TYPES = ['numbered-list', 'bulleted-list'] as const;
const TEXT_ALIGN_TYPES = ['left', 'center', 'right', 'justify'] as const;

type AlignType = (typeof TEXT_ALIGN_TYPES)[number];
type ListType = (typeof LIST_TYPES)[number];
type CustomElementFormat = CustomElementType | AlignType | ListType;

function EditorViewport({
  initialValue,
  onChange,
  readOnly
}: {
  readonly initialValue: Descendant[];
  readonly onChange: (values: Descendant[]) => void;
  readonly readOnly?: boolean;
}) {
  const renderElement = useCallback((props: RenderElementProps) => <Element {...props} />, []);
  const renderLeaf = useCallback((props: RenderLeafProps) => <Leaf {...props} />, []);
  const editor = useMemo(() => withHistory(withReact(createEditor())), []);

  return (
    <Slate editor={editor} initialValue={initialValue} onChange={onChange}>
      {!readOnly && (
        <Wrap justifyContent="center" alignItems="center" gap={1}>
          <MarkButton format="bold" icon="nf nf-oct-bold" />
          <MarkButton format="italic" icon="nf nf-oct-italic" />
          <MarkButton format="underline" icon="nf nf-md-format_underline" />
          <MarkButton format="code" icon="nf nf-oct-code" />
          <BlockButton format="heading-one" icon="nf nf-fa-heading" text="1" />
          <BlockButton format="heading-two" icon="nf nf-fa-heading" text="2" />
          <BlockButton format="block-quote" icon="nf nf-oct-quote" />
          <BlockButton format="numbered-list" icon="nf nf-fa-list_ol" />
          <BlockButton format="bulleted-list" icon="nf nf-fa-list_ul" />
          <BlockButton format="left" icon="nf nf-fa-align_left" />
          <BlockButton format="center" icon="nf nf-fa-align_center" />
          <BlockButton format="right" icon="nf nf-fa-align_right" />
          <BlockButton format="justify" icon="nf nf-fa-align_justify" />
        </Wrap>
      )}
      <Stack
        width="100%"
        maxWidth="100%"
        height="100%"
        paddingX={3}
        display="flex"
        justifyContent="center"
        alignItems="center"
        flex={1}
      >
        <Prose width="100%" minWidth="100%" height="100%" display="flex" flex={1}>
          <Editable
            className="slate-editor"
            style={{
              outline: 'none',
              minWidth: '100%',
              maxWidth: 'unset',
              maxHeight: readOnly ? undefined : '60vh',
              height: '100%',
              padding: 0,
              overflowY: 'auto',
              overflowX: 'clip'
            }}
            renderElement={renderElement}
            renderLeaf={renderLeaf}
            readOnly={readOnly}
            placeholder=""
            spellCheck
            autoFocus
            onKeyDown={(event: KeyboardEvent<HTMLDivElement>) => {
              for (const hotkey in HOTKEYS) {
                if (isHotkey(hotkey, event as any)) {
                  event.preventDefault();
                  const mark = HOTKEYS[hotkey];
                  toggleMark(editor, mark);
                }
              }
            }}
          />
        </Prose>
      </Stack>
    </Slate>
  );
}

function toggleBlock(editor: CustomEditor, format: CustomElementFormat) {
  const isActive = isBlockActive(editor, format, isAlignType(format) ? 'align' : 'type');
  const isList = isListType(format);

  Transforms.unwrapNodes(editor, {
    match: n =>
      !Editor.isEditor(n) &&
      SlateElement.isElement(n) &&
      isListType(n.type) &&
      !isAlignType(format),
    split: true
  });
  let newProperties: Partial<SlateElement>;
  if (isAlignType(format)) {
    newProperties = {
      align: isActive ? undefined : format
    };
  } else {
    newProperties = {
      type: isActive ? 'paragraph' : isList ? 'list-item' : format
    };
  }
  Transforms.setNodes<SlateElement>(editor, newProperties);

  if (!isActive && isList) {
    const block = { type: format, children: [] };
    Transforms.wrapNodes(editor, block);
  }
}

function toggleMark(editor: CustomEditor, format: CustomTextKey) {
  const isActive = isMarkActive(editor, format);

  if (isActive) {
    Editor.removeMark(editor, format);
  } else {
    Editor.addMark(editor, format, true);
  }
}

function isBlockActive(
  editor: CustomEditor,
  format: CustomElementFormat,
  blockType: 'type' | 'align' = 'type'
) {
  const { selection } = editor;
  if (!selection) return false;

  const [match] = Array.from(
    Editor.nodes(editor, {
      at: Editor.unhangRange(editor, selection),
      match: n => {
        if (!Editor.isEditor(n) && SlateElement.isElement(n)) {
          if (blockType === 'align' && isAlignElement(n)) {
            return n.align === format;
          }
          return n.type === format;
        }
        return false;
      }
    })
  );

  return Boolean(match);
}

function isMarkActive(editor: CustomEditor, format: CustomTextKey) {
  const marks = Editor.marks(editor);
  return marks ? marks[format] === true : false;
}

function Element({ attributes, children, element }: RenderElementProps) {
  const style: React.CSSProperties = {};
  if (isAlignElement(element)) {
    style.textAlign = element.align as AlignType;
  }
  switch (element.type) {
    case 'block-quote':
      return (
        <blockquote style={style} {...attributes}>
          {children}
        </blockquote>
      );
    case 'bulleted-list':
      return (
        <ul style={style} {...attributes}>
          {children}
        </ul>
      );
    case 'heading-one':
      return (
        <h1 style={style} {...attributes}>
          {children}
        </h1>
      );
    case 'heading-two':
      return (
        <h2 style={style} {...attributes}>
          {children}
        </h2>
      );
    case 'list-item':
      return (
        <li style={style} {...attributes}>
          {children}
        </li>
      );
    case 'numbered-list':
      return (
        <ol style={style} {...attributes}>
          {children}
        </ol>
      );
    default:
      return (
        <p style={style} {...attributes}>
          {children}
        </p>
      );
  }
}

function Leaf({ attributes, children, leaf }: RenderLeafProps) {
  if (leaf.bold) {
    children = <strong>{children}</strong>;
  }

  if (leaf.code) {
    children = <code>{children}</code>;
  }

  if (leaf.italic) {
    children = <em style={{ fontStyle: 'italic' }}>{children}</em>;
  }

  if (leaf.underline) {
    children = <u>{children}</u>;
  }

  return <span {...attributes}>{children}</span>;
}

interface BlockButtonProps {
  format: CustomElementFormat;
  icon: string;
  text?: string;
}

function BlockButton({ format, icon, text }: BlockButtonProps) {
  const editor = useSlate();
  return (
    <Button
      variant={isBlockActive(editor, format) ? 'solid' : 'ghost'}
      onMouseDown={(event: MouseEvent<HTMLSpanElement>) => {
        event.preventDefault();
        toggleBlock(editor, format);
      }}
      gap={0.5}
    >
      <i className={icon} />
      <Stack alignItems="end">
        <Text fontSize="0.8rem">{text}</Text>
      </Stack>
    </Button>
  );
}

interface MarkButtonProps {
  format: CustomTextKey;
  icon: string;
  text?: string;
}

function MarkButton({ format, icon, text }: MarkButtonProps) {
  const editor = useSlate();
  return (
    <Button
      variant={isMarkActive(editor, format) ? 'solid' : 'ghost'}
      onMouseDown={(event: MouseEvent<HTMLSpanElement>) => {
        event.preventDefault();
        toggleMark(editor, format);
      }}
    >
      <i className={icon} />
      {text}
    </Button>
  );
}

function isAlignType(format: CustomElementFormat): format is AlignType {
  return TEXT_ALIGN_TYPES.includes(format as AlignType);
}

function isListType(format: CustomElementFormat): format is ListType {
  return LIST_TYPES.includes(format as ListType);
}

function isAlignElement(element: CustomElement): element is CustomElementWithAlign {
  return 'align' in element;
}