import { Descendant, Editor } from 'slate';
import invariant from 'tiny-invariant';
import { Awareness } from 'y-protocols/awareness';
import { absolutePositionToRelativePosition } from '../cursor/utils';
import { YjsEditor } from './yjs-editor';

const AWARENESS: WeakMap<Editor, Awareness> = new WeakMap();

export interface CursorEditor extends YjsEditor {
    awareness: Awareness;
}

export const CursorEditor = {
    awareness(editor: CursorEditor): Awareness {
        const awareness = AWARENESS.get(editor);
        invariant(awareness, 'CursorEditor without attaches awareness');
        return awareness;
    },

    updateCursor: (editor: CursorEditor): void => {
        const sharedType = YjsEditor.sharedType(editor);
        const { selection } = editor;

        try {
            const anchor =
                selection &&
                absolutePositionToRelativePosition(sharedType, selection.anchor);

            const focus =
                selection &&
                absolutePositionToRelativePosition(sharedType, selection.focus);

            const awareness = CursorEditor.awareness(editor);
            awareness.setLocalState({ ...awareness.getLocalState(), anchor, focus });
        } catch (error) {
            const e: YjsEditor & {
                onError: (errorData: {
                    code?: number,
                    name?: string,
                    nativeError?: any,
                    data?: Descendant[]
                }) => void
            } = editor as any;
            if (e.onError) {
                e.onError({ code: 10003, name: 'update cursor', nativeError: error });
            }
        }
    }
};

export function withCursor<T extends YjsEditor>(
    editor: T,
    awareness: Awareness
): T & CursorEditor {
    const e = editor as T & CursorEditor;

    AWARENESS.set(e, awareness);
    e.awareness = awareness;

    const { onChange } = editor;

    e.onChange = () => {
        setTimeout(() => CursorEditor.updateCursor(e), 0);

        if (onChange) {
            onChange();
        }
    };

    return e;
}