/*
 * Copyright 2025 coze-dev Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import React, { useLayoutEffect } from 'react';

import { useForceUpdate } from './use-force-update';

/** createSlots is a factory that can create a
 *  typesafe Slots + Slot pair to use in a component definition
 *  For example: ActionList.Item uses createSlots to get a Slots wrapper
 *  + Slot component that is used by LeadingVisual, Description
 */
const createSlots = <SlotNames extends string>(slotNames: SlotNames[]) => {
  type Slots = {
    [key in SlotNames]?: React.ReactNode;
  };

  interface ContextProps {
    registerSlot: (name: SlotNames, contents: React.ReactNode) => void;
    unregisterSlot: (name: SlotNames) => void;
    context: Record<string, unknown>;
  }
  const SlotsContext = React.createContext<ContextProps>({
    registerSlot: () => null,
    unregisterSlot: () => null,
    context: {},
  });

  // maintain a static reference to avoid infinite render loop
  const defaultContext = Object.freeze({});

  /** Slots uses a Double render strategy inspired by [reach-ui/descendants](https://github.com/reach/reach-ui/tree/develop/packages/descendants)
   *  Slot registers themself with the Slots parent.
   *  When all the children have mounted = registered themselves in slot,
   *  we re-render the parent component to render with slots
   */
  const Slots: React.FC<{
    context?: ContextProps['context'];
    children: (slots: Slots) => React.ReactNode;
  }> = ({ context = defaultContext, children }) => {
    // initialise slots
    const slotsDefinition: Slots = {};
    slotNames.map(name => (slotsDefinition[name] = null));
    const slotsRef = React.useRef<Slots>(slotsDefinition);

    const rerenderWithSlots = useForceUpdate();
    const [isMounted, setIsMounted] = React.useState(false);

    // fires after all the effects in children
    useLayoutEffect(() => {
      rerenderWithSlots();
      setIsMounted(true);
    }, [rerenderWithSlots]);

    const registerSlot = React.useCallback(
      (name: SlotNames, contents: React.ReactNode) => {
        slotsRef.current[name] = contents;

        // don't render until the component mounts = all slots are registered
        if (isMounted) {
          rerenderWithSlots();
        }
      },
      [isMounted, rerenderWithSlots],
    );

    // Slot can be removed from the tree as well,
    // we need to unregister them from the slot
    const unregisterSlot = React.useCallback(
      (name: SlotNames) => {
        slotsRef.current[name] = null;
        rerenderWithSlots();
      },
      [rerenderWithSlots],
    );

    /**
     * Slots uses a render prop API so abstract the
     * implementation detail of using a context provider.
     */
    const slots = slotsRef.current;

    return (
      <SlotsContext.Provider value={{ registerSlot, unregisterSlot, context }}>
        {children(slots)}
      </SlotsContext.Provider>
    );
  };

  const Slot: React.FC<{
    name: SlotNames;
    children:
      | React.ReactNode
      | ((context: ContextProps['context']) => React.ReactNode);
  }> = ({ name, children }) => {
    const { registerSlot, unregisterSlot, context } =
      React.useContext(SlotsContext);

    useLayoutEffect(() => {
      registerSlot(
        name,
        typeof children === 'function' ? children(context) : children,
      );
      return () => unregisterSlot(name);
    }, [name, children, registerSlot, unregisterSlot, context]);

    return null;
  };

  return { Slots, Slot };
};

export default createSlots;