import React, { type JSX, type ReactNode } from 'react';
import { RuntimeAPIContext } from '@/contexts/runtimeAPIContext';
import type { FilesAPI, RuntimeAPIs } from '@/lib/api/types';
import {
  approxStringBytes,
  evictContentLru,
  setContentBytes,
  touchContent as touchContentLru,
  removeContentBytes,
} from '@/sync/content-cache';

/** Wrap a FilesAPI with an in-memory LRU content cache. */
function withContentCache(files: FilesAPI): FilesAPI {
  const cache = new Map<string, { content: string; path: string }>();

  const cachedReadFile: FilesAPI['readFile'] = files.readFile
    ? async (path: string) => {
        const hit = cache.get(path);
        if (hit) {
          touchContentLru(path);
          return hit;
        }

        const result = await files.readFile!(path);
        const bytes = approxStringBytes(result.content);
        cache.set(path, result);
        setContentBytes(path, bytes);

        // Evict if over limits
        const keep = new Set<string>();
        evictContentLru(keep, (evictPath) => {
          cache.delete(evictPath);
        });

        return result;
      }
    : undefined;

  // Invalidate cache on writes, deletes, renames
  const cachedWriteFile: FilesAPI['writeFile'] = files.writeFile
    ? async (path, content) => {
        cache.delete(path);
        removeContentBytes(path);
        return files.writeFile!(path, content);
      }
    : undefined;

  const cachedDelete: FilesAPI['delete'] = files.delete
    ? async (path) => {
        cache.delete(path);
        removeContentBytes(path);
        return files.delete!(path);
      }
    : undefined;

  const cachedRename: FilesAPI['rename'] = files.rename
    ? async (oldPath, newPath) => {
        cache.delete(oldPath);
        removeContentBytes(oldPath);
        cache.delete(newPath);
        removeContentBytes(newPath);
        return files.rename!(oldPath, newPath);
      }
    : undefined;

  return {
    ...files,
    readFile: cachedReadFile,
    writeFile: cachedWriteFile,
    delete: cachedDelete,
    rename: cachedRename,
  };
}

export function RuntimeAPIProvider({ apis, children }: { apis: RuntimeAPIs; children: ReactNode }): JSX.Element {
  const cachedApis = React.useMemo<RuntimeAPIs>(
    () => ({
      ...apis,
      files: withContentCache(apis.files),
    }),
    [apis],
  );
  return <RuntimeAPIContext.Provider value={cachedApis}>{children}</RuntimeAPIContext.Provider>;
}