import { useState, useEffect, useCallback } from 'react';
import type { Settings } from '../types';

interface UseContextPreviewResult {
  preview: string;
  isLoading: boolean;
  error: string | null;
  refresh: () => Promise<void>;
  projects: string[];
  selectedProject: string | null;
  setSelectedProject: (project: string) => void;
}

export function useContextPreview(settings: Settings): UseContextPreviewResult {
  const [preview, setPreview] = useState<string>('');
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [projects, setProjects] = useState<string[]>([]);
  const [selectedProject, setSelectedProject] = useState<string | null>(null);

  // Fetch projects on mount
  useEffect(() => {
    async function fetchProjects() {
      try {
        const response = await fetch('/api/projects');
        const data = await response.json();
        if (data.projects && data.projects.length > 0) {
          setProjects(data.projects);
          setSelectedProject(data.projects[0]); // Default to first project
        }
      } catch (err) {
        console.error('Failed to fetch projects:', err);
      }
    }
    fetchProjects();
  }, []);

  const refresh = useCallback(async () => {
    if (!selectedProject) {
      setPreview('No project selected');
      return;
    }

    setIsLoading(true);
    setError(null);

    try {
      const params = new URLSearchParams({
        project: selectedProject
      });

      const response = await fetch(`/api/context/preview?${params}`);
      const text = await response.text();

      if (response.ok) {
        setPreview(text);
      } else {
        setError('Failed to load preview');
      }
    } catch (err) {
      console.warn('Failed to load context preview:', err);
      setError((err as Error).message);
    } finally {
      setIsLoading(false);
    }
  }, [selectedProject]);

  // Debounced refresh when settings or selectedProject change
  useEffect(() => {
    const timeout = setTimeout(() => {
      refresh();
    }, 300);
    return () => clearTimeout(timeout);
  }, [settings, refresh]);

  return { preview, isLoading, error, refresh, projects, selectedProject, setSelectedProject };
}