-- Create sessions table
CREATE TABLE public.sessions (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id UUID NOT NULL REFERENCES auth.users(id) ON DELETE CASCADE,
  grade TEXT,
  subject TEXT,
  chapter TEXT,
  preview TEXT,
  created_at TIMESTAMPTZ DEFAULT now(),
  updated_at TIMESTAMPTZ DEFAULT now()
);

-- Create messages table
CREATE TABLE public.messages (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  session_id UUID NOT NULL REFERENCES public.sessions(id) ON DELETE CASCADE,
  role TEXT NOT NULL CHECK (role IN ('user', 'assistant')),
  text TEXT NOT NULL,
  created_at TIMESTAMPTZ DEFAULT now()
);

-- Create profiles table (optional, for future user metadata)
CREATE TABLE public.profiles (
  id UUID PRIMARY KEY REFERENCES auth.users(id) ON DELETE CASCADE,
  email TEXT NOT NULL,
  display_name TEXT,
  avatar_url TEXT,
  created_at TIMESTAMPTZ DEFAULT now(),
  updated_at TIMESTAMPTZ DEFAULT now()
);

-- Create indexes for faster queries
CREATE INDEX idx_sessions_user_id ON public.sessions(user_id);
CREATE INDEX idx_messages_session_id ON public.messages(session_id);

-- Enable RLS
ALTER TABLE public.sessions ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.messages ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.profiles ENABLE ROW LEVEL SECURITY;

-- RLS Policies for sessions: users can CRUD only their own sessions
CREATE POLICY "Users can view own sessions"
  ON public.sessions FOR SELECT
  USING (auth.uid() = user_id);

CREATE POLICY "Users can create sessions"
  ON public.sessions FOR INSERT
  WITH CHECK (auth.uid() = user_id);

CREATE POLICY "Users can update own sessions"
  ON public.sessions FOR UPDATE
  USING (auth.uid() = user_id)
  WITH CHECK (auth.uid() = user_id);

CREATE POLICY "Users can delete own sessions"
  ON public.sessions FOR DELETE
  USING (auth.uid() = user_id);

-- RLS Policies for messages: users can CRUD only messages in their own sessions
CREATE POLICY "Users can view messages in own sessions"
  ON public.messages FOR SELECT
  USING (session_id IN (SELECT id FROM public.sessions WHERE user_id = auth.uid()));

CREATE POLICY "Users can insert messages in own sessions"
  ON public.messages FOR INSERT
  WITH CHECK (session_id IN (SELECT id FROM public.sessions WHERE user_id = auth.uid()));

CREATE POLICY "Users can delete own messages"
  ON public.messages FOR DELETE
  USING (session_id IN (SELECT id FROM public.sessions WHERE user_id = auth.uid()));

-- RLS Policies for profiles
CREATE POLICY "Users can view own profile"
  ON public.profiles FOR SELECT
  USING (auth.uid() = id);

CREATE POLICY "Users can update own profile"
  ON public.profiles FOR UPDATE
  USING (auth.uid() = id)
  WITH CHECK (auth.uid() = id);