-- ============================================================
-- Chat actions: reply linkage + reactions
--
-- Adds two things the chat UI now needs:
--
--   1. `messages.reply_to_message_id` — a self-FK so a message can
--      point at the message it replies to. We use the internal UUID
--      (not Meta's message_id text), because Meta IDs aren't unique
--      across phone numbers and can't be FK-constrained. The webhook
--      resolves `context.id` from Meta into our internal UUID before
--      writing. ON DELETE SET NULL — a deleted parent must not nuke
--      its replies (which today never happens, but the constraint
--      should match intent).
--
--   2. `message_reactions` table — one row per (message, actor).
--      Reactions arrive concurrently from agents (UI) and customers
--      (webhook). A row-level uniqueness constraint enforces "one
--      reaction per actor per message" without read-modify-write
--      games on a JSONB column.
--
--      `conversation_id` is denormalised purely so Supabase Realtime
--      can filter on it with a plain `eq`. Realtime can't join.
--
-- Idempotent — safe to run multiple times.
-- ============================================================

-- ============================================================
-- 1. Reply linkage on messages
-- ============================================================
ALTER TABLE messages
  ADD COLUMN IF NOT EXISTS reply_to_message_id UUID
  REFERENCES messages(id) ON DELETE SET NULL;

-- Partial index — most messages aren't replies, so skip nulls.
CREATE INDEX IF NOT EXISTS idx_messages_reply_to
  ON messages(reply_to_message_id)
  WHERE reply_to_message_id IS NOT NULL;

-- ============================================================
-- 2. message_reactions
-- ============================================================
CREATE TABLE IF NOT EXISTS message_reactions (
  id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
  message_id UUID NOT NULL REFERENCES messages(id) ON DELETE CASCADE,
  conversation_id UUID NOT NULL REFERENCES conversations(id) ON DELETE CASCADE,
  actor_type TEXT NOT NULL CHECK (actor_type IN ('customer', 'agent')),
  actor_id UUID,
  emoji TEXT NOT NULL,
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  UNIQUE (message_id, actor_type, actor_id)
);

CREATE INDEX IF NOT EXISTS idx_message_reactions_conversation
  ON message_reactions(conversation_id);

CREATE INDEX IF NOT EXISTS idx_message_reactions_message
  ON message_reactions(message_id);

ALTER TABLE message_reactions ENABLE ROW LEVEL SECURITY;

DROP POLICY IF EXISTS "Users see reactions on their conversations" ON message_reactions;
CREATE POLICY "Users see reactions on their conversations" ON message_reactions FOR SELECT
  USING (EXISTS (
    SELECT 1 FROM conversations c
    WHERE c.id = message_reactions.conversation_id
      AND c.user_id = auth.uid()
  ));

DROP POLICY IF EXISTS "Users insert reactions on their conversations" ON message_reactions;
CREATE POLICY "Users insert reactions on their conversations" ON message_reactions FOR INSERT
  WITH CHECK (EXISTS (
    SELECT 1 FROM conversations c
    WHERE c.id = message_reactions.conversation_id
      AND c.user_id = auth.uid()
  ));

-- Agents may remove their own reactions. Customer reactions are managed
-- by the webhook (service-role bypass), not the UI.
DROP POLICY IF EXISTS "Users delete their own agent reactions" ON message_reactions;
CREATE POLICY "Users delete their own agent reactions" ON message_reactions FOR DELETE
  USING (
    actor_type = 'agent'
    AND actor_id = auth.uid()
    AND EXISTS (
      SELECT 1 FROM conversations c
      WHERE c.id = message_reactions.conversation_id
        AND c.user_id = auth.uid()
    )
  );

-- Agents may swap their own reaction emoji (UPDATE path is also used by
-- the upsert in /api/whatsapp/react).
DROP POLICY IF EXISTS "Users update their own agent reactions" ON message_reactions;
CREATE POLICY "Users update their own agent reactions" ON message_reactions FOR UPDATE
  USING (
    actor_type = 'agent'
    AND actor_id = auth.uid()
    AND EXISTS (
      SELECT 1 FROM conversations c
      WHERE c.id = message_reactions.conversation_id
        AND c.user_id = auth.uid()
    )
  );

-- Realtime — let the thread subscribe filtered by conversation_id.
DO $$
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM pg_publication_tables
    WHERE pubname = 'supabase_realtime' AND tablename = 'message_reactions'
  ) THEN
    ALTER PUBLICATION supabase_realtime ADD TABLE message_reactions;
  END IF;
END $$;