-- 004_inventory.sql — Player inventory and equipment slots.

CREATE TABLE IF NOT EXISTS inventory (
  id            INTEGER PRIMARY KEY AUTOINCREMENT,
  character_id  INTEGER NOT NULL REFERENCES characters(id) ON DELETE CASCADE,
  item_id       INTEGER NOT NULL REFERENCES items(id),
  quantity      INTEGER NOT NULL DEFAULT 1 CHECK (quantity >= 1),
  equipped_slot TEXT CHECK (equipped_slot IN ('weapon', 'armor', 'trinket')),
  acquired_at   INTEGER NOT NULL
);

CREATE INDEX IF NOT EXISTS idx_inventory_char ON inventory(character_id);

-- One equipped item per slot per character (partial unique index).
CREATE UNIQUE INDEX IF NOT EXISTS idx_inventory_equipped
  ON inventory(character_id, equipped_slot) WHERE equipped_slot IS NOT NULL;