CREATE TABLE IF NOT EXISTS tasks (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  title TEXT NOT NULL CHECK (length(trim(title)) > 0),
  description TEXT NOT NULL DEFAULT '',
  due_date TEXT NOT NULL CHECK (due_date GLOB '[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]'),
  topic TEXT NOT NULL CHECK (length(trim(topic)) > 0),
  status TEXT NOT NULL DEFAULT 'Todo' CHECK (status IN ('Todo', 'In-Progress', 'Complete')),
  archived_at TEXT,
  created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX IF NOT EXISTS idx_tasks_active_status
ON tasks (archived_at, status, due_date);

CREATE INDEX IF NOT EXISTS idx_tasks_topic
ON tasks (topic COLLATE NOCASE);