CREATE TABLE IF NOT EXISTS work_groups (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  name TEXT NOT NULL UNIQUE
);

CREATE TABLE IF NOT EXISTS users (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  class TEXT NOT NULL,
  name TEXT NOT NULL,
  volunteer_no TEXT,
  group_id INTEGER,
  FOREIGN KEY (group_id) REFERENCES work_groups(id) ON DELETE SET NULL,
  UNIQUE(class, name)
);

CREATE TABLE IF NOT EXISTS user_groups (
  user_id INTEGER NOT NULL,
  group_id INTEGER NOT NULL,
  PRIMARY KEY (user_id, group_id),
  FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
  FOREIGN KEY (group_id) REFERENCES work_groups(id) ON DELETE CASCADE
);

CREATE TABLE IF NOT EXISTS activities (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  title TEXT NOT NULL,
  content TEXT,
  start_time TEXT NOT NULL,
  end_time TEXT NOT NULL,
  created_at TEXT NOT NULL DEFAULT (datetime('now','+8 hours'))
);

CREATE TABLE IF NOT EXISTS activity_groups (
  activity_id INTEGER NOT NULL,
  group_id INTEGER NOT NULL,
  PRIMARY KEY (activity_id, group_id),
  FOREIGN KEY (activity_id) REFERENCES activities(id) ON DELETE CASCADE,
  FOREIGN KEY (group_id) REFERENCES work_groups(id) ON DELETE CASCADE
);

CREATE TABLE IF NOT EXISTS hours (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  activity_id INTEGER NOT NULL,
  user_id INTEGER NOT NULL,
  hours REAL NOT NULL DEFAULT 0,
  exported_hours REAL NOT NULL DEFAULT 0,
  remark TEXT,
  created_at TEXT NOT NULL DEFAULT (datetime('now','+8 hours')),
  FOREIGN KEY (activity_id) REFERENCES activities(id) ON DELETE CASCADE,
  FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
);

CREATE TABLE IF NOT EXISTS admins (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  username TEXT NOT NULL UNIQUE,
  password_hash TEXT NOT NULL,
  created_at TEXT NOT NULL DEFAULT (datetime('now','+8 hours'))
);

CREATE TABLE IF NOT EXISTS four_hour_exports (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  status TEXT NOT NULL DEFAULT 'active',
  admin_username TEXT,
  eligible_count INTEGER NOT NULL DEFAULT 0,
  eligible_hours_total REAL NOT NULL DEFAULT 0,
  items_updated INTEGER NOT NULL DEFAULT 0,
  plan_json TEXT,
  note TEXT,
  created_at TEXT NOT NULL DEFAULT (datetime('now','+8 hours')),
  voided_at TEXT
);

CREATE TABLE IF NOT EXISTS four_hour_export_items (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  export_id INTEGER NOT NULL,
  hour_id INTEGER NOT NULL,
  delta REAL NOT NULL,
  FOREIGN KEY (export_id) REFERENCES four_hour_exports(id) ON DELETE CASCADE
);
CREATE INDEX IF NOT EXISTS idx_fhe_items_export ON four_hour_export_items(export_id);
CREATE INDEX IF NOT EXISTS idx_fhe_items_hour ON four_hour_export_items(hour_id);