-- Feature flag for textbooks module
INSERT OR IGNORE INTO app_settings (key, value) VALUES ('feature_textbooks_enabled', '1');

-- Catalog of textbooks (admin-editable; html_path is relative to /frontend/textbooks/)
CREATE TABLE textbooks (
  id           INTEGER PRIMARY KEY AUTOINCREMENT,
  slug         TEXT    UNIQUE NOT NULL,
  subject      TEXT    NOT NULL,                -- 'chemistry', 'physics', 'math', 'biology', ...
  grade        INTEGER NOT NULL,                -- 9, 10, 11, ...
  title        TEXT    NOT NULL,
  author       TEXT    NOT NULL DEFAULT '',
  description  TEXT    NOT NULL DEFAULT '',
  html_path    TEXT    NOT NULL,                -- relative filename: 'chemistry_9.html'
  para_count   INTEGER NOT NULL DEFAULT 0,      -- total paragraphs (for progress %)
  color        TEXT    NOT NULL DEFAULT 'violet',-- visual theme: 'amber','blue','violet','green',...
  sort_order   INTEGER NOT NULL DEFAULT 0,
  is_active    INTEGER NOT NULL DEFAULT 1,
  created_at   TEXT    NOT NULL DEFAULT (datetime('now'))
);

-- Per-user reading progress (one row per (user, textbook))
CREATE TABLE textbook_progress (
  user_id          INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  textbook_id      INTEGER NOT NULL REFERENCES textbooks(id) ON DELETE CASCADE,
  paragraphs_read  TEXT    NOT NULL DEFAULT '[]',   -- JSON array of para keys like ["p1","p3","p7"]
  last_para        TEXT,                            -- last opened paragraph key (e.g. 'p15')
  last_at          TEXT    NOT NULL DEFAULT (datetime('now')),
  PRIMARY KEY (user_id, textbook_id)
);

-- Assignment extension: link to textbook + paragraph range string ("1-5" or "1,3,5")
ALTER TABLE assignments ADD COLUMN textbook_id INTEGER REFERENCES textbooks(id) ON DELETE SET NULL;
ALTER TABLE assignments ADD COLUMN textbook_paragraphs TEXT;

-- Seed: chemistry 9 + physics 9 (the two files we just copied)
INSERT INTO textbooks (slug, subject, grade, title, author, description, html_path, para_count, color, sort_order) VALUES
  ('chemistry-9', 'chemistry', 9, 'Химия — 9 класс',  'Шиманович Е. Я.',
   'Полный курс химии за 9 класс. §1–60: строение атома, химическая связь, классы соединений, ОВР, металлы и их соединения, электролиз.',
   'chemistry_9.html', 60, 'amber', 1),
  ('physics-9',   'physics',   9, 'Физика — 9 класс', 'Исаченкова Л. А.',
   'Полный курс физики за 9 класс: §1–38. Механика, кинематика, динамика, статика, законы сохранения, импульс, работа и энергия.',
   'physics_9.html', 38, 'blue', 2);