CREATE TABLE student_profiles (
  id UUID PRIMARY KEY,
  owner_id UUID NOT NULL,
  name VARCHAR(20) NOT NULL CHECK (char_length(btrim(name)) BETWEEN 1 AND 20),
  grade VARCHAR(40) NOT NULL CHECK (char_length(btrim(grade)) > 0),
  subject VARCHAR(40) NOT NULL CHECK (char_length(btrim(subject)) > 0),
  academic_year SMALLINT NOT NULL CHECK (academic_year BETWEEN 2000 AND 2200),
  term VARCHAR(1) NOT NULL CHECK (term IN ('春', '暑', '秋', '寒')),
  guardian_title VARCHAR(24) NOT NULL CHECK (char_length(btrim(guardian_title)) BETWEEN 1 AND 24),
  start_time CHAR(5) NOT NULL,
  end_time CHAR(5) NOT NULL,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX student_profiles_owner_updated_idx
  ON student_profiles (owner_id, updated_at DESC);

CREATE INDEX student_profiles_owner_grade_subject_idx
  ON student_profiles (owner_id, grade, subject);

CREATE TABLE student_profile_defaults (
  owner_id UUID PRIMARY KEY,
  grade VARCHAR(40) NOT NULL CHECK (char_length(btrim(grade)) > 0),
  subject VARCHAR(40) NOT NULL CHECK (char_length(btrim(subject)) > 0),
  lesson_duration_minutes SMALLINT NOT NULL
    CHECK (lesson_duration_minutes BETWEEN 15 AND 360 AND lesson_duration_minutes % 15 = 0),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE TABLE feedback_records (
  id UUID PRIMARY KEY,
  owner_id UUID NOT NULL,
  profile_id UUID REFERENCES student_profiles(id) ON DELETE SET NULL,
  feedback_date DATE NOT NULL,
  content TEXT NOT NULL CHECK (char_length(btrim(content)) > 0),
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX feedback_records_owner_date_idx
  ON feedback_records (owner_id, feedback_date DESC, updated_at DESC);

CREATE INDEX feedback_records_owner_profile_idx
  ON feedback_records (owner_id, profile_id);