CREATE TABLE assessment_questions (
    id BIGSERIAL PRIMARY KEY,
    title TEXT NOT NULL,
    description TEXT,
    question_type VARCHAR(50) NOT NULL, -- MULTIPLE_CHOICE, TRUE_FALSE, SHORT_ANSWER
    difficulty_level VARCHAR(50) NOT NULL, -- BEGINNER, INTERMEDIATE, ADVANCED
    is_active BOOLEAN NOT NULL DEFAULT TRUE,
    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ
);

CREATE TABLE assessment_question_options (
    id BIGSERIAL PRIMARY KEY,
    question_id BIGINT NOT NULL REFERENCES assessment_questions(id) ON DELETE CASCADE,
    option_text TEXT NOT NULL,
    is_correct BOOLEAN NOT NULL DEFAULT FALSE
);

CREATE TABLE assessment_attempts (
    id BIGSERIAL PRIMARY KEY,
    user_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    total_questions INT NOT NULL,
    correct_answers INT NOT NULL,
    score_percentage NUMERIC(5,2) NOT NULL,
    knowledge_level VARCHAR(50) NOT NULL, -- BEGINNER, INTERMEDIATE, ADVANCED
    completed_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE assessment_answers (
    id BIGSERIAL PRIMARY KEY,
    attempt_id BIGINT NOT NULL REFERENCES assessment_attempts(id) ON DELETE CASCADE,
    question_id BIGINT NOT NULL REFERENCES assessment_questions(id),
    selected_option_id BIGINT REFERENCES assessment_question_options(id),
    short_answer TEXT,
    is_correct BOOLEAN NOT NULL
);

CREATE TABLE IF NOT EXISTS users (
    id BIGSERIAL PRIMARY KEY,
    first_name VARCHAR(255) NOT NULL,
    last_name VARCHAR(255) NOT NULL,
    user_name VARCHAR(100) NOT NULL,
    email VARCHAR(255) UNIQUE,
    phone_number VARCHAR(20) UNIQUE,

    role VARCHAR(50) NOT NULL, -- SUPER_ADMIN, INSTRUCTOR, STUDENT, SUPPORT
    password BYTEA NOT NULL,
    age INT,
    education_level VARCHAR(100),
    country VARCHAR(100),
    region VARCHAR(100),

    knowledge_level VARCHAR(50), -- BEGINNER, INTERMEDIATE, ADVANCED    
    nick_name VARCHAR(100),
    occupation VARCHAR(150),
    learning_goal TEXT,
    language_goal TEXT,
    language_challange TEXT,
    favoutite_topic TEXT,

    initial_assessment_completed BOOLEAN NOT NULL DEFAULT FALSE,    
    email_verified BOOLEAN NOT NULL DEFAULT FALSE,
    phone_verified BOOLEAN NOT NULL DEFAULT FALSE,
    status VARCHAR(50) NOT NULL, -- PENDING, ACTIVE, SUSPENDED, DEACTIVATED
    last_login TIMESTAMPTZ,
    profile_completed BOOLEAN NOT NULL DEFAULT FALSE,
    profile_picture_url TEXT,
    preferred_language VARCHAR(50),

    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ,

    CHECK (email IS NOT NULL OR phone_number IS NOT NULL)
);

CREATE TABLE refresh_tokens (
    id BIGSERIAL PRIMARY KEY,
    user_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    token TEXT NOT NULL UNIQUE,
    expires_at TIMESTAMPTZ NOT NULL,
    revoked BOOLEAN NOT NULL DEFAULT FALSE,
    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE otps (
    id BIGSERIAL PRIMARY KEY,
    user_name VARCHAR(100) NOT NULL,
    sent_to VARCHAR(255) NOT NULL,
    medium VARCHAR(50) NOT NULL, -- email, sms
    otp_for VARCHAR(50) NOT NULL, -- register, reset
    otp VARCHAR(10) NOT NULL,
    used BOOLEAN NOT NULL DEFAULT FALSE,
    used_at TIMESTAMPTZ,
    expires_at TIMESTAMPTZ NOT NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE IF NOT EXISTS notifications (
    id BIGSERIAL PRIMARY KEY,
    user_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,

    type TEXT NOT NULL CHECK (
        type IN (
            'course_enrolled',
            'lesson_completed',
            'assessment_assigned',
            'assessment_submitted',
            'assessment_graded',
            'course_completed',
            'certificate_issued',
            'announcement',
            'otp_sent',
            'signup_welcome',
            'system_alert'
        )
    ),

    level TEXT NOT NULL CHECK (
        level IN ('info', 'warning', 'success', 'error')
    ),

    channel TEXT CHECK (
        channel IN ('email', 'sms', 'push', 'in_app')
    ),

    title TEXT NOT NULL,
    message TEXT NOT NULL,

    payload JSONB,
    is_read BOOLEAN NOT NULL DEFAULT FALSE,

    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
    read_at TIMESTAMPTZ
);

CREATE TABLE global_settings (
    key TEXT PRIMARY KEY,
    value TEXT NOT NULL,
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE IF NOT EXISTS reported_issues (
    id BIGSERIAL PRIMARY KEY,
    user_id BIGINT NOT NULL REFERENCES users(id),
    user_role VARCHAR(255) NOT NULL,
    subject TEXT NOT NULL,
    description TEXT NOT NULL,
    issue_type TEXT NOT NULL,
    -- e.g., "deposit", "withdrawal", "bet", "technical"
    status TEXT NOT NULL DEFAULT 'pending',
    -- pending, in_progress, resolved, rejected
    metadata JSONB,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);