CREATE TABLE IF NOT EXISTS users (
    id BIGSERIAL PRIMARY KEY,
    first_name VARCHAR(255) NOT NULL,
    last_name VARCHAR(255) NOT NULL,
    nick_name VARCHAR(100),
    email VARCHAR(255) UNIQUE,
    phone_number VARCHAR(20) UNIQUE,
    role VARCHAR(50) NOT NULL, -- SUPER_ADMIN, ORG_ADMIN, INSTRUCTOR, STUDENT, SUPPORT
    password BYTEA NOT NULL,
    age INT,
    education_level VARCHAR(100),
    country VARCHAR(100),
    region VARCHAR(100),
    email_verified BOOLEAN NOT NULL DEFAULT FALSE,
    phone_verified BOOLEAN NOT NULL DEFAULT FALSE,
    suspended BOOLEAN NOT NULL DEFAULT FALSE,
    suspended_at TIMESTAMPTZ,
    organization_id BIGINT,
    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ,
    CHECK (email IS NOT NULL OR phone_number IS NOT NULL),
    UNIQUE (email, organization_id),
    UNIQUE (phone_number, organization_id)
);

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,
    sent_to VARCHAR(255) NOT NULL,
    medium VARCHAR(50) NOT NULL, -- email, sms
    otp_for VARCHAR(50) NOT NULL, -- login, reset_password, verify
    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 organizations (
    id BIGSERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    slug TEXT UNIQUE NOT NULL,
    owner_id BIGINT NOT NULL REFERENCES users(id),
    is_active BOOLEAN NOT NULL DEFAULT TRUE,
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE courses (
    id BIGSERIAL PRIMARY KEY,
    organization_id BIGINT NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
    instructor_id BIGINT NOT NULL REFERENCES users(id),
    title TEXT NOT NULL,
    description TEXT,
    level TEXT,
    language TEXT,
    is_published BOOLEAN NOT NULL DEFAULT FALSE,
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE course_modules (
    id BIGSERIAL PRIMARY KEY,
    course_id BIGINT NOT NULL REFERENCES courses(id) ON DELETE CASCADE,
    title TEXT NOT NULL,
    position INT NOT NULL,
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE lessons (
    id BIGSERIAL PRIMARY KEY,
    module_id BIGINT NOT NULL REFERENCES course_modules(id) ON DELETE CASCADE,
    title TEXT NOT NULL,
    content_type TEXT NOT NULL, -- video, article, quiz
    content_url TEXT,
    duration_minutes INT,
    position INT NOT NULL,
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE enrollments (
    id BIGSERIAL PRIMARY KEY,
    course_id BIGINT NOT NULL REFERENCES courses(id) ON DELETE CASCADE,
    student_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    enrolled_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    completed_at TIMESTAMPTZ,
    UNIQUE (course_id, student_id)
);

CREATE TABLE lesson_progress (
    id BIGSERIAL PRIMARY KEY,
    lesson_id BIGINT NOT NULL REFERENCES lessons(id) ON DELETE CASCADE,
    student_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    completed BOOLEAN NOT NULL DEFAULT FALSE,
    completed_at TIMESTAMPTZ,
    UNIQUE (lesson_id, student_id)
);

CREATE TABLE assessments (
    id BIGSERIAL PRIMARY KEY,
    course_id BIGINT NOT NULL REFERENCES courses(id) ON DELETE CASCADE,
    title TEXT NOT NULL,
    type TEXT NOT NULL, -- quiz, assignment
    total_score INT NOT NULL,
    due_date TIMESTAMPTZ,
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE assessment_submissions (
    id BIGSERIAL PRIMARY KEY,
    assessment_id BIGINT NOT NULL REFERENCES assessments(id) ON DELETE CASCADE,
    student_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    score INT,
    feedback TEXT,
    submitted_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    graded_at TIMESTAMPTZ,
    UNIQUE (assessment_id, student_id)
);

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 organization_settings (
    organization_id BIGINT NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
    key TEXT NOT NULL,
    value TEXT NOT NULL,
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (organization_id, key)
);

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
);