-- Course Announcements System
-- Allows instructors to post announcements to students with automatic notifications

CREATE TABLE IF NOT EXISTS course_announcements (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    organization_id UUID NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
    course_id UUID NOT NULL REFERENCES courses(id) ON DELETE CASCADE,
    author_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    title TEXT NOT NULL,
    content TEXT NOT NULL,
    is_pinned BOOLEAN DEFAULT false,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

-- Indexes for performance
CREATE INDEX idx_announcements_course ON course_announcements(course_id);
CREATE INDEX idx_announcements_org ON course_announcements(organization_id);
CREATE INDEX idx_announcements_pinned ON course_announcements(is_pinned, created_at DESC);

-- Trigger to update updated_at timestamp
CREATE OR REPLACE FUNCTION update_announcement_timestamp()
RETURNS TRIGGER AS $$
BEGIN
    NEW.updated_at = NOW();
    RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER announcement_updated_at
    BEFORE UPDATE ON course_announcements
    FOR EACH ROW
    EXECUTE FUNCTION update_announcement_timestamp();