-- Create comments table
CREATE TABLE IF NOT EXISTS comments (
    id SERIAL PRIMARY KEY,
    item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE,
    user_id INTEGER NOT NULL REFERENCES "user"(id) ON DELETE CASCADE,
    parent_id INTEGER REFERENCES comments(id) ON DELETE SET NULL,
    content TEXT NOT NULL,
    is_deleted BOOLEAN DEFAULT FALSE,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    updated_at TIMESTAMP WITH TIME ZONE,
    vote_score INTEGER DEFAULT 0
);

-- Create notifications table
CREATE TABLE IF NOT EXISTS notifications (
    id SERIAL PRIMARY KEY,
    user_id INTEGER NOT NULL REFERENCES "user"(id) ON DELETE CASCADE,
    type VARCHAR(32) NOT NULL, -- 'reply', 'comment', 'mention'
    reference_id INTEGER NOT NULL, -- ID of the comment
    item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE,
    is_read BOOLEAN DEFAULT FALSE,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
);

-- Create comment_subscriptions table (for subscribing to posts)
CREATE TABLE IF NOT EXISTS comment_subscriptions (
    user_id INTEGER NOT NULL REFERENCES "user"(id) ON DELETE CASCADE,
    item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    PRIMARY KEY (user_id, item_id)
);

-- Indexes for performance
CREATE INDEX idx_comments_item_id ON comments(item_id);
CREATE INDEX idx_comments_user_id ON comments(user_id);
CREATE INDEX idx_notifications_user_id ON notifications(user_id);
CREATE INDEX idx_notifications_unread ON notifications(user_id) WHERE is_read = FALSE;