-- Create invite_codes table
CREATE TABLE invite_codes (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    code VARCHAR(20) NOT NULL UNIQUE,
    created_by UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    used_by UUID REFERENCES users(id) ON DELETE SET NULL,
    is_used BOOLEAN NOT NULL DEFAULT FALSE,
    expires_at TIMESTAMPTZ,
    created_at TIMESTAMPTZ DEFAULT NOW(),
    used_at TIMESTAMPTZ
);

-- Create indexes for better performance
CREATE INDEX idx_invite_codes_code ON invite_codes(code);
CREATE INDEX idx_invite_codes_created_by ON invite_codes(created_by);
CREATE INDEX idx_invite_codes_used_by ON invite_codes(used_by);
CREATE INDEX idx_invite_codes_is_used ON invite_codes(is_used);
CREATE INDEX idx_invite_codes_expires_at ON invite_codes(expires_at);

-- Add invite_code_id column to users table
ALTER TABLE users ADD COLUMN invite_code_id UUID REFERENCES invite_codes(id) ON DELETE SET NULL;

-- Create index on the new column
CREATE INDEX idx_users_invite_code_id ON users(invite_code_id);

-- Create function to generate random invite codes
CREATE OR REPLACE FUNCTION generate_invite_code()
RETURNS VARCHAR(20) AS $$
DECLARE
    chars TEXT := 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
    result VARCHAR(20) := '';
    i INTEGER;
BEGIN
    FOR i IN 1..8 LOOP
        result := result || substr(chars, floor(random() * length(chars))::integer + 1, 1);
    END LOOP;
    RETURN result;
END;
$$ LANGUAGE plpgsql;

-- Create function to create a new invite code
CREATE OR REPLACE FUNCTION create_invite_code(creator_id UUID, expires_in_days INTEGER DEFAULT 30)
RETURNS VARCHAR(20) AS $$
DECLARE
    new_code VARCHAR(20);
    code_exists BOOLEAN;
BEGIN
    LOOP
        new_code := generate_invite_code();
        SELECT EXISTS(SELECT 1 FROM invite_codes WHERE code = new_code) INTO code_exists;
        EXIT WHEN NOT code_exists;
    END LOOP;
    
    INSERT INTO invite_codes (code, created_by, expires_at)
    VALUES (new_code, creator_id, NOW() + (expires_in_days || ' days')::INTERVAL);
    
    RETURN new_code;
END;
$$ LANGUAGE plpgsql;