-- Migration: Create user_blocked_emails table
-- Purpose: Store blocked email addresses for each user to prevent unwanted sharing
--
-- Rationale for this Cassandra Table Structure:
-- This table is designed around the primary query: "Fetch all email addresses blocked by a specific user."

CREATE TABLE IF NOT EXISTS user_blocked_emails (
    -- PARTITION KEY: This is the first component of the primary key. It determines
    -- data distribution across the cluster. All data for a single user_id will reside
    -- on the same node (and its replicas), making lookups by user_id very fast.
    user_id UUID,

    -- CLUSTERING KEY: This determines the on-disk sorting order of rows within a
    -- partition. For a given user, blocked emails will be stored sorted alphabetically.
    -- This allows for efficient retrieval of sorted data and enables range queries on the email.
    blocked_email TEXT,

    -- Data columns associated with the block action.
    blocked_user_id UUID,
    reason TEXT,
    created_at TIMESTAMP,

    -- The PRIMARY KEY defines how data is stored and retrieved.
    -- The first element (`user_id`) is the Partition Key.
    -- Subsequent elements (`blocked_email`) are Clustering Keys.
    -- The combination of all primary key columns uniquely identifies a row, meaning a
    -- user can block a specific email only once.
    PRIMARY KEY (user_id, blocked_email)
)
-- This clause specifies the on-disk sorting order for the clustering key(s).
-- In this case, blocked emails within each user's partition will be sorted in
-- ascending alphabetical order, which is efficient for display.
WITH CLUSTERING ORDER BY (blocked_email ASC);