-- ============================================================================
-- Migration 053: Analytics Engine Indexes
-- ============================================================================
--
-- Purpose: Add indexes optimized for analytics queries on canonical tables.
--          These indexes support price trends, brand penetration, category
--          growth, and state-level analytics.
--
-- SAFETY RULES:
--   - Uses CREATE INDEX IF NOT EXISTS (idempotent)
--   - Uses ADD COLUMN IF NOT EXISTS for helper columns
--   - NO DROP, DELETE, TRUNCATE, or destructive operations
--   - Safe to run multiple times
--
-- Run with:
--   psql "$DATABASE_URL" -f migrations/053_analytics_indexes.sql
--
-- ============================================================================


-- ============================================================================
-- SECTION 1: Helper columns for analytics (if missing)
-- ============================================================================

-- Ensure store_products has brand_id for faster brand analytics joins
-- (brand_name exists, but a normalized brand_id helps)
ALTER TABLE store_products ADD COLUMN IF NOT EXISTS brand_id INTEGER;

-- Ensure snapshots have category for time-series category analytics
ALTER TABLE store_product_snapshots ADD COLUMN IF NOT EXISTS category VARCHAR(100);


-- ============================================================================
-- SECTION 2: Price Analytics Indexes
-- ============================================================================

-- Price trends by store_product over time
CREATE INDEX IF NOT EXISTS idx_snapshots_product_price_time
    ON store_product_snapshots(store_product_id, captured_at DESC, price_rec, price_med)
    WHERE store_product_id IS NOT NULL;

-- Price by category over time (for category price trends)
CREATE INDEX IF NOT EXISTS idx_snapshots_category_price_time
    ON store_product_snapshots(category, captured_at DESC, price_rec)
    WHERE category IS NOT NULL;

-- Price changes detection (for volatility analysis)
CREATE INDEX IF NOT EXISTS idx_products_price_change
    ON store_products(last_price_change_at DESC)
    WHERE last_price_change_at IS NOT NULL;


-- ============================================================================
-- SECTION 3: Brand Penetration Indexes
-- ============================================================================

-- Brand by dispensary (for penetration counts)
CREATE INDEX IF NOT EXISTS idx_products_brand_dispensary
    ON store_products(brand_name, dispensary_id)
    WHERE brand_name IS NOT NULL;

-- Brand by state (for state-level brand analytics)
CREATE INDEX IF NOT EXISTS idx_products_brand_state
    ON store_products(brand_name, state_id)
    WHERE brand_name IS NOT NULL AND state_id IS NOT NULL;

-- Brand first/last seen (for penetration trends)
CREATE INDEX IF NOT EXISTS idx_products_brand_first_seen
    ON store_products(brand_name, first_seen_at)
    WHERE brand_name IS NOT NULL;


-- ============================================================================
-- SECTION 4: Category Analytics Indexes
-- ============================================================================

-- Category by state (for state-level category analytics)
CREATE INDEX IF NOT EXISTS idx_products_category_state
    ON store_products(category, state_id)
    WHERE category IS NOT NULL;

-- Category by dispensary
CREATE INDEX IF NOT EXISTS idx_products_category_dispensary
    ON store_products(category, dispensary_id)
    WHERE category IS NOT NULL;

-- Category first seen (for growth tracking)
CREATE INDEX IF NOT EXISTS idx_products_category_first_seen
    ON store_products(category, first_seen_at)
    WHERE category IS NOT NULL;


-- ============================================================================
-- SECTION 5: Store Analytics Indexes
-- ============================================================================

-- Products added/removed by dispensary
CREATE INDEX IF NOT EXISTS idx_products_dispensary_first_seen
    ON store_products(dispensary_id, first_seen_at DESC);

CREATE INDEX IF NOT EXISTS idx_products_dispensary_last_seen
    ON store_products(dispensary_id, last_seen_at DESC);

-- Stock status changes
CREATE INDEX IF NOT EXISTS idx_products_stock_change
    ON store_products(dispensary_id, last_stock_change_at DESC)
    WHERE last_stock_change_at IS NOT NULL;


-- ============================================================================
-- SECTION 6: State Analytics Indexes
-- ============================================================================

-- Dispensary count by state
CREATE INDEX IF NOT EXISTS idx_dispensaries_state_active
    ON dispensaries(state_id)
    WHERE state_id IS NOT NULL;

-- Products by state
CREATE INDEX IF NOT EXISTS idx_products_state_active
    ON store_products(state_id, is_in_stock)
    WHERE state_id IS NOT NULL;

-- Snapshots by state for time-series
CREATE INDEX IF NOT EXISTS idx_snapshots_state_time
    ON store_product_snapshots(state_id, captured_at DESC)
    WHERE state_id IS NOT NULL;


-- ============================================================================
-- SECTION 7: Composite indexes for common analytics queries
-- ============================================================================

-- Brand + Category + State (for market share calculations)
CREATE INDEX IF NOT EXISTS idx_products_brand_category_state
    ON store_products(brand_name, category, state_id)
    WHERE brand_name IS NOT NULL AND category IS NOT NULL;

-- Dispensary + Category + Brand (for store-level brand analysis)
CREATE INDEX IF NOT EXISTS idx_products_disp_cat_brand
    ON store_products(dispensary_id, category, brand_name)
    WHERE category IS NOT NULL;

-- Special pricing by category (for promo analysis)
CREATE INDEX IF NOT EXISTS idx_products_special_category
    ON store_products(category, is_on_special)
    WHERE is_on_special = TRUE;


-- ============================================================================
-- SECTION 8: Verification
-- ============================================================================

SELECT
    'Migration 053 completed successfully.' AS status,
    (SELECT COUNT(*) FROM pg_indexes WHERE indexname LIKE 'idx_products_%') AS product_indexes,
    (SELECT COUNT(*) FROM pg_indexes WHERE indexname LIKE 'idx_snapshots_%') AS snapshot_indexes;