-- ============================================================================
-- Migration 070: Product Variants Tables
-- ============================================================================
--
-- Purpose: Store variant-level pricing and inventory as first-class entities
--          to enable time-series analytics, price comparisons, and sale tracking.
--
-- Enables queries like:
--   - Price history for a specific variant (1g Blue Dream over time)
--   - Sale frequency analysis (how often is this on special?)
--   - Cross-store price comparison (who has cheapest 1g flower?)
--   - Current specials across all stores
--
-- RULES:
--   - STRICTLY ADDITIVE (no DROP, DELETE, TRUNCATE)
--   - All new tables use IF NOT EXISTS
--   - All indexes use IF NOT EXISTS
--
-- ============================================================================

-- ============================================================================
-- SECTION 1: PRODUCT_VARIANTS TABLE (Current State)
-- ============================================================================
-- One row per product+option combination. Tracks current pricing/inventory.

CREATE TABLE IF NOT EXISTS product_variants (
    id SERIAL PRIMARY KEY,
    store_product_id INTEGER NOT NULL REFERENCES store_products(id) ON DELETE CASCADE,
    dispensary_id INTEGER NOT NULL REFERENCES dispensaries(id) ON DELETE CASCADE,

    -- Variant identity (from Dutchie POSMetaData.children)
    option VARCHAR(100) NOT NULL,              -- "1g", "3.5g", "1/8oz", "100mg"
    canonical_sku VARCHAR(100),                -- Dutchie canonicalSKU
    canonical_id VARCHAR(100),                 -- Dutchie canonicalID
    canonical_name VARCHAR(500),               -- Dutchie canonicalName

    -- Current pricing (in dollars, not cents)
    price_rec NUMERIC(10,2),
    price_med NUMERIC(10,2),
    price_rec_special NUMERIC(10,2),
    price_med_special NUMERIC(10,2),

    -- Current inventory
    quantity INTEGER,
    quantity_available INTEGER,
    in_stock BOOLEAN DEFAULT TRUE,

    -- Special/sale status
    is_on_special BOOLEAN DEFAULT FALSE,

    -- Weight/size parsing (for analytics)
    weight_value NUMERIC(10,2),               -- 1, 3.5, 28, etc.
    weight_unit VARCHAR(20),                  -- g, oz, mg, ml, etc.

    -- Timestamps
    first_seen_at TIMESTAMPTZ DEFAULT NOW(),
    last_seen_at TIMESTAMPTZ DEFAULT NOW(),
    last_price_change_at TIMESTAMPTZ,
    last_stock_change_at TIMESTAMPTZ,

    created_at TIMESTAMPTZ DEFAULT NOW(),
    updated_at TIMESTAMPTZ DEFAULT NOW(),

    UNIQUE(store_product_id, option)
);

-- Indexes for common queries
CREATE INDEX IF NOT EXISTS idx_variants_store_product ON product_variants(store_product_id);
CREATE INDEX IF NOT EXISTS idx_variants_dispensary ON product_variants(dispensary_id);
CREATE INDEX IF NOT EXISTS idx_variants_option ON product_variants(option);
CREATE INDEX IF NOT EXISTS idx_variants_in_stock ON product_variants(dispensary_id, in_stock) WHERE in_stock = TRUE;
CREATE INDEX IF NOT EXISTS idx_variants_on_special ON product_variants(dispensary_id, is_on_special) WHERE is_on_special = TRUE;
CREATE INDEX IF NOT EXISTS idx_variants_canonical_sku ON product_variants(canonical_sku) WHERE canonical_sku IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_variants_price_rec ON product_variants(price_rec) WHERE price_rec IS NOT NULL;

COMMENT ON TABLE product_variants IS 'Current state of each product variant (weight/size option). One row per product+option.';
COMMENT ON COLUMN product_variants.option IS 'Weight/size option string from Dutchie (e.g., "1g", "3.5g", "1/8oz")';
COMMENT ON COLUMN product_variants.canonical_sku IS 'Dutchie POS SKU for cross-store matching';


-- ============================================================================
-- SECTION 2: PRODUCT_VARIANT_SNAPSHOTS TABLE (Historical Data)
-- ============================================================================
-- Time-series data for variant pricing. One row per variant per crawl.
-- CRITICAL: NEVER DELETE from this table.

CREATE TABLE IF NOT EXISTS product_variant_snapshots (
    id SERIAL PRIMARY KEY,
    product_variant_id INTEGER NOT NULL REFERENCES product_variants(id) ON DELETE CASCADE,
    store_product_id INTEGER REFERENCES store_products(id) ON DELETE SET NULL,
    dispensary_id INTEGER NOT NULL REFERENCES dispensaries(id) ON DELETE CASCADE,
    crawl_run_id INTEGER REFERENCES crawl_runs(id) ON DELETE SET NULL,

    -- Variant identity (denormalized for query performance)
    option VARCHAR(100) NOT NULL,

    -- Pricing at time of capture
    price_rec NUMERIC(10,2),
    price_med NUMERIC(10,2),
    price_rec_special NUMERIC(10,2),
    price_med_special NUMERIC(10,2),

    -- Inventory at time of capture
    quantity INTEGER,
    in_stock BOOLEAN DEFAULT TRUE,

    -- Special status at time of capture
    is_on_special BOOLEAN DEFAULT FALSE,

    -- Feed presence (FALSE = variant missing from crawl)
    is_present_in_feed BOOLEAN DEFAULT TRUE,

    -- Capture timestamp
    captured_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    created_at TIMESTAMPTZ DEFAULT NOW()
);

-- Indexes for time-series queries
CREATE INDEX IF NOT EXISTS idx_variant_snapshots_variant ON product_variant_snapshots(product_variant_id, captured_at DESC);
CREATE INDEX IF NOT EXISTS idx_variant_snapshots_dispensary ON product_variant_snapshots(dispensary_id, captured_at DESC);
CREATE INDEX IF NOT EXISTS idx_variant_snapshots_crawl ON product_variant_snapshots(crawl_run_id) WHERE crawl_run_id IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_variant_snapshots_captured ON product_variant_snapshots(captured_at DESC);
CREATE INDEX IF NOT EXISTS idx_variant_snapshots_special ON product_variant_snapshots(is_on_special, captured_at DESC) WHERE is_on_special = TRUE;
CREATE INDEX IF NOT EXISTS idx_variant_snapshots_option ON product_variant_snapshots(option, captured_at DESC);

COMMENT ON TABLE product_variant_snapshots IS 'Historical variant pricing/inventory. One row per variant per crawl. NEVER DELETE.';


-- ============================================================================
-- SECTION 3: USEFUL VIEWS
-- ============================================================================

-- View: Current specials across all stores
CREATE OR REPLACE VIEW v_current_specials AS
SELECT
    pv.id as variant_id,
    sp.id as product_id,
    sp.name_raw as product_name,
    sp.brand_name_raw as brand_name,
    sp.category_raw as category,
    d.id as dispensary_id,
    d.name as dispensary_name,
    d.city,
    d.state,
    pv.option,
    pv.price_rec,
    pv.price_rec_special,
    ROUND(((pv.price_rec - pv.price_rec_special) / NULLIF(pv.price_rec, 0)) * 100, 1) as discount_percent,
    pv.quantity,
    pv.in_stock,
    pv.last_seen_at
FROM product_variants pv
JOIN store_products sp ON sp.id = pv.store_product_id
JOIN dispensaries d ON d.id = pv.dispensary_id
WHERE pv.is_on_special = TRUE
  AND pv.in_stock = TRUE
  AND pv.price_rec_special IS NOT NULL
  AND pv.price_rec_special < pv.price_rec;

COMMENT ON VIEW v_current_specials IS 'All products currently on special across all stores';


-- View: Price comparison for a product across stores
CREATE OR REPLACE VIEW v_price_comparison AS
SELECT
    sp.name_raw as product_name,
    sp.brand_name_raw as brand_name,
    sp.category_raw as category,
    pv.option,
    d.id as dispensary_id,
    d.name as dispensary_name,
    d.city,
    pv.price_rec,
    pv.price_rec_special,
    pv.is_on_special,
    pv.in_stock,
    pv.quantity,
    RANK() OVER (PARTITION BY sp.name_raw, pv.option ORDER BY COALESCE(pv.price_rec_special, pv.price_rec) ASC) as price_rank
FROM product_variants pv
JOIN store_products sp ON sp.id = pv.store_product_id
JOIN dispensaries d ON d.id = pv.dispensary_id
WHERE pv.in_stock = TRUE
  AND (pv.price_rec IS NOT NULL OR pv.price_rec_special IS NOT NULL);

COMMENT ON VIEW v_price_comparison IS 'Compare prices for same product across stores, ranked by price';


-- View: Latest snapshot per variant
CREATE OR REPLACE VIEW v_latest_variant_snapshots AS
SELECT DISTINCT ON (product_variant_id)
    pvs.*
FROM product_variant_snapshots pvs
ORDER BY product_variant_id, captured_at DESC;


-- ============================================================================
-- SECTION 4: HELPER FUNCTION FOR SALE FREQUENCY
-- ============================================================================

-- Function to calculate sale frequency for a variant
CREATE OR REPLACE FUNCTION get_variant_sale_stats(p_variant_id INTEGER, p_days INTEGER DEFAULT 30)
RETURNS TABLE (
    total_snapshots BIGINT,
    times_on_special BIGINT,
    special_frequency_pct NUMERIC,
    avg_discount_pct NUMERIC,
    min_price NUMERIC,
    max_price NUMERIC,
    avg_price NUMERIC
) AS $$
BEGIN
    RETURN QUERY
    SELECT
        COUNT(*)::BIGINT as total_snapshots,
        COUNT(*) FILTER (WHERE is_on_special)::BIGINT as times_on_special,
        ROUND((COUNT(*) FILTER (WHERE is_on_special)::NUMERIC / NULLIF(COUNT(*), 0)) * 100, 1) as special_frequency_pct,
        ROUND(AVG(
            CASE WHEN is_on_special AND price_rec_special IS NOT NULL AND price_rec IS NOT NULL
            THEN ((price_rec - price_rec_special) / NULLIF(price_rec, 0)) * 100
            END
        ), 1) as avg_discount_pct,
        MIN(COALESCE(price_rec_special, price_rec)) as min_price,
        MAX(price_rec) as max_price,
        ROUND(AVG(COALESCE(price_rec_special, price_rec)), 2) as avg_price
    FROM product_variant_snapshots
    WHERE product_variant_id = p_variant_id
      AND captured_at >= NOW() - (p_days || ' days')::INTERVAL;
END;
$$ LANGUAGE plpgsql;

COMMENT ON FUNCTION get_variant_sale_stats IS 'Get sale frequency and price stats for a variant over N days';


-- ============================================================================
-- DONE
-- ============================================================================

SELECT 'Migration 070 completed. Product variants tables ready for time-series analytics.' AS status;