Add forecasting page

inventory-server/db/metrics-schema.sql

@@ -18,6 +18,7 @@ CREATE TABLE IF NOT EXISTS temp_purchase_metrics (
     product_id BIGINT NOT NULL,
     avg_lead_time_days INT,
     last_purchase_date DATE,
+    first_received_date DATE,
     last_received_date DATE,
     PRIMARY KEY (product_id)
 );
@@ -51,6 +52,7 @@ CREATE TABLE IF NOT EXISTS product_metrics (
     -- Purchase metrics
     avg_lead_time_days INT,
     last_purchase_date DATE,
+    first_received_date DATE,
     last_received_date DATE,
     -- Classification
     abc_class CHAR(1),
@@ -107,6 +109,23 @@ CREATE TABLE IF NOT EXISTS vendor_metrics (
     INDEX idx_vendor_performance (on_time_delivery_rate)
 );
 
+-- New table for category-based sales metrics
+CREATE TABLE IF NOT EXISTS category_sales_metrics (
+    category_id BIGINT NOT NULL,
+    brand VARCHAR(100) NOT NULL,
+    period_start DATE NOT NULL,
+    period_end DATE NOT NULL,
+    avg_daily_sales DECIMAL(10,3) DEFAULT 0,
+    total_sold INT DEFAULT 0,
+    num_products INT DEFAULT 0,
+    avg_price DECIMAL(10,3) DEFAULT 0,
+    last_calculated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (category_id, brand, period_start, period_end),
+    FOREIGN KEY (category_id) REFERENCES categories(id) ON DELETE CASCADE,
+    INDEX idx_category_brand (category_id, brand),
+    INDEX idx_period (period_start, period_end)
+);
+
 -- Re-enable foreign key checks
 SET FOREIGN_KEY_CHECKS = 1;
 
@@ -223,4 +242,27 @@ LEFT JOIN
 WHERE 
     o.canceled = false
 GROUP BY 
-    p.product_id, p.SKU, p.title; 
+    p.product_id, p.SKU, p.title; 
+
+-- Create view for category sales trends
+CREATE OR REPLACE VIEW category_sales_trends AS
+SELECT 
+    c.id as category_id,
+    c.name as category_name,
+    p.brand,
+    COUNT(DISTINCT p.product_id) as num_products,
+    COALESCE(AVG(o.quantity), 0) as avg_daily_sales,
+    COALESCE(SUM(o.quantity), 0) as total_sold,
+    COALESCE(AVG(o.price), 0) as avg_price,
+    MIN(o.date) as first_sale_date,
+    MAX(o.date) as last_sale_date
+FROM 
+    categories c
+JOIN 
+    product_categories pc ON c.id = pc.category_id
+JOIN 
+    products p ON pc.product_id = p.product_id
+LEFT JOIN 
+    orders o ON p.product_id = o.product_id AND o.canceled = false
+GROUP BY 
+    c.id, c.name, p.brand;