CSV Rewriting script

We need a script to retrieve an external CSV data feed which has the incorrect header fields, and recreate it with the correct header fields and perform a simple change on one field. The script will be Cron triggered daily. Approx lines of data to process: 2500 This is the process of the script. 1. Fetch an external source file url which is a CSV file with one header line. 2. To rewrite, copying the content of the source file, saved locally as a CSV. Rename the column headers into Virtuemart table names. 3. Perform a calculation to increase the price value by a predefined % markup Source Header example: code,name,short desc,category,price; 112,Shovel,Metal shovel,Tools,10; Converted to: product_sku,product_name,product_s_desc,category_name,product_price; 112,Shovel,Metal shovel,Tools,15;