🧾 Personal Invoice Processor

This N8N workflow automates the extraction and organization of personal invoices in Colombia received via Gmail. It includes the following key steps:

🔁 Flow Summary

1. Email Trigger

   • Polls Gmail every 30 minutes for emails with .zip attachments (assumed to contain invoices).
   • Expects ZIP file following DIAN standards.

2. ZIP File Handling

   • Extracts all files.
   • Filters only PDF and XML files for processing.

3. Data Extraction & Processing

   • Uses LangChain Agent + OpenAI (GPT-4o-mini) to extract:
     • Tipo de documento (Factura / Nota Crédito)
     • Número de factura
     • Fecha de emisión (YYYY-MM-DD)
     • NIT emisor y receptor (sin dígito de verificación)
     • Razón social del emisor
     • Subtotal, IVA, Total
     • CUFE
     • Resumen de compra (max 20 words, formatted sentence)

4. Validation

   • Ensures Total = Subtotal + IVA using a calculator node.

5. Storage

   • Uploads the original PDF to Google Drive.
   • Renames the file to: YYYY-MM-DD-NUMERO_FACTURA.pdf.
   • Inserts or updates invoice details in Google Sheets using a unique Key (NIT_Emisor + Numero_Factura) to prevent duplication.

⚙️ Designed for personal use with minimal latency tolerance and high automation reliability.