product_inventory/docs/ARCHITECTURE.md

Architecture Documentation

System Overview

This project serves as a bridge between Google Sheets and Shopify. It enables a two-way sync (primarily Sheets to Shopify for products) and allows managing inventory directly from a spreadsheet.

Core Flows

1. Product Updates:

   • User edits a cell in the "product_inventory" sheet.
   • onEditQueue trigger fires, capturing the SKU and timestamp.
   • Edits are batched in PropertiesService (script properties).
   • A time-based trigger runs processBatchedEdits every minute.
   • The processing function locks the script, reads the queue, and pushes changes to Shopify via the Admin API.

2. Order Sync:

   • Users can run menu commands to fetch orders from Shopify.
   • The Shop class fetches orders via the REST API, handling pagination.
   • Data is populated into specific sheets (_orders, _line_items, _customer, etc.).

Key Components

1. Queue System (src/onEditQueue.ts)

To avoid hitting Shopify API rate limits and Google Apps Script execution time limits, edits are not processed immediately.

• onEditQueue(e):

  • Triggered on every cell edit.
  • Checks if the edit is valid (correct sheet, valid SKU).
  • Acquires a DocumentLock.
  • Updates a JSON list in ScriptProperties (pendingEdits).
  • Debounces edits (updates timestamp if SKU is already pending).

• processBatchedEdits():

  • Run via time-based trigger (every 1 minute).
  • Acquires a ScriptLock.
  • Reads pendingEdits.
  • Filters for edits older than BATCH_INTERVAL_MS (30s) to allow for multiple quick edits to the same SKU.
  • Iterates through valid edits and calls Product.UpdateShopifyProduct.

2. Shopify Integration (src/shopifyApi.ts)

The project uses a hybrid approach for the Shopify Admin API:

• REST API: Used primarily for fetching Orders (legacy support).
• GraphQL API: Used for fetching and updating Products and Inventory.

The Shop class handles authentication using credentials stored in the "vars" sheet.

3. Configuration (src/config.ts)

Configuration, including API keys, is stored in a dedicated Google Sheet named "vars". The Config class reads these values at runtime using a vlookup style helper.

Required "vars" columns:

• key: The name of the configuration variable.
• value: The actual value.

4. Global Entry Points (src/global.ts)

Since Apps Script functions must be top-level to be triggered or attached to buttons, src/global.ts explicitly exposes necessary functions from the modules to the global scope.

Triggers

Triggers are managed programmatically via src/triggers.ts. Running reinstallTriggers will wipe existing project triggers and set up the standard set:

• onEdit -> newSkuHandler
• onEdit -> matchProductToShopifyOnEditHandler
• onEdit -> onEditQueue
• TimeBased (1 min) -> processBatchedEdits