Auto-sort collections by product properties, with Mechanic.

mechanic/user/trigger
user/collection_sort/process
user/collection_sort/complete
{% if options.run_hourly__boolean %}
  mechanic/scheduler/hourly
{% elsif options.run_daily__boolean %}
  mechanic/scheduler/daily
{% endif %}

{% assign product_property_lookups = options.product_property_lookups__array_required %}
{% assign only_sort_these_collections = options.only_sort_these_collections__array %}
{% assign reverse_sort = options.reverse_sort__boolean %}

{% if event.topic == "mechanic/user/trigger" or event.topic contains "mechanic/scheduler/" %}
  {% comment %}
    -- get IDs for all manually sorted collections, optionally restricted to specific collections by ID or title
  {% endcomment %}

  {% assign collection_ids_to_sort = array %}
  {% assign cursor = nil %}

  {% for n in (1..50) %}
    {% capture query %}
      query {
        collections(
          first: 250
          after: {{ cursor | json }}
          query: {{ search_query | json }}
        ) {
          pageInfo {
            hasNextPage
            endCursor
          }
          nodes {
            legacyResourceId
            sortOrder
            title
          }
        }
      }
    {% endcapture %}

    {% assign result = query | shopify %}

    {% if event.preview %}
      {% capture result_json %}
        {
          "data": {
            "collections": {
              "nodes": [
                {
                  "legacyResourceId": "1234567890",
                  "sortOrder": "MANUAL"
                }
              ]
            }
          }
        }
      {% endcapture %}

      {% assign result = result_json | parse_json %}
    {% endif %}

    {% for collection in result.data.collections.nodes %}
      {% if only_sort_these_collections != blank %}
        {% unless only_sort_these_collections contains collection.legacyResourceId
          or only_sort_these_collections contains collection.title
          or event.preview
        %}
          {% continue %}
        {% endunless %}
      {% endif %}

      {% if collection.sortOrder != "MANUAL" %}
        {% log
          message: "Collection is not configured for manual sorting; skipping.",
          collection: collection
        %}
        {% continue %}
      {% endif %}

      {% assign collection_ids_to_sort = collection_ids_to_sort | push: collection.legacyResourceId %}
    {% endfor %}

    {% if result.data.collections.pageInfo.hasNextPage %}
      {% assign cursor = result.data.collections.pageInfo.endCursor %}
    {% else %}
      {% break %}
    {% endif %}
  {% endfor %}

  {% if collection_ids_to_sort == blank %}
    {% log "No collections qualified to be sorted on this task run." %}
    {% break %}
  {% endif %}

  {% comment %}
    -- save the qualified collection IDs to the cache for lookup in later child events
    -- NOTE: using event ID instead of task ID in case one instance of this task runs concurrent with another
  {% endcomment %}

  {% assign cache_key = event.id | prepend: "collection_ids_to_sort_" %}
  {% action "cache", "set", cache_key, collection_ids_to_sort %}

  {% log
    message: "Begin processing collections loop using sequential child events.",
    total_collections_to_sort: collection_ids_to_sort.size
  %}

  {% action "event" %}
    {
      "topic": "user/collection_sort/process",
      "task_id": {{ task.id | json }},
      "data": {
        "cache_key": {{ cache_key | json }},
        "cache_index": 0
      }
    }
  {% endaction %}

{% elsif event.topic == "user/collection_sort/process" %}
  {% assign cache_key = event.data.cache_key %}
  {% assign cache_index = event.data.cache_index %}
  {% assign collection_ids_to_sort = cache[cache_key] %}
  {% assign collection_id = collection_ids_to_sort[cache_index] %}
  {% assign collection = shop.collections[collection_id] %}

  {% if event.preview %}
    {% comment %}
      -- use stub data instead of a preview event to incorporate the configured product properties
    {% endcomment %}

    {% assign product_ids = array | push: "1234567890", "3456789012", "2345678901" %}
    {% assign products = array %}

    {% for product_id in product_ids %}
      {% assign product = hash %}

      {% for lookup in product_property_lookups reversed %}
        {% if forloop.first %}
          {% assign product[lookup] = product_id %}

        {% else %}
          {% assign temp = product %}
          {% assign product = hash %}
          {% assign product[lookup] = temp %}
        {% endif %}
      {% endfor %}

      {% assign product["id"] = product_id %}
      {% assign product["admin_graphql_api_id"] = "gid://shopify/Product/" | append: product_id %}
      {% assign products[products.size] = product %}
    {% endfor %}

    {% capture collection_json %}
      {
        "title": {{ only_sort_these_collections[0] | default: "Some collection" | json }},
        "admin_graphql_api_id": "gid://shopify/Collection/1234567890",
        "products": {{ products | json }}
      }
    {% endcapture %}

    {% assign collection = collection_json | parse_json %}
  {% endif %}

  {% comment %}
    -- process products using REST resources to align with configured product properties
  {% endcomment %}

  {% assign moves = array %}
  {% assign product_ids_and_positions = hash %}
  {% assign product_ids_and_values = array %}

  {% for product in collection.products %}
    {% assign product_ids_and_positions[product.admin_graphql_api_id] = forloop.index0 %}

    {% assign product_id_and_value = hash %}
    {% assign product_id_and_value["id"] = product.admin_graphql_api_id %}

    {% assign value = product %}

    {% for lookup in options.product_property_lookups__array_required %}
      {% comment %}
        -- NOTE: command methods (size, first, last) can only be invoked via dot notation
      {% endcomment %}

      {% case lookup %}
        {% when "size" %}
          {% assign value = value.size %}
        {% when "first" %}
          {% assign value = value.first %}
        {% when "last" %}
          {% assign value = value.last %}
        {% else %}
          {% assign value = value[lookup] %}
      {% endcase %}
    {% endfor %}

    {% comment %}
      -- make sure this is always a serializable/sortable object, defaulting to nil in the case of an empty string so that SKU values which are *either* nil or an empty string always end up at the end of the list.
    {% endcomment %}

    {% assign product_id_and_value["value"] = value | json | parse_json | default: nil %}

    {% assign product_ids_and_values[product_ids_and_values.size] = product_id_and_value %}
  {% endfor %}

  {% assign sorted_product_values = product_ids_and_values | sort: "value" %}
  {% assign sorted_product_ids = product_ids_and_values | sort: "value" | map: "id" %}

  {% if reverse_sort %}
    {% assign sorted_product_ids = sorted_product_ids | reverse %}
  {% endif %}

  {% comment %}
    -- determine the moves necessary to place products in their sorted positions
  {% endcomment %}

  {% for sorted_product_id in sorted_product_ids %}
    {% if forloop.index0 != product_ids_and_positions[sorted_product_id] %}
      {% assign move = hash %}
      {% assign move["id"] = sorted_product_id %}
      {% assign move["newPosition"] = "" | append: forloop.index0 %}
      {% assign moves[moves.size] = move %}
    {% endif %}
  {% endfor %}

  {% if moves == blank %}
    {% log
      message: "No moves necessary for this collection, everything is already in its appropriate sort order.",
      collection: collection.title
    %}

  {% else %}
    {% log
      message: "Collection requires sorting.",
      collection: collection.title
    %}

    {% assign moves_in_groups = moves | in_groups_of: 250, fill_with: false %}

    {% for move_group in moves_in_groups %}
      {% action "shopify" %}
        mutation {
          collectionReorderProducts(
            id: {{ collection.admin_graphql_api_id | json }}
            moves: {{ move_group | graphql_arguments }}
          ) {
            userErrors {
              field
              message
            }
          }
        }
      {% endaction %}
    {% endfor %}
  {% endif %}

  {% assign new_cache_index = cache_index | plus: 1 %}

  {% log
    collections_seen: new_cache_index,
    total_collections_to_sort: collection_ids_to_sort.size
  %}

  {% comment %}
    -- process next collection in the cache if there is one
  {% endcomment %}

  {% if new_cache_index < collection_ids_to_sort.size %}
    {% action "event" %}
      {
        "topic": "user/collection_sort/process",
        "task_id": {{ task.id | json }},
        "data": {
          "cache_key": {{ cache_key | json }},
          "cache_index": {{ new_cache_index }}
        }
      }
    {% endaction %}

  {% else %}
    {% comment %}
      -- use a distinct user event to indicate the entire task run is complete, so it can be filtered in the event log
    {% endcomment %}

    {% action "event" %}
      {
        "topic": "user/collection_sort/complete",
        "task_id": {{ task.id | json }},
        "data": {
          "cache_key": {{ cache_key | json }},
          "cache_index": {{ new_cache_index }}
        }
      }
    {% endaction %}
  {% endif %}

{% elsif event.topic == "user/collection_sort/complete" %}
  {% assign cache_key = event.data.cache_key %}
  {% assign cache_index = event.data.cache_index %}

  {% log
    message: "Collection sorting complete. Deleting cached collection IDs.",
    collections_seen: cache_index
  %}

  {% action "cache", "del", cache_key %}
{% endif %}