{
  "Comment": "PDF metadata index pipeline — list keys, then per-key extract + DDB write in parallel.",
  "StartAt": "ListPdfs",
  "States": {
    "ListPdfs": {
      "Type": "Task",
      "Resource": "arn:aws:states:::lambda:invoke",
      "Parameters": {
        "FunctionName": "${ListPdfsFunctionArn}",
        "Payload": {}
      },
      "ResultSelector": {
        "keys.$": "$.Payload.keys",
        "count.$": "$.Payload.count"
      },
      "ResultPath": "$.list",
      "Next": "ExtractAndIndex"
    },
    "ExtractAndIndex": {
      "Type": "Map",
      "ItemsPath": "$.list.keys",
      "MaxConcurrency": 10,
      "ItemProcessor": {
        "ProcessorConfig": {
          "Mode": "INLINE"
        },
        "StartAt": "ExtractMetadata",
        "States": {
          "ExtractMetadata": {
            "Type": "Task",
            "Resource": "arn:aws:states:::lambda:invoke",
            "Parameters": {
              "FunctionName": "${ExtractMetadataFunctionArn}",
              "Payload": {
                "key.$": "$"
              }
            },
            "ResultSelector": {
              "key.$": "$.Payload.key",
              "pages.$": "$.Payload.pages",
              "size_bytes.$": "$.Payload.size_bytes"
            },
            "Retry": [
              {
                "ErrorEquals": ["States.ALL"],
                "IntervalSeconds": 1,
                "MaxAttempts": 2,
                "BackoffRate": 2.0
              }
            ],
            "Next": "WriteToIndex"
          },
          "WriteToIndex": {
            "Type": "Task",
            "Resource": "arn:aws:states:::dynamodb:putItem",
            "Parameters": {
              "TableName": "${PdfIndexTableName}",
              "Item": {
                "key":        { "S.$": "$.key" },
                "pages":      { "N.$": "States.Format('{}', $.pages)" },
                "size_bytes": { "N.$": "States.Format('{}', $.size_bytes)" }
              }
            },
            "End": true
          }
        }
      },
      "End": true
    }
  }
}