{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id":     "https://civitasconnect.digital/core/pipeline/v1",
  "title":   "CORE Pipeline",
  "description": "A CORE integration pipeline — a directed acyclic graph (DAG) connecting data sources, mapping transformations, and data sinks. Each exported Pipeline document carries '$schema': 'https://civitasconnect.digital/core/pipeline/v1'.\n\nThe 'x-core-ref' annotations on node reference fields (sourceRef, mappingRef, sinkRef) declare that each value is the CORE URN of the referenced artifact; existence is checked by registry-aware services.",
  "type": "object",
  "required": ["$schema", "id", "nodes", "edges"],
  "properties": {
    "$schema": {
      "type": "string",
      "enum": [
        "https://civitasconnect.digital/core/pipeline/v1",
        "https://civitasconnect.digital/core-dataset/v1#/$defs/Pipeline"
      ]
    },
    "id": {
      "type": "string",
      "description": "Versioned CORE URN of this Pipeline.",
      "pattern": "^urn:core:[^:]+:[^:]+:pipeline:[^:]+:[^:]+:[^:]+(:[^:]+)?$"
    },
    "title":       { "type": "string", "description": "Human-readable display name." },
    "description": { "type": "string" },
    "debug": {
      "type": "boolean",
      "description": "When true, MiNiFi emits additional debug log events.",
      "default": false
    },
    "nodes": {
      "type": "array",
      "description": "Ordered list of pipeline nodes.",
      "items": { "$ref": "#/$defs/PipelineNode" }
    },
    "edges": {
      "type": "array",
      "description": "Connections between nodes.",
      "items": { "$ref": "#/$defs/PipelineEdge" }
    }
  },
  "$defs": {
    "Position": {
      "description": "Visual position in the pipeline canvas (x/y coordinates in pixels).",
      "type": "object",
      "properties": {
        "x": { "type": "number" },
        "y": { "type": "number" }
      }
    },
    "PipelineNode": {
      "description": "Discriminated union of all pipeline node types. The 'kind' property selects the concrete type.",
      "oneOf": [
        { "$ref": "#/$defs/StartNode"   },
        { "$ref": "#/$defs/EndNode"     },
        { "$ref": "#/$defs/CronNode"    },
        { "$ref": "#/$defs/SourceNode"  },
        { "$ref": "#/$defs/FilterNode"  },
        { "$ref": "#/$defs/EnrichNode"  },
        { "$ref": "#/$defs/MappingNode" },
        { "$ref": "#/$defs/SinkNode"    },
        { "$ref": "#/$defs/SplitNode"   }
      ]
    },
    "PipelineNodeBase": {
      "description": "Common fields shared by all pipeline nodes.",
      "type": "object",
      "required": ["id", "kind"],
      "properties": {
        "id":            { "type": "string" },
        "kind":          { "type": "string" },
        "label":         { "type": "string" },
        "description":   { "type": "string" },
        "x-ui-position": { "$ref": "#/$defs/Position" }
      }
    },
    "StartNode": {
      "description": "Entry point of the pipeline. Exactly one per pipeline.",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "properties": {
            "kind": { "type": "string", "const": "start" }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "EndNode": {
      "description": "Exit point of the pipeline. Exactly one per pipeline.",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "properties": {
            "kind": { "type": "string", "const": "end" }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "CronNode": {
      "description": "Scheduled trigger — fires the pipeline's source on a cron schedule (e.g. a polling SQL source).",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "properties": {
            "kind":           { "type": "string", "const": "cron" },
            "cronExpression": { "type": "string", "description": "Quartz/NiFi cron expression, e.g. '0 0/5 * * * ?'." },
            "cronPreview":    { "type": "string", "description": "Human-readable schedule preview (editor hint)." }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "SourceNode": {
      "description": "Reads structured data from a DataSource (e.g. MQTT broker).",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "properties": {
            "kind": { "type": "string", "const": "source" },
            "sourceRef": {
              "type": "string",
              "description": "CORE URN of the referenced DataSource.",
              "x-core-ref": { "type": "urn:core:type:DataSource" }
            }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "FilterNode": {
      "description": "Filters events with a boolean expression.",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "required": ["expression"],
          "properties": {
            "kind":       { "type": "string", "const": "filter" },
            "expression": { "type": "string" }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "EnrichNode": {
      "description": "Enriches events through a lookup source.",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "required": ["lookupSourceRef", "lookupKey"],
          "properties": {
            "kind": { "type": "string", "const": "enrich" },
            "lookupSourceRef": {
              "type": "string",
              "description": "CORE URN of the DataSource used for enrichment lookups.",
              "x-core-ref": { "type": "urn:core:type:DataSource" }
            },
            "lookupKey": { "type": "string" }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "MappingNode": {
      "description": "Applies a declarative field mapping to transform the data stream.",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "properties": {
            "kind": { "type": "string", "const": "mapping" },
            "mappingRef": {
              "type": "string",
              "description": "CORE URN of the referenced Mapping.",
              "x-core-ref": { "type": "urn:core:type:Mapping" }
            }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "SinkNode": {
      "description": "Writes transformed data to a DataSink (e.g. SQL database).",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "properties": {
            "kind": { "type": "string", "const": "sink" },
            "sinkRef": {
              "type": "string",
              "description": "CORE URN of the referenced DataSink.",
              "x-core-ref": { "type": "urn:core:type:DataSink" }
            }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "SplitNode": {
      "description": "Splits one incoming flow record into multiple outgoing records.",
      "allOf": [
        { "$ref": "#/$defs/PipelineNodeBase" },
        {
          "type": "object",
          "properties": {
            "kind": { "type": "string", "const": "split" }
          }
        }
      ],
      "unevaluatedProperties": false
    },
    "PipelineEdge": {
      "description": "A directed connection between two pipeline nodes.",
      "type": "object",
      "required": ["id", "source", "target"],
      "properties": {
        "id":     { "type": "string" },
        "source": { "type": "string", "description": "ID of the source node." },
        "target": { "type": "string", "description": "ID of the target node." },
        "label":  { "type": "string" },
        "kind": {
          "type": "string",
          "enum": ["data", "control"],
          "default": "data",
          "description": "'data' edges carry the transformed payload; 'control' edges signal completion."
        }
      }
    }
  }
}