{
  "$schema": "https://json-schema.org/draft-07/schema",
  "$defs": {
    "collection_spec": {
      "type": "object",
      "properties": {
        "header": {"type": "object"},
        "charts": {
          "type": "array",
          "items": {
            "oneOf": [ {"$ref": "#/$defs/chart_spec"}, {"type": "string"} ]
          },
          "default": []
        }
      },
      "required": ["charts"]
    },
    "chart_spec": {
      "type": "object",
      "properties": {
        "header": {
          "type": "object",
          "properties": {
            "metadata": {
              "type": "object",
              "properties": {
                "htmltitle"   : {"type": "string",  "default": ""},
                "title"       : {"type": "string",  "default": ""},
                "displaytitle": {"type": "string",  "default": ""},
                "id"          : {"type": "integer"               }
              }
            },
            "coordinates": {
              "type": ["null", "integer", "array"],
              "default": null,
              "items": {"type": "integer"},
              "minLength": 0,
              "maxLength": 2
            },
            "chart": {
              "type": "object",
              "properties": {
                "width"      : {"$ref": "#/$defs/dimensionRange"},
                "height"     : {"$ref": "#/$defs/dimensionRange"},
                "scale"      : {"type": "number", "default": 60.00},
                "nodeSize"   : {"type": "number", "default": 0.04},
                "nodeSpacing": {"type": "number", "default": 0.02},
                "nodeSlope"  : { "type": ["number", "null"], "default": 0.00 }
              },
              "additionalProperties": false
            },
            "aliases": {
              "type": "object",
              "properties": {
                "colors": {
                  "type": "object",
                  "properties": {
                    "backgroundColor": {"type": "string", "default": "white"},
                    "borderColor"    : {"type": "string", "default": "black"},
                    "textColor"      : {"type": "string", "default": "black"}
                  },
                  "additionalProperties": {"type": "string"},
                  "default": {}
                },
                "attributes": {
                  "type": "object",
                  "properties": {
                    "grid": {
                      "$ref": "#/$defs/attributes",
                      "default": [ {"color": "#ccc", "thickness": 0.01} ]
                    },
                    "defaultNode": {
                      "$ref": "#/$defs/attributes",
                      "default": [ {"color": "black"} ]
                    },
                    "defaultEdge": {
                      "$ref": "#/$defs/attributes",
                      "default": [ {"color": "black", "thickness": 0.02} ]
                    }
                  },
                  "additionalProperties": {"$ref": "#/$defs/attributes"},
                  "default": {}
                }
              },
              "additionalProperties": false
            }
          },
          "additionalProperties": false
        },
        "nodes": {
          "type": "object",
          "additionalProperties": {
            "type": "object",
            "properties": {
              "x"         : {"type": "integer"},
              "absoluteX" : {"type": "number"},
              "y"         : {"type": "integer"},
              "absoluteY" : {"type": "number"},
              "position"  : {"type": "integer", "default": 0},
              "label"     : {"type": "string"},
              "attributes": {"$ref": "#/$defs/attributes"}
            },
            "allOf": [
              {
                "oneOf": [
                  { "required": ["x"        ] },
                  { "required": ["absoluteX"] }
                ]
              },
              {
                "oneOf": [
                  { "required": ["y"        ] },
                  { "required": ["absoluteY"] }
                ]
              }
            ],
            "additionalProperties": false
          }
        },
        "edges": {
          "type": "array",
          "items": {
            "type": "object",
            "properties": {
              "source": {"type": "string"},
              "target": {"type": "string"},
              "offset": {
                "type": ["object"],
                "description": "The endpoint of the edge relative to its source",
                "properties": {
                  "x": {"type": "number"},
                  "y": {"type": "number"}
                },
                "required": ["x", "y"]
              },
              "label": {"type": "string"},
              "bezier": {
                "type": "array",
                "items": {
                  "type": "object",
                  "properties": {
                    "x": {"type": "number"},
                    "y": {"type": "number"}
                  },
                  "required": ["x", "y"]
                },
                "minLength": 1,
                "maxLength": 2
              },
              "attributes": {"$ref": "#/$defs/attributes"}
            },
            "required": ["source"],
            "oneOf": [
              { "required": ["target"] },
              { "required": ["offset"] }
            ],
            "additionalProperties": false
          }
        }
      }
    },
    "attributes": {
      "type": "array",
      "items": {
        "type": ["string", "object"],
        "properties": {
          "color"    : {"type": "string"},
          "size"     : {"type": "number"},
          "thickness": {"type": "number"},
          "arrowTip" : { "enum": ["simple", "none"] },
          "pattern"  : { "enum": ["solid", "dashed", "dotted"] }
        },
        "additionalProperties": {"type": "string"}
      },
      "default": []
    },
    "dimensionRange": {
      "type": "object",
      "properties": {
        "min": { "type": ["integer", "null"] },
        "max": { "type": ["integer", "null"] }
      }
    }
  },
  "anyOf": [
    {"$ref": "#/$defs/chart_spec"     },
    {"$ref": "#/$defs/collection_spec"}
  ]
}