{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://www.openhistorymap.org/cited-geojson/0.1/schema.json",
  "title": "Cited GeoJSON 0.1",
  "description": "A GeoJSON FeatureCollection whose features cite the sources they come from. Cross-references (citation.source in sources, citation.file among that source's files, derivedFrom in sources, unique feature ids) are checked by tools/check.py, not by this schema.",
  "type": "object",
  "required": ["type", "features", "conformsTo", "sources"],
  "properties": {
    "type": { "const": "FeatureCollection" },
    "@context": {
      "description": "JSON-LD context; SHOULD be https://www.openhistorymap.org/cited-geojson/0.1/context.jsonld",
      "oneOf": [
        { "type": "string", "format": "uri" },
        { "type": "array" },
        { "type": "object" }
      ]
    },
    "conformsTo": {
      "type": "array",
      "items": { "type": "string", "format": "uri" },
      "contains": { "const": "https://www.openhistorymap.org/cited-geojson/0.1" }
    },
    "name": { "type": "string" },
    "description": { "type": "string" },
    "license": { "type": "string", "format": "uri" },
    "creator": { "$ref": "#/$defs/stringOrStrings" },
    "created": { "type": "string" },
    "modified": { "type": "string" },
    "calendar": { "$ref": "#/$defs/calendar" },
    "sources": {
      "type": "object",
      "minProperties": 1,
      "propertyNames": { "format": "iri" },
      "additionalProperties": { "$ref": "#/$defs/source" }
    },
    "georeferences": {
      "type": "array",
      "items": { "$ref": "#/$defs/georeference" }
    },
    "bbox": { "type": "array", "minItems": 4, "items": { "type": "number" } },
    "features": {
      "type": "array",
      "items": { "$ref": "#/$defs/feature" }
    }
  },
  "$defs": {
    "stringOrStrings": {
      "oneOf": [
        { "type": "string" },
        { "type": "array", "items": { "type": "string" }, "minItems": 1 }
      ]
    },
    "calendar": {
      "type": "object",
      "required": ["label"],
      "properties": {
        "label": { "type": "string" },
        "id": { "type": "string", "format": "uri" },
        "epoch": { "type": "string" }
      }
    },
    "source": {
      "type": "object",
      "required": ["title"],
      "properties": {
        "title": { "type": "string", "minLength": 1 },
        "type": { "enum": ["text", "map", "dataset", "image", "webpage", "software", "other"] },
        "creator": { "$ref": "#/$defs/stringOrStrings" },
        "issued": { "type": "string" },
        "publisher": { "type": "string" },
        "identifier": { "$ref": "#/$defs/stringOrStrings" },
        "license": { "type": "string", "format": "uri" },
        "url": { "type": "string", "format": "uri" },
        "files": {
          "type": "array",
          "items": { "$ref": "#/$defs/file" }
        },
        "derivedFrom": {
          "type": "array",
          "items": { "type": "string", "format": "iri" }
        }
      }
    },
    "file": {
      "type": "object",
      "required": ["id"],
      "properties": {
        "id": { "type": "string", "minLength": 1 },
        "checksum": { "type": "string", "pattern": "^sha256:[0-9a-f]{64}$" },
        "url": { "type": "string", "format": "uri" },
        "iiif": { "type": "string", "format": "uri" },
        "mediaType": { "type": "string", "pattern": "^[a-z]+/[A-Za-z0-9.+-]+$" },
        "label": { "type": "string" }
      }
    },
    "feature": {
      "type": "object",
      "required": ["type", "id", "geometry", "properties"],
      "properties": {
        "type": { "const": "Feature" },
        "id": {
          "description": "Stable identifier of the feature across edits and releases.",
          "type": "string",
          "minLength": 1
        },
        "@id": { "type": "string", "format": "iri" },
        "geometry": {
          "oneOf": [
            { "type": "null" },
            {
              "type": "object",
              "required": ["type"],
              "properties": {
                "type": { "enum": ["Point", "MultiPoint", "LineString", "MultiLineString", "Polygon", "MultiPolygon", "GeometryCollection"] }
              }
            }
          ]
        },
        "properties": { "type": ["object", "null"] },
        "when": { "$ref": "#/$defs/when" },
        "citations": {
          "type": "array",
          "items": { "$ref": "#/$defs/citation" }
        }
      }
    },
    "when": {
      "description": "Linked Places Format `when` object.",
      "type": "object",
      "properties": {
        "timespans": {
          "type": "array",
          "items": {
            "type": "object",
            "minProperties": 1,
            "properties": {
              "start": { "$ref": "#/$defs/timepoint" },
              "end": { "$ref": "#/$defs/timepoint" }
            }
          }
        },
        "periods": {
          "type": "array",
          "items": {
            "type": "object",
            "properties": {
              "name": { "type": "string" },
              "uri": { "type": "string", "format": "uri" }
            }
          }
        },
        "label": { "type": "string" },
        "duration": { "type": "string" }
      }
    },
    "timepoint": {
      "type": "object",
      "minProperties": 1,
      "properties": {
        "in": { "$ref": "#/$defs/edtf" },
        "earliest": { "$ref": "#/$defs/edtf" },
        "latest": { "$ref": "#/$defs/edtf" }
      },
      "not": { "anyOf": [
        { "required": ["in", "earliest"] },
        { "required": ["in", "latest"] }
      ] }
    },
    "edtf": {
      "description": "ISO 8601-2 / EDTF date string, e.g. 1450, -0044, 1450~, 1047/1050, 1302-05.",
      "type": "string",
      "pattern": "^[-+]?[0-9X]{1,}.*$"
    },
    "citation": {
      "type": "object",
      "required": ["source"],
      "properties": {
        "id": { "type": "string", "format": "iri" },
        "source": { "type": "string", "format": "iri" },
        "file": { "type": "string", "minLength": 1 },
        "selector": {
          "type": "array",
          "minItems": 1,
          "items": { "$ref": "#/$defs/selector" }
        },
        "supports": {
          "type": "array",
          "minItems": 1,
          "uniqueItems": true,
          "items": {
            "anyOf": [
              { "enum": ["existence", "geometry", "name", "when"] },
              { "type": "string", "pattern": "^properties\\.[^\\s]+$" }
            ]
          }
        },
        "method": { "enum": ["traced", "transcribed", "surveyed", "imported", "inferred", "generated"] },
        "label": { "type": "string" },
        "confidence": { "type": "number", "minimum": 0, "maximum": 1 },
        "note": { "type": "string" },
        "created": { "type": "string" },
        "creator": { "$ref": "#/$defs/stringOrStrings" }
      }
    },
    "selector": {
      "type": "object",
      "required": ["type"],
      "oneOf": [
        {
          "properties": {
            "type": { "const": "TextQuoteSelector" },
            "exact": { "type": "string", "minLength": 1 },
            "prefix": { "type": "string" },
            "suffix": { "type": "string" }
          },
          "required": ["exact"]
        },
        {
          "properties": {
            "type": { "const": "TextPositionSelector" },
            "start": { "type": "integer", "minimum": 0 },
            "end": { "type": "integer", "minimum": 0 }
          },
          "required": ["start", "end"]
        },
        {
          "properties": {
            "type": { "const": "PageSelector" },
            "pageStart": { "type": "integer", "minimum": 1 },
            "pageEnd": { "type": "integer", "minimum": 1 },
            "pageLabel": { "type": "string" },
            "pageLabelEnd": { "type": "string" }
          },
          "required": ["pageStart"]
        },
        {
          "properties": {
            "type": { "const": "SectionSelector" },
            "headingPath": { "type": "array", "minItems": 1, "items": { "type": "string" } },
            "sectionTitle": { "type": "string" }
          },
          "required": ["headingPath"]
        },
        {
          "properties": {
            "type": { "const": "FragmentSelector" },
            "value": { "type": "string", "minLength": 1 },
            "conformsTo": { "type": "string", "format": "uri" }
          },
          "required": ["value"]
        },
        {
          "properties": {
            "type": { "const": "SvgSelector" },
            "value": { "type": "string", "pattern": "^\\s*<svg" }
          },
          "required": ["value"]
        }
      ]
    },
    "georeference": {
      "description": "IIIF Georeference Annotation (as produced by Allmaps), with optional accuracy.",
      "type": "object",
      "required": ["type", "target", "body"],
      "properties": {
        "id": { "type": "string" },
        "type": { "const": "Annotation" },
        "motivation": { "type": "string" },
        "target": { "type": ["object", "string"] },
        "body": {
          "type": "object",
          "required": ["type", "features"],
          "properties": {
            "type": { "const": "FeatureCollection" },
            "transformation": { "type": "object" },
            "features": {
              "type": "array",
              "minItems": 3,
              "items": {
                "type": "object",
                "required": ["type", "properties", "geometry"],
                "properties": {
                  "properties": {
                    "type": "object",
                    "required": ["resourceCoords"],
                    "properties": {
                      "resourceCoords": { "type": "array", "minItems": 2, "maxItems": 2, "items": { "type": "number" } }
                    }
                  }
                }
              }
            }
          }
        },
        "accuracy": {
          "type": "object",
          "required": ["rmse", "unit"],
          "properties": {
            "rmse": { "type": "number", "minimum": 0 },
            "unit": { "enum": ["m", "px"] },
            "method": { "type": "string" },
            "controlPoints": { "type": "integer", "minimum": 0 }
          }
        }
      }
    }
  }
}