{
    "$schema": "http://json-schema.org/draft-07/schema",
    "title": "Geo JSON object",
    "description": "Schema for a Geo JSON object",
    "type": "object",
    "required": ["type"],
    "properties": {
        "crs": { "$ref": "#/definitions/crs" },
        "bbox": { "$ref": "#/definitions/bbox" }
    },
    "oneOf": [
        { "$ref": "#/definitions/geometry" },
        { "$ref": "#/definitions/geometryCollection" },
        { "$ref": "#/definitions/feature" },
        { "$ref": "#/definitions/featureCollection" }
    ],
    "definitions": {
        "geometryCollection": {
            "title": "GeometryCollection",
            "description": "A collection of geometry objects",
            "required": ["geometries"],
            "properties": {
                "type": { "enum": ["GeometryCollection"] },
                "geometries": {
                    "type": "array",
                    "items": { "$ref": "#/definitions/geometry" }
                }
            }
        },
        "feature": {
            "title": "Feature",
            "description": "A Geo JSON feature object",
            "required": ["geometry", "properties"],
            "properties": {
                "type": { "enum": ["Feature"] },
                "geometry": {
                    "oneOf": [{ "type": "null" }, { "$ref": "#/definitions/geometry" }]
                },
                "properties": { "type": ["object", "null"] },
                "id": { "FIXME": "may be there, type not known (string? number?)" }
            }
        },
        "featureCollection": {
            "title": "FeatureCollection",
            "description": "A Geo JSON feature collection",
            "required": ["features"],
            "properties": {
                "type": { "enum": ["FeatureCollection"] },
                "features": {
                    "type": "array",
                    "items": { "$ref": "#/definitions/feature" }
                }
            }
        },
        "geometry": {
            "title": "geometry",
            "description": "One geometry as defined by GeoJSON",
            "type": "object",
            "required": ["type", "coordinates"],
            "oneOf": [
                {
                    "title": "Point",
                    "properties": {
                        "type": { "enum": ["Point"] },
                        "coordinates": {
                            "$ref": "#/definitions/geometry/definitions/position"
                        }
                    }
                },
                {
                    "title": "MultiPoint",
                    "properties": {
                        "type": { "enum": ["MultiPoint"] },
                        "coordinates": {
                            "$ref": "#/definitions/geometry/definitions/positionArray"
                        }
                    }
                },
                {
                    "title": "LineString",
                    "properties": {
                        "type": { "enum": ["LineString"] },
                        "coordinates": {
                            "$ref": "#/definitions/geometry/definitions/lineString"
                        }
                    }
                },
                {
                    "title": "MultiLineString",
                    "properties": {
                        "type": { "enum": ["MultiLineString"] },
                        "coordinates": {
                            "type": "array",
                            "items": {
                                "$ref": "#/definitions/geometry/definitions/lineString"
                            }
                        }
                    }
                },
                {
                    "title": "Polygon",
                    "properties": {
                        "type": { "enum": ["Polygon"] },
                        "coordinates": {
                            "$ref": "#/definitions/geometry/definitions/polygon"
                        }
                    }
                },
                {
                    "title": "MultiPolygon",
                    "properties": {
                        "type": { "enum": ["MultiPolygon"] },
                        "coordinates": {
                            "type": "array",
                            "items": { "$ref": "#/definitions/geometry/definitions/polygon" }
                        }
                    }
                }
            ],
            "definitions": {
                "position": {
                    "description": "A single position",
                    "type": "array",
                    "minItems": 2,
                    "items": [{ "type": "number" }, { "type": "number" }],
                    "additionalItems": false
                },
                "positionArray": {
                    "description": "An array of positions",
                    "type": "array",
                    "items": { "$ref": "#/definitions/geometry/definitions/position" }
                },
                "lineString": {
                    "description": "An array of two or more positions",
                    "allOf": [
                        { "$ref": "#/definitions/geometry/definitions/positionArray" },
                        { "minItems": 2 }
                    ]
                },
                "linearRing": {
                    "description": "An array of four positions where the first equals the last",
                    "allOf": [
                        { "$ref": "#/definitions/geometry/definitions/positionArray" },
                        { "minItems": 4 }
                    ]
                },
                "polygon": {
                    "description": "An array of linear rings",
                    "type": "array",
                    "items": { "$ref": "#/definitions/geometry/definitions/linearRing" }
                }
            }
        },
        "crs": {
            "title": "crs",
            "description": "a Coordinate Reference System object",
            "type": ["object", "null"],
            "required": ["type", "properties"],
            "properties": {
                "type": { "type": "string" },
                "properties": { "type": "object" }
            },
            "additionalProperties": false,
            "oneOf": [
                { "$ref": "#/definitions/crs/definitions/namedCrs" },
                { "$ref": "#/definitions/crs/definitions/linkedCrs" }
            ],
            "definitions": {
                "namedCrs": {
                    "properties": {
                        "type": { "enum": ["name"] },
                        "properties": {
                            "required": ["name"],
                            "additionalProperties": false,
                            "properties": {
                                "name": {
                                    "type": "string",
                                    "FIXME": "semantic validation necessary"
                                }
                            }
                        }
                    }
                },
                "linkedObject": {
                    "type": "object",
                    "required": ["href"],
                    "properties": {
                        "href": {
                            "type": "string",
                            "format": "uri",
                            "FIXME": "spec says \"dereferenceable\", cannot enforce that"
                        },
                        "type": {
                            "type": "string",
                            "description": "Suggested values: proj4, ogjwkt, esriwkt"
                        }
                    }
                },
                "linkedCrs": {
                    "properties": {
                        "type": { "enum": ["link"] },
                        "properties": {
                            "$ref": "#/definitions/crs/definitions/linkedObject"
                        }
                    }
                }
            }
        },
        "bbox": {
            "description": "A bounding box as defined by GeoJSON",
            "FIXME": "unenforceable constraint: even number of elements in array",
            "type": "array",
            "items": { "type": "number" }
        }
    }
}