{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://stac-extensions.github.io/projection/v2.1.0/schema.json#",
  "title": "Projection Extension",
  "description": "STAC Projection Extension for STAC Catalogs, STAC Collections and STAC Items.",
  "type": "object",
  "required": [
    "stac_extensions",
    "type"
  ],
  "properties": {
    "stac_extensions": {
      "type": "array",
      "contains": {
        "const": "https://stac-extensions.github.io/projection/v2.1.0/schema.json"
      }
    },
    "type": {
      "type": "string",
      "enum": [
        "Catalog",
        "Collection",
        "Feature"
      ]
    },
    "assets": {
      "$comment": "This validates the fields in Item and Collection Assets, but does not require them.",
      "type": "object",
      "additionalProperties": {
        "$ref": "#/definitions/fieldsAndBands"
      }
    },
    "links": {
      "$comment": "This validates the fields in links.",
      "type": "array",
      "items": {
        "$ref": "#/definitions/fields"
      }
    },
    "assetTemplates": {
      "$comment": "This validates the fields in asset templates.",
      "type": "object",
      "additionalProperties": {
        "$ref": "#/definitions/fieldsAndBands"
      }
    },
    "linkTemplates": {
      "$comment": "This validates the fields in link templates.",
      "type": "array",
      "items": {
        "$ref": "#/definitions/fields"
      }
    }
  },
  "oneOf": [
    {
      "$comment": "This validates the fields in the Item Properties.",
      "type": "object",
      "required": [
        "type",
        "properties"
      ],
      "properties": {
        "type": {
          "const": "Feature"
        },
        "properties": {
          "$ref": "#/definitions/fieldsAndBands"
        }
      }
    },
    {
      "$comment": "This is the schema for top-level fields, summaries and item assets in STAC Collections.",
      "type": "object",
      "required": [
        "type"
      ],
      "properties": {
        "type": {
          "const": "Collection"
        },
        "summaries": {
          "$ref": "#/definitions/summaries"
        },
        "item_assets": {
          "$comment": "This validates the fields in item assets.",
          "type": "object",
          "additionalProperties": {
            "$ref": "#/definitions/fieldsAndBands"
          }
        }
      },
      "allOf": [
        {
          "$ref": "#/definitions/fieldsAndBands"
        }
      ]
    },
    {
      "$comment": "The fields can't be used at the top-level of STAC Catalogs, only in links.",
      "type": "object",
      "required": [
        "type"
      ],
      "properties": {
        "type": {
          "const": "Catalog"
        }
      }
    }
  ],
  "definitions": {
    "proj:code": {
      "title": "Projection code",
      "type": [
        "string",
        "null"
      ]
    },
    "proj:wkt2": {
      "title": "Coordinate Reference System in WKT2 format",
      "type": [
        "string",
        "null"
      ]
    },
    "proj:projjson": {
      "title": "Coordinate Reference System in PROJJSON format",
      "oneOf": [
        {
          "$ref": "https://proj.org/schemas/v0.7/projjson.schema.json"
        },
        {
          "type": "null"
        }
      ]
    },
    "proj:geometry": {
      "$ref": "https://geojson.org/schema/Geometry.json"
    },
    "proj:bbox": {
      "title": "Extent",
      "type": "array",
      "oneOf": [
        {
          "minItems": 4,
          "maxItems": 4
        },
        {
          "minItems": 6,
          "maxItems": 6
        }
      ],
      "items": {
        "type": "number"
      }
    },
    "proj:centroid": {
      "title": "Centroid",
      "type": "object",
      "required": [
        "lat",
        "lon"
      ],
      "properties": {
        "lat": {
          "type": "number",
          "minimum": -90,
          "maximum": 90
        },
        "lon": {
          "type": "number",
          "minimum": -180,
          "maximum": 180
        }
      }
    },
    "proj:shape": {
      "title": "Shape",
      "type": "array",
      "minItems": 2,
      "maxItems": 2,
      "items": {
        "type": "integer"
      }
    },
    "proj:transform": {
      "title": "Transform",
      "type": "array",
      "oneOf": [
        {
          "minItems": 6,
          "maxItems": 6
        },
        {
          "minItems": 9,
          "maxItems": 9
        }
      ],
      "items": {
        "type": "number"
      }
    },
    "fields": {
      "type": "object",
      "properties": {
        "proj:code": {
          "$ref": "#/definitions/proj:code"
        },
        "proj:wkt2": {
          "$ref": "#/definitions/proj:wkt2"
        },
        "proj:projjson": {
          "$ref": "#/definitions/proj:projjson"
        },
        "proj:geometry": {
          "$ref": "#/definitions/proj:geometry"
        },
        "proj:bbox": {
          "$ref": "#/definitions/proj:bbox"
        },
        "proj:centroid": {
          "$ref": "#/definitions/proj:centroid"
        },
        "proj:shape": {
          "$ref": "#/definitions/proj:shape"
        },
        "proj:transform": {
          "$ref": "#/definitions/proj:transform"
        }
      },
      "patternProperties": {
        "^(?!proj:)": {}
      },
      "additionalProperties": false
    },
    "fieldsAndBands": {
      "allOf": [
        {
          "$ref": "#/definitions/fields"
        },
        {
          "properties": {
            "bands": {
              "type": "array",
              "items": {
                "$ref": "#/definitions/fields"
              }
            }
          }
        }
      ]
    },
    "summaries": {
      "$comment": "Summaries allow lists and JSON Schemas for all fields, ranges don't make sense for any of the fields.",
      "type": "object",
      "properties": {
        "proj:code": {
          "type": [
            "array",
            "object"
          ],
          "items": {
            "$ref": "#/definitions/proj:code"
          }
        },
        "proj:wkt2": {
          "type": [
            "array",
            "object"
          ],
          "items": {
            "$ref": "#/definitions/proj:wkt2"
          }
        },
        "proj:projjson": {
          "type": [
            "array",
            "object"
          ],
          "items": {
            "$ref": "#/definitions/proj:projjson"
          }
        },
        "proj:geometry": {
          "type": [
            "array",
            "object"
          ],
          "items": {
            "$ref": "#/definitions/proj:geometry"
          }
        },
        "proj:bbox": {
          "type": [
            "array",
            "object"
          ],
          "items": {
            "$ref": "#/definitions/proj:bbox"
          }
        },
        "proj:centroid": {
          "type": [
            "array",
            "object"
          ],
          "items": {
            "$ref": "#/definitions/proj:centroid"
          }
        },
        "proj:shape": {
          "type": [
            "array",
            "object"
          ],
          "items": {
            "$ref": "#/definitions/proj:shape"
          }
        },
        "proj:transform": {
          "type": [
            "array",
            "object"
          ],
          "items": {
            "$ref": "#/definitions/proj:transform"
          }
        }
      },
      "patternProperties": {
        "^(?!proj:)": {}
      },
      "additionalProperties": false
    }
  }
}