{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "description": "Schema for triangulation based transformation",
  "type": "object",
  "properties": {
    "file_type": {
      "type": "string",
      "enum": [
        "triangulation_file"
      ],
      "description": "File type. Always \"triangulation_file\""
    },
    "format_version": {
      "type": "string",
      "enum": [
        "1.0"
      ]
    },
    "name": {
      "type": "string",
      "description": "A brief descriptive name of the triangulation"
    },
    "version": {
      "type": "string",
      "description": "A string identifying the version of the triangulation. The format for specifying version will be defined by the agency responsible for the triangulation"
    },
    "publication_date": {
      "$ref": "#/definitions/datetime",
      "description": "The date on which this version of the triangulation was published (or possibly the date on which it takes effect?)"
    },
    "license": {
      "type": "string",
      "description": "License under which the file is published"
    },
    "description": {
      "type": "string",
      "description": "A text description of the file"
    },
    "authority": {
      "type": "object",
      "description": "Basic information about the agency responsible for the data set",
      "properties": {
        "name": {
          "type": "string",
          "description": "The name of the agency"
        },
        "url": {
          "type": "string",
          "description": "The url of the agency website",
          "format": "uri"
        },
        "address": {
          "type": "string",
          "description": "The postal address of the agency"
        },
        "email": {
          "type": "string",
          "description": "An email contact address for the agency",
          "format": "email"
        }
      },
      "required": [
        "name"
      ],
      "additionalProperties": false
    },
    "links": {
      "type": "array",
      "description": "Links to related information",
      "items": {
        "type": "object",
        "properties": {
          "href": {
            "type": "string",
            "description": "The URL holding the information",
            "format": "uri"
          },
          "rel": {
            "type": "string",
            "description": "The relationship to the dataset. Proposed relationships are:\n- \"about\": a web page for human consumption describing the model\n- \"source\": the authoritative source data from which the triangulation is built.\n- \"metadata\": ISO 19115 XML metadata regarding the triangulation."
          },
          "type": {
            "type": "string",
            "description": "MIME type"
          },
          "title": {
            "type": "string",
            "description": "Description of the link"
          }
        },
        "required": [
          "href"
        ],
        "additionalProperties": false
      }
    },
    "input_crs": {
      "$ref": "#/definitions/crs",
      "description": "String identifying the CRS of source coordinates in the vertices. Typically \"EPSG:XXXX\". If the transformation is for vertical component, this should be the code for a compound CRS (can be EPSG:XXXX+YYYY where XXXX is the code of the horizontal CRS and YYYY the code of the vertical CRS). For example, for the KKJ->ETRS89 transformation, this is EPSG:2393 (\"KKJ / Finland Uniform Coordinate System\"). The input coordinates are assumed to be passed in the \"normalized for visualisation\" / \"GIS friendly\" order, that is longitude, latitude for geographic coordinates and easting, northing for projected coordinates."
    },
    "output_crs": {
      "$ref": "#/definitions/crs",
      "description": "String identifying the CRS of target coordinates in the vertices. Typically \"EPSG:XXXX\". If the transformation is for vertical component, this should be the code for a compound CRS (can be EPSG:XXXX+YYYY where XXXX is the code of the horizontal CRS and YYYY the code of the vertical CRS). For example, for the KKJ->ETRS89 transformation, this is EPSG:3067 (\"ETRS89 / TM35FIN(E,N)\"). The output coordinates will be returned in the \"normalized for visualisation\" / \"GIS friendly\" order, that is easting, that is longitude, latitude for geographic coordinates and easting, northing for projected coordinates."
    },
    "transformed_components": {
      "type": "array",
      "description": "Specify which component of the coordinates are transformed. Either \"horizontal\", \"vertical\" or both",
      "minItems": 1,
      "maxItems": 2,
      "items": {
        "type": "string",
        "enum": [
          "horizontal",
          "vertical"
        ]
      }
    },
    "vertices_columns": {
      "type": "array",
      "description": "Specify the name of the columns of the rows in the \"vertices\" array. There must be exactly as many elements in \"vertices_columns\" as in a row of \"vertices\". The following names have a special meaning: \"source_x\", \"source_y\", \"target_x\", \"target_y\", \"source_z\", \"target_z\" and \"offset_z\".  \"source_x\" and \"source_y\" are compulsory. \"source_x\" is for the source longitude (in degree) or easting. \"source_y\" is for the source latitude (in degree) or northing.  \"target_x\" and \"target_y\" are compulsory when \"horizontal\" is specified in \"transformed_components\". (\"source_z\" and \"target_z\") or \"offset_z\" are compulsory when \"vertical\" is specified in \"transformed_components\".",
      "minItems": 3,
      "items": {
        "type": "string"
      }
    },
    "triangles_columns": {
      "type": "array",
      "description": "Specify the name of the columns of the rows in the \"triangles\" array. There must be exactly as many elements in \"triangles_columns\" as in a row of \"triangles\". The following names have a special meaning: \"idx_vertex1\", \"idx_vertex2\", \"idx_vertex3\". They are compulsory.",
      "minItems": 3,
      "items": {
        "type": "string"
      }
    },
    "vertices": {
      "type": "array",
      "description": "an array whose items are themselves arrays with as many columns as described in \"vertices_columns\"",
      "items": {
        "type": "array"
      }
    },
    "triangles": {
      "type": "array",
      "description": "an array whose items are themselves arrays with as many columns as described in \"triangles_columns\". The value of the \"idx_vertexN\" columns must be indices (between 0 and len(\"vertices\"-1) of items of the \"vertices\" array",
      "items": {
        "type": "array"
      }
    }
  },
  "required": [
    "file_type",
    "format_version",
    "transformed_components",
    "vertices_columns",
    "triangles_columns",
    "vertices",
    "triangles"
  ],
  "additionalProperties": false,
  "definitions": {
    "crs": {
      "type": "string"
    },
     "datetime": {
      "type": "string",
      "format": "date-time",
      "pattern": "^[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}Z$"
    }
  }
}