{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "JSON Diagnostic Schema",
  "description": "A Schema for specifying GHC diagnostics output as JSON",
  "type": "object",
  "properties": {
    "version": {
      "description": "The current JSON schema version this object conforms to",
      "type": "string"
    },
    "ghcVersion": {
      "description": "The GHC version",
      "type": "string"
    },
    "span": {
      "oneOf": [
        { "$ref": "#/$defs/span" },
        { "type": "null" }
      ]
    },
    "severity": {
      "description": "The diagnostic severity",
      "type": "string",
      "enum": [
        "Warning",
        "Error"
      ]
    },
    "code": {
      "description": "The diagnostic code (if it exists)",
      "type": [
        "integer",
        "null"
      ]
    },
    "message": {
      "description": "The string output of the diagnostic message by GHC",
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "hints": {
      "description": "The suggested fixes",
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "reason" : {
      "description": "The GHC flag that was responsible for the emission of the diagnostic message",
      "oneOf": [
        {
          "type": "object",
          "description": "The diagnostic message was controlled by one or more GHC flags",
          "properties": {
            "flags": {
              "type": "array",
              "items": {
                "description": "The name of a GHC flag controlling the diagnostic message",
                "type": "string"
              },
              "minItems": 1
            }
          },
          "required": ["flags"]
        },
        {
          "type": "object",
          "description": "The diagnostic message was controlled by a GHC diagnostic message category",
          "properties": {
            "category": {
              "description": "The name of the GHC diagnostic message category controlling the diagnostic message",
              "type": "string"
            }
          },
          "required": ["category"]
        }
      ]
    }
  },
  "required": [
    "version",
    "ghcVersion",
    "span",
    "severity",
    "code",
    "message",
    "hints"
  ],
  "additionalProperties": false,
  "$defs": {
    "span": {
      "description": "The span of the diagnostic",
      "type": "object",
      "properties": {
        "file": {
          "description": "The file in which the diagnostic occurs",
          "type": "string"
        },
        "start": {
          "description": "The start location of the diagnostic",
          "$ref": "#/$defs/location"
        },
        "end": {
          "description": "The end location of the diagnostic",
          "$ref": "#/$defs/location"
        }
      },
      "required": [
        "file",
        "start",
        "end"
      ],
      "additionalProperties": false
    },
    "location": {
      "description": "A location in a text file",
      "type": "object",
      "properties": {
        "line": {
          "description": "The line number",
          "type": "integer"
        },
        "column": {
          "description": "The column number",
          "type": "integer"
        }
      },
      "required": [
        "line",
        "column"
      ],
      "additionalProperties": false
    }
  }
}