{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://firebase.google.com/schemas/fcm/message.json",
  "title": "Firebase Cloud Messaging Message",
  "description": "Schema for a Firebase Cloud Messaging (FCM) HTTP v1 API send request, used to deliver push notifications and data messages to devices.",
  "type": "object",
  "required": ["message"],
  "properties": {
    "message": {
      "type": "object",
      "description": "The message to send",
      "properties": {
        "token": {
          "type": "string",
          "description": "Registration token of the target device"
        },
        "topic": {
          "type": "string",
          "description": "Topic name to send the message to"
        },
        "condition": {
          "type": "string",
          "description": "Condition expression for targeting multiple topics"
        },
        "notification": {
          "$ref": "#/$defs/Notification"
        },
        "data": {
          "type": "object",
          "additionalProperties": {
            "type": "string"
          },
          "description": "Arbitrary key-value payload delivered to the client app"
        },
        "android": {
          "$ref": "#/$defs/AndroidConfig"
        },
        "webpush": {
          "$ref": "#/$defs/WebpushConfig"
        },
        "apns": {
          "$ref": "#/$defs/ApnsConfig"
        }
      }
    },
    "validate_only": {
      "type": "boolean",
      "description": "If true, the message is validated but not sent",
      "default": false
    }
  },
  "$defs": {
    "Notification": {
      "type": "object",
      "description": "Basic notification template",
      "properties": {
        "title": {
          "type": "string",
          "description": "The notification title"
        },
        "body": {
          "type": "string",
          "description": "The notification body text"
        },
        "image": {
          "type": "string",
          "format": "uri",
          "description": "URL of an image to display in the notification"
        }
      }
    },
    "AndroidConfig": {
      "type": "object",
      "description": "Android-specific message configuration",
      "properties": {
        "priority": {
          "type": "string",
          "enum": ["NORMAL", "HIGH"]
        },
        "ttl": {
          "type": "string",
          "description": "Message time-to-live as a duration string (e.g. 3600s)"
        },
        "collapse_key": {
          "type": "string"
        }
      }
    },
    "WebpushConfig": {
      "type": "object",
      "description": "Web push-specific message configuration",
      "properties": {
        "headers": {
          "type": "object",
          "additionalProperties": { "type": "string" }
        }
      }
    },
    "ApnsConfig": {
      "type": "object",
      "description": "Apple Push Notification Service configuration",
      "properties": {
        "headers": {
          "type": "object",
          "additionalProperties": { "type": "string" }
        },
        "payload": {
          "type": "object",
          "additionalProperties": true
        }
      }
    }
  }
}