{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://example.com/telemetry.schema.json",
    "title": "Telemetry Message",
    "description": "Schema describing a telemetry message exchanged by devices.",
    "type": "object",
    "additionalProperties": false,
    "properties": {
        "version": {
            "type": "integer",
            "minimum": 1,
            "description": "Protocol semantic version (integer)."
        },
        "msg_type": {
            "type": "string",
            "enum": [
                "telemetry"
            ],
            "description": "Currently only the literal string 'telemetry' is supported."
        },
        "dev_id": {
            "$ref": "#/$defs/uuid"
        },
        "dev_type": {
            "description": "Device type identifier (string or one-of helper objects).",
            "oneOf": [
                {
                    "type": "string"
                },
                {
                    "type": "object",
                    "required": [
                        "type_id"
                    ],
                    "additionalProperties": false,
                    "properties": {
                        "type_id": {
                            "$ref": "#/$defs/uuid"
                        }
                    }
                },
                {
                    "type": "object",
                    "required": [
                        "type_name"
                    ],
                    "additionalProperties": false,
                    "properties": {
                        "type_name": {
                            "type": "string"
                        }
                    }
                }
            ]
        },
        "timestamp": {
            "$ref": "#/$defs/timestamp"
        },
        "fields": {
            "type": "array",
            "description": "Array of discrete or batch field objects.",
            "items": {
                "oneOf": [
                    {
                        "$ref": "#/$defs/discrete_field"
                    },
                    {
                        "$ref": "#/$defs/batch_field"
                    }
                ]
            }
        },
        "enum": {
            "type": "array",
            "items": {
                "$ref": "#/$defs/enum_definition"
            }
        },
        "location": {
            "$ref": "#/$defs/location"
        },
        "battery": {
            "type": "integer",
            "minimum": 0,
            "maximum": 100,
            "description": "Battery percentage (0-100)."
        },
        "sqe": {
            "type": "integer",
            "minimum": 0,
            "maximum": 4294967295,
            "description": "Sample sequence counter (uint32)."
        }
    },
    "required": [
        "version",
        "msg_type",
        "dev_id",
        "dev_type",
        "timestamp",
        "fields"
    ],
    "$defs": {
        "uuid": {
            "type": "string",
            "pattern": "^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-5][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}$",
            "description": "UUID v4 string."
        },
        "timestamp": {
            "description": "UNIX epoch (seconds) or an object with a single alternative timestamp representation.",
            "oneOf": [
                {
                    "type": "number"
                },
                {
                    "type": "object",
                    "minProperties": 1,
                    "maxProperties": 1,
                    "additionalProperties": false,
                    "properties": {
                        "unix_ns": {
                            "type": "number"
                        },
                        "unix_us": {
                            "type": "number"
                        },
                        "unix_ms": {
                            "type": "number"
                        },
                        "unix_s": {
                            "type": "number"
                        },
                        "iso8601": {
                            "type": "string",
                            "format": "date-time"
                        }
                    }
                }
            ]
        },
        "sample_interval": {
            "oneOf": [
                {
                    "type": "number",
                    "description": "Interval in seconds."
                },
                {
                    "type": "object",
                    "additionalProperties": false,
                    "properties": {
                        "ms": {
                            "type": "number"
                        },
                        "s": {
                            "type": "number"
                        },
                        "m": {
                            "type": "number"
                        },
                        "h": {
                            "type": "number"
                        },
                        "d": {
                            "type": "number"
                        },
                        "w": {
                            "type": "number"
                        }
                    }
                }
            ]
        },
        "confidence": {
            "oneOf": [
                {
                    "type": "number",
                    "minimum": 0,
                    "maximum": 1
                },
                {
                    "type": "array",
                    "items": {
                        "type": "number",
                        "minimum": 0,
                        "maximum": 1
                    }
                }
            ]
        },
        "discrete_field": {
            "type": "object",
            "additionalProperties": false,
            "required": [
                "name",
                "data_type",
                "value",
                "timestamp"
            ],
            "properties": {
                "name": {
                    "type": "string"
                },
                "data_type": {
                    "type": "string"
                },
                "value": {
                    "oneOf": [
                        {
                            "type": "string"
                        },
                        {
                            "type": "number"
                        },
                        {
                            "type": "boolean"
                        }
                    ]
                },
                "timestamp": {
                    "$ref": "#/$defs/timestamp"
                },
                "unit": {
                    "type": "string"
                },
                "confidence": {
                    "$ref": "#/$defs/confidence"
                }
            }
        },
        "batch_field": {
            "type": "object",
            "additionalProperties": false,
            "required": [
                "name",
                "array_type",
                "value",
                "timestamp"
            ],
            "properties": {
                "name": {
                    "type": "string"
                },
                "array_type": {
                    "type": "string"
                },
                "value": {
                    "type": "array",
                    "items": {
                        "oneOf": [
                            {
                                "type": "string"
                            },
                            {
                                "type": "number"
                            },
                            {
                                "type": "boolean"
                            }
                        ]
                    }
                },
                "timestamp": {
                    "$ref": "#/$defs/timestamp"
                },
                "sample_interval": {
                    "$ref": "#/$defs/sample_interval"
                },
                "unit": {
                    "type": "string"
                },
                "confidence": {
                    "$ref": "#/$defs/confidence"
                }
            }
        },
        "enum_definition": {
            "type": "object",
            "additionalProperties": false,
            "required": [
                "identifier",
                "value"
            ],
            "properties": {
                "identifier": {
                    "type": "string"
                },
                "value": {
                    "type": "object",
                    "additionalProperties": {
                        "type": "number"
                    }
                }
            }
        },
        "location": {
            "type": "object",
            "additionalProperties": false,
            "required": [
                "coordinates"
            ],
            "properties": {
                "coordinates": {
                    "type": "array",
                    "minItems": 2,
                    "maxItems": 2,
                    "items": [
                        {
                            "type": "number",
                            "minimum": -90,
                            "maximum": 90
                        },
                        {
                            "type": "number",
                            "minimum": -180,
                            "maximum": 180
                        }
                    ]
                },
                "coordinate_system": {
                    "type": "string",
                    "enum": [
                        "wgs84",
                        "gcj02",
                        "bd09"
                    ],
                    "default": "gcj02"
                },
                "accuracy": {
                    "type": "number",
                    "minimum": 0
                },
                "altitude": {
                    "type": "number"
                }
            }
        }
    }
}