{
    "$id": "https://gros.liacs.nl/schema/metadata/features.json",
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "title": "Feature metadata",
    "$ref": "#/$defs/features-metadata",
    "$defs": {
        "features-metadata": {
            "type": "object",
            "properties": {
                "values": {"$ref": "#/$defs/features-values"},
                "measurement": {"$ref": "#/$defs/features-measurement"},
                "preferred": {
                    "type": "object",
                    "patternProperties": {
                        ".*": {
                            "type": "boolean",
                            "description": "Whether the feature should be displayed prominently as a useful feature for tracking. When this is `false`, then the feature may be internal, used as a dependent feature for another feature, or more complicated than used simply in reports."
                        }
                    }
                },
                "prediction": {"$ref": "#/$defs/features-prediction"}
            }
        },
        "features-values": {
            "type": "object",
            "patternProperties": {
                ".*": {
                    "type": "object",
                    "properties": {
                        "type": {
                            "type": "string",
                            "enum": ["fraction", "duration", "icon"],
                            "description": "The format type of a feature."
                        },
                        "denominator": {
                            "type": "integer",
                            "minimum": 1,
                            "description": "The maximum denominator to be used when formatting a value of a feature with the `fraction` type."
                        },
                        "intervals": {
                            "type": "array",
                            "items": {
                                "type": "object",
                                "description": "Interval specification for a feature with the `duration` type. Values of this feature can be formatted by dividing the value by the intervals, until the value is small enough.",
                                "properties": {
                                    "unit": {
                                        "$ref": "#/$defs/moment_key",
                                        "description": "The interval unit size. The length of the interval is defined by `num` of this unit."
                                    },
                                    "key": {
                                        "type": "string",
                                        "enum": ["y", "M", "w", "d", "h", "m", "s"],
                                        "description": "The shorthand key for the interval unit."
                                    },
                                    "num": {
                                        "type": "integer",
                                        "minimum": 1,
                                        "description": "The interval size."
                                    }
                                }
                            }
                        },
                        "icons": {
                            "type": "object",
                            "description": "Icons to use in place of a value in order to format it for a feature with the `icon` type.",
                            "patternProperties": {
                                "^[0-9]+$": {
                                    "type": "array",
                                    "minItems": 2,
                                    "description": "FontAwesome specification for an icon that represents the value."
                                }
                            }
                        }
                    },
                    "required": ["type"]
                }
            }
        },
        "features-measurement": {
            "type": "object",
            "patternProperties": {
                ".*": {
                    "type": "object",
                    "properties": {
                        "unit": {
                            "description": "The type of unit that the feature describes. Potentially described in a (recursive) fractional manner where terms have different units.",
                            "$ref": "#/$defs/measurement_unit"
                        },
                        "dividend": {
                            "description": "Feature that is used (in part) in the numerator of a unit fraction in order to end up with this feature.",
                            "$ref": "#/$defs/measurement_unit"
                        },
                        "divisor": {
                            "description": "Feature that is used (in part) in the denominator of a unit fraction in order to end up with this feature.",
                            "$ref": "#/$defs/measurement_unit"
                        },
                        "superset": {
                            "description": "Feature that represents a wider number of the same unit compared to this feature.",
                            "type": "string"
                        },
                        "moment": {
                            "description": "Indicator of when the feature is measured compared to the sprint. `post` means that the value is only complete once the sprint is ended.",
                            "oneOf": [
                                {
                                    "type": "array",
                                    "minItems": 2,
                                    "maxItems": 2,
                                    "items": {
                                        "oneOf": [
                                            {"type": "integer"},
                                            {"type": "string"}
                                        ]
                                    },
                                    "prefixItems": [
                                        {"type": "integer"},
                                        {"type": "string"}
                                    ]
                                },
                                {
                                    "type": "string",
                                    "enum": ["post"]
                                }
                            ]
                        },
                        "pre": {
                            "description": "Feature that indicates a value at the start of a sprint that is related to this feature, and could be used to compare progress during the sprint.",
                            "type": "string"
                        }
                    }
                }
            }
        },
        "features-prediction": {
            "type": "object",
            "patternProperties": {
                ".*": {
                    "type": "array",
                    "minItems": 1,
                    "description": "Different methods of predicting the feature.",
                    "items": {
                        "type": "object",
                        "properties": {
                            "url": {
                                "type": "string",
                                "description": "Template for a URL to retrieve prediction data values for this feature."
                            },
                            "reference": {
                                "type": "string",
                                "description": "Feature that can be used as a linear regression over sprints to predict the overall change of the feature."
                            },
                            "monte_carlo": {"$ref": "#/$defs/monte_carlo"}
                        }
                    }
                }
            }
        },
        "monte_carlo": {
            "type": "object",
            "description": "Parameters for a Monte Carlo simulation to predict the feature.",
            "properties": {
                "name": {
                    "type": "string",
                    "description": "Name of the simulation."
                },
                "factors": {
                    "type": "array",
                    "items": {
                        "type": "object",
                        "properties": {
                            "column": {
                                "type": "string",
                                "description": "Feature to use for the base factor."
                            },
                            "multiplier": {
                                "type": "string",
                                "description": "Feature to use as multiplication of the column feature."
                            },
                            "scalar": {
                                "type": "number",
                                "description": "Weight to apply to this factor."
                            },
                            "prob": {
                                "type": "string",
                                "description": "Probability density function."
                            },
                            "params": {
                                "type": "array",
                                "description": "Parameters for the probability density function.",
                                "items": {
                                    "type": "number"
                                }
                            },
                            "sample": {
                                "type": "boolean",
                                "description": "Whether to use the probability function to select new random data. When this is missing or `false`, the actual data from the column feature is selected instead."
                            }
                        }
                    }
                }
            }
        },
        "moment_key": {
            "type": "string",
            "enum": ["years", "months", "weeks", "days", "hours", "minutes", "seconds"]
        },
        "measurement_unit": {
            "oneOf": [
                {"type": "string"},
                {
                    "type": "array",
                    "minItems": 2,
                    "items": {"$ref": "#/$defs/measurement_unit"}
                }
            ]
        }
    }
}