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use crate::search::*;
use crate::util::*;

/// A `single-value` metrics aggregation that keeps track and returns the maximum value among the
/// numeric values extracted from the aggregated documents.
///
/// > The `min` and `max` aggregation operate on the `double` representation of the data. As a
/// consequence, the result may be approximate when running on longs whose absolute value is greater
/// than `2^53`.
///
/// <https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-metrics-max-aggregation.html>
#[derive(Debug, Clone, Serialize, PartialEq)]
pub struct MaxAggregation {
    max: MaxAggregationInner,
}

#[derive(Debug, Clone, Serialize, PartialEq)]
struct MaxAggregationInner {
    #[serde(skip_serializing_if = "ShouldSkip::should_skip")]
    field: Option<String>,

    #[serde(skip_serializing_if = "ShouldSkip::should_skip")]
    script: Option<Script>,

    #[serde(skip_serializing_if = "ShouldSkip::should_skip")]
    missing: Option<Number>,
}

impl Aggregation {
    /// Creates an instance of [`MaxAggregation`]
    ///
    /// - `field` - field to aggregate
    pub fn max<T>(field: T) -> MaxAggregation
    where
        T: ToString,
    {
        MaxAggregation {
            max: MaxAggregationInner {
                field: field.to_string().into(),
                script: None,
                missing: None,
            },
        }
    }

    /// Creates an instance of [`MaxAggregation`]
    ///
    /// - `script` - script to aggregate
    pub fn max_script(script: Script) -> MaxAggregation {
        MaxAggregation {
            max: MaxAggregationInner {
                script: script.into(),
                field: None,
                missing: None,
            },
        }
    }
}

impl MaxAggregation {
    /// The `missing` parameter defines how documents that are missing a value should be treated. By
    /// default they will be ignored but it is also possible to treat them as if they had a value.
    pub fn missing<T>(mut self, missing: T) -> Self
    where
        T: Into<Number>,
    {
        self.max.missing = Some(missing.into());
        self
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn serialization() {
        assert_serialize_aggregation(
            Aggregation::max("test_field"),
            json!({ "max": { "field": "test_field" } }),
        );

        assert_serialize_aggregation(
            Aggregation::max("test_field").missing(100.1),
            json!({
                "max": {
                    "field": "test_field",
                    "missing": 100.1
                }
            }),
        );

        assert_serialize_aggregation(
            Aggregation::max_script(Script::source("_score")),
            json!({
                "max": {
                    "script": {
                        "source": "_score"
                    }
                }
            }),
        );
    }
}