#[macro_export]
macro_rules! query_def_type {
    (@ ($type:ty)) => {
        $type
    };
    (@ 'dyn ($type:ty)) => {
        $type
    };
    (@ 'vec ($type:ty)) => {
        Vec<$type>
    };
    (@ 'map ($key:ty, $value:ty)) => {
        ::std::collections::HashMap<$key, $value>
    };
}

#[macro_export]
macro_rules! query_def_field {
    (@dyn $type:ty) => {
        Option<<$type as $crate::DynamicQuery>::Definition>
    };
    (@ ($type:ty)) => {
        bool
    };
    (@ 'dyn ($type:ty)) => {
        $crate::query_def_field!(@dyn $type)
    };
    (@ 'vec ($type:ty)) => {
        $crate::query_def_field!(@dyn $type)
    };
    (@ 'map ($key:ty, $value:ty)) => {
        $crate::query_def_field!(@dyn $value)
    };
}

#[macro_export]
macro_rules! query_def_filter {
    // note about this: 'dyn is implied for 'vec and 'map because if the type is not 'dyn, then the
    // special handling is not necessary in the first place.
    (@ $query:expr, $value:ident, 'vec ($_type:path)) => {
        match $query {
            Some(query) => {
                if let Some(ref mut value) = $value {
                    for value in value.iter_mut() {
                        value.filter_ref(&query);
                    }
                }
            }
            None => {
                *$value = None;
            }
        }
    };
    (@ $query:expr, $value:ident, 'map ($_key:path, $_value:path)) => {
        match $query {
            Some(query) => {
                if let Some(ref mut value) = $value {
                    for (_, value) in value.iter_mut() {
                        value.filter_ref(&query);
                    }
                }
            }
            None => {
                *$value = None;
            }
        }
    };
    (@ $query:expr, $value:ident, 'dyn ($($_type:tt)+)) => {
        if let Some(ref mut value) = $value {
            if let Some(ref query) = $query {
                value.filter_ref(&query);
            }
        }
    };
    (@ $query:expr, $value:ident, ($($_type:tt)+)) => {
        if !*$query {
            *$value = None;
        }
    };
}

/// Defines a dynamic query structure.
#[macro_export]
macro_rules! query_def {
    (
        $($vis:vis $data:ident($def:ident) {
            $(
                $(#[$field_meta:meta])
                *
                $field:ident: $($qualifier:lifetime)? ($($type:tt)+),
            )+
        })
        *
    ) => {
        $(
            #[derive(Debug, Clone)]
            #[cfg_attr(feature = "serde", derive(::serde::Serialize, ::serde::Deserialize))]
            $vis struct $data {
                $(
                    #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none"))]
                    $(#[$field_meta])
                    *
                    pub $field: Option<$crate::query_def_type!(@ $($qualifier)? ($($type)+))>,
                )+
            }

            #[derive(Debug, Clone)]
            #[cfg_attr(feature = "serde", derive(::serde::Serialize, ::serde::Deserialize))]
            $vis struct $def {
                $(
                    #[cfg_attr(feature = "serde", serde(default))]
                    pub $field: $crate::query_def_field!(@ $($qualifier)? ($($type)+)),
                )+
            }

            impl $crate::DynamicQuery for $data {
                type Definition = $def;

                fn filter_ref(&mut self, def: &Self::Definition) {
                    $(
                        let query = &def.$field;
                        let value = &mut self.$field;
                        $crate::query_def_filter!(@ query, value, $($qualifier)? ($($type)+));
                    )
                    +
                }
            }
        )
        *
    };
}