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use attribute_derive::FromAttr;
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use manyhow::Result;
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use proc_macro2::TokenStream;
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use quote::quote;
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use syn::punctuated::Punctuated;
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use syn::token::Paren;
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use syn::{DeriveInput, Ident, LitStr, Path, Type, TypeTuple};
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use crate::core_path;
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#[derive(FromAttr)]
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#[attribute(ident = view)]
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struct ViewAttribute {
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    #[attribute(example = "CollectionType")]
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    collection: Type,
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    #[attribute(example = "KeyType")]
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    key: Type,
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    #[attribute(example = "\"by-name\"")]
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    name: Option<LitStr>,
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    #[attribute(example = "ValueType")]
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    value: Option<Type>,
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    #[attribute(example = "bosaidb::core")]
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    core: Option<Path>,
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    #[attribute(example = "Format or None")]
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    serialization: Option<Path>,
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}
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pub fn derive(
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    DeriveInput {
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        attrs,
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        ident,
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        generics,
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        ..
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    }: DeriveInput,
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) -> Result {
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    let ViewAttribute {
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        collection,
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        key,
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        name,
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        value,
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        core,
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        serialization,
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    } = ViewAttribute::from_attributes(&attrs)?;
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    let core = core.unwrap_or_else(core_path);
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    let value = value.unwrap_or_else(|| {
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        Type::Tuple(TypeTuple {
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            paren_token: Paren::default(),
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            elems: Punctuated::new(),
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        })
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    });
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    let name = name
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        .as_ref()
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        .map_or_else(|| ident.to_string(), LitStr::value);
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    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
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    let serialization = match serialization {
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        Some(serialization) if serialization.is_ident("None") => TokenStream::new(),
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        Some(serialization) => quote! {
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            impl #impl_generics #core::schema::SerializedView for #ident #ty_generics #where_clause {
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                type Format = #serialization;
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                fn format() -> Self::Format {
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                    #serialization::default()
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                }
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            }
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        },
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        None => quote! {
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            impl #impl_generics #core::schema::DefaultViewSerialization for #ident #ty_generics #where_clause {}
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        },
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    };
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    Ok(quote! {
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        impl #impl_generics #core::schema::View for #ident #ty_generics #where_clause {
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            type Collection = #collection;
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            type Key = #key;
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            type Value = #value;
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            fn name(&self) -> #core::schema::Name {
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                #core::schema::Name::new(#name)
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            }
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        }
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        #serialization
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    })
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}
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#[derive(FromAttr)]
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#[attribute(ident = view_schema)]
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struct ViewSchemaAttribute {
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    #[attribute(example = "ViewType")]
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    view: Option<Type>,
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    #[attribute(example = "KeyType<'doc>")]
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    mapped_key: Option<Type>,
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    #[attribute(example = "\"by-name\"")]
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    version: Option<u64>,
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    #[attribute(example = "Lazy")]
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    policy: Option<Ident>,
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    #[attribute(example = "bosaidb::core")]
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    core: Option<Path>,
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}
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pub fn derive_schema(
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    DeriveInput {
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        attrs,
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        ident,
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        generics,
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        ..
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    }: DeriveInput,
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) -> Result {
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    let ViewSchemaAttribute {
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        view,
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        mapped_key,
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        version,
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        policy,
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        core,
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    } = ViewSchemaAttribute::from_attributes(&attrs)?;
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    let core = core.unwrap_or_else(core_path);
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    let view = view.map_or_else(|| quote!(Self), |ty| quote!(#ty));
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    let mapped_key = mapped_key.map_or_else(
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        || quote!(<Self as #core::schema::View>::Key),
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        |ty| quote!(#ty),
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    );
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    let version = version.map(|version| {
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        quote!(fn version(&self) -> u64 {
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            #version
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        })
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    });
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    let policy = policy.map(|policy| {
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        quote!(fn update_policy(&self) -> #core::schema::view::ViewUpdatePolicy {
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            #core::schema::view::ViewUpdatePolicy::#policy
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        })
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    });
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    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
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    Ok(quote! {
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        impl #impl_generics #core::schema::ViewSchema for #ident #ty_generics #where_clause {
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            type View = #view;
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            type MappedKey<'doc> = #mapped_key;
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            #version
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            #policy
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        }
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    })
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}