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use proc_macro2::TokenStream as TokenStream2;
use quote::{quote, ToTokens, TokenStreamExt};
use syn::{parse_quote, Error, ItemStruct, Result, Type};

use super::{extract_documents, parse_pyo3_attrs, util::quote_option, Attr, MemberInfo, StubType};

pub struct PyClassInfo {
    pyclass_name: String,
    struct_type: Type,
    module: Option<String>,
    members: Vec<MemberInfo>,
    doc: String,
}

impl From<&PyClassInfo> for StubType {
    fn from(info: &PyClassInfo) -> Self {
        let PyClassInfo {
            pyclass_name,
            module,
            struct_type,
            ..
        } = info;
        Self {
            ty: struct_type.clone(),
            name: pyclass_name.clone(),
            module: module.clone(),
        }
    }
}

impl TryFrom<ItemStruct> for PyClassInfo {
    type Error = Error;
    fn try_from(item: ItemStruct) -> Result<Self> {
        let ItemStruct {
            ident,
            attrs,
            fields,
            ..
        } = item;
        let struct_type: Type = parse_quote!(#ident);
        let mut pyclass_name = None;
        let mut module = None;
        let mut is_get_all = false;
        for attr in parse_pyo3_attrs(&attrs)? {
            match attr {
                Attr::Name(name) => pyclass_name = Some(name),
                Attr::Module(name) => {
                    module = Some(name);
                }
                Attr::GetAll => is_get_all = true,
                _ => {}
            }
        }
        let pyclass_name = pyclass_name.unwrap_or_else(|| ident.to_string());
        let mut members = Vec::new();
        for field in fields {
            if is_get_all || MemberInfo::is_candidate_field(&field)? {
                members.push(MemberInfo::try_from(field)?)
            }
        }
        let doc = extract_documents(&attrs).join("\n");
        Ok(Self {
            struct_type,
            pyclass_name,
            members,
            module,
            doc,
        })
    }
}

impl ToTokens for PyClassInfo {
    fn to_tokens(&self, tokens: &mut TokenStream2) {
        let Self {
            pyclass_name,
            struct_type,
            members,
            doc,
            module,
        } = self;
        let module = quote_option(module);
        tokens.append_all(quote! {
            ::pyo3_stub_gen::type_info::PyClassInfo {
                pyclass_name: #pyclass_name,
                struct_id: std::any::TypeId::of::<#struct_type>,
                members: &[ #( #members),* ],
                module: #module,
                doc: #doc,
            }
        })
    }
}

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

    #[test]
    fn test_pyclass() -> Result<()> {
        let input: ItemStruct = parse_str(
            r#"
            #[pyclass(mapping, module = "my_module", name = "Placeholder")]
            #[derive(
                Debug, Clone, PyNeg, PyAdd, PySub, PyMul, PyDiv, PyMod, PyPow, PyCmp, PyIndex, PyPrint,
            )]
            pub struct PyPlaceholder {
                #[pyo3(get)]
                pub name: String,
                #[pyo3(get)]
                pub ndim: usize,
                #[pyo3(get)]
                pub description: Option<String>,
                pub custom_latex: Option<String>,
            }
            "#,
        )?;
        let out = PyClassInfo::try_from(input)?.to_token_stream();
        insta::assert_snapshot!(format_as_value(out), @r###"
        ::pyo3_stub_gen::type_info::PyClassInfo {
            pyclass_name: "Placeholder",
            struct_id: std::any::TypeId::of::<PyPlaceholder>,
            members: &[
                ::pyo3_stub_gen::type_info::MemberInfo {
                    name: "name",
                    r#type: <String as ::pyo3_stub_gen::PyStubType>::type_output,
                },
                ::pyo3_stub_gen::type_info::MemberInfo {
                    name: "ndim",
                    r#type: <usize as ::pyo3_stub_gen::PyStubType>::type_output,
                },
                ::pyo3_stub_gen::type_info::MemberInfo {
                    name: "description",
                    r#type: <Option<String> as ::pyo3_stub_gen::PyStubType>::type_output,
                },
            ],
            module: Some("my_module"),
            doc: "",
        }
        "###);
        Ok(())
    }

    fn format_as_value(tt: TokenStream2) -> String {
        let ttt = quote! { const _: () = #tt; };
        let formatted = prettyplease::unparse(&syn::parse_file(&ttt.to_string()).unwrap());
        formatted
            .trim()
            .strip_prefix("const _: () = ")
            .unwrap()
            .strip_suffix(';')
            .unwrap()
            .to_string()
    }
}