savvy-bindgen 0.1.9

use quote::format_ident;
use syn::{parse_quote, Attribute, Block, FnArg::Typed, Pat::Ident, PatType, Signature, Stmt};

use crate::{savvy_impl::SavvyImpl, utils::extract_docs};

// For main.rs
pub struct ParsedResult {
    pub bare_fns: Vec<SavvyFn>,
    pub impls: Vec<SavvyImpl>,
}

#[allow(clippy::enum_variant_names)]
pub enum SavvySupportedTypes {
    IntegerSxp,
    RealSxp,
    LogicalSxp,
    StringSxp,
    ListSxp,
    // scalar
    BareI32,
    BareF64,
    BareStr,
    BareBool,
}

#[allow(dead_code)]
impl SavvySupportedTypes {
    fn from_type(ty: &syn::Type) -> Option<Self> {
        // Use only the last part to support both the qualified type path (e.g.,
        // `savvy::IntegerSxp`), and single type (e.g., `IntegerSxp`)
        match ty {
            syn::Type::Path(type_path) => {
                let type_ident = &type_path.path.segments.last().unwrap().ident;
                match type_ident.to_string().as_str() {
                    "IntegerSxp" => Some(Self::IntegerSxp),
                    "RealSxp" => Some(Self::RealSxp),
                    "LogicalSxp" => Some(Self::LogicalSxp),
                    "StringSxp" => Some(Self::StringSxp),
                    "ListSxp" => Some(Self::ListSxp),
                    "i32" => Some(Self::BareI32),
                    "f64" => Some(Self::BareF64),
                    "bool" => Some(Self::BareBool),
                    _ => None,
                }
            }
            syn::Type::Reference(type_ref) => {
                if let syn::Type::Path(type_path) = type_ref.elem.as_ref() {
                    let type_ident = &type_path.path.segments.last().unwrap().ident;
                    if type_ident.to_string().as_str() == "str" {
                        return Some(Self::BareStr);
                    }
                }
                None
            }
            _ => None,
        }
    }

    /// Return the corresponding type for internal function.
    fn to_rust_type_outer(&self) -> syn::Type {
        match &self {
            Self::IntegerSxp => parse_quote!(savvy::IntegerSxp),
            Self::RealSxp => parse_quote!(savvy::RealSxp),
            Self::LogicalSxp => parse_quote!(savvy::LogicalSxp),
            Self::StringSxp => parse_quote!(savvy::StringSxp),
            Self::ListSxp => parse_quote!(savvy::ListSxp),
            Self::BareI32 => parse_quote!(i32),
            Self::BareF64 => parse_quote!(f64),
            Self::BareStr => parse_quote!(&str),
            Self::BareBool => parse_quote!(bool),
        }
    }

    /// Return the corresponding type for API function (at the moment, only `SEXP` is supported).
    fn to_rust_type_inner(&self) -> syn::Type {
        parse_quote!(savvy::SEXP)
    }

    /// Return the corresponding type for C function (at the moment, only `SEXP` is supported).
    fn to_c_type(&self) -> String {
        "SEXP".to_string()
    }
}

pub struct SavvyFnArg {
    pat: syn::Ident,
    ty: SavvySupportedTypes,
}

impl SavvyFnArg {
    pub fn pat(&self) -> syn::Ident {
        self.pat.clone()
    }

    pub fn pat_string(&self) -> String {
        self.pat.to_string()
    }

    pub fn to_c_type_string(&self) -> String {
        self.ty.to_c_type()
    }

    pub fn to_rust_type_outer(&self) -> syn::Type {
        self.ty.to_rust_type_outer()
    }

    pub fn to_rust_type_inner(&self) -> syn::Type {
        self.ty.to_rust_type_inner()
    }
}

pub enum SavvyFnType {
    BareFunction,
    Constructor(syn::Type),
    Method(syn::Type),
    AssociatedFunction(syn::Type),
}

pub struct SavvyFn {
    /// Doc comments
    pub docs: Vec<String>,
    /// Attributes except for `#[savvy]`
    pub attrs: Vec<syn::Attribute>,
    /// Original function name
    pub fn_name: syn::Ident,
    /// type path of `self` in the case of impl function
    pub fn_type: SavvyFnType,
    /// Function arguments
    pub args: Vec<SavvyFnArg>,
    /// Whether the function has return value
    pub has_result: bool,
    /// Original body of the function
    pub stmts_orig: Vec<syn::Stmt>,
    /// Additional lines to convert `SEXP` to the specific types
    pub stmts_additional: Vec<syn::Stmt>,
}

#[allow(dead_code)]
impl SavvyFn {
    pub(crate) fn get_self_ty_ident(&self) -> Option<syn::Ident> {
        let self_ty = match &self.fn_type {
            SavvyFnType::BareFunction => return None,
            SavvyFnType::Constructor(ty) => ty,
            SavvyFnType::Method(ty) => ty,
            SavvyFnType::AssociatedFunction(ty) => ty,
        };
        if let syn::Type::Path(type_path) = self_ty {
            let ty = type_path
                .path
                .segments
                .last()
                .expect("Unexpected type path")
                .ident
                .clone();
            Some(ty)
        } else {
            panic!("Unexpected self type!")
        }
    }

    pub fn fn_name_inner(&self) -> syn::Ident {
        match self.get_self_ty_ident() {
            Some(ty) => format_ident!("savvy_{}_{}_inner", ty, self.fn_name),
            None => format_ident!("savvy_{}_inner", self.fn_name),
        }
    }

    pub fn fn_name_outer(&self) -> syn::Ident {
        match self.get_self_ty_ident() {
            Some(ty) => format_ident!("{}_{}", ty, self.fn_name),
            None => self.fn_name.clone(),
        }
    }

    pub fn from_fn(orig: &syn::ItemFn) -> Self {
        Self::new(
            &orig.attrs,
            &orig.sig,
            orig.block.as_ref(),
            SavvyFnType::BareFunction,
        )
    }

    pub fn from_impl_fn(orig: &syn::ImplItemFn, fn_type: SavvyFnType) -> Self {
        Self::new(&orig.attrs, &orig.sig, &orig.block, fn_type)
    }

    pub fn new(attrs: &[Attribute], sig: &Signature, block: &Block, fn_type: SavvyFnType) -> Self {
        // TODO: check function signature and abort if any of it is unexpected one.

        let mut attrs = attrs.to_vec();
        // Remove #[savvy]
        attrs.retain(|attr| attr != &parse_quote!(#[savvy]));

        // Extract doc comments
        let docs = extract_docs(attrs.as_slice());

        let fn_name = sig.ident.clone();

        let stmts_orig = block.stmts.clone();
        let mut stmts_additional: Vec<Stmt> = Vec::new();

        let args_new: Vec<SavvyFnArg> = sig
            .inputs
            .iter()
            .filter_map(|arg| match arg {
                Typed(PatType { pat, ty, .. }) => {
                    let pat = match pat.as_ref() {
                        Ident(arg) => arg.ident.clone(),
                        _ => panic!("non-ident is not supported"),
                    };

                    let ty = SavvySupportedTypes::from_type(ty.as_ref())
                        .expect("the type is not supported");

                    let ty_ident = ty.to_rust_type_outer();

                    stmts_additional.push(parse_quote! {
                        let #pat = <#ty_ident>::try_from(savvy::Sxp(#pat))?;
                    });

                    Some(SavvyFnArg { pat, ty })
                }
                // Skip `self`
                syn::FnArg::Receiver(syn::Receiver { reference, .. }) => {
                    if reference.is_none() {
                        // TODO: raise compile error if no reference.
                        // The function should not consume the object
                        // because the EXTPTRSXP still live even after
                        // the function returns.
                    }

                    None
                }
            })
            .collect();

        let has_result = match sig.output {
            syn::ReturnType::Default => false,
            syn::ReturnType::Type(_, _) => true,
        };

        Self {
            docs,
            attrs,
            fn_name,
            fn_type,
            args: args_new,
            has_result,
            stmts_orig,
            stmts_additional,
        }
    }
}