use proc_macro::TokenStream;
use quote::quote;
use syn::parse::{Parse, ParseStream};
use syn::{Attribute, Ident, Result as SynResult, Token, Type};

struct PackInput {
    attrs: Vec<Attribute>,
    type_name: Ident,
    inner_type: Type,
}

impl Parse for PackInput {
    fn parse(input: ParseStream) -> SynResult<Self> {
        let attrs = input.call(Attribute::parse_outer)?;
        let type_name: Ident = input.parse()?;
        input.parse::<Token![=]>()?;
        let inner_type: Type = input.parse()?;

        Ok(PackInput {
            attrs,
            type_name,
            inner_type,
        })
    }
}

#[allow(clippy::too_many_lines)]
pub fn pack(input: TokenStream) -> TokenStream {
    let pack_input = syn::parse_macro_input!(input as PackInput);

    let group_name = crate::default_program_path();
    let type_name = pack_input.type_name;
    let inner_type = pack_input.inner_type;
    let attrs = pack_input.attrs;

    // Generate the struct definition
    // Note: No longer derives Serialize under structural_renderer.
    // Use pack_structual! for structured output support.
    let struct_def = quote! {
        #(#attrs)*
        pub struct #type_name {
            pub(crate) inner: #inner_type,
        }
    };

    // Generate the new() method
    let new_impl = quote! {
        impl #type_name {
            /// Creates a new instance of the wrapper type
            pub fn new(inner: #inner_type) -> Self {
                Self { inner }
            }
        }
    };

    // Generate From and Into implementations
    let from_into_impl = quote! {
        impl From<#inner_type> for #type_name {
            fn from(inner: #inner_type) -> Self {
                Self::new(inner)
            }
        }

        impl From<#type_name> for #inner_type {
            fn from(wrapper: #type_name) -> #inner_type {
                wrapper.inner
            }
        }
    };

    // Generate AsRef and AsMut implementations
    let as_ref_impl = quote! {
        impl ::std::convert::AsRef<#inner_type> for #type_name {
            fn as_ref(&self) -> &#inner_type {
                &self.inner
            }
        }

        impl ::std::convert::AsMut<#inner_type> for #type_name {
            fn as_mut(&mut self) -> &mut #inner_type {
                &mut self.inner
            }
        }
    };

    // Generate Deref and DerefMut implementations
    let deref_impl = quote! {
        impl ::std::ops::Deref for #type_name {
            type Target = #inner_type;

            fn deref(&self) -> &Self::Target {
                &self.inner
            }
        }

        impl ::std::ops::DerefMut for #type_name {
            fn deref_mut(&mut self) -> &mut Self::Target {
                &mut self.inner
            }
        }
    };

    // Check if the inner type implements Default by generating conditional code
    let default_impl = quote! {
        impl ::std::default::Default for #type_name
        where
            #inner_type: ::std::default::Default,
        {
            fn default() -> Self {
                Self::new(::std::default::Default::default())
            }
        }
    };

    let register_impl = quote! {
        ::mingling::macros::register_type!(#type_name);
    };

    let expanded = quote! {
        #struct_def

        #new_impl
        #from_into_impl
        #as_ref_impl
        #deref_impl
        #default_impl
        #register_impl

        impl Into<mingling::AnyOutput<#group_name>> for #type_name {
            fn into(self) -> mingling::AnyOutput<#group_name> {
                mingling::AnyOutput::new(self)
            }
        }

        impl Into<mingling::ChainProcess<#group_name>> for #type_name {
            fn into(self) -> mingling::ChainProcess<#group_name> {
                mingling::AnyOutput::new(self).route_chain()
            }
        }

        impl ::mingling::Groupped<#group_name> for #type_name {
            fn member_id() -> #group_name {
                #group_name::#type_name
            }
        }
    };

    expanded.into()
}