use proc_macro::TokenStream;
use quote::quote;
use syn::parse::Parse;
use syn::parse_macro_input;
use syn::token;
use syn::Expr;
use syn::Ident;
use syn::ItemFn;
use syn::Lit;
use syn::LitInt;
use syn::LitStr;

#[proc_macro]
pub fn define_struct_reader_fn(item: TokenStream) -> TokenStream {
    let i = parse_macro_input!(item as Ident);
    let lefname = format!("read_le_{}", i);
    let lefname = Ident::new(&lefname, i.span());
    let befname = format!("read_be_{}", i);
    let befname = Ident::new(&befname, i.span());
    let stream = quote! {
        #[doc = concat!("Read [", stringify!(#i), "] in little endian.")]
        fn #lefname(&mut self) -> Result<#i, Self::Error>;
        #[doc = concat!("Read [", stringify!(#i), "] in big endian.")]
        fn #befname(&mut self) -> Result<#i, Self::Error>;
    };
    stream.into()
}

#[proc_macro]
pub fn impl_struct_reader_read(item: TokenStream) -> TokenStream {
    let i = parse_macro_input!(item as Ident);
    let lefname = format!("read_le_{}", i);
    let lefname = Ident::new(&lefname, i.span());
    let befname = format!("read_be_{}", i);
    let befname = Ident::new(&befname, i.span());
    let stream = quote! {
        fn #lefname(&mut self) -> Result<#i, Self::Error> {
            let mut buf = [0u8; std::mem::size_of::<#i>()];
            self.read_exact(&mut buf)?;
            Ok(<#i>::from_le_bytes(buf))
        }
        fn #befname(&mut self) -> Result<#i, Self::Error> {
            let mut buf = [0u8; std::mem::size_of::<#i>()];
            self.read_exact(&mut buf)?;
            Ok(<#i>::from_be_bytes(buf))
        }
    };
    stream.into()
}

#[proc_macro]
pub fn define_struct_writer_fn(item: TokenStream) -> TokenStream {
    let i = parse_macro_input!(item as Ident);
    let lefname = format!("write_le_{}", i);
    let lefname = Ident::new(&lefname, i.span());
    let befname = format!("write_be_{}", i);
    let befname = Ident::new(&befname, i.span());
    let stream = quote! {
        #[doc = concat!("Write [", stringify!(#i), "] in little endian.")]
        fn #lefname(&mut self, data: #i) -> Result<(), Self::Error>;
        #[doc = concat!("Write [", stringify!(#i), "] in big endian.")]
        fn #befname(&mut self, data: #i) -> Result<(), Self::Error>;
    };
    stream.into()
}

#[proc_macro]
pub fn impl_struct_writer_write(item: TokenStream) -> TokenStream {
    let i = parse_macro_input!(item as Ident);
    let lefname = format!("write_le_{}", i);
    let lefname = Ident::new(&lefname, i.span());
    let befname = format!("write_be_{}", i);
    let befname = Ident::new(&befname, i.span());
    let stream = quote! {
        #[inline]
        fn #lefname(&mut self, data: #i) -> Result<(), Self::Error> {
            self.write_all(&data.to_le_bytes())
        }
        #[inline]
        fn #befname(&mut self, data: #i) -> Result<(), Self::Error> {
            self.write_all(&data.to_be_bytes())
        }
    };
    stream.into()
}

#[proc_macro_attribute]
pub fn async_timeout_test(attr: TokenStream, item: TokenStream) -> TokenStream {
    let ItemFn {
        attrs,
        vis,
        sig,
        block,
    } = parse_macro_input!(item as ItemFn);
    let dura = parse_duration::parse(attr.to_string().as_str()).unwrap();
    let secs = LitInt::new(format!("{}", dura.as_secs()).as_str(), sig.ident.span());
    let nanos = LitInt::new(
        format!("{}", dura.subsec_nanos()).as_str(),
        sig.ident.span(),
    );
    let stmts = &block.stmts;
    let stream = quote! {
        #(#attrs)* #vis #sig {
            let dura = std::time::Duration::new(#secs, #nanos);
            let f = async {
                #(#stmts)*
            };
            tokio::time::timeout(dura, f).await.unwrap();
        }
    };
    stream.into()
}

struct FanboxApiTest {
    pub name: Ident,
    pub expr: Expr,
    pub errmsg: LitStr,
}

impl Parse for FanboxApiTest {
    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
        let name = Ident::parse(input)?;
        token::Comma::parse(input)?;
        let expr = Expr::parse(input)?;
        token::Comma::parse(input)?;
        let errmsg = Lit::parse(input)?;
        match errmsg {
            Lit::Str(errmsg) => Ok(Self { name, expr, errmsg }),
            _ => Err(syn::Error::new(errmsg.span(), "Failed to parse string.")),
        }
    }
}

#[proc_macro]
pub fn fanbox_api_quick_test(item: TokenStream) -> TokenStream {
    let FanboxApiTest { name, expr, errmsg } = parse_macro_input!(item as FanboxApiTest);
    let stream = quote! {
        #[proc_macros::async_timeout_test(120s)]
        #[tokio::test(flavor = "multi_thread")]
        async fn #name() {
            match std::env::var("FANBOX_COOKIES_FILE") {
                Ok(path) => {
                    let client = FanboxClient::new();
                    if !client.init(Some(path)) {
                        panic!("Failed to initiailze the client.");
                    }
                    if !client.check_login().await {
                        println!("The client is not logined. Skip test.");
                        return;
                    }
                    match #expr.await {
                        Some(_) => {}
                        None => {
                            panic!("{}", #errmsg);
                        }
                    }
                }
                Err(_) => {
                    println!("No cookies files specified, skip test.")
                }
            }
        }
    };
    stream.into()
}