use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, ItemEnum, DeriveInput, Fields, Data};



#[proc_macro_attribute]
pub fn http_response(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let item_for_ast = item.clone();
    let item_for_quote = item.clone();

    let ast: DeriveInput = parse_macro_input!(item_for_ast as DeriveInput);
    let name = &ast.ident;

    let impl_block = match &ast.data {
        Data::Struct(_) => {
            // Impl for struct: deserialize entire response body as Self
            quote! {
                #[async_trait::async_trait]
                impl Responsable for #name
                where
                    Self: serde::de::DeserializeOwned + Sized + Send,
                {
                    async fn receive(mut resp: actix_web::ClientResponse) -> Result<Self, Box<dyn std::error::Error>> {
                        let parsed = resp.json::<Self>().await?;
                        Ok(parsed)
                    }
                }
            }
        }
        Data::Enum(data_enum) => {
            // Impl for enum with tuple variants of length 1 (newtype variants)
            let variant_arms = data_enum.variants.iter().filter_map(|variant| {
                let vname = &variant.ident;
                match &variant.fields {
                    Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {
                        let inner_ty = &fields.unnamed.first().unwrap().ty;
                        Some(quote! {
                            if let Ok(inner) = serde_json::from_slice::<#inner_ty>(&body) {
                                return Ok(#name::#vname(inner));
                            }
                        })
                    }
                    _ => None,
                }
            });

            quote! {
                #[async_trait::async_trait]
                impl Responsable for #name
                where
                    Self: Sized + Send,
                {
                    async fn receive(mut resp: actix_web::ClientResponse) -> Result<Self, Box<dyn std::error::Error>> {
                        let body = resp.body().await?;
                        #(#variant_arms)*
                        Err(Box::new(std::io::Error::new(
                            std::io::ErrorKind::Other,
                            concat!("No matching enum variant in ", stringify!(#name))
                        )))
                    }
                }
            }
        }
        _ => panic!("#[http_response] only supports structs and tuple-style enum variants"),
    };

    let original: syn::Item = syn::parse(item_for_quote).expect("Failed to parse item as syn::Item");

    let output = quote! {
        #original
        #impl_block
    };

    output.into()
}

#[proc_macro_derive(ResponseVec)]
pub fn derive_response_vec(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let name = &input.ident;

    let expanded = quote! {
        impl #name {
            /// Deserializes all responses sequentially into a Vec<Self>.
            /// Assumes `Self` implements `DeserializeOwned`.
            pub async fn response_vec(
                responses: Vec<awc::ClientResponse>,
            ) -> Result<Vec<Self>, std::error::Error>
            where
                Self: Sized + serde::de::DeserializeOwned,
            {
                let mut results = Vec::with_capacity(responses.len());
                for resp in responses {
                    let item = resp.json::<Self>().await?;
                    results.push(item);
                }
                Ok(results)
            }
        }
    };

    TokenStream::from(expanded)
}

#[proc_macro_attribute]
pub fn alpaca_cli(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let input_enum = parse_macro_input!(item as ItemEnum);
    let enum_name = &input_enum.ident;
    let variants = &input_enum.variants;

    // Match arms for regular command variants (Single, Asset, etc.)
    let regular_arms = variants.iter().filter_map(|v| {
        let v_name = &v.ident;

        // Skip Bulk variant — we handle it separately
        if v_name == "Bulk" {
            return None;
        }

        Some(quote! {
            #enum_name::#v_name(req) => {
                let res = req.send(client.clone(), &api_key).await?;
                let body = res.body().await?;
                println!("{}", std::str::from_utf8(&body)?);
            }
        })
    });

    let expanded = quote! {
        #[derive(structopt::StructOpt, Debug)]
        #input_enum

        #[tokio::main]
        async fn main() -> Result<(), Box<dyn std::error::Error>> {
            use structopt::StructOpt;
            use std::fs::File;
            use std::io::{BufReader, Read};
            use std::sync::Arc;
            use std::thread;

            const THREADS: usize = 4;

            // Initialize shared HTTP client and API key
            let client = Arc::new(awc::Client::default());
            let api_key = std::env::var("APCA_API_KEY_ID")?;
            let cmd = #enum_name::from_args();

            match cmd {
                #(#regular_arms)*

                #enum_name::Bulk { input } => {
                    // Choose input source: file or stdin
                    let mut reader: Box<dyn Read> = match input {
                        Some(path) => Box::new(File::open(path)?),
                        None => Box::new(std::io::stdin()),
                    };

                    // Read input JSON into buffer
                    let mut buf = String::new();
                    reader.read_to_string(&mut buf)?;

                    // Deserialize into Vec<Query>
                    let queries: Vec<Query> = serde_json::from_str(&buf)?;
                    let total = queries.len();

                    if total == 0 {
                        eprintln!("No queries provided.");
                        return Ok(());
                    }

                    let shared_queries = Arc::new(queries);
                    let shared_key = Arc::new(api_key);

                    let per_thread = total / THREADS;

                    let mut handles = Vec::with_capacity(THREADS);
                    for i in 0..THREADS {
                        let queries_clone = Arc::clone(&shared_queries);
                        let client_clone = Arc::clone(&client);
                        let key_clone = Arc::clone(&shared_key);

                        let start_index = i * per_thread;
                        let end_index = if i == THREADS - 1 {
                            total // Last thread gets the remainder
                        } else {
                            start_index + per_thread
                        };

                        let handle = thread::spawn(move || {
                            let rt = tokio::runtime::Runtime::new().expect("Failed to create runtime");
                            for idx in start_index..end_index {
                                let query = &queries_clone[idx];
                                let send_result = rt.block_on(query.send(client_clone.clone(), &key_clone));

                                match send_result {
                                    Ok(response) => {
                                        let body_result = rt.block_on(response.body());
                                        match body_result {
                                            Ok(body) => println!("{}", String::from_utf8_lossy(&body)),
                                            Err(e) => eprintln!("Error reading response body: {:?}", e),
                                        }
                                    }
                                    Err(e) => {
                                        eprintln!("Request failed: {:?}", e);
                                    }
                                }
                            }
                        });

                        handles.push(handle);
                    }

                    // Wait for all threads to complete
                    for handle in handles {
                        handle.join().expect("A thread panicked");
                    }
                }
            }

            Ok(())
        }
    };

    TokenStream::from(expanded)
}