use defmt_parser::{Level, ParserMode};
use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use proc_macro_error2::abort;
use quote::quote;
use syn::{parse_macro_input, parse_quote};

use crate::construct;

use self::env_filter::EnvFilter;
pub(crate) use self::{args::Args, codegen::Codegen};

mod args;
mod codegen;
mod env_filter;

pub(crate) fn expand(level: Level, args: TokenStream) -> TokenStream {
    expand_parsed(level, parse_macro_input!(args as Args)).into()
}

pub(crate) fn expand_parsed(level: Level, args: Args) -> TokenStream2 {
    let format_string = args.format_string.value();
    let fragments = match defmt_parser::parse(&format_string, ParserMode::Strict) {
        Ok(args) => args,
        Err(e) => abort!(args.format_string, "{}", e),
    };

    let formatting_exprs = args
        .formatting_args
        .map(|punctuated| punctuated.into_iter().collect::<Vec<_>>())
        .unwrap_or_default();

    let Codegen { patterns, exprs } = Codegen::new(
        &fragments,
        formatting_exprs.len(),
        args.format_string.span(),
    );

    let header = construct::interned_string(
        &format_string,
        level.as_str(),
        true,
        Some(level.as_str()),
        &parse_quote!(defmt),
    );
    let env_filter = EnvFilter::from_env_var();

    let content = if exprs.is_empty() {
        quote!(
            defmt::export::acquire_header_and_release(&#header);
        )
    } else {
        quote!(
            // safety: will be released a few lines further down
            unsafe { defmt::export::acquire_and_header(&#header); };
            #(#exprs;)*
            // safety: acquire() was called a few lines above
            unsafe { defmt::export::release() }
        )
    };

    let filter_check = env_filter.path_check(level).unwrap_or(quote!(false));

    quote!(
        {
            option_env!("DEFMT_LOG");
            match (#(&(#formatting_exprs)),*) {
                (#(#patterns),*) => {
                    if #filter_check {
                        #content
                    }
                }
            }
        }
    )
}
