use std::{
    env,
    fs::{self, File},
    io::Write,
    iter,
    path::{Path, PathBuf},
    process::Command,
};

use trixy_parser::parse_trixy_lang;
use trixy_types::C_TYPE_HEADER;

use crate::config::TrixyConfig;

pub mod config;
mod generate;

const VIM_LINE_RUST: &'static str = "// vim: filetype=rust\n";
const VIM_LINE_C: &'static str = "// vim: filetype=c\n";

impl TrixyConfig {
    /// This is the heart of Trixy
    /// It mainly does one thing:
    ///     - Generate a tree of modules from the input trixy file
    ///
    pub fn generate(&self) {
        let source_code = fs::read_to_string(&self.trixy_path).unwrap_or_else(|err| {
            panic! {"Can't read file at path: '{}'. The Error is: '{}'",
            self.trixy_path.display(), err};
        });

        let trixy_code = parse_trixy_lang(&source_code).unwrap_or_else(|err| {
            panic! {"Parsing of the trixy file failed: \n{}", err}
        });

        // host code
        let tokens = generate::generate(&trixy_code, &self);
        eprintln!("{}", tokens);
        let host_code = prettyplease::unparse(
            &syn::parse2(tokens).expect("This code was generated, it should also be parsable"),
        );
        let mut host_code_out = fs::File::create(PathBuf::from(format!(
            "{}/{}",
            env::var("OUT_DIR").expect("The build script should have this define"),
            &self.host_code_name.display()
        )))
        .expect("This file should always be free to use");
        write!(host_code_out, "{}\n{}", host_code, VIM_LINE_RUST).expect("Write should work");

        // c header
        let c_header = generate::c_api::header::generate(&trixy_code, &self);
        let c_header_path = PathBuf::from(format!(
            "{}/{}",
            env::var("OUT_DIR").expect("The build script should have this define"),
            &self.c_header_name.display()
        ));
        let mut c_header_out =
            fs::File::create(&c_header_path).expect("This file should always be free to use");
        write!(c_header_out, "{}\n{}", c_header, VIM_LINE_C).expect("Write should work");

        Command::new("clang-format")
            .args(["-i", &c_header_path.to_str().unwrap()])
            .status()
            .unwrap_or_else(|err| {
                panic!(
                    "Failed to format the c header file with `clang-format`; Error: `{}`",
                    err
                )
            });

        if let Some(dist_dir) = &self.dist_dir_path {
            if !dist_dir.is_dir() {
                fs::create_dir(dist_dir).unwrap_or_else(|err| {
                    panic! {
                    "Failed to create the dist directory ('{}') because of: `{}`",
                    dist_dir.display(), err}
                });
            }
            let c_header_dist = PathBuf::from(format!("{}/{}", dist_dir.display(), "generated.h"));
            fs::copy(c_header_path, c_header_dist).unwrap_or_else(
                |err| panic! {"Failed to copy the c header ('generated.h') to the dist dir because of: `{}`", err},
            );
            let (interface_name, interface_content) = {
                let interface_header = format!(
                    "\
                /* This file is automatcially generated by Trixy */ \n\
                #ifndef TRIXY_INTERFACE_H \n\
                #define TRIXY_INTERFACE_H \n\
                #include \"generated.h\" \n\
                #endif // TRIXY_INTERFACE_H \n\
                 "
                );
                ("interface.h", interface_header)
            };

            C_TYPE_HEADER
                .iter()
                .chain(iter::once(&(interface_name, &interface_content[..])))
                .for_each(|(name, content)| {
                    let path: &Path = &Path::new(name);
                    if self.check_dist_dir {
                        if path.exists() {
                            panic! {
                                "The file ('{}') already exists in your dist dir ('{}')!
                                If you want to silence this check set `check_dist_dir` to false",
                                path.display(), dist_dir.display()
                            }
                        }
                    }
                    let header_path =
                        PathBuf::from(format!("{}/{}", dist_dir.display(), path.display()));
                    let mut file = File::create(&header_path).unwrap_or_else(|err| {
                        panic! {
                            "Failed to create the file at '{}' because of: '{}'",
                            header_path.display(),
                            err
                        }
                    });
                    write!(file, "{}", content).unwrap_or_else(|err| {
                        panic! {
                        "Failed to copy the c header ('{}') to the dist dir because of: `{}`",
                        path.display(),
                        err}
                    });
                });
        }
    }
}