use std::convert::{TryFrom, TryInto};
use std::env::var;
use std::fs::canonicalize;
use std::path::PathBuf;
use std::process::Command;

enum TargetArch {
    X86_64,
    Aarch64,
}

impl TryFrom<String> for TargetArch {
    type Error = String;

    fn try_from(string: String) -> Result<Self, Self::Error> {
        match string.to_lowercase().as_str() {
            "x86_64" => Ok(Self::X86_64),
            "aarch64" => Ok(Self::Aarch64),
            _ => Err(format!("This target '{}' is not supported", string)),
        }
    }
}

fn run(command: &mut Command) {
    println!("Running: {:?}", command);
    match command.status() {
        Ok(status) => {
            if !status.success() {
                panic!("`{:?}` failed: {}", command, status);
            }
        }
        Err(error) => {
            panic!("failed to execute `{:?}`: {}", command, error);
        }
    }
}

fn set_common_configure_arguments(configure: &mut Command, target_arch: &TargetArch) {
    configure
        .arg("--with-pic")
        .arg("--enable-static")
        .arg("--disable-doc");

    // The -arch flag only works for clang, which is the default and most common compiler used on
    // macOS. However, gcc also exists on macOS, so using gcc would not work for now.
    match target_arch {
        TargetArch::Aarch64 => {
            // No generic simd here as it's gcc specific and is not the compiler of choice on macOS
            // TODO this only works for single precision, check if we can have neon in general
            // configure.arg("--enable-neon");

            if cfg!(macos) {
                configure.arg("CFLAGS=-arch aarch64");
            }
        }
        TargetArch::X86_64 => {
            configure
                .arg("--enable-avx")
                .arg("--enable-avx2")
                .arg("--enable-sse2")
                .arg("--enable-generic-simd128");
            // TODO: revert once fixed in fftw
            // .arg("--enable-generic-simd256");

            if cfg!(macos) {
                configure.arg("CFLAGS=-arch x86_64");
            }
        }
    }
}

fn main() {
    // ========================================================================= Check configuration
    if cfg!(windows) {
        panic!("Windows platform is not supported.")
    }

    let target_arch: TargetArch = std::env::var("CARGO_CFG_TARGET_ARCH")
        .expect("CARGO_CFG_TARGET_ARCH is not set")
        .try_into()
        .unwrap();

    // ================================================================================ Copy sources
    let out_dir = PathBuf::from(var("OUT_DIR").unwrap());
    let src_dir = PathBuf::from(var("CARGO_MANIFEST_DIR").unwrap()).join("fftw-3.3.8");
    let out_src_dir = out_dir.join("src");
    fs_extra::dir::copy(
        src_dir.as_path(),
        &out_src_dir,
        &fs_extra::dir::CopyOptions {
            overwrite: true,
            skip_exist: false,
            buffer_size: 64000,
            copy_inside: true,
            depth: 0,
            content_only: false,
        },
    )
    .expect("Failed to copy sources.");

    // ===================================================================================== Compile
    let mut configure = Command::new(canonicalize(out_src_dir.join("configure")).unwrap());
    set_common_configure_arguments(&mut configure, &target_arch);
    configure
        .arg(format!("--prefix={}", out_dir.display()))
        .current_dir(&out_src_dir);

    run(&mut configure);
    run(Command::new("make")
        .arg(format!("-j{}", var("NUM_JOBS").unwrap()))
        .current_dir(&out_src_dir));
    run(Command::new("make")
        .arg("install")
        .current_dir(&out_src_dir));

    // run(Command::new("make distclean").current_dir(&out_src_dir));
    let mut configure = Command::new(canonicalize(out_src_dir.join("configure")).unwrap());
    set_common_configure_arguments(&mut configure, &target_arch);
    configure
        .arg("--enable-single")
        .arg(format!("--prefix={}", out_dir.display()))
        .current_dir(&out_src_dir);

    run(&mut configure);
    run(Command::new("make")
        .arg(format!("-j{}", var("NUM_JOBS").unwrap()))
        .current_dir(&out_src_dir));
    run(Command::new("make")
        .arg("install")
        .current_dir(&out_src_dir));

    // ================================================================================== Emit flags
    println!("cargo:rustc-link-search={}", out_dir.join("lib").display());
    println!("cargo:rustc-link-lib=static=fftw3");
    println!("cargo:rustc-link-lib=static=fftw3f");
}