//! derived from https://github.com/Rust-SDL2/rust-sdl2/blob/master/sdl2-sys/build.rs
use std::path::{Path, PathBuf};
use std::process::Command;
use std::{env, fs};

// means the latest stable version that can be downloaded from Tcl's source
const LATEST_TCL_VERSION: &str = "8.6.11";

macro_rules! add_msvc_includes_to_bindings {
    ($bindings:expr) => {
        $bindings = $bindings.clang_arg(format!(
            "-IC:/Program Files (x86)/Windows Kits/8.1/Include/shared"
        ));
        $bindings = $bindings.clang_arg(format!("-IC:/Program Files/LLVM/lib/clang/5.0.0/include"));
        $bindings = $bindings.clang_arg(format!(
            "-IC:/Program Files (x86)/Windows Kits/10/Include/10.0.10240.0/ucrt"
        ));
        $bindings = $bindings.clang_arg(format!(
            "-IC:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/include"
        ));
        $bindings = $bindings.clang_arg(format!(
            "-IC:/Program Files (x86)/Windows Kits/8.1/Include/um"
        ));
    };
}

fn run_command(cmd: &str, args: &[&str]) {
    match Command::new(cmd).args(args).output() {
        Ok(output) => {
            if !output.status.success() {
                let error = std::str::from_utf8(&output.stderr).unwrap();
                panic!("Command '{}' failed: {}", cmd, error);
            }
        }
        Err(error) => {
            panic!("Error running command '{}': {:#}", cmd, error);
        }
    }
}

fn download_to(url: &str, dest: &str) {
    if cfg!(windows) {
        run_command(
            "powershell",
            &[
                "-NoProfile",
                "-NonInteractive",
                "-Command",
                &format!(
                    "& {{
                $client = New-Object System.Net.WebClient
                $client.DownloadFile(\"{0}\", \"{1}\")
                if (!$?) {{ Exit 1 }}
            }}",
                    url, dest
                )
                .as_str(),
            ],
        );
    } else {
        run_command("curl", &[url, "-o", dest]);
    }
}

// returns the location of the downloaded source
fn download_tcl() -> PathBuf {
    let out_dir = env::var("OUT_DIR").unwrap();

    let tcl_archive_name = format!("tcl{}-src.tar.gz", LATEST_TCL_VERSION);
    let tcl_archive_url = format!(
        "https://iweb.dl.sourceforge.net/project/tcl/Tcl/{}/{}",
        LATEST_TCL_VERSION, tcl_archive_name
    );

    let tcl_archive_path = Path::new(&out_dir).join(tcl_archive_name);
    let tcl_build_path = Path::new(&out_dir).join(format!("tcl{}", LATEST_TCL_VERSION));

    // avoid re-downloading the archive if it already exists
    if !tcl_archive_path.exists() {
        download_to(&tcl_archive_url, tcl_archive_path.to_str().unwrap());
    }

    let reader = flate2::read::GzDecoder::new(fs::File::open(&tcl_archive_path).unwrap());
    let mut ar = tar::Archive::new(reader);
    ar.unpack(&out_dir).unwrap();

    tcl_build_path
}

// compile a static lib
fn compile_tcl(tcl_build_path: &Path, target_os: &str) -> PathBuf {
    let out_dir = env::var("OUT_DIR").unwrap();
    let install_dir = Path::new(&out_dir).join("install");
    if target_os == "windows-msvc" {
        let vswhere =
            Command::new(r"C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe")
                .args(&[
                    "-products",
                    "*",
                    "-prerelease",
                    "-latest",
                    "-property",
                    "installationPath",
                ])
                .output()
                .unwrap();
        if !vswhere.status.success() {
            panic!("vswhere failed??");
        }
        let output = String::from_utf8(vswhere.stdout).unwrap();
        let vs_root = output.trim();
        if vs_root.lines().count() != 1 {
            panic!("vswhere found multiple roots??");
        }
        // TODO i am going to stab a bitch why is this the easiest way to do this
        let bat = format!(
            r#"
                call "{}\Common7\Tools\VSDevCmd.bat" -arch=amd64 -host_arch=amd64
                nmake -nologo -f makefile.vc shell dlls install OPTS=msvcrt,static,staticpkg "INSTALLDIR={}"
            "#,
            vs_root,
            install_dir.to_str().unwrap(),
        );
        let bat_file = Path::new(&out_dir).join("build.bat");
        fs::write(&bat_file, bat).unwrap();
        let build = Command::new("cmd.exe")
            .arg("/c")
            .arg(bat_file.as_os_str())
            .current_dir(tcl_build_path.join("win"))
            .env_remove("OUT_DIR")
            .status()
            .unwrap();
        if !build.success() {
            panic!("nmake failed??");
        }
    } else if target_os == "windows-gnu" {
        todo!("need to run configure in bash but how to find bash??")
    } else {
        let unix_dir = tcl_build_path.join("unix");
        let configure = Command::new("./configure")
            .args(&[
                &format!("--prefix={}", install_dir.to_str().unwrap()),
                "--enable-shared=no",
            ])
            .current_dir(&unix_dir)
            .status()
            .unwrap();
        if !configure.success() {
            panic!("configure failed??");
        }
        let make = Command::new("make")
            .args(&["binaries", "install"])
            .current_dir(&unix_dir)
            .status()
            .unwrap();
        if !make.success() {
            panic!("make failed??");
        }
    }
    install_dir
}

fn link_tcl(target_os: &str) {
    if target_os == "windows-msvc" {
        println!("cargo:rustc-link-lib=static=tcl86tsx");
        println!("cargo:rustc-link-lib=static=tclstub86");
    } else if target_os == "windows-gnu" {
        todo!("which things get built under msys")
    } else {
        println!("cargo:rustc-link-lib=static=tcl8.6");
        println!("cargo:rustc-link-lib=static=tclstub8.6");
    }

    // Also linked to any required libraries for each supported platform
    if target_os.contains("windows") {
        println!("cargo:rustc-link-lib=user32");
        println!("cargo:rustc-link-lib=netapi32");
    } else {
        println!("cargo:rustc-link-lib=z"); // TODO does this always get used or only sometimes
    }
}

fn main() {
    let target = env::var("TARGET").expect("Cargo build scripts always have TARGET");
    let host = env::var("HOST").expect("Cargo build scripts always have HOST");
    let target_os = get_os_from_triple(target.as_str()).unwrap();

    let tcl_source_path = download_tcl();
    println!("cargo:tcl-source={}", tcl_source_path.to_str().unwrap());
    let tcl_compiled_path = compile_tcl(tcl_source_path.as_path(), target_os);

    let tcl_include_path = tcl_compiled_path.join("include");
    let tcl_lib_path = tcl_compiled_path.join("lib");

    println!("cargo:rustc-link-search={}", tcl_lib_path.to_str().unwrap());

    let include_paths = vec![String::from(tcl_include_path.to_str().unwrap())];
    println!("cargo:include={}", include_paths.join(":"));
    generate_bindings(target.as_str(), host.as_str(), include_paths.as_slice());

    link_tcl(target_os);
    compress_stdlib(tcl_lib_path.join("tcl8.6"));

    println!("cargo:rerun-if-changed=build.rs");
}

// headers_path is a list of directories where the Tcl headers are expected
// to be found by bindgen
fn generate_bindings(target: &str, host: &str, headers_paths: &[String]) {
    let target_os = get_os_from_triple(target).unwrap();
    let mut bindings = bindgen::Builder::default()
        // enable no_std-friendly output by only using core definitions
        .use_core()
        .default_enum_style(bindgen::EnumVariation::Rust {
            non_exhaustive: false,
        })
        .ctypes_prefix("libc");

    // Set correct target triple for bindgen when cross-compiling
    if target != host {
        bindings = bindings.clang_arg("-target");
        bindings = bindings.clang_arg(target.clone());
    }

    if headers_paths.len() == 0 {
        panic!("no headers");
    } else {
        // if paths are included, use them for bindgen. Bindgen should use the first one.
        println!("cargo:include={}", headers_paths.join(":"));
        for headers_path in headers_paths {
            bindings = bindings.clang_arg(format!("-I{}", headers_path));
        }
    }

    if target_os == "windows-msvc" {
        add_msvc_includes_to_bindings!(bindings);
    };

    let bindings = bindings
        .header("wrapper.h")
        .allowlist_type("Tcl_.*")
        .allowlist_var("TCL_.*")
        .allowlist_function("Tcl_.*")
        .generate()
        .expect("Unable to generate bindings!");

    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());

    bindings
        .write_to_file(out_path.join("bindings.rs"))
        .expect("Couldn't write bindings!");
}

fn compress_stdlib(stdlib_root: PathBuf) {
    let out_dir = env::var("OUT_DIR").unwrap();
    let tcl_stdlib_archive_path = Path::new(&out_dir).join("stdlib.tar.gz");
    let writer = flate2::write::GzEncoder::new(
        fs::File::create(tcl_stdlib_archive_path).unwrap(),
        flate2::Compression::best(),
    );
    let mut ar = tar::Builder::new(writer);

    for child in stdlib_root.read_dir().unwrap() {
        let child = child.unwrap();
        if child.path().is_dir() {
            ar.append_dir_all(child.file_name(), child.path()).unwrap();
        } else {
            ar.append_path_with_name(child.path(), child.file_name())
                .unwrap();
        }
    }
}

fn get_os_from_triple(triple: &str) -> Option<&str> {
    triple.splitn(3, "-").nth(2)
}