#![allow(dead_code)]

use std::fs;
use std::io;

const DEFINES: &[(&str, Option<&str>)] = &[
    // Rust `char` is a unicode scalar value, e.g. 32 bits.
    ("IMGUI_USE_WCHAR32", None),
    // Disabled due to linking issues
    ("CIMGUI_NO_EXPORT", None),
    ("IMGUI_DISABLE_WIN32_FUNCTIONS", None),
    ("IMGUI_DISABLE_OSX_FUNCTIONS", None),
];

fn assert_file_exists(path: &str) -> io::Result<()> {
    match fs::metadata(path) {
        Ok(_) => Ok(()),
        Err(ref e) if e.kind() == io::ErrorKind::NotFound => {
            panic!(
                "Can't access {}. Did you forget to fetch git submodules?",
                path
            );
        }
        Err(e) => Err(e),
    }
}

fn main() -> io::Result<()> {
    // Output define args for compiler
    for (key, value) in DEFINES.iter() {
        println!("cargo:DEFINE_{}={}", key, value.unwrap_or(""));
    }

    // If we aren't building WASM output, bunch of extra stuff to do
    if std::env::var_os("CARGO_FEATURE_WASM").is_none() {
        // C++ compiler
        let mut build = cc::Build::new();
        build.cpp(true);

        // Set defines for compiler
        for (key, value) in DEFINES.iter() {
            build.define(key, *value);
        }

        // Freetype font rasterizer feature
        #[cfg(feature = "freetype")]
        {
            let freetype = pkg_config::Config::new().find("freetype2").unwrap();
            for include in freetype.include_paths.iter() {
                build.include(include);
            }
            build.define("IMGUI_ENABLE_FREETYPE", None);
            println!("cargo:DEFINE_IMGUI_ENABLE_FREETYPE=");

            // imgui_freetype.cpp needs access to `#include "imgui.h"`
            let manifest_dir = std::path::Path::new(env!("CARGO_MANIFEST_DIR"));
            #[cfg(feature = "docking")]
            build.include(manifest_dir.join("third-party/imgui-docking/imgui"));
            #[cfg(not(feature = "docking"))]
            build.include(manifest_dir.join("third-party/imgui-master/imgui"));
        }

        #[cfg(feature = "docking")]
        let imgui_cpp = "include_imgui_docking.cpp";
        #[cfg(not(feature = "docking"))]
        let imgui_cpp = "include_imgui_master.cpp";

        let compiler = build.get_compiler();

        // Avoid the if-supported flag functions for easy cases, as they're
        // kinda costly.
        if compiler.is_like_gnu() || compiler.is_like_clang() {
            build.flag("-fno-exceptions").flag("-fno-rtti");
        }
        // TODO: disable linking C++ stdlib? Not sure if it's allowed.
        build.warnings(false).file(imgui_cpp).compile("libcimgui.a");
    }
    Ok(())
}