// Copyright 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

extern crate cmake;

use std::env;
use std::path::{Path, PathBuf};
use std::process::Command;

fn git_submodule_update(dir: &PathBuf) {
    let status = Command::new("git")
        .args(&["submodule", "update", "--init"])
        .current_dir(dir)
        .status()
        .expect("cannot execute git submodule");
    if !status.success() {
        panic!("git submodule update --init failed")
    }
}

fn build_shaderc(shaderc_dir: &PathBuf) -> PathBuf {
        cmake::Config::new(shaderc_dir)
            .profile("Release")
            .define("CMAKE_POSITION_INDEPENDENT_CODE", "ON")
            .define("SPIRV_SKIP_EXECUTABLES", "ON")
            .define("SHADERC_SKIP_TESTS", "ON")
            .build()
}

fn build_shaderc_msvc(shaderc_dir: &PathBuf) -> PathBuf {
    cmake::Config::new(shaderc_dir)
            .profile("Release")
            .define("CMAKE_POSITION_INDEPENDENT_CODE", "ON")
            .define("SPIRV_SKIP_EXECUTABLES", "ON")
            .define("SHADERC_SKIP_TESTS", "ON")
            // cmake-rs tries to be clever on Windows by injecting several
            // C/C++ flags, which causes problems. So I have to manually
            // define CMAKE_*_FLAGS_* here to suppress that.
            .define("CMAKE_C_FLAGS", " /nologo /EHsc")
            .define("CMAKE_CXX_FLAGS", " /nologo /EHsc")
            .define("CMAKE_C_FLAGS_RELEASE", " /nologo /EHsc")
            .define("CMAKE_CXX_FLAGS_RELEASE", " /nologo /EHsc")
            .build()
}

fn main() {
    if env::var("CARGO_FEATURE_BUILD_NATIVE_SHADERC").is_err() {
        println!("cargo:warning=requested to skip building native C++ shaderc");
        return
    }

    let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
    let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();

    let manifest_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
    let shaderc_dir = Path::new(&manifest_dir).join("build");

    git_submodule_update(&shaderc_dir);

    let mut lib_path = if target_env == "msvc" {
        build_shaderc_msvc(&shaderc_dir)
    } else {
        build_shaderc(&shaderc_dir)
    };

    lib_path.push("lib");

    println!("cargo:rustc-link-search=native={}", lib_path.display());
    if target_os == "windows" {
        println!("cargo:rustc-link-lib=static=shaderc_combined");
    } else {
        println!("cargo:rustc-link-lib=dylib=shaderc_shared");
    }
}
