// Copyright 2020 Parity Technologies
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use std::process::Command;
use std::{env, fs};

fn try_to_find_and_link_lib(lib_name: &str) -> bool {
    println!("cargo:rerun-if-env-changed={lib_name}_COMPILE");
    if let Ok(v) = env::var(format!("{lib_name}_COMPILE")) {
        if v.to_lowercase() == "true" || v == "1" {
            return false;
        }
    }

    println!("cargo:rerun-if-env-changed={lib_name}_LIB_DIR");
    println!("cargo:rerun-if-env-changed={lib_name}_STATIC");

    if let Ok(lib_dir) = env::var(format!("{lib_name}_LIB_DIR")) {
        println!("cargo:rustc-link-search=native={lib_dir}");
        let mode = match env::var_os(format!("{lib_name}_STATIC")) {
            Some(_) => "static",
            None => "dylib",
        };
        println!("cargo:rustc-link-lib={}={}", mode, lib_name.to_lowercase());
        return true;
    }
    false
}

fn build_snappy() {
    let target = env::var("TARGET").unwrap();
    let out_dir = env::var("OUT_DIR").unwrap();
    Command::new("cmake")
        .arg("-DCMAKE_BUILD_TYPE=Release")
        .arg("-S snappy")
        .arg(format!("-B {out_dir}"))
        .output()
        .expect("Failed to execute CMake command");

    let endianness = env::var("CARGO_CFG_TARGET_ENDIAN").unwrap();
    let mut config = cc::Build::new();

    config.include("snappy/");
    config.include(".");
    config.include(out_dir);
    config.define("NDEBUG", Some("1"));
    config.extra_warnings(false);

    if target.contains("msvc") {
        config.flag("-EHsc");
    } else {
        // Snappy requires C++11.
        // See: https://github.com/google/snappy/blob/master/CMakeLists.txt#L32-L38
        config.flag("-std=c++11");
    }

    if endianness == "big" {
        config.define("SNAPPY_IS_BIG_ENDIAN", Some("1"));
    }

    config.file("snappy/snappy.cc");
    config.file("snappy/snappy-sinksource.cc");
    config.file("snappy/snappy-c.cc");
    config.cpp(true);
    config.compile("libsnappy.a");
}

fn build_snappy_win() {
    let src = env::current_dir().unwrap().join("snappy");

    let out = cmake::Config::new("snappy")
        .define("CMAKE_VERBOSE_MAKEFILE", "ON")
        .define("SNAPPY_BUILD_TESTS", "OFF")
        .define("SNAPPY_BUILD_BENCHMARKS", "OFF")
        .build_target("snappy")
        .build();

    let mut build = out.join("build");

    // NOTE: the cfg! macro doesn't work when cross-compiling, it would return values for the host
    let target_os = env::var("CARGO_CFG_TARGET_OS").expect("CARGO_CFG_TARGET_OS is set by cargo.");
    let target_env =
        env::var("CARGO_CFG_TARGET_ENV").expect("CARGO_CFG_TARGET_ENV is set by cargo.");

    if target_os.contains("windows") && target_env.contains("msvc") {
        let stub = build.join("snappy-stubs-public.h");

        let profile = match &*env::var("PROFILE").unwrap_or("debug".to_owned()) {
            "bench" | "release" => "Release",
            _ => "Debug",
        };
        build = build.join(profile);

        fs::copy(stub, build.join("snappy-stubs-public.h")).unwrap();
    }

    fs::copy(src.join("snappy.h"), build.join("snappy.h")).unwrap();

    println!("cargo:rustc-link-search=native={}", build.display());
    println!("cargo:rustc-link-lib=static=snappy");
    println!("cargo:include={}", build.display());

    // https://github.com/alexcrichton/cc-rs/blob/ca70fd32c10f8cea805700e944f3a8d1f97d96d4/src/lib.rs#L891
    if target_os.contains("apple") || target_os.contains("freebsd") || target_os.contains("openbsd")
    {
        println!("cargo:rustc-link-lib=c++");
    } else if !target_env.contains("msvc") && !target_os.contains("android") {
        println!("cargo:rustc-link-lib=stdc++");
    }
}

fn main() {
    if !try_to_find_and_link_lib("SNAPPY") {
        println!("cargo:rerun-if-changed=snappy/");
        let target = env::var("TARGET").unwrap();
        if target.contains("windows") {
            build_snappy_win()
        } else {
            build_snappy();
        }
    } else {
        let target = env::var("TARGET").unwrap();
        if target.contains("apple") || target.contains("freebsd") || target.contains("openbsd") {
            println!("cargo:rustc-link-lib=dylib=c++");
        } else if target.contains("linux") {
            println!("cargo:rustc-link-lib=dylib=stdc++");
        }
    }
}