use std::{
    env, fs,
    path::{Path, PathBuf},
};

/// Link vcppkg package.
fn link_vcpkg(mut path: PathBuf, name: &str) -> PathBuf {
    let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
    let mut target_arch = std::env::var("CARGO_CFG_TARGET_ARCH").unwrap();
    if target_arch == "x86_64" {
        target_arch = "x64".to_owned();
    } else if target_arch == "aarch64" {
        target_arch = "arm64".to_owned();
    }
    let mut target = if target_os == "macos" {
        "x64-osx".to_owned()
    } else if target_os == "windows" {
        "x64-windows-static".to_owned()
    } else {
        format!("{}-{}", target_arch, target_os)
    };
    if target_arch == "x86" {
        target = target.replace("x64", "x86");
    }
    println!("cargo:info={}", target);
    path.push("installed");
    path.push(target);
    println!(
        "{}",
        format!(
            "cargo:rustc-link-lib=static={}",
            name.trim_start_matches("lib")
        )
    );
    println!(
        "{}",
        format!(
            "cargo:rustc-link-search={}",
            path.join("lib").to_str().unwrap()
        )
    );
    let include = path.join("include");
    println!("{}", format!("cargo:include={}", include.to_str().unwrap()));
    include
}

/// Link homebrew package(for Mac M1).
fn link_homebrew_m1(name: &str) -> PathBuf {
    let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
    let target_arch = std::env::var("CARGO_CFG_TARGET_ARCH").unwrap();
    if target_os != "macos" || target_arch != "aarch64" {
        panic!("Couldn't find VCPKG_ROOT, also can't fallback to homebrew because it's only for macos aarch64.");
    }
    let mut path = PathBuf::from("/opt/homebrew/Cellar");
    path.push(name);
    let entries = if let Ok(dir) = std::fs::read_dir(&path) {
        dir
    } else {
        panic!("Could not find package in {}. Make sure your homebrew and package {} are all installed.", path.to_str().unwrap(),&name);
    };
    let mut directories = entries
        .into_iter()
        .filter(|x| x.is_ok())
        .map(|x| x.unwrap().path())
        .filter(|x| x.is_dir())
        .collect::<Vec<_>>();
    // Find the newest version.
    directories.sort_unstable();
    if directories.is_empty() {
        panic!(
            "There's no installed version of {} in /opt/homebrew/Cellar",
            name
        );
    }
    path.push(directories.pop().unwrap());
    // Link the library.
    println!(
        "{}",
        format!(
            "cargo:rustc-link-lib=static={}",
            name.trim_start_matches("lib")
        )
    );
    // Add the library path.
    println!(
        "{}",
        format!(
            "cargo:rustc-link-search={}",
            path.join("lib").to_str().unwrap()
        )
    );
    // Add the include path.
    let include = path.join("include");
    println!("{}", format!("cargo:include={}", include.to_str().unwrap()));
    include
}

/// Find package. By default, it will try to find vcpkg first, then homebrew(currently only for Mac M1).
fn find_package(name: &str) -> Vec<PathBuf> {
    if let Ok(vcpkg_root) = std::env::var("VCPKG_ROOT") {
        vec![link_vcpkg(vcpkg_root.into(), name)]
    } else {
        // Try using homebrew
        vec![link_homebrew_m1(name)]
    }
}

fn generate_bindings(
    ffi_header: &Path,
    include_paths: &[PathBuf],
    ffi_rs: &Path,
    exact_file: &Path,
) {
    let mut b = bindgen::builder()
        .header(ffi_header.to_str().unwrap())
        .allowlist_type("^[vV].*")
        .allowlist_var("^[vV].*")
        .allowlist_function("^[vV].*")
        .rustified_enum("^v.*")
        .trust_clang_mangling(false)
        .layout_tests(false) // breaks 32/64-bit compat
        .generate_comments(false); // vpx comments have prefix /*!\

    for dir in include_paths {
        b = b.clang_arg(format!("-I{}", dir.display()));
    }

    b.generate().unwrap().write_to_file(ffi_rs).unwrap();
    fs::copy(ffi_rs, exact_file).ok(); // ignore failure
}

fn gen_vpx() {
    let includes = find_package("libvpx");
    let src_dir = env::var_os("CARGO_MANIFEST_DIR").unwrap();
    let src_dir = Path::new(&src_dir);
    let out_dir = env::var_os("OUT_DIR").unwrap();
    let out_dir = Path::new(&out_dir);

    let ffi_header = src_dir.join("vpx_ffi.h");
    println!("rerun-if-changed={}", ffi_header.display());
    for dir in &includes {
        println!("rerun-if-changed={}", dir.display());
    }

    let ffi_rs = out_dir.join("vpx_ffi.rs");
    let exact_file = src_dir.join("generated").join("vpx_ffi.rs");
    generate_bindings(&ffi_header, &includes, &ffi_rs, &exact_file);
}

fn main() {
    // note: all link symbol names in x86 (32-bit) are prefixed wth "_".
    // run "rustup show" to show current default toolchain, if it is stable-x86-pc-windows-msvc,
    // please install x64 toolchain by "rustup toolchain install stable-x86_64-pc-windows-msvc",
    // then set x64 to default by "rustup default stable-x86_64-pc-windows-msvc"
    let target = target_build_utils::TargetInfo::new();
    if target.unwrap().target_pointer_width() != "64" {
        // panic!("Only support 64bit system");
    }
    env::remove_var("CARGO_CFG_TARGET_FEATURE");
    env::set_var("CARGO_CFG_TARGET_FEATURE", "crt-static");

    find_package("libyuv");
    gen_vpx();

    // there is problem with cfg(target_os) in build.rs, so use our workaround
    let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
    if target_os == "ios" {
        // nothing
    } else if target_os == "android" {
        println!("cargo:rustc-cfg=android");
    } else if cfg!(windows) {
        // The first choice is Windows because DXGI is amazing.
        println!("cargo:rustc-cfg=dxgi");
    } else if cfg!(target_os = "macos") {
        // Quartz is second because macOS is the (annoying) exception.
        println!("cargo:rustc-cfg=quartz");
    } else if cfg!(unix) {
        // On UNIX we pray that X11 (with XCB) is available.
        println!("cargo:rustc-cfg=x11");
    }
}