use std::env::var;
use std::process::Command;
use std::path::PathBuf;
use std::fs::{ read_dir, copy };

fn get_build_dir () -> Option<PathBuf> {
  let out_dir = PathBuf::from(var("OUT_DIR").ok()?);
  Some(out_dir.parent()?.parent()?.parent()?.to_owned())
}

fn main () {
  let tgt = var("TARGET").unwrap();

  if tgt.contains("windows") {
    assert!(tgt.contains("msvc"), "Only msvc target is supported on windows");

    let vcpkg = Command::new("where").arg("vcpkg").output().expect("Failed to execute where.exe");

    assert!(vcpkg.status.code().expect("Did not receive an exit code from where.exe") == 0, "Where.exe failed to find vcpkg");

    let vcpkg_dir = [ PathBuf::from(String::from_utf8_lossy(&vcpkg.stdout).into_owned()).parent().expect("Failed to get directory for vcpkg").to_str().unwrap(), "installed", "x64-windows", ].iter().collect::<PathBuf>();
    
    let bin = [ vcpkg_dir.to_str().unwrap(), "bin" ].iter().collect::<PathBuf>();
    let lib = [ vcpkg_dir.to_str().unwrap(), "lib" ].iter().collect::<PathBuf>();

    assert!(lib.exists(), "Expected lib directory [{}] does not exist", lib.display());

    println!("cargo:rustc-link-search=all={}", lib.display());

    let build_dir = get_build_dir().expect("Failed to get build directory").to_str().unwrap().to_owned();

    // TODO: Don't copy all dll's indescriminately
    // If the user has other libs through vcpkg this would suck
    for entry in read_dir(bin).expect("Can't read bin dir") {
      let entry_path = entry.unwrap().path();

      if let Some(entry_name) = entry_path.file_name() {
        let entry_name = entry_name.to_str().unwrap();

        if entry_name.ends_with(".dll") {
          let new_path = [ &build_dir, entry_name ].iter().collect::<PathBuf>();
          copy(&entry_path, new_path.as_path()).expect("Can't copy DLL to build directory");
        }
      }
    }
  } else {
    panic!("Build script is not implemented for this OS");
  }
}