module RbSys::Mkmf

def rust_toolchain_env(builder)
  <<~MAKE
    #{conditional_assign("RB_SYS_RUSTUP_PROFILE", "minimal")}
    # If the user passed true, we assume stable Rust. Otherwise, use what
    # was specified (i.e. RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN=beta)
    #{if_eq_stmt("$(RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN)", "true")}
      RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN = stable
    #{endif_stmt}
    # If a $RUST_TARGET is specified (i.e. for rake-compiler-dock), append
    # that to the profile.
    #{if_eq_stmt("$(RUST_TARGET)", "")}
      RB_SYS_DEFAULT_TOOLCHAIN = $(RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN)
    #{else_stmt}
      RB_SYS_DEFAULT_TOOLCHAIN = $(RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN)-$(RUST_TARGET)
    #{endif_stmt}
    # Since we are forcing the installation of the Rust toolchain, we need
    # to set these env vars unconditionally for the build.
    #{export_env("CARGO_HOME", "$(RB_SYS_BUILD_DIR)/$(RB_SYS_DEFAULT_TOOLCHAIN)/cargo")}
    #{export_env("RUSTUP_HOME", "$(RB_SYS_BUILD_DIR)/$(RB_SYS_DEFAULT_TOOLCHAIN)/rustup")}
    #{export_env("PATH", "$(CARGO_HOME)/bin:$(RUSTUP_HOME)/bin:$(PATH)")}
    #{export_env("RUSTUP_TOOLCHAIN", "$(RB_SYS_DEFAULT_TOOLCHAIN)")}
    #{export_env("CARGO", "$(CARGO_HOME)/bin/cargo")}
  MAKE
end