module RbSys::Mkmf

def optional_rust_toolchain(builder)
  <<~MAKE
    RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN ?= #{builder.force_install_rust_toolchain}
    # Only run if the we are told to explicitly install the Rust toolchain
    ifneq ($(RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN),false)
    RB_SYS_RUSTUP_PROFILE ?= minimal
    # If the user passed true, we assume stable Rust. Otherwise, use what
    # was specified (i.e. RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN=beta)
    ifeq ($(RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN),true)
      RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN = stable
    endif
    # If a $RUST_TARGET is specified (i.e. for rake-compiler-dock), append
    # that to the profile.
    ifeq ($(RUST_TARGET),)
      RB_SYS_DEFAULT_TOOLCHAIN = $(RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN)
    else
      RB_SYS_DEFAULT_TOOLCHAIN = $(RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN)-$(RUST_TARGET)
    endif
    export CARGO_HOME ?= $(RB_SYS_BUILD_DIR)/$(RB_SYS_DEFAULT_TOOLCHAIN)/cargo
    export RUSTUP_HOME ?= $(RB_SYS_BUILD_DIR)/$(RB_SYS_DEFAULT_TOOLCHAIN)/rustup
    export PATH := $(CARGO_HOME)/bin:$(RUSTUP_HOME)/bin:$(PATH)
    export RUSTUP_TOOLCHAIN := $(RB_SYS_DEFAULT_TOOLCHAIN)
    export CARGO := $(CARGO_HOME)/bin/cargo
    $(CARGO): 
    \t$(Q) $(MAKEDIRS) $(CARGO_HOME) $(RUSTUP_HOME)
    \tcurl --proto '=https' --tlsv1.2 --retry 10 --retry-connrefused -fsSL "https://sh.rustup.rs" | sh -s -- --default-toolchain none -y
    \trustup toolchain install $(RB_SYS_DEFAULT_TOOLCHAIN) --profile $(RB_SYS_RUSTUP_PROFILE)
    \trustup default $(RB_SYS_DEFAULT_TOOLCHAIN)
    $(DLLIB): $(CARGO)
    endif
  MAKE
end