module RbSys::Mkmf

def base_makefile(cargo_dir)
  base_makefile = dummy_makefile(__dir__).join("\n")
  base_makefile.gsub!("all install static install-so install-rb", "all static install-rb")
  base_makefile.gsub!(/^srcdir = .*$/, "srcdir = #{cargo_dir}")
  base_makefile
end

def cargo_command(cargo_dir, builder)
  builder.ext_dir = cargo_dir
  dest_path = File.join(Dir.pwd, "target")
  args = ARGV.dup
  args.shift if args.first == "--"
  cargo_cmd = builder.cargo_command(dest_path, args)
  Shellwords.join(cargo_cmd).gsub("\\=", "=").gsub(/\Acargo/, "$(CARGO)").gsub(/-v=\d/, "")
end

def create_rust_makefile(target, &blk)
  if target.include?("/")
    target_prefix, target = File.split(target)
    target_prefix[0, 0] = "/"
  else
    target_prefix = ""
  end
  spec = Struct.new(:name, :metadata).new(target, {})
  cargo_builder = CargoBuilder.new(spec)
  builder = Config.new(cargo_builder)
  yield builder if blk
  srcprefix = "$(srcdir)/#{builder.ext_dir}".chomp("/")
  RbConfig.expand(srcdir = srcprefix.dup)
  full_cargo_command = cargo_command(srcdir, builder)
  # rubocop:disable Style/GlobalVars
  make_install = +<<~MAKE
    RB_SYS_BUILD_DIR ?= #{File.join(Dir.pwd, ".rb-sys")}
    CARGO ?= cargo
    CARGO_BUILD_TARGET ?= #{builder.target}
    SOEXT ?= #{builder.so_ext}
    # Determine the prefix Cargo uses for the lib.
    ifneq ($(SOEXT),dll)
      SOEXT_PREFIX ?= lib
    endif
    RB_SYS_CARGO_PROFILE ?= #{builder.profile}
    RB_SYS_CARGO_FEATURES ?= #{builder.features.join(",")}
    RB_SYS_EXTRA_RUSTFLAGS ?= #{builder.extra_rustflags.join(" ")}
    # Set dirname for the profile, since the profiles do not directly map to target dir (i.e. dev -> debug)
    ifeq ($(RB_SYS_CARGO_PROFILE),dev)
      RB_SYS_CARGO_PROFILE_DIR ?= debug
    else
      RB_SYS_CARGO_PROFILE_DIR ?= $(RB_SYS_CARGO_PROFILE)
    endif
    # Set the build profile (dev, release, etc.) Compat with Rust 1.51.
    ifeq ($(RB_SYS_CARGO_PROFILE),release)
      RB_SYS_CARGO_PROFILE_FLAG = --release
    else
      RB_SYS_CARGO_PROFILE_FLAG = --profile $(RB_SYS_CARGO_PROFILE)
    endif
    # Account for sub-directories when using `--target` argument with Cargo
    ifneq ($(CARGO_BUILD_TARGET),)
      RB_SYS_CARGO_BUILD_TARGET_DIR ?= target/$(CARGO_BUILD_TARGET)
    else
      RB_SYS_CARGO_BUILD_TARGET_DIR ?= target
    endif
    target_prefix = #{target_prefix}
    TARGET_NAME = #{target[/\A\w+/]}
    TARGET_ENTRY = #{RbConfig::CONFIG["EXPORT_PREFIX"]}Init_$(TARGET_NAME)
    RUBYARCHDIR   = $(sitearchdir)$(target_prefix)
    TARGET = #{target}
    DLLIB = $(TARGET).#{RbConfig::CONFIG["DLEXT"]}
    TARGET_DIR = #{Dir.pwd}/$(RB_SYS_CARGO_BUILD_TARGET_DIR)/$(RB_SYS_CARGO_PROFILE_DIR)
    RUSTLIB = $(TARGET_DIR)/$(SOEXT_PREFIX)$(TARGET_NAME).$(SOEXT)
    CLEANOBJS = $(TARGET_DIR)/.fingerprint $(TARGET_DIR)/incremental $(TARGET_DIR)/examples $(TARGET_DIR)/deps $(TARGET_DIR)/build $(TARGET_DIR)/.cargo-lock $(TARGET_DIR)/*.d $(TARGET_DIR)/*.rlib $(RB_SYS_BUILD_DIR)
    DEFFILE = $(TARGET_DIR)/$(TARGET)-$(arch).def
    CLEANLIBS = $(DLLIB) $(RUSTLIB) $(DEFFILE)
    #{base_makefile(srcdir)}
    ifneq ($(RB_SYS_VERBOSE),)
      Q = $(0=@)
    endif
    #{env_vars(builder)}
    $(RUSTLIB): export RUSTFLAGS := $(RUSTFLAGS) $(RB_SYS_EXTRA_RUSTFLAGS)
    FORCE: ;
    $(TARGET_DIR):
    \t$(ECHO) creating target directory \\($(@)\\)
    \t$(Q) $(MAKEDIRS) $(TARGET_DIR)
    $(DEFFILE): $(TARGET_DIR)
    \t$(ECHO) generating $(@)
    \t$(Q) ($(COPY) $(srcdir)/$(TARGET).def $@ 2> /dev/null) || (echo EXPORTS && echo $(TARGET_ENTRY)) > $@
    #{optional_rust_toolchain(builder)}
    $(RUSTLIB): $(DEFFILE) FORCE
    \t$(ECHO) generating $(@) \\("$(RB_SYS_CARGO_PROFILE)"\\)
    \t$(Q) #{full_cargo_command}
    $(DLLIB): $(RUSTLIB)
    \t$(Q) $(COPY) "$(RUSTLIB)" $@
    install-so: $(DLLIB)
    \t$(ECHO) installing $(DLLIB) to $(RUBYARCHDIR)
    \t$(Q) $(MAKEDIRS) $(RUBYARCHDIR)
    \t$(INSTALL_PROG) $(DLLIB) $(RUBYARCHDIR)
    install: #{builder.clean_after_install ? "install-so realclean" : "install-so"}
    all: #{$extout ? "install" : "$(DLLIB)"}
  MAKE
  gsub_cargo_command!(make_install, builder: builder)
  File.write("Makefile", make_install)
end

def env_line(k, v)
  return unless v
  %($(RUSTLIB): export #{k} = #{v.gsub("\n", '\n')})
end

def env_or_makefile_config(key)
  ENV[key] || RbConfig::MAKEFILE_CONFIG[key]
end

def env_vars(builder)
  lines = builder.build_env.map { |k, v| env_line(k, v) }
  lines << env_line("CC", env_or_makefile_config("CC"))
  lines << env_line("CXX", env_or_makefile_config("CXX"))
  lines << env_line("AR", env_or_makefile_config("AR")) unless env_or_makefile_config("AR") == "libtool -static"
  lines.compact.join("\n")
end

def gsub_cargo_command!(cargo_command, builder:)
  cargo_command.gsub!(/--profile \w+/, "$(RB_SYS_CARGO_PROFILE_FLAG)")
  cargo_command.gsub!(%r{--features \S+}, "--features $(RB_SYS_CARGO_FEATURES)")
  cargo_command.gsub!(%r{--target \S+}, "--target $(CARGO_BUILD_TARGET)")
  target_dir = "target/#{builder.target}".chomp("/")
  cargo_command.gsub!(%r{/#{target_dir}/[^/]+}, "/$(RB_SYS_CARGO_BUILD_TARGET_DIR)/$(RB_SYS_CARGO_PROFILE_DIR)")
  cargo_command
end

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 -- --no-modify-path --profile minimal --default-toolchain none -y
    \trustup toolchain install $(RB_SYS_DEFAULT_TOOLCHAIN) --profile $(RB_SYS_RUSTUP_PROFILE)
    \trustup default $(RB_SYS_DEFAULT_TOOLCHAIN)
    $(RUSTLIB): $(CARGO)
    endif
  MAKE
end