module RbSys::Mkmf

def assign_stmt(a, b, indent: 0)
  if $nmake
    "#{a} = #{b}"
  else
    "#{"\t" * indent}#{a} = #{b}"
  end
end

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 conditional_assign(a, b, export: false, indent: 0)
  if $nmake
    result = +"!IFNDEF #{a}\n#{a} = #{b}\n!ENDIF\n"
    result << export_env(a, b) if export
    result
  else
    "#{"\t" * indent}#{export ? "export " : ""}#{a} ?= #{b}"
  end
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 = "$(srcdir)/#{builder.ext_dir}".chomp("/")
  RbConfig.expand(srcdir = srcprefix.dup)
  full_cargo_command = cargo_command(srcdir, builder)
  make_install = +<<~MAKE
    #{conditional_assign("RB_SYS_BUILD_DIR", File.join(Dir.pwd, ".rb-sys"))}
    #{conditional_assign("CARGO", "cargo")}
    #{conditional_assign("CARGO_BUILD_TARGET", builder.target)}
    #{conditional_assign("SOEXT", builder.so_ext)}
    # Determine the prefix Cargo uses for the lib.
    #{if_neq_stmt("$(SOEXT)", "dll")}
    #{conditional_assign("SOEXT_PREFIX", "lib", indent: 1)}
    #{endif_stmt}
    #{conditional_assign("RB_SYS_CARGO_PROFILE", builder.profile)}
    #{conditional_assign("RB_SYS_CARGO_FEATURES", builder.features.join(","))}
    #{conditional_assign("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)
    #{if_eq_stmt("$(RB_SYS_CARGO_PROFILE)", "dev")}
    #{conditional_assign("RB_SYS_CARGO_PROFILE_DIR", "debug", indent: 1)}
    #{else_stmt}
    #{conditional_assign("RB_SYS_CARGO_PROFILE_DIR", "$(RB_SYS_CARGO_PROFILE)", indent: 1)}
    #{endif_stmt}
    # Set the build profile (dev, release, etc.) Compat with Rust 1.51.
    #{if_eq_stmt("$(RB_SYS_CARGO_PROFILE)", "release")}
    #{assign_stmt("RB_SYS_CARGO_PROFILE_FLAG", "--release", indent: 1)}
    #{else_stmt}
    #{assign_stmt("RB_SYS_CARGO_PROFILE_FLAG", "--profile $(RB_SYS_CARGO_PROFILE)", indent: 1)}
    #{endif_stmt}
    # Account for sub-directories when using `--target` argument with Cargo
    #{if_neq_stmt("$(CARGO_BUILD_TARGET)", "")}
    #{assign_stmt("RB_SYS_CARGO_BUILD_TARGET_DIR", "target/$(CARGO_BUILD_TARGET)", indent: 1)}
    #{else_stmt}
    #{assign_stmt("RB_SYS_CARGO_BUILD_TARGET_DIR", "target", indent: 1)}
    #{endif_stmt}
    target_prefix = #{target_prefix}
    TARGET_NAME = #{target[/\A\w+/]}
    TARGET_ENTRY = #{RbConfig::CONFIG["EXPORT_PREFIX"]}Init_$(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) $(DEFFILE)
    #{base_makefile(srcdir)}
    #{if_neq_stmt("$(RB_SYS_VERBOSE)", "")}
    #{assign_stmt("Q", "$(0=@)", indent: 1)}
    #{endif_stmt}
    #{env_vars(builder)}
    #{export_env("RUSTFLAGS", "$(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 else_stmt
  if $nmake
    "!ELSE"
  else
    "else"
  end
end

def endif_stmt
  if $nmake
    "!ENDIF"
  else
    "endif"
  end
end

def env_line(k, v)
  return unless v
  export_env(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 export_env(k, v)
  if $nmake
    "!if [set #{k}=#{v}]\n!endif"
  else
    "export #{k} := #{v}"
  end
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 if_eq_stmt(a, b)
  if $nmake
    "!IF #{a.inspect} == #{b.inspect}"
  else
    "ifeq (#{a},#{b})"
  end
end

def if_neq_stmt(a, b)
  if $nmake
    "!IF #{a.inspect} != #{b.inspect}"
  else
    "ifneq (#{a},#{b})"
  end
end

def optional_rust_toolchain(builder)
  <<~MAKE
    #{conditional_assign("RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN", builder.force_install_rust_toolchain)}
    # Only run if the we are told to explicitly install the Rust toolchain
    #{if_neq_stmt("$(RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN)", "false")}
    #{conditional_assign("RB_SYS_RUSTUP_PROFILE", "minimal")}
    # If the user passed true, we assume stable Rust. Otherwise, use what
    # was specified (i.e. RB_SYS_FORCE_INSTALL_RUST_TOOLCHAIN=beta)
    #{if_eq_stmt("$(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}
    #{conditional_assign("CARGO_HOME", "$(RB_SYS_BUILD_DIR)/$(RB_SYS_DEFAULT_TOOLCHAIN)/cargo", export: true)}
    #{conditional_assign("RUSTUP_HOME", "$(RB_SYS_BUILD_DIR)/$(RB_SYS_DEFAULT_TOOLCHAIN)/rustup", export: true)}
    #{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")}
    $(CARGO): 
    \t$(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 $(RB_SYS_RUSTUP_PROFILE) --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_stmt}
  MAKE
end