stdlib_label = "//build_extra/rust:stdlib"

declare_args() {
  # Absolute path of rust build files.
  rust_build = "//build_extra/rust/"
}

template("run_rustc") {
  action(target_name) {
    assert(defined(invoker.source_root), "Must specify source_root")
    forward_variables_from(invoker,
                           [
                             "cfg",
                             "crate_type",
                             "source_root",
                             "deps",
                             "extern",
                             "is_test",
                           ])
    if (defined(invoker.testonly)) {
      testonly = invoker.testonly
    }
    if (defined(invoker.crate_name)) {
      crate_name = invoker.crate_name
    } else {
      crate_name = target_name
    }

    sources = [
      source_root,
    ]
    outputs = []
    script = "//tools/run_rustc.py"

    args = [
      rebase_path(source_root, root_build_dir),
      "--crate-name=$crate_name",
      "--crate-type=$crate_type",
    ]

    if (defined(is_test) && is_test) {
      # Test outputs are executables which should be in root_out_dir.
      output_file = "$root_out_dir/$crate_name"
      args += [
        "--test",
        "-o",
        rebase_path(output_file, root_build_dir),
      ]
      outputs += [ output_file ]
    } else {
      # Non-test targets are handled differently.

      if (crate_type == "staticlib") {
        output_file = "$target_out_dir/$crate_name.a"
        emit_type = "link"
      } else if (crate_type == "bin") {
        output_file = "$target_out_dir/$crate_name.o"
        emit_type = "obj"
      } else if (crate_type == "rlib") {
        output_file = "$target_out_dir/lib$crate_name.rlib"
        emit_type = "link"
      }
      outputs += [ output_file ]
      output_file_rel = rebase_path(output_file, root_build_dir)
      args += [ "--emit=$emit_type=$output_file_rel" ]

      # TODO(ry) For unknown reasons emitting a depfile on tests doesn't work.
      depfile = "$target_out_dir/$crate_name.d"
      args += [
        "--emit=dep-info=" + rebase_path(depfile, root_build_dir),

        # The following two args are used by run_rustc.py to fix
        # the depfile on the fly. They are not passed thru to rustc.
        "--depfile=" + rebase_path(depfile, root_build_dir),
        "--output_file=" + output_file_rel,
      ]
    }

    if (is_debug) {
      args += [ "-g" ]
    }

    if (is_official_build) {
      args += [ "-O" ]
    }

    if (defined(cfg)) {
      foreach(c, cfg) {
        args += [
          "--cfg",
          c,
        ]
      }
    }

    if (!defined(deps)) {
      deps = []
    }

    if (defined(extern)) {
      deps += extern
      foreach(label, extern) {
        name = get_label_info(label, "name")
        dir = get_label_info(label, "target_out_dir")
        rlib = "$dir/lib$name.rlib"
        args += [
          "--extern",
          "$name=" + rebase_path(rlib, root_build_dir),
        ]
      }
    }
  }
}

template("rust_component") {
  rustc_name = target_name + "_rustc"
  rustc_label = ":" + rustc_name
  crate_name = target_name
  run_rustc(rustc_name) {
    forward_variables_from(invoker,
                           [
                             "crate_name",
                             "crate_type",
                             "extern",
                             "cfg",
                             "source_root",
                             "testonly",
                           ])
    if (!defined(invoker.crate_type)) {
      crate_type = "rlib"
    }
  }

  crate_outputs = get_target_outputs(rustc_label)
  crate_obj = crate_outputs[0]

  component(target_name) {
    forward_variables_from(invoker,
                           [
                             "libs",
                             "deps",
                             "testonly",
                           ])
    if (!defined(deps)) {
      deps = []
    }
    if (!defined(libs)) {
      libs = []
    }
    libs += [ crate_obj ]
    deps += [ rustc_label ]
  }
}

template("rust_executable") {
  bin_name = target_name + "_bin"
  bin_label = ":" + bin_name

  rust_component(bin_name) {
    crate_type = "bin"
    forward_variables_from(invoker, "*")
  }

  executable(target_name) {
    forward_variables_from(invoker, "*")

    if (!defined(deps)) {
      deps = []
    }

    deps += [
      bin_label,
      stdlib_label,
    ]

    if (defined(extern)) {
      deps += extern
    }
  }
}

template("rust_test") {
  run_rustc(target_name) {
    crate_name = target_name
    crate_type = "bin"
    testonly = true
    is_test = true
    forward_variables_from(invoker,
                           [
                             "extern",
                             "cfg",
                             "source_root",
                           ])
  }
}