// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "tools/gn/build_settings.h"
#include "tools/gn/functions.h"
#include "tools/gn/parse_tree.h"
#include "tools/gn/settings.h"
#include "tools/gn/substitution_writer.h"
#include "tools/gn/target.h"
#include "tools/gn/value.h"

namespace functions {

const char kGetTargetOutputs[] = "get_target_outputs";
const char kGetTargetOutputs_HelpShort[] =
    "get_target_outputs: [file list] Get the list of outputs from a target.";
const char kGetTargetOutputs_Help[] =
    "get_target_outputs: [file list] Get the list of outputs from a target.\n"
    "\n"
    "  get_target_outputs(target_label)\n"
    "\n"
    "  Returns a list of output files for the named target. The named target\n"
    "  must have been previously defined in the current file before this\n"
    "  function is called (it can't reference targets in other files because\n"
    "  there isn't a defined execution order, and it obviously can't\n"
    "  reference targets that are defined after the function call).\n"
    "\n"
    "  Only copy and action targets are supported. The outputs from binary\n"
    "  targets will depend on the toolchain definition which won't\n"
    "  necessarily have been loaded by the time a given line of code has run,\n"
    "  and source sets and groups have no useful output file.\n"
    "\n"
    "Return value\n"
    "\n"
    "  The names in the resulting list will be absolute file paths (normally\n"
    "  like \"//out/Debug/bar.exe\", depending on the build directory).\n"
    "\n"
    "  action targets: this will just return the files specified in the\n"
    "  \"outputs\" variable of the target.\n"
    "\n"
    "  action_foreach targets: this will return the result of applying\n"
    "  the output template to the sources (see \"gn help source_expansion\").\n"
    "  This will be the same result (though with guaranteed absolute file\n"
    "  paths), as process_file_template will return for those inputs\n"
    "  (see \"gn help process_file_template\").\n"
    "\n"
    "  binary targets (executables, libraries): this will return a list\n"
    "  of the resulting binary file(s). The \"main output\" (the actual\n"
    "  binary or library) will always be the 0th element in the result.\n"
    "  Depending on the platform and output type, there may be other output\n"
    "  files as well (like import libraries) which will follow.\n"
    "\n"
    "  source sets and groups: this will return a list containing the path of\n"
    "  the \"stamp\" file that Ninja will produce once all outputs are\n"
    "  generated. This probably isn't very useful.\n"
    "\n"
    "Example\n"
    "\n"
    "  # Say this action generates a bunch of C source files.\n"
    "  action_foreach(\"my_action\") {\n"
    "    sources = [ ... ]\n"
    "    outputs = [ ... ]\n"
    "  }\n"
    "\n"
    "  # Compile the resulting source files into a source set.\n"
    "  source_set(\"my_lib\") {\n"
    "    sources = get_target_outputs(\":my_action\")\n"
    "  }\n";

Value RunGetTargetOutputs(Scope* scope,
                          const FunctionCallNode* function,
                          const std::vector<Value>& args,
                          Err* err) {
  if (args.size() != 1) {
    *err = Err(function, "Expected one argument.");
    return Value();
  }

  // Resolve the requested label.
  Label label = Label::Resolve(scope->GetSourceDir(),
                               ToolchainLabelForScope(scope), args[0], err);
  if (label.is_null())
    return Value();

  // Find the referenced target. The targets previously encountered in this
  // scope will have been stashed in the item collector (they'll be dispatched
  // when this file is done running) so we can look through them.
  const Target* target = nullptr;
  Scope::ItemVector* collector = scope->GetItemCollector();
  if (!collector) {
    *err = Err(function, "No targets defined in this context.");
    return Value();
  }
  for (const auto& item : *collector) {
    if (item->label() != label)
      continue;

    const Target* as_target = item->AsTarget();
    if (!as_target) {
      *err = Err(function, "Label does not refer to a target.",
          label.GetUserVisibleName(false) +
          "\nrefers to a " + item->GetItemTypeName());
      return Value();
    }
    target = as_target;
    break;
  }

  if (!target) {
    *err = Err(function, "Target not found in this context.",
        label.GetUserVisibleName(false) +
        "\nwas not found. get_target_outputs() can only be used for targets\n"
        "previously defined in the current file.");
    return Value();
  }

  // Compute the output list.
  std::vector<SourceFile> files;
  if (target->output_type() == Target::ACTION ||
      target->output_type() == Target::COPY_FILES ||
      target->output_type() == Target::ACTION_FOREACH) {
    target->action_values().GetOutputsAsSourceFiles(target, &files);
  } else {
    // Other types of targets are not supported.
    *err = Err(args[0], "Target is not an action, action_foreach, or copy.",
               "Only these target types are supported by get_target_outputs.");
    return Value();
  }

  // Convert to Values.
  Value ret(function, Value::LIST);
  ret.list_value().reserve(files.size());
  for (const auto& file : files)
    ret.list_value().push_back(Value(function, file.value()));

  return ret;
}

}  // namespace functions