// 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/label_pattern.h"

#include <stddef.h>

#include "base/strings/string_util.h"
#include "build/build_config.h"
#include "tools/gn/err.h"
#include "tools/gn/filesystem_utils.h"
#include "tools/gn/value.h"

const char kLabelPattern_Help[] =
    "Label patterns\n"
    "\n"
    "  A label pattern is a way of expressing one or more labels in a portion\n"
    "  of the source tree. They are not general regular expressions.\n"
    "\n"
    "  They can take the following forms only:\n"
    "\n"
    "   - Explicit (no wildcard):\n"
    "       \"//foo/bar:baz\"\n"
    "       \":baz\"\n"
    "\n"
    "   - Wildcard target names:\n"
    "       \"//foo/bar:*\" (all targets in the //foo/bar/BUILD.gn file)\n"
    "       \":*\"  (all targets in the current build file)\n"
    "\n"
    "   - Wildcard directory names (\"*\" is only supported at the end)\n"
    "       \"*\"  (all targets)\n"
    "       \"//foo/bar/*\"  (all targets in any subdir of //foo/bar)\n"
    "       \"./*\"  (all targets in the current build file or sub dirs)\n"
    "\n"
    "  Any of the above forms can additionally take an explicit toolchain.\n"
    "  In this case, the toolchain must be fully qualified (no wildcards\n"
    "  are supported in the toolchain name).\n"
    "\n"
    "    \"//foo:bar(//build/toochain:mac)\"\n"
    "        An explicit target in an explicit toolchain.\n"
    "\n"
    "    \":*(//build/toolchain/linux:32bit)\"\n"
    "        All targets in the current build file using the 32-bit Linux\n"
    "        toolchain.\n"
    "\n"
    "    \"//foo/*(//build/toolchain:win)\"\n"
    "        All targets in //foo and any subdirectory using the Windows\n"
    "        toolchain.\n";

LabelPattern::LabelPattern() : type_(MATCH) {
}

LabelPattern::LabelPattern(Type type,
                           const SourceDir& dir,
                           const base::StringPiece& name,
                           const Label& toolchain_label)
    : toolchain_(toolchain_label),
      type_(type),
      dir_(dir) {
  name.CopyToString(&name_);
}

LabelPattern::LabelPattern(const LabelPattern& other) = default;

LabelPattern::~LabelPattern() {
}

// static
LabelPattern LabelPattern::GetPattern(const SourceDir& current_dir,
                                      const Value& value,
                                      Err* err) {
  if (!value.VerifyTypeIs(Value::STRING, err))
    return LabelPattern();

  base::StringPiece str(value.string_value());
  if (str.empty()) {
    *err = Err(value, "Label pattern must not be empty.");
    return LabelPattern();
  }

  // If there's no wildcard, this is specifying an exact label, use the
  // label resolution code to get all the implicit name stuff.
  size_t star = str.find('*');
  if (star == std::string::npos) {
    Label label = Label::Resolve(current_dir, Label(), value, err);
    if (err->has_error())
      return LabelPattern();

    // Toolchain.
    Label toolchain_label;
    if (!label.toolchain_dir().is_null() || !label.toolchain_name().empty())
      toolchain_label = label.GetToolchainLabel();

    return LabelPattern(MATCH, label.dir(), label.name(), toolchain_label);
  }

  // Wildcard case, need to split apart the label to see what it specifies.
  Label toolchain_label;
  size_t open_paren = str.find('(');
  if (open_paren != std::string::npos) {
    // Has a toolchain definition, extract inside the parens.
    size_t close_paren = str.find(')', open_paren);
    if (close_paren == std::string::npos) {
      *err = Err(value, "No close paren when looking for toolchain name.");
      return LabelPattern();
    }

    std::string toolchain_string =
        str.substr(open_paren + 1, close_paren - open_paren - 1).as_string();
    if (toolchain_string.find('*') != std::string::npos) {
      *err = Err(value, "Can't have a wildcard in the toolchain.");
      return LabelPattern();
    }

    // Parse the inside of the parens as a label for a toolchain.
    Value value_for_toolchain(value.origin(), toolchain_string);
    toolchain_label =
        Label::Resolve(current_dir, Label(), value_for_toolchain, err);
    if (err->has_error())
      return LabelPattern();

    // Trim off the toolchain for the processing below.
    str = str.substr(0, open_paren);
  }

  // Extract path and name.
  base::StringPiece path;
  base::StringPiece name;
  size_t offset = 0;
#if defined(OS_WIN)
  if (IsPathAbsolute(str)) {
    size_t drive_letter_pos = str[0] == '/' ? 1 : 0;
    if (str.size() > drive_letter_pos + 2 && str[drive_letter_pos + 1] == ':' &&
        IsSlash(str[drive_letter_pos + 2]) &&
        base::IsAsciiAlpha(str[drive_letter_pos])) {
      // Skip over the drive letter colon.
      offset = drive_letter_pos + 2;
    }
  }
#endif
  size_t colon = str.find(':', offset);
  if (colon == std::string::npos) {
    path = base::StringPiece(str);
  } else {
    path = str.substr(0, colon);
    name = str.substr(colon + 1);
  }

  // The path can have these forms:
  //   1. <empty>  (use current dir)
  //   2. <non wildcard stuff>  (send through directory resolution)
  //   3. <non wildcard stuff>*  (send stuff through dir resolution, note star)
  //   4. *  (matches anything)
  SourceDir dir;
  bool has_path_star = false;
  if (path.empty()) {
    // Looks like ":foo".
    dir = current_dir;
  } else if (path[path.size() - 1] == '*') {
    // Case 3 or 4 above.
    has_path_star = true;

    // Adjust path to contain everything but the star.
    path = path.substr(0, path.size() - 1);

    if (!path.empty() && path[path.size() - 1] != '/') {
      // The input was "foo*" which is invalid.
      *err = Err(value, "'*' must match full directories in a label pattern.",
          "You did \"foo*\" but this thing doesn't do general pattern\n"
          "matching. Instead, you have to add a slash: \"foo/*\" to match\n"
          "all targets in a directory hierarchy.");
      return LabelPattern();
    }
  }

  // Resolve the part of the path that's not the wildcard.
  if (!path.empty()) {
    // The non-wildcard stuff better not have a wildcard.
    if (path.find('*') != base::StringPiece::npos) {
      *err = Err(value, "Label patterns only support wildcard suffixes.",
          "The pattern contained a '*' that wasn't at the end.");
      return LabelPattern();
    }

    // Resolve the non-wildcard stuff.
    dir = current_dir.ResolveRelativeDir(value, path, err);
    if (err->has_error())
      return LabelPattern();
  }

  // Resolve the name. At this point, we're doing wildcard matches so the
  // name should either be empty ("foo/*") or a wildcard ("foo:*");
  if (colon != std::string::npos && name != "*") {
    *err = Err(value, "Invalid label pattern.",
        "You seem to be using the wildcard more generally that is supported.\n"
        "Did you mean \"foo:*\" to match everything in the file, or\n"
        "\"./*\" to recursively match everything in the currend subtree.");
    return LabelPattern();
  }

  Type type;
  if (has_path_star) {
    // We know there's a wildcard, so if the name is empty it looks like
    // "foo/*".
    type = RECURSIVE_DIRECTORY;
  } else {
    // Everything else should be of the form "foo:*".
    type = DIRECTORY;
  }

  // When we're doing wildcard matching, the name is always empty.
  return LabelPattern(type, dir, base::StringPiece(), toolchain_label);
}

bool LabelPattern::HasWildcard(const std::string& str) {
  // Just look for a star. In the future, we may want to handle escaping or
  // other types of patterns.
  return str.find('*') != std::string::npos;
}

bool LabelPattern::Matches(const Label& label) const {
  if (!toolchain_.is_null()) {
    // Toolchain must match exactly.
    if (toolchain_.dir() != label.toolchain_dir() ||
        toolchain_.name() != label.toolchain_name())
      return false;
  }

  switch (type_) {
    case MATCH:
      return label.name() == name_ && label.dir() == dir_;
    case DIRECTORY:
      // The directories must match exactly.
      return label.dir() == dir_;
    case RECURSIVE_DIRECTORY:
      // Our directory must be a prefix of the input label for recursive.
      return label.dir().value().compare(0, dir_.value().size(), dir_.value())
          == 0;
    default:
      NOTREACHED();
      return false;
  }
}

std::string LabelPattern::Describe() const {
  std::string result;

  switch (type()) {
    case MATCH:
      result = DirectoryWithNoLastSlash(dir()) + ":" + name();
      break;
    case DIRECTORY:
      result = DirectoryWithNoLastSlash(dir()) + ":*";
      break;
    case RECURSIVE_DIRECTORY:
      result = dir().value() + "*";
      break;
  }

  if (!toolchain_.is_null()) {
    result.push_back('(');
    result.append(toolchain_.GetUserVisibleName(false));
    result.push_back(')');
  }
  return result;
}