// Copyright (c) 2013 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/filesystem_utils.h"

#include "base/logging.h"
#include "base/strings/utf_string_conversions.h"
#include "build/build_config.h"
#include "tools/gn/location.h"
#include "tools/gn/source_dir.h"

namespace {

enum DotDisposition {
  // The given dot is just part of a filename and is not special.
  NOT_A_DIRECTORY,

  // The given dot is the current directory.
  DIRECTORY_CUR,

  // The given dot is the first of a double dot that should take us up one.
  DIRECTORY_UP
};

// When we find a dot, this function is called with the character following
// that dot to see what it is. The return value indicates what type this dot is
// (see above). This code handles the case where the dot is at the end of the
// input.
//
// |*consumed_len| will contain the number of characters in the input that
// express what we found.
DotDisposition ClassifyAfterDot(const std::string& path,
                                size_t after_dot,
                                size_t* consumed_len) {
  if (after_dot == path.size()) {
    // Single dot at the end.
    *consumed_len = 1;
    return DIRECTORY_CUR;
  }
  if (path[after_dot] == '/') {
    // Single dot followed by a slash.
    *consumed_len = 2;  // Consume the slash
    return DIRECTORY_CUR;
  }

  if (path[after_dot] == '.') {
    // Two dots.
    if (after_dot + 1 == path.size()) {
      // Double dot at the end.
      *consumed_len = 2;
      return DIRECTORY_UP;
    }
    if (path[after_dot + 1] == '/') {
      // Double dot folowed by a slash.
      *consumed_len = 3;
      return DIRECTORY_UP;
    }
  }

  // The dots are followed by something else, not a directory.
  *consumed_len = 1;
  return NOT_A_DIRECTORY;
}

}  // namesapce

SourceFileType GetSourceFileType(const SourceFile& file,
                                 Settings::TargetOS os) {
  base::StringPiece extension = FindExtension(&file.value());
  if (extension == "cc" || extension == "cpp" || extension == "cxx")
    return SOURCE_CC;
  if (extension == "h")
    return SOURCE_H;
  if (extension == "c")
    return SOURCE_C;

  switch (os) {
    case Settings::MAC:
      if (extension == "m")
        return SOURCE_M;
      if (extension == "mm")
        return SOURCE_MM;
      break;

    case Settings::WIN:
      if (extension == "rc")
        return SOURCE_RC;
      break;

    default:
      break;
  }

  // TODO(brettw) asm files.
  // TODO(brettw) weird thing with .S on non-Windows platforms.
  return SOURCE_UNKNOWN;
}

const char* GetExtensionForOutputType(Target::OutputType type,
                                      Settings::TargetOS os) {
  switch (os) {
    case Settings::WIN:
      switch (type) {
        case Target::NONE:
          NOTREACHED();
          return "";
        case Target::EXECUTABLE:
          return "exe";
        case Target::SHARED_LIBRARY:
          return "dll.lib";  // Extension of import library.
        case Target::STATIC_LIBRARY:
          return "lib";
        case Target::LOADABLE_MODULE:
          return "dll";  // TODO(brettw) what's this?
        default:
          NOTREACHED();
      }
      break;

    default:
      NOTREACHED();
  }
  return "";
}

std::string FilePathToUTF8(const base::FilePath& path) {
#if defined(OS_WIN)
  return WideToUTF8(path.value());
#else
  return path.value();
#endif
}

base::FilePath UTF8ToFilePath(const base::StringPiece& sp) {
#if defined(OS_WIN)
  return base::FilePath(UTF8ToWide(sp));
#else
  return base::FilePath(sp.as_string());
#endif
}

size_t FindExtensionOffset(const std::string& path) {
  for (int i = static_cast<int>(path.size()); i >= 0; i--) {
    if (path[i] == '/')
      break;
    if (path[i] == '.')
      return i + 1;
  }
  return std::string::npos;
}

base::StringPiece FindExtension(const std::string* path) {
  size_t extension_offset = FindExtensionOffset(*path);
  if (extension_offset == std::string::npos)
    return base::StringPiece();
  return base::StringPiece(&path->data()[extension_offset],
                           path->size() - extension_offset);
}

size_t FindFilenameOffset(const std::string& path) {
  for (int i = static_cast<int>(path.size()) - 1; i >= 0; i--) {
    if (path[i] == '/')
      return i + 1;
  }
  return 0;  // No filename found means everything was the filename.
}

base::StringPiece FindFilename(const std::string* path) {
  size_t filename_offset = FindFilenameOffset(*path);
  if (filename_offset == 0)
    return base::StringPiece(*path);  // Everything is the file name.
  return base::StringPiece(&(*path).data()[filename_offset],
                           path->size() - filename_offset);
}

base::StringPiece FindFilenameNoExtension(const std::string* path) {
  if (path->empty())
    return base::StringPiece();
  size_t filename_offset = FindFilenameOffset(*path);
  size_t extension_offset = FindExtensionOffset(*path);

  size_t name_len;
  if (extension_offset == std::string::npos)
    name_len = path->size() - filename_offset;
  else
    name_len = extension_offset - filename_offset - 1;

  return base::StringPiece(&(*path).data()[filename_offset], name_len);
}

void RemoveFilename(std::string* path) {
  path->resize(FindFilenameOffset(*path));
}

bool EndsWithSlash(const std::string& s) {
  return !s.empty() && s[s.size() - 1] == '/';
}

base::StringPiece FindDir(const std::string* path) {
  size_t filename_offset = FindFilenameOffset(*path);
  if (filename_offset == 0u)
    return base::StringPiece();
  return base::StringPiece(path->data(), filename_offset);
}

bool EnsureStringIsInOutputDir(const SourceDir& dir,
                               const std::string& str,
                               const Value& originating,
                               Err* err) {
  // The last char of the dir will be a slash. We don't care if the input ends
  // in a slash or not, so just compare up until there.
  //
  // This check will be wrong for all proper prefixes "e.g. "/output" will
  // match "/out" but we don't really care since this is just a sanity check.
  const std::string& dir_str = dir.value();
  if (str.compare(0, dir_str.length() - 1, dir_str, 0, dir_str.length() - 1)
      != 0) {
    *err = Err(originating, "File not inside output directory.",
        "The given file should be in the output directory. Normally you would "
        "specify\n\"$target_output_dir/foo\" or "
        "\"$target_gen_dir/foo\". I interpreted this as\n\""
        + str + "\".");
    return false;
  }
  return true;
}

std::string InvertDir(const SourceDir& path) {
  const std::string value = path.value();
  if (value.empty())
    return std::string();

  DCHECK(value[0] == '/');
  size_t begin_index = 1;

  // If the input begins with two slashes, skip over both (this is a
  // source-relative dir).
  if (value.size() > 1 && value[1] == '/')
    begin_index = 2;

  std::string ret;
  for (size_t i = begin_index; i < value.size(); i++) {
    if (value[i] == '/')
      ret.append("../");
  }
  return ret;
}

void NormalizePath(std::string* path) {
  char* pathbuf = path->empty() ? NULL : &(*path)[0];

  // top_index is the first character we can modify in the path. Anything
  // before this indicates where the path is relative to.
  size_t top_index = 0;
  bool is_relative = true;
  if (!path->empty() && pathbuf[0] == '/') {
    is_relative = false;

    if (path->size() > 1 && pathbuf[1] == '/') {
      // Two leading slashes, this is a path into the source dir.
      top_index = 2;
    } else {
      // One leading slash, this is a system-absolute path.
      top_index = 1;
    }
  }

  size_t dest_i = top_index;
  for (size_t src_i = top_index; src_i < path->size(); /* nothing */) {
    if (pathbuf[src_i] == '.') {
      if (src_i == 0 || pathbuf[src_i - 1] == '/') {
        // Slash followed by a dot, see if it's something special.
        size_t consumed_len;
        switch (ClassifyAfterDot(*path, src_i + 1, &consumed_len)) {
          case NOT_A_DIRECTORY:
            // Copy the dot to the output, it means nothing special.
            pathbuf[dest_i++] = pathbuf[src_i++];
            break;
          case DIRECTORY_CUR:
            // Current directory, just skip the input.
            src_i += consumed_len;
            break;
          case DIRECTORY_UP:
            // Back up over previous directory component. If we're already
            // at the top, preserve the "..".
            if (dest_i > top_index) {
              // The previous char was a slash, remove it.
              dest_i--;
            }

            if (dest_i == top_index) {
              if (is_relative) {
                // We're already at the beginning of a relative input, copy the
                // ".." and continue. We need the trailing slash if there was
                // one before (otherwise we're at the end of the input).
                pathbuf[dest_i++] = '.';
                pathbuf[dest_i++] = '.';
                if (consumed_len == 3)
                  pathbuf[dest_i++] = '/';

                // This also makes a new "root" that we can't delete by going
                // up more levels.  Otherwise "../.." would collapse to
                // nothing.
                top_index = dest_i;
              }
              // Otherwise we're at the beginning of an absolute path. Don't
              // allow ".." to go up another level and just eat it.
            } else {
              // Just find the previous slash or the beginning of input.
              while (dest_i > 0 && pathbuf[dest_i - 1] != '/')
                dest_i--;
            }
            src_i += consumed_len;
        }
      } else {
        // Dot not preceeded by a slash, copy it literally.
        pathbuf[dest_i++] = pathbuf[src_i++];
      }
    } else if (pathbuf[src_i] == '/') {
      if (src_i > 0 && pathbuf[src_i - 1] == '/') {
        // Two slashes in a row, skip over it.
        src_i++;
      } else {
        // Just one slash, copy it.
        pathbuf[dest_i++] = pathbuf[src_i++];
      }
    } else {
      // Input nothing special, just copy it.
      pathbuf[dest_i++] = pathbuf[src_i++];
    }
  }
  path->resize(dest_i);
}

void ConvertPathToSystem(std::string* path) {
#if defined(OS_WIN)
  for (size_t i = 0; i < path->size(); i++) {
    if ((*path)[i] == '/')
      (*path)[i] = '\\';
  }
#endif
}

std::string PathToSystem(const std::string& path) {
  std::string ret(path);
  ConvertPathToSystem(&ret);
  return ret;
}