// Copyright 2014 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "src/main/cpp/option_processor.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <cassert>
#include <set>
#include <utility>

#include "src/main/cpp/blaze_util.h"
#include "src/main/cpp/blaze_util_platform.h"
#include "src/main/cpp/util/file.h"
#include "src/main/cpp/util/logging.h"
#include "src/main/cpp/util/strings.h"
#include "src/main/cpp/workspace_layout.h"

// On OSX, there apparently is no header that defines this.
extern char **environ;

namespace blaze {

using std::list;
using std::map;
using std::set;
using std::string;
using std::vector;

constexpr char WorkspaceLayout::WorkspacePrefix[];

OptionProcessor::RcOption::RcOption(int rcfile_index, const string& option)
    : rcfile_index_(rcfile_index), option_(option) {
}

OptionProcessor::RcFile::RcFile(const string& filename, int index)
    : filename_(filename), index_(index) {
}

blaze_exit_code::ExitCode OptionProcessor::RcFile::Parse(
    const string& workspace,
    const WorkspaceLayout* workspace_layout,
    vector<RcFile*>* rcfiles,
    map<string, vector<RcOption> >* rcoptions,
    string* error) {
  list<string> initial_import_stack;
  initial_import_stack.push_back(filename_);
  return Parse(
      workspace, filename_, index_, workspace_layout,
      rcfiles, rcoptions, &initial_import_stack,
      error);
}

blaze_exit_code::ExitCode OptionProcessor::RcFile::Parse(
    const string& workspace,
    const string& filename_ref,
    const int index,
    const WorkspaceLayout* workspace_layout,
    vector<RcFile*>* rcfiles,
    map<string, vector<RcOption> >* rcoptions,
    list<string>* import_stack,
    string* error) {
  string filename(filename_ref);  // file
  BAZEL_LOG(INFO) << "Parsing the RcFile " << filename;
  string contents;
  if (!blaze_util::ReadFile(filename, &contents)) {
    // We checked for file readability before, so this is unexpected.
    blaze_util::StringPrintf(error,
        "Unexpected error reading .blazerc file '%s'", filename.c_str());
    return blaze_exit_code::INTERNAL_ERROR;
  }

  // A '\' at the end of a line continues the line.
  blaze_util::Replace("\\\r\n", "", &contents);
  blaze_util::Replace("\\\n", "", &contents);

  vector<string> lines = blaze_util::Split(contents, '\n');
  for (string& line : lines) {
    blaze_util::StripWhitespace(&line);

    // Check for an empty line.
    if (line.empty()) {
      continue;
    }

    vector<string> words;

    // This will treat "#" as a comment, and properly
    // quote single and double quotes, and treat '\'
    // as an escape character.
    // TODO(bazel-team): This function silently ignores
    // dangling backslash escapes and missing end-quotes.
    blaze_util::Tokenize(line, '#', &words);

    if (words.empty()) {
      // Could happen if line starts with "#"
      continue;
    }

    string command = words[0];

    if (command == "import") {
      if (words.size() != 2
          || (words[1].compare(0, workspace_layout->WorkspacePrefixLength,
                               workspace_layout->WorkspacePrefix) == 0
              && !workspace_layout->WorkspaceRelativizeRcFilePath(
                  workspace, &words[1]))) {
        blaze_util::StringPrintf(
            error,
            "Invalid import declaration in .blazerc file '%s': '%s'"
            " (are you in your source checkout/WORKSPACE?)",
            filename.c_str(), line.c_str());
        return blaze_exit_code::BAD_ARGV;
      }
      if (std::find(import_stack->begin(), import_stack->end(), words[1]) !=
          import_stack->end()) {
        string loop;
        for (list<string>::const_iterator imported_rc = import_stack->begin();
             imported_rc != import_stack->end(); ++imported_rc) {
          loop += "  " + *imported_rc + "\n";
        }
        blaze_util::StringPrintf(error,
            "Import loop detected:\n%s", loop.c_str());
        return blaze_exit_code::BAD_ARGV;
      }

      rcfiles->push_back(new RcFile(words[1], rcfiles->size()));
      import_stack->push_back(words[1]);
      blaze_exit_code::ExitCode parse_exit_code =
        RcFile::Parse(workspace, rcfiles->back()->Filename(),
                      rcfiles->back()->Index(), workspace_layout,
                      rcfiles, rcoptions, import_stack, error);
      if (parse_exit_code != blaze_exit_code::SUCCESS) {
        return parse_exit_code;
      }
      import_stack->pop_back();
    } else {
      vector<string>::const_iterator words_it = words.begin();
      words_it++;  // Advance past command.
      for (; words_it != words.end(); words_it++) {
        (*rcoptions)[command].push_back(RcOption(index, *words_it));
      }
    }
  }

  return blaze_exit_code::SUCCESS;
}

OptionProcessor::OptionProcessor(
    const WorkspaceLayout* workspace_layout,
    std::unique_ptr<StartupOptions> default_startup_options)
    : workspace_layout_(workspace_layout),
      parsed_startup_options_(std::move(default_startup_options)) {
}

std::unique_ptr<CommandLine> OptionProcessor::SplitCommandLine(
    const vector<string>& args, string* error) const {
  const string lowercase_product_name =
      parsed_startup_options_->GetLowercaseProductName();

  if (args.empty()) {
    blaze_util::StringPrintf(error,
                             "Unable to split command line, args is empty");
    return nullptr;
  }

  const string path_to_binary(args[0]);

  // Process the startup options.
  vector<string> startup_args;
  vector<string>::size_type i = 1;
  while (i < args.size() && IsArg(args[i])) {
    const string current_arg(args[i]);
    // If the current argument is a valid nullary startup option such as
    // --master_bazelrc or --nomaster_bazelrc proceed to examine the next
    // argument.
    if (parsed_startup_options_->IsNullary(current_arg)) {
      startup_args.push_back(current_arg);
      i++;
    } else if (parsed_startup_options_->IsUnary(current_arg)) {
      // If the current argument is a valid unary startup option such as
      // --bazelrc there are two cases to consider.

      // The option is of the form '--bazelrc=value', hence proceed to
      // examine the next argument.
      if (current_arg.find("=") != string::npos) {
        startup_args.push_back(current_arg);
        i++;
      } else {
        // Otherwise, the option is of the form '--bazelrc value', hence
        // skip the next argument and proceed to examine the argument located
        // two places after.
        if (i + 1 >= args.size()) {
          blaze_util::StringPrintf(
              error,
              "Startup option '%s' expects a value.\n"
              "Usage: '%s=somevalue' or '%s somevalue'.\n"
              "  For more info, run '%s help startup_options'.",
              current_arg.c_str(), current_arg.c_str(), current_arg.c_str(),
              lowercase_product_name.c_str());
          return nullptr;
        }
        // In this case we transform it to the form '--bazelrc=value'.
        startup_args.push_back(current_arg + string("=") + args[i + 1]);
        i += 2;
      }
    } else {
      // If the current argument is not a valid unary or nullary startup option
      // then fail.
      blaze_util::StringPrintf(
          error,
          "Unknown startup option: '%s'.\n"
          "  For more info, run '%s help startup_options'.",
          current_arg.c_str(), lowercase_product_name.c_str());
      return nullptr;
    }
  }

  // The command is the arg right after the startup options.
  if (i == args.size()) {
    return std::unique_ptr<CommandLine>(
        new CommandLine(path_to_binary, startup_args, "", {}));
  }
  const string command(args[i]);

  // The rest are the command arguments.
  const vector<string> command_args(args.begin() + i + 1, args.end());

  return std::unique_ptr<CommandLine>(
      new CommandLine(path_to_binary, startup_args, command, command_args));
}

// Return the path to the user's rc file.  If cmdLineRcFile != NULL,
// use it, dying if it is not readable.  Otherwise, return the first
// readable file called rc_basename from [workspace, $HOME]
//
// If no readable .blazerc file is found, return the empty string.
blaze_exit_code::ExitCode OptionProcessor::FindUserBlazerc(
    const char* cmdLineRcFile,
    const string& workspace,
    string* blaze_rc_file,
    string* error) {
  const string rc_basename =
      "." + parsed_startup_options_->GetLowercaseProductName() + "rc";

  if (cmdLineRcFile != NULL) {
    string rcFile = MakeAbsolute(cmdLineRcFile);
    if (!blaze_util::CanReadFile(rcFile)) {
      blaze_util::StringPrintf(error,
          "Error: Unable to read %s file '%s'.", rc_basename.c_str(),
          rcFile.c_str());
      return blaze_exit_code::BAD_ARGV;
    }
    *blaze_rc_file = rcFile;
    return blaze_exit_code::SUCCESS;
  }

  string workspaceRcFile = blaze_util::JoinPath(workspace, rc_basename);
  if (blaze_util::CanReadFile(workspaceRcFile)) {
    *blaze_rc_file = workspaceRcFile;
    return blaze_exit_code::SUCCESS;
  }

  string home = blaze::GetHomeDir();
  if (home.empty()) {
    *blaze_rc_file = "";
    return blaze_exit_code::SUCCESS;
  }

  string userRcFile = blaze_util::JoinPath(home, rc_basename);
  if (blaze_util::CanReadFile(userRcFile)) {
    *blaze_rc_file = userRcFile;
    return blaze_exit_code::SUCCESS;
  }
  *blaze_rc_file = "";
  return blaze_exit_code::SUCCESS;
}

namespace internal {

vector<string> DedupeBlazercPaths(const vector<string>& paths) {
  set<string> canonical_paths;
  vector<string> result;
  for (const string& path : paths) {
    const string canonical_path = blaze_util::MakeCanonical(path.c_str());
    if (canonical_path.empty()) {
      // MakeCanonical returns an empty string when it fails. We ignore this
      // failure since blazerc paths may point to invalid locations.
    } else if (canonical_paths.find(canonical_path) == canonical_paths.end()) {
      result.push_back(path);
      canonical_paths.insert(canonical_path);
    }
  }
  return result;
}

}  // namespace internal

// Parses the arguments provided in args using the workspace path and the
// current working directory (cwd) and stores the results.
blaze_exit_code::ExitCode OptionProcessor::ParseOptions(
    const vector<string>& args,
    const string& workspace,
    const string& cwd,
    string* error) {

  cmd_line_ = SplitCommandLine(args, error);
  if (cmd_line_ == nullptr) {
    return blaze_exit_code::BAD_ARGV;
  }
  const char* blazerc = SearchUnaryOption(cmd_line_->startup_args, "--blazerc");
  if (blazerc == NULL) {
    blazerc = SearchUnaryOption(cmd_line_->startup_args, "--bazelrc");
  }

  bool use_master_blazerc = true;
  if (SearchNullaryOption(cmd_line_->startup_args, "--nomaster_blazerc") ||
      SearchNullaryOption(cmd_line_->startup_args, "--nomaster_bazelrc")) {
    use_master_blazerc = false;
  }

  // Use the workspace path, the current working directory, the path to the
  // blaze binary and the startup args to determine the list of possible
  // paths to the rc files. This list may contain duplicates.
  vector<string> candidate_blazerc_paths;
  if (use_master_blazerc) {
    workspace_layout_->FindCandidateBlazercPaths(
        workspace, cwd, cmd_line_->path_to_binary, cmd_line_->startup_args,
        &candidate_blazerc_paths);
  }

  string user_blazerc_path;
  blaze_exit_code::ExitCode find_blazerc_exit_code = FindUserBlazerc(
      blazerc, workspace, &user_blazerc_path, error);
  if (find_blazerc_exit_code != blaze_exit_code::SUCCESS) {
    return find_blazerc_exit_code;
  }

  vector<string> deduped_blazerc_paths =
      internal::DedupeBlazercPaths(candidate_blazerc_paths);
  // TODO(b/37731193): Decide whether the user blazerc should be included in
  // the deduplication process. If so then we need to handle all cases
  // (e.g. user rc coming from process substitution).
  deduped_blazerc_paths.push_back(user_blazerc_path);

  for (const auto& blazerc_path : deduped_blazerc_paths) {
    if (!blazerc_path.empty()) {
      blazercs_.push_back(new RcFile(blazerc_path, blazercs_.size()));
      blaze_exit_code::ExitCode parse_exit_code =
          blazercs_.back()->Parse(workspace, workspace_layout_, &blazercs_,
                                  &rcoptions_, error);
      if (parse_exit_code != blaze_exit_code::SUCCESS) {
        return parse_exit_code;
      }
    }
  }

  blaze_exit_code::ExitCode parse_startup_options_exit_code =
      ParseStartupOptions(error);
  if (parse_startup_options_exit_code != blaze_exit_code::SUCCESS) {
    return parse_startup_options_exit_code;
  }

  blazerc_and_env_command_args_ = GetBlazercAndEnvCommandArgs(
      cwd, blazercs_, rcoptions_);
  return blaze_exit_code::SUCCESS;
}

static void PrintStartupOptions(const std::string& source,
                                const std::vector<std::string>& options) {
  if (!source.empty()) {
    std::string startup_args;
    blaze_util::JoinStrings(options, ' ', &startup_args);
    fprintf(stderr, "INFO: Reading 'startup' options from %s: %s\n",
            source.c_str(), startup_args.c_str());
  }
}

void OptionProcessor::PrintStartupOptionsProvenanceMessage() const {
  StartupOptions* parsed_startup_options = GetParsedStartupOptions();

  // Print the startup flags in the order they are parsed, to keep the
  // precendence clear. In order to minimize the number of lines of output in
  // the terminal, group sequential flags by origin. Note that an rc file may
  // turn up multiple times in this list, if, for example, it imports another
  // rc file and contains startup options on either side of the import
  // statement. This is done intentionally to make option priority clear.
  std::string command_line_source;
  std::string& most_recent_blazerc = command_line_source;
  std::vector<std::string> accumulated_options;
  for (auto flag : parsed_startup_options->original_startup_options_) {
    if (flag.source == most_recent_blazerc) {
      accumulated_options.push_back(flag.value);
    } else {
      PrintStartupOptions(most_recent_blazerc, accumulated_options);
      // Start accumulating again.
      accumulated_options.clear();
      accumulated_options.push_back(flag.value);
      most_recent_blazerc = flag.source;
    }
  }
  // Don't forget to print out the last ones.
  PrintStartupOptions(most_recent_blazerc, accumulated_options);
}

blaze_exit_code::ExitCode OptionProcessor::ParseStartupOptions(
    std::string *error) {
  // Rc files can import other files at any point, and these imported rcs are
  // expanded in place. The effective ordering of rc flags is stored in
  // rcoptions_ and should be processed in that order. Here, we isolate just the
  // startup options, but keep the file they came from attached for the
  // option_sources tracking and for sending to the server.
  std::vector<RcStartupFlag> rcstartup_flags;

  auto iter = rcoptions_.find("startup");
  if (iter != rcoptions_.end()) {
    const vector<RcOption>& startup_rcoptions = iter->second;
    for (const RcOption& option : startup_rcoptions) {
      rcstartup_flags.push_back(
          RcStartupFlag(blazercs_[option.rcfile_index()]->Filename(),
                        option.option()));
    }
  }

  for (const std::string& arg : cmd_line_->startup_args) {
    if (!IsArg(arg)) {
      break;
    }
    rcstartup_flags.push_back(RcStartupFlag("", arg));
  }

  return parsed_startup_options_->ProcessArgs(rcstartup_flags, error);
}

static bool IsValidEnvName(const char* p) {
#if defined(COMPILER_MSVC) || defined(__CYGWIN__)
  for (; *p && *p != '='; ++p) {
    if (!((*p >= 'a' && *p <= 'z') || (*p >= 'A' && *p <= 'Z') ||
          (*p >= '0' && *p <= '9') || *p == '_')) {
      return false;
    }
  }
#endif
  return true;
}

#if defined(COMPILER_MSVC)
static void PreprocessEnvString(string* env_str) {
  static std::set<string> vars_to_uppercase = {"PATH", "TMP", "TEMP", "TEMPDIR",
                                               "SYSTEMROOT"};

  int pos = env_str->find_first_of('=');
  if (pos == string::npos) return;

  string name = env_str->substr(0, pos);
  // We do not care about locale. All variable names are ASCII.
  std::transform(name.begin(), name.end(), name.begin(), ::toupper);
  if (vars_to_uppercase.find(name) != vars_to_uppercase.end()) {
    env_str->assign(name + "=" + env_str->substr(pos + 1));
  }
}

#elif defined(__CYGWIN__)  // not defined(COMPILER_MSVC)

static void PreprocessEnvString(string* env_str) {
  int pos = env_str->find_first_of('=');
  if (pos == string::npos) return;
  string name = env_str->substr(0, pos);
  if (name == "PATH") {
    env_str->assign("PATH=" + ConvertPathList(env_str->substr(pos + 1)));
  } else if (name == "TMP") {
    // A valid Windows path "c:/foo" is also a valid Unix path list of
    // ["c", "/foo"] so must use ConvertPath here. See GitHub issue #1684.
    env_str->assign("TMP=" + ConvertPath(env_str->substr(pos + 1)));
  }
}

#else  // Non-Windows platforms.

static void PreprocessEnvString(const string* env_str) {
  // do nothing.
}
#endif  // defined(COMPILER_MSVC)

// IMPORTANT: Keep the options added here in sync with
// BlazeCommandDispatcher.INTERNAL_COMMAND_OPTIONS!
std::vector<std::string> OptionProcessor::GetBlazercAndEnvCommandArgs(
    const std::string& cwd,
    const std::vector<RcFile*>& blazercs,
    const std::map<std::string, std::vector<RcOption>>& rcoptions) {
  // Provide terminal options as coming from the least important rc file.
  std::vector<std::string> result = {
    "--rc_source=client",
    "--default_override=0:common=--isatty=" +
        ToString(IsStandardTerminal()),
    "--default_override=0:common=--terminal_columns=" +
        ToString(GetTerminalColumns())};

  // Push the options mapping .blazerc numbers to filenames.
  for (const RcFile* blazerc : blazercs) {
    result.push_back("--rc_source=" + blaze::ConvertPath(blazerc->Filename()));
  }

  // Process RcOptions except for the startup flags that are already parsed
  // by the client and shouldn't be included in the command args.
  for (auto it = rcoptions.begin(); it != rcoptions.end(); ++it) {
    if (it->first != "startup") {
      for (const RcOption& rcoption : it->second) {
        result.push_back(
            "--default_override=" + ToString(rcoption.rcfile_index() + 1) + ":"
            + it->first + "=" + rcoption.option());
      }
    }
  }

  // Pass the client environment to the server.
  for (char** env = environ; *env != NULL; env++) {
    string env_str(*env);
    if (IsValidEnvName(*env)) {
      PreprocessEnvString(&env_str);
      debug_log("--client_env=%s", env_str.c_str());
      result.push_back("--client_env=" + env_str);
    }
  }
  result.push_back("--client_cwd=" + blaze::ConvertPath(cwd));

  if (IsEmacsTerminal()) {
    result.push_back("--emacs");
  }
  return result;
}

std::vector<std::string> OptionProcessor::GetCommandArguments() const {
  assert(cmd_line_ != nullptr);
  // When the user didn't specify a command, the server expects the command
  // arguments to be empty in order to display the help message.
  if (cmd_line_->command.empty()) {
    return {};
  }

  std::vector<std::string> command_args = blazerc_and_env_command_args_;
  command_args.insert(command_args.end(),
                      cmd_line_->command_args.begin(),
                      cmd_line_->command_args.end());
  return command_args;
}

std::vector<std::string> OptionProcessor::GetExplicitCommandArguments() const {
  assert(cmd_line_ != nullptr);
  return cmd_line_->command_args;
}

std::string OptionProcessor::GetCommand() const {
  assert(cmd_line_ != nullptr);
  return cmd_line_->command;
}

StartupOptions* OptionProcessor::GetParsedStartupOptions() const {
  assert(parsed_startup_options_ != NULL);
  return parsed_startup_options_.get();
}

OptionProcessor::~OptionProcessor() {
  for (auto it : blazercs_) {
    delete it;
  }
}

}  // namespace blaze