// Copyright 2017-2018 ccls Authors
// SPDX-License-Identifier: Apache-2.0

#include "project.hh"

#include "clang_tu.hh" // llvm::vfs
#include "filesystem.hh"
#include "log.hh"
#include "match.hh"
#include "pipeline.hh"
#include "platform.hh"
#include "serializers/json.hh"
#include "utils.hh"
#include "working_files.hh"

#include <clang/Driver/Compilation.h>
#include <clang/Driver/Driver.h>
#include <clang/Driver/Types.h>
#include <clang/Frontend/CompilerInstance.h>
#include <clang/Tooling/CompilationDatabase.h>
#include <llvm/ADT/STLExtras.h>
#include <llvm/ADT/StringSet.h>
#include <llvm/Support/LineIterator.h>

#include <rapidjson/writer.h>

#if defined(__unix__) || defined(__APPLE__)
#include <unistd.h>
#endif

#include <limits.h>
#include <unordered_set>
#include <vector>

using namespace clang;
using namespace llvm;

namespace ccls {
std::pair<LanguageId, bool> lookupExtension(std::string_view filename) {
  using namespace clang::driver;
  auto I = types::lookupTypeForExtension(
      sys::path::extension({filename.data(), filename.size()}).substr(1));
  bool header = I == types::TY_CHeader || I == types::TY_CXXHeader ||
                I == types::TY_ObjCXXHeader;
  bool objc = types::isObjC(I);
  LanguageId ret;
  if (types::isCXX(I))
    ret = objc ? LanguageId::ObjCpp : LanguageId::Cpp;
  else if (objc)
    ret = LanguageId::ObjC;
  else if (I == types::TY_C || I == types::TY_CHeader)
    ret = LanguageId::C;
  else
    ret = LanguageId::Unknown;
  return {ret, header};
}

namespace {

enum class ProjectMode { CompileCommandsJson, DotCcls, ExternalCommand };

struct ProjectConfig {
  std::unordered_set<std::string> quote_dirs;
  std::unordered_set<std::string> angle_dirs;
  std::string root;
  ProjectMode mode = ProjectMode::CompileCommandsJson;
};

enum OptionClass {
  EqOrJoinOrSep,
  EqOrSep,
  JoinOrSep,
  Separate,
};

struct ProjectProcessor {
  ProjectConfig *config;
  std::unordered_set<size_t> command_set;
  StringSet<> excludeArgs;
  ProjectProcessor(ProjectConfig *config) : config(config) {
    for (auto &arg : g_config->clang.excludeArgs)
      excludeArgs.insert(arg);
  }

  void Process(Project::Entry &entry) {
    const std::string base_name = sys::path::filename(entry.filename);

    // Expand %c %cpp %clang
    std::vector<const char *> args;
    args.reserve(entry.args.size() + g_config->clang.extraArgs.size() + 1);
    const LanguageId lang = lookupExtension(entry.filename).first;
    for (const char *arg : entry.args) {
      if (strncmp(arg, "%c ", 3) == 0) {
        if (lang == LanguageId::C)
          args.push_back(arg + 3);
      } else if (strncmp(arg, "%cpp ", 5) == 0) {
        if (lang == LanguageId::Cpp)
          args.push_back(arg + 5);
      } else if (strcmp(arg, "%clang") == 0) {
        args.push_back(lang == LanguageId::Cpp ? "clang++" : "clang");
      } else if (!excludeArgs.count(arg)) {
        args.push_back(arg);
      }
    }
    if (args.empty())
      return;
    for (const std::string &arg : g_config->clang.extraArgs)
      args.push_back(Intern(arg));

    size_t hash = std::hash<std::string>{}(entry.directory);
    bool OPT_o = false;
    for (auto &arg : args) {
      bool last_o = OPT_o;
      OPT_o = false;
      if (arg[0] == '-') {
        OPT_o = arg[1] == 'o' && arg[2] == '\0';
        if (OPT_o || arg[1] == 'D' || arg[1] == 'W')
          continue;
      } else if (last_o) {
        continue;
      } else if (sys::path::filename(arg) == base_name) {
        LanguageId lang = lookupExtension(arg).first;
        if (lang != LanguageId::Unknown) {
          hash_combine(hash, (size_t)lang);
          continue;
        }
      }
      hash_combine(hash, std::hash<std::string_view>{}(arg));
    }
    args.push_back(Intern("-working-directory=" + entry.directory));
    entry.args = args;
#if LLVM_VERSION_MAJOR < 8
    args.push_back("-fsyntax-only");
    if (!command_set.insert(hash).second)
      return;

    // a weird C++ deduction guide heap-use-after-free causes libclang to crash.
    IgnoringDiagConsumer DiagC;
    IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts(new DiagnosticOptions());
    DiagnosticsEngine Diags(
      IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs()), &*DiagOpts,
      &DiagC, false);

    driver::Driver Driver(args[0], llvm::sys::getDefaultTargetTriple(), Diags);
    auto TargetAndMode =
      driver::ToolChain::getTargetAndModeFromProgramName(args[0]);
    if (!TargetAndMode.TargetPrefix.empty()) {
      const char *arr[] = {"-target", TargetAndMode.TargetPrefix.c_str()};
      args.insert(args.begin() + 1, std::begin(arr), std::end(arr));
      Driver.setTargetAndMode(TargetAndMode);
    }
    Driver.setCheckInputsExist(false);

    std::unique_ptr<driver::Compilation> C(Driver.BuildCompilation(args));
    const driver::JobList &Jobs = C->getJobs();
    if (Jobs.size() != 1)
      return;
    const auto &CCArgs = Jobs.begin()->getArguments();

    auto CI = std::make_unique<CompilerInvocation>();
    CompilerInvocation::CreateFromArgs(*CI, CCArgs.data(),
      CCArgs.data() + CCArgs.size(), Diags);
    CI->getFrontendOpts().DisableFree = false;
    CI->getCodeGenOpts().DisableFree = false;

    HeaderSearchOptions &HeaderOpts = CI->getHeaderSearchOpts();
    for (auto &E : HeaderOpts.UserEntries) {
      std::string path =
          NormalizePath(ResolveIfRelative(entry.directory, E.Path));
      switch (E.Group) {
      default:
        config->angle_dirs.insert(path);
        break;
      case frontend::Quoted:
        config->quote_dirs.insert(path);
        break;
      case frontend::Angled:
        config->angle_dirs.insert(path);
        config->quote_dirs.insert(path);
        break;
      }
    }
#endif
  }
};

std::vector<const char *>
ReadCompilerArgumentsFromFile(const std::string &path) {
  auto MBOrErr = MemoryBuffer::getFile(path);
  if (!MBOrErr)
    return {};
  std::vector<const char *> args;
  for (line_iterator I(*MBOrErr.get(), true, '#'), E; I != E; ++I) {
    std::string line = *I;
    DoPathMapping(line);
    args.push_back(Intern(line));
  }
  return args;
}

std::vector<Project::Entry> LoadFromDirectoryListing(ProjectConfig *config) {
  std::vector<Project::Entry> result;
  config->mode = ProjectMode::DotCcls;

  std::unordered_map<std::string, std::vector<const char *>> folder_args;
  std::vector<std::string> files;
  const std::string &root = config->root;

  GetFilesInFolder(root, true /*recursive*/,
                   true /*add_folder_to_path*/,
                   [&folder_args, &files](const std::string &path) {
                     std::pair<LanguageId, bool> lang = lookupExtension(path);
                     if (lang.first != LanguageId::Unknown && !lang.second) {
                       files.push_back(path);
                     } else if (sys::path::filename(path) == ".ccls") {
                       std::vector<const char *> args = ReadCompilerArgumentsFromFile(path);
                       folder_args.emplace(sys::path::parent_path(path), args);
                       std::string l;
                       for (size_t i = 0; i < args.size(); i++) {
                         if (i)
                           l += ' ';
                         l += args[i];
                       }
                       LOG_S(INFO) << "use " << path << ": " << l;
                     }
                   });

  auto GetCompilerArgumentForFile = [&root,
                                     &folder_args](std::string cur) {
    while (!(cur = sys::path::parent_path(cur)).empty()) {
      auto it = folder_args.find(cur);
      if (it != folder_args.end())
        return it->second;
      std::string normalized = NormalizePath(cur);
      // Break if outside of the project root.
      if (normalized.size() <= root.size() ||
          normalized.compare(0, root.size(), root) != 0)
        break;
    }
    return folder_args[root];
  };

  ProjectProcessor proc(config);
  for (const std::string &file : files) {
    Project::Entry e;
    e.root = config->root;
    e.directory = config->root;
    e.filename = file;
    e.args = GetCompilerArgumentForFile(file);
    if (e.args.empty())
      e.args.push_back("%clang"); // Add a Dummy.
    e.args.push_back(Intern(e.filename));
    proc.Process(e);
    result.push_back(e);
  }

  return result;
}

std::vector<Project::Entry>
LoadEntriesFromDirectory(ProjectConfig *project,
                         const std::string &opt_compdb_dir) {
  // If there is a .ccls file always load using directory listing.
  SmallString<256> Path, CclsPath;
  sys::path::append(CclsPath, project->root, ".ccls");
  if (sys::fs::exists(CclsPath))
    return LoadFromDirectoryListing(project);

  // If |compilationDatabaseCommand| is specified, execute it to get the compdb.
  std::string comp_db_dir;
  if (g_config->compilationDatabaseCommand.empty()) {
    project->mode = ProjectMode::CompileCommandsJson;
    // Try to load compile_commands.json, but fallback to a project listing.
    comp_db_dir = opt_compdb_dir.empty() ? project->root : opt_compdb_dir;
    sys::path::append(Path, comp_db_dir, "compile_commands.json");
  } else {
    project->mode = ProjectMode::ExternalCommand;
#ifdef _WIN32
    // TODO
#else
    char tmpdir[] = "/tmp/ccls-compdb-XXXXXX";
    if (!mkdtemp(tmpdir))
      return {};
    comp_db_dir = tmpdir;
    sys::path::append(Path, comp_db_dir, "compile_commands.json");
    rapidjson::StringBuffer input;
    rapidjson::Writer<rapidjson::StringBuffer> writer(input);
    JsonWriter json_writer(&writer);
    Reflect(json_writer, *g_config);
    std::string contents = GetExternalCommandOutput(
        std::vector<std::string>{g_config->compilationDatabaseCommand,
                                 project->root},
        input.GetString());
    FILE *fout = fopen(Path.c_str(), "wb");
    fwrite(contents.c_str(), contents.size(), 1, fout);
    fclose(fout);
#endif
  }

  std::string err_msg;
  std::unique_ptr<tooling::CompilationDatabase> CDB =
      tooling::CompilationDatabase::loadFromDirectory(comp_db_dir, err_msg);
  if (!g_config->compilationDatabaseCommand.empty()) {
#ifdef _WIN32
    // TODO
#else
    unlink(Path.c_str());
    rmdir(comp_db_dir.c_str());
#endif
  }
  if (!CDB) {
    LOG_S(WARNING) << "no .ccls or compile_commands.json . Consider adding one";
    return LoadFromDirectoryListing(project);
  }

  LOG_S(INFO) << "loaded " << Path.c_str();

  StringSet<> Seen;
  std::vector<Project::Entry> result;
  ProjectProcessor proc(project);
  for (tooling::CompileCommand &Cmd : CDB->getAllCompileCommands()) {
    static bool once;
    Project::Entry entry;
    entry.root = project->root;
    DoPathMapping(entry.root);
    entry.directory = NormalizePath(Cmd.Directory);
    DoPathMapping(entry.directory);
    entry.filename =
        NormalizePath(ResolveIfRelative(entry.directory, Cmd.Filename));
    DoPathMapping(entry.filename);
    std::vector<std::string> args = std::move(Cmd.CommandLine);
    entry.args.reserve(args.size());
    for (std::string &arg : args) {
      DoPathMapping(arg);
      entry.args.push_back(Intern(arg));
    }

    // Work around relative --sysroot= as it isn't affected by
    // -working-directory=. chdir is thread hostile but this function runs
    // before indexers do actual work and it works when there is only one
    // workspace folder.
    if (!once) {
      once = true;
      llvm::vfs::getRealFileSystem()->setCurrentWorkingDirectory(
          entry.directory);
    }
    proc.Process(entry);

    if (Seen.insert(entry.filename).second)
      result.push_back(entry);
  }
  return result;
}

// Computes a score based on how well |a| and |b| match. This is used for
// argument guessing.
int ComputeGuessScore(std::string_view a, std::string_view b) {
  // Increase score based on common prefix and suffix. Prefixes are prioritized.
  if (a.size() < b.size())
    std::swap(a, b);
  size_t i = std::mismatch(a.begin(), a.end(), b.begin()).first - a.begin();
  size_t j = std::mismatch(a.rbegin(), a.rend(), b.rbegin()).first - a.rbegin();
  int score = 10 * i + j;
  if (i + j < b.size())
    score -= 100 * (std::count(a.begin() + i, a.end() - j, '/') +
                    std::count(b.begin() + i, b.end() - j, '/'));
  return score;
}

} // namespace

void Project::Load(const std::string &root) {
  assert(root.back() == '/');
  ProjectConfig project;
  project.root = root;
  Folder &folder = root2folder[root];

  folder.entries = LoadEntriesFromDirectory(
      &project, g_config->compilationDatabaseDirectory);
  folder.quote_search_list.assign(project.quote_dirs.begin(),
                                  project.quote_dirs.end());
  folder.angle_search_list.assign(project.angle_dirs.begin(),
                                  project.angle_dirs.end());
  for (std::string &path : folder.angle_search_list) {
    EnsureEndsInSlash(path);
    LOG_S(INFO) << "angle search: " << path;
  }
  for (std::string &path : folder.quote_search_list) {
    EnsureEndsInSlash(path);
    LOG_S(INFO) << "quote search: " << path;
  }

  // Setup project entries.
  std::lock_guard lock(mutex_);
  folder.path2entry_index.reserve(folder.entries.size());
  for (size_t i = 0; i < folder.entries.size(); ++i) {
    folder.entries[i].id = i;
    folder.path2entry_index[folder.entries[i].filename] = i;
  }
}

void Project::SetArgsForFile(const std::vector<const char *> &args,
                             const std::string &path) {
  std::lock_guard<std::mutex> lock(mutex_);
  for (auto &[root, folder] : root2folder) {
    auto it = folder.path2entry_index.find(path);
    if (it != folder.path2entry_index.end()) {
      // The entry already exists in the project, just set the flags.
      folder.entries[it->second].args = args;
      return;
    }
  }
}

Project::Entry Project::FindEntry(const std::string &path,
                                  bool can_be_inferred) {
  std::lock_guard<std::mutex> lock(mutex_);
  for (auto &[root, folder] : root2folder) {
    auto it = folder.path2entry_index.find(path);
    if (it != folder.path2entry_index.end()) {
      Project::Entry &entry = folder.entries[it->second];
      if (can_be_inferred || entry.filename == path)
        return entry;
    }
  }

  Project::Entry result;
  const Entry *best_entry = nullptr;
  int best_score = INT_MIN;
  for (auto &[root, folder] : root2folder) {
    for (const Entry &entry : folder.entries) {
      int score = ComputeGuessScore(path, entry.filename);
      if (score > best_score) {
        best_score = score;
        best_entry = &entry;
      }
    }
    if (StringRef(path).startswith(root))
      result.root = root;
  }
  if (result.root.empty())
    result.root = g_config->fallbackFolder;

  result.is_inferred = true;
  result.filename = path;
  if (!best_entry) {
    result.args.push_back("%clang");
    result.args.push_back(Intern(path));
  } else {
    result.args = best_entry->args;

    // |best_entry| probably has its own path in the arguments. We need to remap
    // that path to the new filename.
    std::string best_entry_base_name =
        sys::path::filename(best_entry->filename);
    for (const char *&arg : result.args) {
      try {
        if (arg == best_entry->filename ||
            sys::path::filename(arg) == best_entry_base_name)
          arg = Intern(path);
      } catch (...) {
      }
    }
  }

  return result;
}

void Project::Index(WorkingFiles *wfiles, RequestId id) {
  auto &gi = g_config->index;
  GroupMatch match(gi.whitelist, gi.blacklist),
      match_i(gi.initialWhitelist, gi.initialBlacklist);
  {
    std::lock_guard lock(mutex_);
    for (auto &[root, folder] : root2folder) {
      int i = 0;
      for (const Project::Entry &entry : folder.entries) {
        std::string reason;
        if (match.IsMatch(entry.filename, &reason) &&
            match_i.IsMatch(entry.filename, &reason)) {
          bool interactive =
              wfiles->GetFileByFilename(entry.filename) != nullptr;
          pipeline::Index(
              entry.filename, entry.args,
              interactive ? IndexMode::Normal : IndexMode::NonInteractive, id);
        } else {
          LOG_V(1) << "[" << i << "/" << folder.entries.size() << "]: " << reason
                   << "; skip " << entry.filename;
        }
        i++;
      }
    }
  }

  pipeline::loaded_ts = pipeline::tick;
  // Dummy request to indicate that project is loaded and
  // trigger refreshing semantic highlight for all working files.
  pipeline::Index("", {}, IndexMode::NonInteractive);
}
} // namespace ccls