// 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 "pipeline.hh"
#include "platform.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 OptionClass {
  EqOrJoinOrSep,
  EqOrSep,
  JoinOrSep,
  Separate,
};

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

  // Expand %c %cpp ... in .ccls
  void Process(Project::Entry &entry) {
    std::vector<const char *> args(entry.args.begin(),
                                   entry.args.begin() + entry.compdb_size);
    auto [lang, header] = lookupExtension(entry.filename);
    for (int i = entry.compdb_size; i < entry.args.size(); i++) {
      const char *arg = entry.args[i];
      StringRef A(arg);
      if (A[0] == '%') {
        bool ok = false;
        for (;;) {
          if (A.consume_front("%c "))
            ok |= lang == LanguageId::C;
          else if (A.consume_front("%h "))
            ok |= lang == LanguageId::C && header;
          else if (A.consume_front("%cpp "))
            ok |= lang == LanguageId::Cpp;
          else if (A.consume_front("%hpp "))
            ok |= lang == LanguageId::Cpp && header;
          else if (A.consume_front("%objective-c "))
            ok |= lang == LanguageId::ObjC;
          else if (A.consume_front("%objective-cpp "))
            ok |= lang == LanguageId::ObjCpp;
          else
            break;
        }
        if (ok)
          args.push_back(A.data());
      } else if (!excludeArgs.count(A)) {
        args.push_back(arg);
      }
    }
    entry.args = args;
    GetSearchDirs(entry);
  }

  void GetSearchDirs(Project::Entry &entry) {
#if LLVM_VERSION_MAJOR < 8
    const std::string base_name = sys::path::filename(entry.filename);
    size_t hash = std::hash<std::string>{}(entry.directory);
    bool OPT_o = false;
    for (auto &arg : entry.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));
    }
    if (!command_set.insert(hash).second)
      return;
    auto args = entry.args;
    args.push_back("-fsyntax-only");
    for (const std::string &arg : g_config->clang.extraArgs)
      args.push_back(Intern(arg));
    args.push_back(Intern("-working-directory=" + entry.directory));
    args.push_back(Intern("-resource-dir=" + g_config->clang.resourceDir));

    // 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));
      EnsureEndsInSlash(path);
      switch (E.Group) {
      default:
        folder.search_dir2kind[path] |= 2;
        break;
      case frontend::Quoted:
        folder.search_dir2kind[path] |= 1;
        break;
      case frontend::Angled:
        folder.search_dir2kind[path] |= 3;
        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;
}

bool AppendToCDB(const std::vector<const char *> &args) {
  return args.size() && StringRef("%compile_commands.json") == args[0];
}

std::vector<const char *> GetFallback(const std::string path) {
  std::vector<const char *> argv{"clang"};
  if (sys::path::extension(path) == ".h")
    argv.push_back("-xobjective-c++-header");
  argv.push_back(Intern(path));
  return argv;
}

void LoadDirectoryListing(ProjectProcessor &proc, const std::string &root,
                          const StringSet<> &Seen) {
  Project::Folder &folder = proc.folder;
  std::vector<std::string> files;

  auto GetDotCcls = [&root, &folder](std::string cur) {
    while (!(cur = sys::path::parent_path(cur)).empty()) {
      auto it = folder.dot_ccls.find(cur);
      if (it != folder.dot_ccls.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.dot_ccls[root];
  };

  GetFilesInFolder(root, true /*recursive*/, true /*add_folder_to_path*/,
                   [&folder, &files, &Seen](const std::string &path) {
                     std::pair<LanguageId, bool> lang = lookupExtension(path);
                     if (lang.first != LanguageId::Unknown && !lang.second) {
                       if (!Seen.count(path))
                         files.push_back(path);
                     } else if (sys::path::filename(path) == ".ccls") {
                       std::vector<const char *> args = ReadCompilerArgumentsFromFile(path);
                       folder.dot_ccls.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;
                     }
                   });

  // If the first line of .ccls is %compile_commands.json, append extra flags.
  for (auto &e : folder.entries)
    if (const auto &args = GetDotCcls(e.filename); AppendToCDB(args)) {
      if (args.size())
        e.args.insert(e.args.end(), args.begin() + 1, args.end());
      proc.Process(e);
    }
  // Set flags for files not in compile_commands.json
  for (const std::string &file : files)
    if (const auto &args = GetDotCcls(file); !AppendToCDB(args)) {
      Project::Entry e;
      e.root = e.directory = root;
      e.filename = file;
      if (args.empty()) {
        e.args = GetFallback(e.filename);
      } else {
        e.args = args;
        e.args.push_back(Intern(e.filename));
      }
      proc.Process(e);
      folder.entries.push_back(e);
    }
}

// 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 < a.size())
    score -= 100 * (std::count(a.begin() + i, a.end() - j, '/') +
                    std::count(b.begin() + i, b.end() - j, '/'));
  return score;
}

} // namespace

void Project::LoadDirectory(const std::string &root, Project::Folder &folder) {
  SmallString<256> Path, CDBDir;
  folder.entries.clear();
  if (g_config->compilationDatabaseCommand.empty()) {
    CDBDir = root;
    if (g_config->compilationDatabaseDirectory.size())
      sys::path::append(CDBDir, g_config->compilationDatabaseDirectory);
    sys::path::append(Path, CDBDir, "compile_commands.json");
  } else {
    // If `compilationDatabaseCommand` is specified, execute it to get the
    // compdb.
#ifdef _WIN32
    // TODO
#else
    char tmpdir[] = "/tmp/ccls-compdb-XXXXXX";
    if (!mkdtemp(tmpdir))
      return;
    CDBDir = tmpdir;
    sys::path::append(Path, CDBDir, "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, 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(CDBDir, err_msg);
  if (!g_config->compilationDatabaseCommand.empty()) {
#ifdef _WIN32
    // TODO
#else
    unlink(Path.c_str());
    rmdir(CDBDir.c_str());
#endif
  }

  ProjectProcessor proc(folder);
  StringSet<> Seen;
  std::vector<Project::Entry> result;
  if (CDB) {
    LOG_S(INFO) << "loaded " << Path.c_str();
    for (tooling::CompileCommand &Cmd : CDB->getAllCompileCommands()) {
      static bool once;
      Project::Entry entry;
      entry.root = 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);
        if (!proc.excludeArgs.count(arg))
          entry.args.push_back(Intern(arg));
      }
      entry.compdb_size = entry.args.size();

      // 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.GetSearchDirs(entry);

      if (Seen.insert(entry.filename).second)
        folder.entries.push_back(entry);
    }
  }

  // Use directory listing if .ccls exists or compile_commands.json does not
  // exist.
  Path.clear();
  sys::path::append(Path, root, ".ccls");
  if (sys::fs::exists(Path))
    LoadDirectoryListing(proc, root, Seen);
  std::vector<const char *> extra_args;
  for (const std::string &arg : g_config->clang.extraArgs)
    extra_args.push_back(Intern(arg));
  for (auto &e : folder.entries) {
    e.args.insert(e.args.end(), extra_args.begin(), extra_args.end());
    e.args.push_back(Intern("-working-directory=" + e.directory));
  }
}

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

  LoadDirectory(root, folder);
  for (auto &[path, kind] : folder.search_dir2kind)
    LOG_S(INFO) << "search directory: " << path << ' ' << " \"< "[kind];

  // Setup project entries.
  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;
  }
}

Project::Entry Project::FindEntry(const std::string &path,
                                  bool can_be_inferred) {
  Project::Folder *best_folder = nullptr;
  const Entry *best = nullptr;
  std::lock_guard lock(mtx);
  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;
    }
  }

  std::string dir;
  const std::vector<const char *> *extra = nullptr;
  Project::Entry ret;
  for (auto &[root, folder] : root2folder)
    if (StringRef(path).startswith(root))
      for (auto &[dir1, args] : folder.dot_ccls)
        if (StringRef(path).startswith(dir1)) {
          if (AppendToCDB(args)) {
            dir = dir1;
            extra = &args;
            goto out;
          }
          ret.root = ret.directory = root;
          ret.filename = path;
          if (args.empty()) {
            ret.args = GetFallback(path);
          } else {
            ret.args = args;
            ret.args.push_back(Intern(path));
          }
          ProjectProcessor(folder).Process(ret);
          for (const std::string &arg : g_config->clang.extraArgs)
            ret.args.push_back(Intern(arg));
          ret.args.push_back(Intern("-working-directory=" + ret.directory));
          return ret;
        }
out:

  if (!best) {
    int best_score = INT_MIN;
    for (auto &[root, folder] : root2folder) {
      if (dir.size() && !StringRef(path).startswith(dir))
        continue;
      for (const Entry &e : folder.entries)
        if (e.compdb_size) {
          int score = ComputeGuessScore(path, e.filename);
          if (score > best_score) {
            best_score = score;
            best = &e;
            best_folder = &folder;
          }
        }
      }
  }

  ret.is_inferred = true;
  ret.filename = path;
  if (!best) {
    if (ret.root.empty())
      ret.root = g_config->fallbackFolder;
    ret.directory = ret.root;
    ret.args = GetFallback(path);
  } else {
    ret.root = best->root;
    ret.directory = best->directory;
    ret.args = best->args;
    std::string base_name = sys::path::filename(best->filename);
    for (const char *&arg : ret.args) {
      try {
        if (arg == best->filename || sys::path::filename(arg) == base_name)
          arg = Intern(path);
      } catch (...) {
      }
    }
    ret.args.resize(best->compdb_size);
    if (extra && extra->size())
      ret.args.insert(ret.args.end(), extra->begin() + 1, extra->end());
    ProjectProcessor(*best_folder).Process(ret);
    for (const std::string &arg : g_config->clang.extraArgs)
      ret.args.push_back(Intern(arg));
    ret.args.push_back(Intern("-working-directory=" + ret.directory));
  }

  return ret;
}

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(mtx);
    for (auto &[root, folder] : root2folder) {
      int i = 0;
      for (const Project::Entry &entry : folder.entries) {
        std::string reason;
        if (match.Matches(entry.filename, &reason) &&
            match_i.Matches(entry.filename, &reason)) {
          bool interactive = wfiles->GetFile(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