/* Copyright 2017-2018 ccls Authors

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 "project.h"

#include "filesystem.hh"
#include "language.h"
#include "log.hh"
#include "match.h"
#include "pipeline.hh"
#include "platform.h"
#include "serializers/json.h"
#include "utils.h"
#include "working_files.h"

#include <clang/Driver/Compilation.h>
#include <clang/Driver/Driver.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 ccls;
using namespace clang;
using namespace llvm;

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 project_dir;
  ProjectMode mode = ProjectMode::CompileCommandsJson;
};

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

struct ProjectProcessor {
  ProjectConfig *config;
  std::unordered_set<size_t> command_set;
  ProjectProcessor(ProjectConfig *config) : config(config) {}

  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 = SourceFileLanguage(entry.filename);
    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 (!llvm::is_contained(g_config->clang.excludeArgs, 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);
    for (auto &arg : args) {
      if (arg[0] != '-' && EndsWith(arg, base_name)) {
        const LanguageId lang = SourceFileLanguage(arg);
        if (lang != LanguageId::Unknown) {
          hash_combine(hash, size_t(lang));
          continue;
        }
      }
      hash_combine(hash, std::hash<std::string>{}(arg));
    }
    args.push_back(Intern("-working-directory=" + entry.directory));

    if (!command_set.insert(hash).second) {
      entry.args = std::move(args);
      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);

    args.push_back("-fsyntax-only");

    std::unique_ptr<driver::Compilation> C(Driver.BuildCompilation(args));
    const driver::JobList &Jobs = C->getJobs();
    if (Jobs.size() != 1)
      return;
    const driver::ArgStringList &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;
      }
    }
    entry.args = std::move(args);
  }
};

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;
  SmallString<256> Path;
  sys::path::append(Path, config->project_dir, ".ccls");
  LOG_IF_S(WARNING, !sys::fs::exists(Path) && g_config->clang.extraArgs.empty())
      << "ccls has no clang arguments. Use either "
         "compile_commands.json or .ccls, See ccls README for "
         "more information.";

  std::unordered_map<std::string, std::vector<const char *>> folder_args;
  std::vector<std::string> files;

  GetFilesInFolder(config->project_dir, true /*recursive*/,
                   true /*add_folder_to_path*/,
                   [&folder_args, &files](const std::string &path) {
                     if (SourceFileLanguage(path) != LanguageId::Unknown) {
                       files.push_back(path);
                     } else if (sys::path::filename(path) == ".ccls") {
                       LOG_S(INFO) << "Using .ccls arguments from " << path;
                       folder_args.emplace(sys::path::parent_path(path),
                                           ReadCompilerArgumentsFromFile(path));
                     }
                   });

  const std::string &project_dir = config->project_dir;
  const auto &project_dir_args = folder_args[project_dir];
  LOG_IF_S(INFO, !project_dir_args.empty())
      << "Using .ccls arguments " << StringJoin(project_dir_args);

  auto GetCompilerArgumentForFile = [&project_dir,
                                     &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() <= project_dir.size() ||
          normalized.compare(0, project_dir.size(), project_dir) != 0)
        break;
    }
    return folder_args[project_dir];
  };

  ProjectProcessor proc(config);
  for (const std::string &file : files) {
    Project::Entry e;
    e.directory = config->project_dir;
    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;
  sys::path::append(Path, project->project_dir, ".ccls");
  if (sys::fs::exists(Path))
    return LoadFromDirectoryListing(project);

  // If |compilationDatabaseCommand| is specified, execute it to get the compdb.
  std::string comp_db_dir;
  Path.clear();
  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->project_dir : 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->project_dir},
        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) << "failed to load " << Path.c_str() << " " << err_msg;
    return {};
  }

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

  StringSet<> Seen;
  std::vector<Project::Entry> result;
  ProjectProcessor proc(project);
  for (tooling::CompileCommand &Cmd : CDB->getAllCompileCommands()) {
    Project::Entry entry;
    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));
    }
    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_directory) {
  ProjectConfig project;
  project.project_dir = root_directory;
  entries = LoadEntriesFromDirectory(&project,
                                     g_config->compilationDatabaseDirectory);

  // Cleanup / postprocess include directories.
  quote_include_directories.assign(project.quote_dirs.begin(),
                                   project.quote_dirs.end());
  angle_include_directories.assign(project.angle_dirs.begin(),
                                   project.angle_dirs.end());
  for (std::string &path : quote_include_directories) {
    EnsureEndsInSlash(path);
    LOG_S(INFO) << "quote_include_dir: " << path;
  }
  for (std::string &path : angle_include_directories) {
    EnsureEndsInSlash(path);
    LOG_S(INFO) << "angle_include_dir: " << path;
  }

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

void Project::SetArgsForFile(const std::vector<const char *> &args,
                             const std::string &path) {
  std::lock_guard<std::mutex> lock(mutex_);
  auto it = path_to_entry_index.find(path);
  if (it != path_to_entry_index.end()) {
    // The entry already exists in the project, just set the flags.
    this->entries[it->second].args = args;
  } else {
    // Entry wasn't found, so we create a new one.
    Entry entry;
    entry.is_inferred = false;
    entry.filename = path;
    entry.args = args;
    this->entries.emplace_back(entry);
  }
}

Project::Entry
Project::FindCompilationEntryForFile(const std::string &filename) {
  {
    std::lock_guard<std::mutex> lock(mutex_);
    auto it = path_to_entry_index.find(filename);
    if (it != path_to_entry_index.end())
      return entries[it->second];
  }

  // We couldn't find the file. Try to infer it.
  // TODO: Cache inferred file in a separate array (using a lock or similar)
  Entry *best_entry = nullptr;
  int best_score = INT_MIN;
  for (Entry &entry : entries) {
    int score = ComputeGuessScore(filename, entry.filename);
    if (score > best_score) {
      best_score = score;
      best_entry = &entry;
    }
  }

  Project::Entry result;
  result.is_inferred = true;
  result.filename = filename;
  if (!best_entry) {
    result.args.push_back("%clang");
    result.args.push_back(Intern(filename));
  } 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(filename);
      } catch (...) {
      }
    }
  }

  return result;
}

void Project::ForAllFilteredFiles(
    std::function<void(int i, const Entry &entry)> action) {
  GroupMatch matcher(g_config->index.whitelist, g_config->index.blacklist);
  for (int i = 0; i < entries.size(); ++i) {
    const Project::Entry &entry = entries[i];
    std::string failure_reason;
    if (matcher.IsMatch(entry.filename, &failure_reason))
      action(i, entries[i]);
    else {
      LOG_V(1) << "[" << i + 1 << "/" << entries.size() << "]: Failed "
               << failure_reason << "; skipping " << entry.filename;
    }
  }
}

void Project::Index(WorkingFiles *wfiles, lsRequestId id) {
  ForAllFilteredFiles([&](int i, const Project::Entry &entry) {
    bool interactive = wfiles->GetFileByFilename(entry.filename) != nullptr;
    pipeline::Index(entry.filename, entry.args,
                    interactive ? IndexMode::Normal : IndexMode::NonInteractive,
                    id);
  });
  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);
}