/* 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 "include_complete.hh"

#include "filesystem.hh"
#include "platform.hh"
#include "project.hh"

#include <llvm/ADT/Twine.h>
#include <llvm/Support/Threading.h>
#include <llvm/Support/Timer.h>

#include <unordered_set>
using namespace llvm;

#include <thread>

namespace ccls {
namespace {

struct CompletionCandidate {
  std::string absolute_path;
  CompletionItem completion_item;
};

std::string ElideLongPath(const std::string &path) {
  if (g_config->completion.include.maxPathSize <= 0 ||
      (int)path.size() <= g_config->completion.include.maxPathSize)
    return path;

  size_t start = path.size() - g_config->completion.include.maxPathSize;
  return ".." + path.substr(start + 2);
}

size_t TrimCommonPathPrefix(const std::string &result,
                            const std::string &trimmer) {
#ifdef _WIN32
  std::string s = result, t = trimmer;
  std::transform(s.begin(), s.end(), s.begin(), ::tolower);
  std::transform(t.begin(), t.end(), t.begin(), ::tolower);
  if (s.compare(0, t.size(), t) == 0)
    return t.size();
#else
  if (result.compare(0, trimmer.size(), trimmer) == 0)
    return trimmer.size();
#endif
  return 0;
}

int TrimPath(Project *project, std::string &path) {
  size_t pos = 0;
  int kind = 0;
  for (auto &[root, folder] : project->root2folder)
    for (auto &[search, search_dir_kind] : folder.search_dir2kind)
      if (int t = TrimCommonPathPrefix(path, search); t > pos)
        pos = t, kind = search_dir_kind;
  path = path.substr(pos);
  return kind;
}

CompletionItem BuildCompletionItem(const std::string &path,
                                   int kind) {
  CompletionItem item;
  item.label = ElideLongPath(path);
  item.detail = path; // the include path, used in de-duplicating
  item.textEdit.newText = path;
  item.insertTextFormat = InsertTextFormat::PlainText;
  item.kind = CompletionItemKind::File;
  item.quote_kind_ = kind;
  item.priority_ = 0;
  return item;
}
} // namespace

IncludeComplete::IncludeComplete(Project *project)
    : is_scanning(false), project_(project) {}

IncludeComplete::~IncludeComplete() {
  // Spin until the scanning has completed.
  while (is_scanning.load())
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
}

void IncludeComplete::Rescan() {
  if (is_scanning || LLVM_VERSION_MAJOR >= 8)
    return;

  completion_items.clear();
  absolute_path_to_completion_item.clear();
  inserted_paths.clear();

  if (!match_ && (g_config->completion.include.whitelist.size() ||
                  g_config->completion.include.blacklist.size()))
    match_ =
        std::make_unique<GroupMatch>(g_config->completion.include.whitelist,
                                     g_config->completion.include.blacklist);

  is_scanning = true;
  std::thread([this]() {
    set_thread_name("include");
    for (auto &[root, folder] : project_->root2folder) {
      for (auto &search_kind : folder.search_dir2kind) {
        const std::string &search = search_kind.first;
        int kind = search_kind.second;
        assert(search.back() == '/');
        if (match_ && !match_->Matches(search))
          return;
        bool include_cpp = search.find("include/c++") != std::string::npos;

        std::vector<CompletionCandidate> results;
        GetFilesInFolder(search, true /*recursive*/,
                         false /*add_folder_to_path*/,
                         [&](const std::string &path) {
                           bool ok = include_cpp;
                           for (StringRef suffix :
                                g_config->completion.include.suffixWhitelist)
                             if (StringRef(path).endswith(suffix))
                               ok = true;
                           if (!ok)
                             return;
                           if (match_ && !match_->Matches(search + path))
                             return;

                           CompletionCandidate candidate;
                           candidate.absolute_path = search + path;
                           candidate.completion_item =
                               BuildCompletionItem(path, kind);
                           results.push_back(candidate);
                         });

        std::lock_guard lock(completion_items_mutex);
        for (CompletionCandidate &result : results)
          InsertCompletionItem(result.absolute_path,
                               std::move(result.completion_item));
      }
    }

    is_scanning = false;
  })
      .detach();
}

void IncludeComplete::InsertCompletionItem(const std::string &absolute_path,
                                           CompletionItem &&item) {
  if (inserted_paths.try_emplace(item.detail, inserted_paths.size()).second) {
    completion_items.push_back(item);
    // insert if not found or with shorter include path
    auto it = absolute_path_to_completion_item.find(absolute_path);
    if (it == absolute_path_to_completion_item.end() ||
        completion_items[it->second].detail.length() > item.detail.length()) {
      absolute_path_to_completion_item[absolute_path] =
          completion_items.size() - 1;
    }
  }
}

void IncludeComplete::AddFile(const std::string &path) {
  bool ok = false;
  for (StringRef suffix : g_config->completion.include.suffixWhitelist)
    if (StringRef(path).endswith(suffix))
      ok = true;
  if (!ok)
    return;
  if (match_ && !match_->Matches(path))
    return;

  std::string trimmed_path = path;
  int kind = TrimPath(project_, trimmed_path);
  CompletionItem item = BuildCompletionItem(trimmed_path, kind);

  std::unique_lock<std::mutex> lock(completion_items_mutex, std::defer_lock);
  if (is_scanning)
    lock.lock();
  InsertCompletionItem(path, std::move(item));
}

std::optional<CompletionItem>
IncludeComplete::FindCompletionItemForAbsolutePath(
    const std::string &absolute_path) {
  std::lock_guard<std::mutex> lock(completion_items_mutex);

  auto it = absolute_path_to_completion_item.find(absolute_path);
  if (it == absolute_path_to_completion_item.end())
    return std::nullopt;
  return completion_items[it->second];
}
} // namespace ccls