#include "filesystem.hpp"
#include "process.hpp"
#include "utility.hpp"
#include <algorithm>
#include <fstream>
#include <iostream>
#include <sstream>

boost::optional<boost::filesystem::path> filesystem::rust_sysroot_path;
boost::optional<boost::filesystem::path> filesystem::rust_nightly_sysroot_path;
boost::optional<std::vector<boost::filesystem::path>> filesystem::executable_search_paths;

//Only use on small files
std::string filesystem::read(const std::string &path) {
  std::string str;
  std::ifstream input(path, std::ios::binary);
  if(input) {
    input.seekg(0, std::ios::end);
    auto size = input.tellg();
    input.seekg(0, std::ios::beg);
    str.reserve(size);
    str.assign(std::istreambuf_iterator<char>(input), std::istreambuf_iterator<char>());
    input.close();
  }
  return str;
}

//Only use on small files
bool filesystem::write(const std::string &path, const std::string &new_content) {
  std::ofstream output(path, std::ios::binary);
  if(output)
    output << new_content;
  else
    return false;
  output.close();
  return true;
}

std::string filesystem::escape_argument(const std::string &argument) noexcept {
  auto escaped = argument;
  for(size_t pos = 0; pos < escaped.size(); ++pos) {
    if(escaped[pos] == ' ' || escaped[pos] == '(' || escaped[pos] == ')' || escaped[pos] == '\'' || escaped[pos] == '"') {
      escaped.insert(pos, "\\");
      ++pos;
    }
  }
  return escaped;
}

std::string filesystem::unescape_argument(const std::string &argument) noexcept {
  auto unescaped = argument;

  if(unescaped.size() >= 2) {
    if((unescaped[0] == '\'' && unescaped[unescaped.size() - 1] == '\'') ||
       (unescaped[0] == '"' && unescaped[unescaped.size() - 1] == '"')) {
      char quotation_mark = unescaped[0];
      unescaped = unescaped.substr(1, unescaped.size() - 2);
      size_t backslash_count = 0;
      for(size_t pos = 0; pos < unescaped.size(); ++pos) {
        if(backslash_count % 2 == 1 && (unescaped[pos] == '\\' || unescaped[pos] == quotation_mark)) {
          unescaped.erase(pos - 1, 1);
          --pos;
          backslash_count = 0;
        }
        else if(unescaped[pos] == '\\')
          ++backslash_count;
        else
          backslash_count = 0;
      }
      return unescaped;
    }
  }

  size_t backslash_count = 0;
  for(size_t pos = 0; pos < unescaped.size(); ++pos) {
    if(backslash_count % 2 == 1 && (unescaped[pos] == '\\' || unescaped[pos] == ' ' || unescaped[pos] == '(' || unescaped[pos] == ')' || unescaped[pos] == '\'' || unescaped[pos] == '"')) {
      unescaped.erase(pos - 1, 1);
      --pos;
      backslash_count = 0;
    }
    else if(unescaped[pos] == '\\')
      ++backslash_count;
    else
      backslash_count = 0;
  }
  return unescaped;
}

const boost::filesystem::path &filesystem::get_current_path() noexcept {
  auto get_path = [] {
#ifdef _WIN32
    boost::system::error_code ec;
    auto path = boost::filesystem::current_path(ec);
    if(!ec)
      return path;
    return boost::filesystem::path();
#else
    std::string path;
    TinyProcessLib::Process process("pwd", "", [&path](const char *buffer, size_t length) {
      path += std::string(buffer, length);
    });
    if(process.get_exit_status() == 0) {
      if(!path.empty() && path.back() == '\n')
        path.pop_back();
      return boost::filesystem::path(path);
    }
    return boost::filesystem::path();
#endif
  };

  static boost::filesystem::path path = get_path();
  return path;
}

const boost::filesystem::path &filesystem::get_home_path() noexcept {
  auto get_path = [] {
    std::vector<std::string> environment_variables = {"HOME", "AppData"};
    for(auto &variable : environment_variables) {
      if(auto ptr = std::getenv(variable.c_str())) {
        boost::system::error_code ec;
        boost::filesystem::path path(ptr);
        if(boost::filesystem::exists(path, ec))
          return path;
      }
    }
    return boost::filesystem::path();
  };

  static boost::filesystem::path path = get_path();
  return path;
}

const boost::filesystem::path &filesystem::get_rust_sysroot_path() noexcept {
  auto get_path = [] {
    std::string path;
    TinyProcessLib::Process process(
        "rustc --print sysroot", "",
        [&path](const char *buffer, size_t length) {
          path += std::string(buffer, length);
        },
        [](const char *buffer, size_t n) {});
    if(process.get_exit_status() == 0) {
      while(!path.empty() && (path.back() == '\n' || path.back() == '\r'))
        path.pop_back();
      return boost::filesystem::path(path);
    }
    return boost::filesystem::path();
  };

  if(!rust_sysroot_path)
    rust_sysroot_path = get_path();
  return *rust_sysroot_path;
}

boost::filesystem::path filesystem::get_rust_nightly_sysroot_path() noexcept {
  auto get_path = [] {
    std::string path;
    TinyProcessLib::Process process(
        // Slightly complicated since "RUSTUP_TOOLCHAIN=nightly rustc --print sysroot" actually installs nightly toolchain if missing...
        "rustup toolchain list|grep nightly > /dev/null && RUSTUP_TOOLCHAIN=nightly rustc --print sysroot", "",
        [&path](const char *buffer, size_t length) {
          path += std::string(buffer, length);
        },
        [](const char *buffer, size_t n) {});
    if(process.get_exit_status() == 0) {
      while(!path.empty() && (path.back() == '\n' || path.back() == '\r'))
        path.pop_back();
      return boost::filesystem::path(path);
    }
    return boost::filesystem::path();
  };

  if(!rust_nightly_sysroot_path)
    rust_nightly_sysroot_path = get_path();
  return *rust_nightly_sysroot_path;
}

boost::filesystem::path filesystem::get_short_path(const boost::filesystem::path &path) noexcept {
#ifdef _WIN32
  return path;
#else
  auto home_path = get_home_path();
  if(!home_path.empty() && file_in_path(path, home_path))
    return "~" / get_relative_path(path, home_path);
  return path;
#endif
}

boost::filesystem::path filesystem::get_long_path(const boost::filesystem::path &path) noexcept {
#ifdef _WIN32
  return path;
#else
  if(!path.empty() && *path.begin() == "~") {
    auto long_path = get_home_path();
    if(!long_path.empty()) {
      auto it = path.begin();
      ++it;
      for(; it != path.end(); ++it)
        long_path /= *it;
      return long_path;
    }
  }
  return path;
#endif
}

bool filesystem::file_in_path(const boost::filesystem::path &file_path, const boost::filesystem::path &path) noexcept {
  if(std::distance(file_path.begin(), file_path.end()) < std::distance(path.begin(), path.end()))
    return false;
  return std::equal(path.begin(), path.end(), file_path.begin());
}

boost::filesystem::path filesystem::find_file_in_path_parents(const std::string &file_name, const boost::filesystem::path &path) noexcept {
  auto current_path = path;
  boost::system::error_code ec;
  while(true) {
    auto test_path = current_path / file_name;
    if(boost::filesystem::exists(test_path, ec))
      return test_path;
    if(current_path == current_path.root_directory())
      return boost::filesystem::path();
    current_path = current_path.parent_path();
  }
}

boost::filesystem::path filesystem::get_normal_path(const boost::filesystem::path &path) noexcept {
  boost::filesystem::path normal_path;

  for(auto &e : path) {
    if(e == ".")
      continue;
    else if(e == "..") {
      auto parent_path = normal_path.parent_path();
      if(!parent_path.empty())
        normal_path = parent_path;
      else
        normal_path /= e;
    }
    else if(e.empty())
      continue;
    else
      normal_path /= e;
  }

  return normal_path;
}

boost::filesystem::path filesystem::get_relative_path(const boost::filesystem::path &path, const boost::filesystem::path &base) noexcept {
  boost::filesystem::path relative_path;
  auto base_it = base.begin();
  auto path_it = path.begin();
  while(path_it != path.end() && base_it != base.end() && *path_it == *base_it) {
    ++path_it;
    ++base_it;
  }
  while(base_it != base.end()) {
    relative_path /= "..";
    ++base_it;
  }
  while(path_it != path.end()) {
    relative_path /= *path_it;
    ++path_it;
  }
  return relative_path;
}

boost::filesystem::path filesystem::get_absolute_path(const boost::filesystem::path &path, const boost::filesystem::path &base) noexcept {
  boost::filesystem::path absolute_path;
  for(auto path_it = path.begin(); path_it != path.end(); ++path_it) {
    if(path_it == path.begin() && (!path.has_root_path() && *path_it != "~"))
      absolute_path /= base;
    absolute_path /= *path_it;
  }
  return absolute_path;
}

boost::filesystem::path filesystem::get_executable(const boost::filesystem::path &executable_name) noexcept {
#if defined(__APPLE__) || defined(_WIN32)
  return executable_name;
#endif

  try {
    for(auto &path : get_executable_search_paths()) {
      if(is_executable(path / executable_name))
        return executable_name;
    }

    auto &executable_name_str = executable_name.string();
    for(auto &folder : get_executable_search_paths()) {
      boost::filesystem::path latest_executable;
      std::string latest_version;
      for(boost::filesystem::directory_iterator it(folder), end; it != end; ++it) {
        const auto &file = it->path();
        auto filename = file.filename().string();
        if(starts_with(filename, executable_name_str)) {
          if(filename.size() > executable_name_str.size() && filename[executable_name_str.size()] >= '0' && filename[executable_name_str.size()] <= '9' && is_executable(file)) {
            auto version = filename.substr(executable_name_str.size());
            if(version_compare(version, latest_version) > 0) {
              latest_executable = file;
              latest_version = version;
            }
          }
          else if(filename.size() > executable_name_str.size() + 1 && filename[executable_name_str.size()] == '-' && filename[executable_name_str.size() + 1] >= '0' && filename[executable_name_str.size() + 1] <= '9' && is_executable(file)) {
            auto version = filename.substr(executable_name_str.size() + 1);
            if(version_compare(version, latest_version) > 0) {
              latest_executable = file;
              latest_version = version;
            }
          }
        }
      }
      if(!latest_executable.empty())
        return latest_executable;
    }
  }
  catch(...) {
  }

  return executable_name;
}

// Based on https://stackoverflow.com/a/11295568
const std::vector<boost::filesystem::path> &filesystem::get_executable_search_paths() noexcept {
  auto get_paths = [] {
    std::vector<boost::filesystem::path> paths;

    auto c_env = std::getenv("PATH");
    if(!c_env)
      return paths;
    const std::string env = c_env;
#ifdef _WIN32
    const char delimiter = ';';
#else
    const char delimiter = ':';
#endif

    size_t previous = 0;
    size_t pos;
    while((pos = env.find(delimiter, previous)) != std::string::npos) {
      paths.emplace_back(env.substr(previous, pos - previous));
      previous = pos + 1;
    }
    paths.emplace_back(env.substr(previous));

    return paths;
  };

  if(!executable_search_paths)
    executable_search_paths = get_paths();
  return *executable_search_paths;
}

boost::filesystem::path filesystem::find_executable(const std::string &executable_name) noexcept {
  for(auto &path : get_executable_search_paths()) {
    auto executable_path = path / executable_name;
    if(is_executable(executable_path))
      return executable_path;
  }
  return boost::filesystem::path();
}

std::string filesystem::get_uri_from_path(const boost::filesystem::path &path) noexcept {
  std::string uri{"file://"};

  static auto hex_chars = "0123456789ABCDEF";

  for(auto &chr : path.string()) {
    static std::string encode_exceptions{"-._~!$&'()*+,;=:@?/\\"};
    if(!((chr >= '0' && chr <= '9') || (chr >= 'A' && chr <= 'Z') || (chr >= 'a' && chr <= 'z') ||
         std::any_of(encode_exceptions.begin(), encode_exceptions.end(), [chr](char e) { return chr == e; })))
      uri += std::string("%") + hex_chars[static_cast<unsigned char>(chr) >> 4] + hex_chars[static_cast<unsigned char>(chr) & 15];
    else
      uri += chr;
  }

#ifdef _WIN32
  if(uri.size() > 9 && ((uri[7] >= 'a' && uri[7] <= 'z') || (uri[7] >= 'A' && uri[7] <= 'Z')) && uri[8] == ':' && uri[9] == '/')
    uri.insert(7, "/");
#endif

  return uri;
}

boost::filesystem::path filesystem::get_path_from_uri(const std::string &uri) noexcept {
  std::string encoded;

  if(starts_with(uri, "file://"))
    encoded = uri.substr(7);
  else
    encoded = uri;

  std::string unencoded;
  for(size_t i = 0; i < encoded.size(); ++i) {
    if(encoded[i] == '%' && i + 2 < encoded.size()) {
      auto hex = encoded.substr(i + 1, 2);
      auto decoded_chr = static_cast<char>(std::strtol(hex.c_str(), nullptr, 16));
      unencoded += decoded_chr;
      i += 2;
    }
    else if(encoded[i] == '+')
      unencoded += ' ';
    else
      unencoded += encoded[i];
  }

#ifdef _WIN32
  if(unencoded.size() > 3 && unencoded[0] == '/' && ((unencoded[1] >= 'a' && unencoded[1] <= 'z') || (unencoded[1] >= 'A' && unencoded[1] <= 'Z')) && unencoded[2] == ':' && unencoded[3] == '/') {
    unencoded.erase(0, 1);
    unencoded[0] = std::toupper(unencoded[0]);
  }
#endif

  return unencoded;
}

boost::filesystem::path filesystem::get_canonical_path(const boost::filesystem::path &path) noexcept {
  try {
    return boost::filesystem::canonical(path);
  }
  catch(...) {
    return path;
  }
}

bool filesystem::is_executable(const boost::filesystem::path &path) noexcept {
  if(path.empty())
    return false;
  boost::system::error_code ec;
#ifdef _WIN32
  // Cannot for sure identify executable files in MSYS2
  if(boost::filesystem::exists(path, ec))
    return !boost::filesystem::is_directory(path, ec);
  auto filename = path.filename().string() + ".exe";
  return boost::filesystem::exists(path.has_parent_path() ? path.parent_path() / filename : filename, ec);
#else
  return boost::filesystem::exists(path, ec) && !boost::filesystem::is_directory(path, ec) && boost::filesystem::status(path, ec).permissions() & (boost::filesystem::perms::owner_exe | boost::filesystem::perms::group_exe | boost::filesystem::perms::others_exe);
#endif
}