#include "nf7.hh"

#include <algorithm>
#include <cassert>
#include <map>
#include <sstream>

#include <imgui.h>
#include <yas/serialize.hpp>
#include <yas/types/std/string.hpp>
#include <yas/types/std/vector.hpp>

#include "common/generic_context.hh"


using namespace std::literals;


namespace nf7 {

// static variable in function ensures that entity is initialized before using
static inline auto& registry_() noexcept {
  static std::map<std::string, const File::TypeInfo*> registry_;
  return registry_;
}


void Exception::UpdatePanic() const noexcept {
  ImGui::BeginGroup();
  ImGui::TextUnformatted(msg_.c_str());
  ImGui::Indent();
  ImGui::Text("from %s:%d", srcloc_.file_name(), srcloc_.line());
  ImGui::Unindent();
  ImGui::EndGroup();
}
std::string Exception::Stringify() const noexcept {
  return msg() + "\n  "+srcloc_.file_name()+":"+std::to_string(srcloc_.line());
}
std::string Exception::StringifyRecursive() const noexcept {
  std::stringstream st;
  st << Stringify() << "\n";

  auto ptr = reason();
  while (ptr)
  try {
    std::rethrow_exception(ptr);
  } catch (nf7::Exception& e) {
    st << e.Stringify() << "\n";
    ptr = e.reason();
  } catch (std::exception& e) {
    st << e.what() << "\n";
    ptr = nullptr;
  }
  return st.str();
}

const std::map<std::string, const File::TypeInfo*>& File::registry() noexcept {
  return registry_();
}
const File::TypeInfo& File::registry(std::string_view name) {
  const auto  sname = std::string(name);
  const auto& reg   = registry_();

  auto itr = reg.find(sname);
  if (itr == reg.end()) {
    throw Exception("unknown file type: "+sname);
  }
  return *itr->second;
}
File::File(const TypeInfo& t, Env& env) noexcept : type_(&t), env_(&env) {
}
File::~File() noexcept {
  assert(id_ == 0);
}
void File::MoveUnder(File& parent, std::string_view name) noexcept {
  assert(parent_ == nullptr);
  assert(id_ == 0);
  assert(name_.empty());
  parent_ = &parent;
  name_   = name;
  id_     = env_->AddFile(*this);

  Handle({ .id = id_, .type = File::Event::kAdd });
}
void File::MakeAsRoot() noexcept {
  assert(parent_ == nullptr);
  assert(id_ == 0);
  assert(name_.empty());
  id_   = env_->AddFile(*this);
  name_ = "$";

  Handle({ .id = id_, .type = File::Event::kAdd });
}
void File::Isolate() noexcept {
  assert(id_ != 0);

  Handle({ .id = id_, .type = File::Event::kRemove });

  env_->RemoveFile(id_);
  id_     = 0;
  parent_ = nullptr;
  name_   = "";
}
void File::Touch() noexcept {
  if (std::exchange(touch_, true)) {
    return;
  }
  env().ExecMain(std::make_shared<nf7::GenericContext>(*this), [this]() {
    if (id()) {
      env().Handle( {.id = id(), .type = Event::kUpdate});
    }
    touch_ = false;
  });
}
File& File::FindOrThrow(std::string_view name) const {
  if (auto ret = Find(name)) return *ret;
  throw NotFoundException("missing child: "+std::string(name));
}
File& File::ResolveOrThrow(const Path& p) const
try {
  assert(id_ != 0);

  auto ret = const_cast<File*>(this);
  for (const auto& term : p.terms()) {
    if (term == "..") {
      if (!ret->parent_) throw NotFoundException("cannot go up over the root");
      ret = ret->parent_;
    } else if (term == ".") {
      // do nothing
    } else if (term == "$") {
      while (ret->parent_) ret = ret->parent_;
    } else {
      ret = &ret->FindOrThrow(term);
    }
  }
  return *ret;
} catch (Exception&) {
  throw NotFoundException("failed to resolve path: "+p.Stringify());
}
File& File::ResolveOrThrow(std::string_view p) const {
  return ResolveOrThrow(Path::Parse(p));
}
File& File::ResolveUpwardOrThrow(const Path& p) const {
  auto f = parent_;
  while (f)
  try {
    return f->ResolveOrThrow(p);
  } catch (NotFoundException&) {
    f = f->parent_;
  }
  throw NotFoundException("failed to resolve upward path: "+p.Stringify());
}
File& File::ResolveUpwardOrThrow(std::string_view p) const {
  return ResolveUpwardOrThrow(Path::Parse(p));
}
File::Interface& File::interfaceOrThrow(const std::type_info& t) {
  if (auto ret = interface(t)) return *ret;
  throw NotImplementedException(t.name()+"is not implemented"s);
}
File::Path File::abspath() const noexcept {
  std::vector<std::string> terms;
  auto f = const_cast<File*>(this);
  while (f) {
    terms.push_back(f->name());
    f = f->parent();
  }
  std::reverse(terms.begin(), terms.end());
  return {std::move(terms)};
}
File& File::ancestorOrThrow(size_t dist) const {
  auto f = this;
  for (size_t i = 0; i < dist && f; ++i) {
    f = f->parent_;
  }
  if (!f) throw NotFoundException("cannot go up over the root");
  return const_cast<File&>(*f);
}

File::TypeInfo::TypeInfo(const std::string& name,
                         std::unordered_set<std::string>&& flags) noexcept :
    name_(name), flags_(std::move(flags)) {
  auto& reg = registry_();
  auto [itr, uniq] = reg.emplace(std::string(name_), this);
  assert(uniq);
  (void) uniq;
}
File::TypeInfo::~TypeInfo() noexcept {
  auto& reg = registry_();
  reg.erase(std::string(name_));
}

File::Path::Path(Deserializer& ar) {
  ar(terms_);
  Validate();
}
void File::Path::Serialize(Serializer& ar) const noexcept {
  ar(terms_);
}
File::Path File::Path::Parse(std::string_view p) {
  Path ret;

  auto st = p.begin(), itr = st;
  for (; itr < p.end(); ++itr) {
    if (*itr == '/') {
      if (st < itr) ret.terms_.push_back(std::string {st, itr});
      st = itr + 1;
    }
  }
  if (st < itr) ret.terms_.push_back(std::string {st, itr});

  ret.Validate();
  return ret;
}
std::string File::Path::Stringify() const noexcept {
  std::string ret;
  for (const auto& term : terms_) {
    ret += term + "/";
  }
  if (ret.size() > 0) ret.erase(ret.end()-1);
  return ret;
}
void File::Path::ValidateTerm(std::string_view term) {
  if (term.empty()) {
    throw Exception("empty term");
  }
  if (term == "$")  return;
  if (term == "..") return;

  constexpr size_t kMaxTermSize = 256;
  if (term.size() > kMaxTermSize) {
    throw Exception("too long term (must be less than 256)");
  }

  static const char kAllowedChars[] =
      "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
      "0123456789_";
  if (term.find_first_not_of(kAllowedChars) != std::string_view::npos) {
    throw Exception("invalid char found in term");
  }
}
void File::Path::Validate() const {
  for (const auto& term : terms_) ValidateTerm(term);
}

Context::Context(File& f, const std::shared_ptr<Context>& parent) noexcept :
    Context(f.env(), f.id(), parent) {
}
Context::Context(Env& env, File::Id initiator, const std::shared_ptr<Context>& parent) noexcept :
    env_(&env), initiator_(initiator),
    parent_(parent), depth_(parent? parent->depth()+1: 0) {
}
Context::~Context() noexcept {
}

File& Env::GetFileOrThrow(File::Id id) const {
  if (auto ret = GetFile(id)) return *ret;
  throw ExpiredException("file ("+std::to_string(id)+") is expired");
}

Env::Watcher::Watcher(Env& env) noexcept : env_(&env) {
}
Env::Watcher::~Watcher() noexcept {
  env_->RemoveWatcher(*this);
}
void Env::Watcher::Watch(File::Id id) noexcept {
  env_->AddWatcher(id, *this);
}


SerializerStream::SerializerStream(const char* path, const char* mode) :
    fp_(std::fopen(path, mode)), off_(0) {
  if (!fp_) {
    throw nf7::Exception {"failed to open file: "+std::string {path}};
  }

  if (0 != std::fseek(fp_, 0, SEEK_END)) {
    throw nf7::Exception {"failed to seek file: "+std::string {path}};
  }
  size_ = static_cast<size_t>(std::ftell(fp_));
  if (0 != std::fseek(fp_, 0, SEEK_SET)) {
    throw nf7::Exception {"failed to seek file: "+std::string {path}};
  }
}

Serializer::ChunkGuard::ChunkGuard(nf7::Serializer& ar) : ar_(&ar) {
  ar_->st_->Seek(ar_->st_->offset()+sizeof(uint64_t));
  begin_ = ar_->st_->offset();
}
Serializer::ChunkGuard::~ChunkGuard() noexcept {
  try {
    const auto end = ar_->st_->offset();
    ar_->st_->Seek(begin_-sizeof(uint64_t));
    *ar_ & static_cast<uint64_t>(end - begin_);
    ar_->st_->Seek(end);
  } catch (nf7::Exception&) {
    ar_->env_->Throw(std::current_exception());
  }
}

Deserializer::ChunkGuard::ChunkGuard(nf7::Deserializer& ar) : ar_(&ar) {
  *ar_ & expect_;
  begin_ = ar_->st_->offset();
}
Deserializer::ChunkGuard::ChunkGuard(nf7::Deserializer& ar, nf7::Env& env) :
    ChunkGuard(ar) {
  env_prev_ = ar_->env_;
  ar_->env_ = &env;
}
Deserializer::ChunkGuard::~ChunkGuard() {
  try {
    if (env_prev_) {
      ar_->env_ = env_prev_;
    }
    const auto end = begin_ + expect_;
    if (ar_->st_->offset() != end) {
      ar_->st_->Seek(end);
    }
  } catch (nf7::Exception&) {
    ar_->env_->Throw(std::current_exception());
  }
}
void Deserializer::ChunkGuard::ValidateEnd() {
  if (begin_+expect_ != ar_->st_->offset()) {
    throw nf7::DeserializeException {"invalid chunk size"};
  }
}

}  // namespace nf7