#include "message_handler.h"

#include "lex_utils.h"
#include "project.h"
#include "query_utils.h"
#include "queue_manager.h"

#include <loguru.hpp>

#include <algorithm>

namespace {

struct Out_CclsSetInactiveRegion
    : public lsOutMessage<Out_CclsSetInactiveRegion> {
  struct Params {
    lsDocumentUri uri;
    std::vector<lsRange> inactiveRegions;
  };
  std::string method = "$ccls/setInactiveRegions";
  Params params;
};
MAKE_REFLECT_STRUCT(Out_CclsSetInactiveRegion::Params, uri, inactiveRegions);
MAKE_REFLECT_STRUCT(Out_CclsSetInactiveRegion, jsonrpc, method, params);

struct ScanLineEvent {
  lsPosition pos;
  lsPosition end_pos;  // Second key when there is a tie for insertion events.
  int id;
  Out_CclsPublishSemanticHighlighting::Symbol* symbol;
  bool operator<(const ScanLineEvent& other) const {
    // See the comments below when insertion/deletion events are inserted.
    if (!(pos == other.pos))
      return pos < other.pos;
    if (!(other.end_pos == end_pos))
      return other.end_pos < end_pos;
    // This comparison essentially order Macro after non-Macro,
    // So that macros will not be rendered as Var/Type/...
    return symbol->kind < other.symbol->kind;
  }
};
}  // namespace

SemanticHighlightSymbolCache::Entry::Entry(
    SemanticHighlightSymbolCache* all_caches,
    const std::string& path)
    : all_caches_(all_caches), path(path) {}

std::optional<int> SemanticHighlightSymbolCache::Entry::TryGetStableId(
    SymbolKind kind,
    const std::string& detailed_name) {
  TNameToId* map = GetMapForSymbol_(kind);
  auto it = map->find(detailed_name);
  if (it != map->end())
    return it->second;

  return std::nullopt;
}

int SemanticHighlightSymbolCache::Entry::GetStableId(
    SymbolKind kind,
    const std::string& detailed_name) {
  std::optional<int> id = TryGetStableId(kind, detailed_name);
  if (id)
    return *id;

  // Create a new id. First try to find a key in another map.
  all_caches_->cache_.IterateValues([&](const std::shared_ptr<Entry>& entry) {
    std::optional<int> other_id = entry->TryGetStableId(kind, detailed_name);
    if (other_id) {
      id = other_id;
      return false;
    }
    return true;
  });

  // Create a new id.
  TNameToId* map = GetMapForSymbol_(kind);
  if (!id)
    id = all_caches_->next_stable_id_++;
  return (*map)[detailed_name] = *id;
}

SemanticHighlightSymbolCache::Entry::TNameToId*
SemanticHighlightSymbolCache::Entry::GetMapForSymbol_(SymbolKind kind) {
  switch (kind) {
    case SymbolKind::Type:
      return &detailed_type_name_to_stable_id;
    case SymbolKind::Func:
      return &detailed_func_name_to_stable_id;
    case SymbolKind::Var:
      return &detailed_var_name_to_stable_id;
    case SymbolKind::File:
    case SymbolKind::Invalid:
      break;
  }
  assert(false);
  return nullptr;
}

SemanticHighlightSymbolCache::SemanticHighlightSymbolCache()
    : cache_(kCacheSize) {}

void SemanticHighlightSymbolCache::Init(Config* config) {
  match_ = std::make_unique<GroupMatch>(config->highlight.whitelist,
                                        config->highlight.blacklist);
}

std::shared_ptr<SemanticHighlightSymbolCache::Entry>
SemanticHighlightSymbolCache::GetCacheForFile(const std::string& path) {
  return cache_.Get(
      path, [&, this]() { return std::make_shared<Entry>(this, path); });
}

MessageHandler::MessageHandler() {
  // Dynamically allocate |message_handlers|, otherwise there will be static
  // initialization order races.
  if (!message_handlers)
    message_handlers = new std::vector<MessageHandler*>();
  message_handlers->push_back(this);
}

// static
std::vector<MessageHandler*>* MessageHandler::message_handlers = nullptr;

bool FindFileOrFail(QueryDatabase* db,
                    const Project* project,
                    std::optional<lsRequestId> id,
                    const std::string& absolute_path,
                    QueryFile** out_query_file,
                    QueryFileId* out_file_id) {
  *out_query_file = nullptr;

  auto it = db->usr_to_file.find(NormalizedPath(absolute_path));
  if (it != db->usr_to_file.end()) {
    QueryFile& file = db->files[it->second.id];
    if (file.def) {
      *out_query_file = &file;
      if (out_file_id)
        *out_file_id = QueryFileId(it->second.id);
      return true;
    }
  }

  if (out_file_id)
    *out_file_id = QueryFileId();

  bool indexing = project->absolute_path_to_entry_index_.find(absolute_path) !=
                  project->absolute_path_to_entry_index_.end();
  if (indexing)
    LOG_S(INFO) << "\"" << absolute_path << "\" is being indexed.";
  else
    LOG_S(INFO) << "Unable to find file \"" << absolute_path << "\"";
  /*
  LOG_S(INFO) << "Files (size=" << db->usr_to_file.size() << "): "
              << StringJoinMap(db->usr_to_file,
                               [](const std::pair<NormalizedPath, QueryFileId>& entry) {
                                 return entry.first.path;
                               });
  */

  if (id) {
    Out_Error out;
    out.id = *id;
    if (indexing) {
      out.error.code = lsErrorCodes::ServerNotInitialized;
      out.error.message = absolute_path + " is being indexed.";
    } else {
      out.error.code = lsErrorCodes::InternalError;
      out.error.message = "Unable to find file " + absolute_path;
    }
    QueueManager::WriteStdout(kMethodType_Unknown, out);
  }

  return false;
}

void EmitInactiveLines(WorkingFile* working_file,
                       const std::vector<Range>& inactive_regions) {
  Out_CclsSetInactiveRegion out;
  out.params.uri = lsDocumentUri::FromPath(working_file->filename);
  for (Range skipped : inactive_regions) {
    std::optional<lsRange> ls_skipped = GetLsRange(working_file, skipped);
    if (ls_skipped)
      out.params.inactiveRegions.push_back(*ls_skipped);
  }
  QueueManager::WriteStdout(kMethodType_CclsPublishInactiveRegions, out);
}

void EmitSemanticHighlighting(QueryDatabase* db,
                              SemanticHighlightSymbolCache* semantic_cache,
                              WorkingFile* working_file,
                              QueryFile* file) {
  assert(file->def);
  if (!semantic_cache->match_->IsMatch(file->def->path))
    return;
  auto semantic_cache_for_file =
      semantic_cache->GetCacheForFile(file->def->path);

  // Group symbols together.
  std::unordered_map<SymbolIdx, Out_CclsPublishSemanticHighlighting::Symbol>
      grouped_symbols;
  for (SymbolRef sym : file->def->all_symbols) {
    std::string_view detailed_name;
    lsSymbolKind parent_kind = lsSymbolKind::Unknown;
    lsSymbolKind kind = lsSymbolKind::Unknown;
    StorageClass storage = StorageClass::Invalid;
    // This switch statement also filters out symbols that are not highlighted.
    switch (sym.kind) {
      case SymbolKind::Func: {
        const QueryFunc& func = db->GetFunc(sym);
        const QueryFunc::Def* def = func.AnyDef();
        if (!def)
          continue;  // applies to for loop
        if (def->spell)
          parent_kind = GetSymbolKind(db, *def->spell);
        if (parent_kind == lsSymbolKind::Unknown) {
          for (Use use : func.declarations) {
            parent_kind = GetSymbolKind(db, use);
            break;
          }
        }
        // Don't highlight overloadable operators or implicit lambda ->
        // std::function constructor.
        std::string_view short_name = def->ShortName();
        if (short_name.compare(0, 8, "operator") == 0 ||
            short_name.compare(0, 27, "function<type-parameter-0-0") == 0)
          continue;  // applies to for loop
        if (def->spell)
          parent_kind = GetSymbolKind(db, *def->spell);
        kind = def->kind;
        storage = def->storage;
        detailed_name = short_name;

        // Check whether the function name is actually there.
        // If not, do not publish the semantic highlight.
        // E.g. copy-initialization of constructors should not be highlighted
        // but we still want to keep the range for jumping to definition.
        std::string_view concise_name =
            detailed_name.substr(0, detailed_name.find('<'));
        int16_t start_line = sym.range.start.line;
        int16_t start_col = sym.range.start.column;
        if (start_line >= 0 && start_line < working_file->index_lines.size()) {
          std::string_view line = working_file->index_lines[start_line];
          sym.range.end.line = start_line;
          if (start_col + concise_name.size() <= line.size() &&
              line.compare(start_col, concise_name.size(), concise_name) == 0)
            sym.range.end.column = start_col + concise_name.size();
          else
            continue;  // applies to for loop
        }
        break;
      }
      case SymbolKind::Type:
        for (auto& def : db->GetType(sym).def) {
          kind = def.kind;
          detailed_name = def.detailed_name;
          if (def.spell) {
            parent_kind = GetSymbolKind(db, *def.spell);
            break;
          }
        }
        break;
      case SymbolKind::Var: {
        const QueryVar& var = db->GetVar(sym);
        for (auto& def : var.def) {
          kind = def.kind;
          storage = def.storage;
          detailed_name = def.detailed_name;
          if (def.spell) {
            parent_kind = GetSymbolKind(db, *def.spell);
            break;
          }
        }
        if (parent_kind == lsSymbolKind::Unknown) {
          for (Use use : var.declarations) {
            parent_kind = GetSymbolKind(db, use);
            break;
          }
        }
        break;
      }
      default:
        continue;  // applies to for loop
    }

    std::optional<lsRange> loc = GetLsRange(working_file, sym.range);
    if (loc) {
      auto it = grouped_symbols.find(sym);
      if (it != grouped_symbols.end()) {
        it->second.ranges.push_back(*loc);
      } else {
        Out_CclsPublishSemanticHighlighting::Symbol symbol;
        symbol.stableId = semantic_cache_for_file->GetStableId(
            sym.kind, std::string(detailed_name));
        symbol.parentKind = parent_kind;
        symbol.kind = kind;
        symbol.storage = storage;
        symbol.ranges.push_back(*loc);
        grouped_symbols[sym] = symbol;
      }
    }
  }

  // Make ranges non-overlapping using a scan line algorithm.
  std::vector<ScanLineEvent> events;
  int id = 0;
  for (auto& entry : grouped_symbols) {
    Out_CclsPublishSemanticHighlighting::Symbol& symbol = entry.second;
    for (auto& loc : symbol.ranges) {
      // For ranges sharing the same start point, the one with leftmost end
      // point comes first.
      events.push_back({loc.start, loc.end, id, &symbol});
      // For ranges sharing the same end point, their relative order does not
      // matter, therefore we arbitrarily assign loc.end to them. We use
      // negative id to indicate a deletion event.
      events.push_back({loc.end, loc.end, ~id, &symbol});
      id++;
    }
    symbol.ranges.clear();
  }
  std::sort(events.begin(), events.end());

  std::vector<uint8_t> deleted(id, 0);
  int top = 0;
  for (size_t i = 0; i < events.size(); i++) {
    while (top && deleted[events[top - 1].id])
      top--;
    // Order [a, b0) after [a, b1) if b0 < b1. The range comes later overrides
    // the ealier. The order of [a0, b) [a1, b) does not matter.
    // The order of [a, b) [b, c) does not as long as we do not emit empty
    // ranges.
    // Attribute range [events[i-1].pos, events[i].pos) to events[top-1].symbol
    // .
    if (top && !(events[i - 1].pos == events[i].pos))
      events[top - 1].symbol->ranges.emplace_back(events[i - 1].pos,
                                                  events[i].pos);
    if (events[i].id >= 0)
      events[top++] = events[i];
    else
      deleted[~events[i].id] = 1;
  }

  // Publish.
  Out_CclsPublishSemanticHighlighting out;
  out.params.uri = lsDocumentUri::FromPath(working_file->filename);
  for (auto& entry : grouped_symbols)
    if (entry.second.ranges.size())
      out.params.symbols.push_back(entry.second);
  QueueManager::WriteStdout(kMethodType_CclsPublishSemanticHighlighting, out);
}