#include "message_handler.h"

#include "log.hh"
#include "pipeline.hh"
#include "project.h"
#include "query_utils.h"
using namespace ccls;

using namespace clang;

#include <algorithm>

MAKE_HASHABLE(SymbolIdx, t.usr, t.kind);

namespace {

struct Out_CclsSetSkippedRanges
    : public lsOutMessage<Out_CclsSetSkippedRanges> {
  struct Params {
    lsDocumentUri uri;
    std::vector<lsRange> skippedRanges;
  };
  std::string method = "$ccls/setSkippedRanges";
  Params params;
};
MAKE_REFLECT_STRUCT(Out_CclsSetSkippedRanges::Params, uri, skippedRanges);
MAKE_REFLECT_STRUCT(Out_CclsSetSkippedRanges, 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() {
  match_ = std::make_unique<GroupMatch>(g_config->highlight.whitelist,
                                        g_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(DB *db, Project *project, std::optional<lsRequestId> id,
                    const std::string &absolute_path,
                    QueryFile **out_query_file, int *out_file_id) {
  *out_query_file = nullptr;

  auto it = db->name2file_id.find(LowerPathIfInsensitive(absolute_path));
  if (it != db->name2file_id.end()) {
    QueryFile &file = db->files[it->second];
    if (file.def) {
      *out_query_file = &file;
      if (out_file_id)
        *out_file_id = it->second;
      return true;
    }
  }

  if (out_file_id)
    *out_file_id = -1;

  bool indexing;
  {
    std::lock_guard<std::mutex> lock(project->mutex_);
    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 << "\"";

  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;
    }
    pipeline::WriteStdout(kMethodType_Unknown, out);
  }

  return false;
}

void EmitSkippedRanges(WorkingFile *working_file,
                       const std::vector<Range> &skipped_ranges) {
  Out_CclsSetSkippedRanges out;
  out.params.uri = lsDocumentUri::FromPath(working_file->filename);
  for (Range skipped : skipped_ranges) {
    std::optional<lsRange> ls_skipped = GetLsRange(working_file, skipped);
    if (ls_skipped)
      out.params.skippedRanges.push_back(*ls_skipped);
  }
  pipeline::WriteStdout(kMethodType_CclsPublishSkippedRanges, out);
}

void EmitSemanticHighlighting(DB *db,
                              SemanticHighlightSymbolCache *semantic_cache,
                              WorkingFile *wfile, QueryFile *file) {
  assert(file->def);
  if (wfile->buffer_content.size() > g_config->largeFileSize ||
      !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;
    uint8_t storage = SC_None;
    // 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->Name(false);
      if (short_name.compare(0, 8, "operator") == 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 >= wfile->index_lines.size())
        continue;
      std::string_view line = wfile->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))
        continue;
      sym.range.end.column = start_col + concise_name.size();
      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(wfile, sym.range);
    if (loc) {
      auto it = grouped_symbols.find(sym);
      if (it != grouped_symbols.end()) {
        it->second.lsRanges.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.lsRanges.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.lsRanges) {
      // 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.lsRanges.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->lsRanges.push_back(
          {events[i - 1].pos, events[i].pos});
    if (events[i].id >= 0)
      events[top++] = events[i];
    else
      deleted[~events[i].id] = 1;
  }

  Out_CclsPublishSemanticHighlighting out;
  out.params.uri = lsDocumentUri::FromPath(wfile->filename);
  // Transform lsRange into pair<int, int> (offset pairs)
  if (!g_config->highlight.lsRanges) {
    std::vector<std::pair<lsRange, Out_CclsPublishSemanticHighlighting::Symbol *>>
      scratch;
    for (auto &entry : grouped_symbols) {
      for (auto &range : entry.second.lsRanges)
        scratch.emplace_back(range, &entry.second);
      entry.second.lsRanges.clear();
    }
    std::sort(scratch.begin(), scratch.end(),
      [](auto &l, auto &r) { return l.first.start < r.first.start; });
    const auto &buf = wfile->buffer_content;
    int l = 0, c = 0, i = 0, p = 0;
    auto mov = [&](int line, int col) {
      if (l < line)
        c = 0;
      for (; l < line && i < buf.size(); i++) {
        if (buf[i] == '\n')
          l++;
        if (uint8_t(buf[i]) < 128 || 192 <= uint8_t(buf[i]))
          p++;
      }
      if (l < line) return true;
      for (; c < col && i < buf.size() && buf[i] != '\n'; c++)
        if (p++, uint8_t(buf[i++]) >= 128)
          // Skip 0b10xxxxxx
          while (i < buf.size() && uint8_t(buf[i]) >= 128 && uint8_t(buf[i]) < 192)
            i++;
      return c < col;
    };
    for (auto &entry : scratch) {
      lsRange &r = entry.first;
      if (mov(r.start.line, r.start.character))
        continue;
      int beg = p;
      if (mov(r.end.line, r.end.character))
        continue;
      entry.second->ranges.emplace_back(beg, p);
    }
  }

  for (auto &entry : grouped_symbols)
    if (entry.second.ranges.size() || entry.second.lsRanges.size())
      out.params.symbols.push_back(std::move(entry.second));
  pipeline::WriteStdout(kMethodType_CclsPublishSemanticHighlighting, out);
}