/* 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 "clang_tu.hh"
#include "hierarchy.hh"
#include "message_handler.hh"
#include "pipeline.hh"
#include "query_utils.hh"

#include <clang/AST/Type.h>
#include <llvm/ADT/DenseSet.h>

#include <unordered_set>

namespace ccls {
using namespace clang;

namespace {
struct Param : TextDocumentPositionParam {
  // If id is specified, expand a node; otherwise textDocument+position should
  // be specified for building the root and |levels| of nodes below.
  Usr usr;
  std::string id;

  bool qualified = false;
  int levels = 1;
  // If Kind::Func and the point is at a type, list member functions instead of
  // member variables.
  Kind kind = Kind::Var;
  bool hierarchy = false;
};

MAKE_REFLECT_STRUCT(Param, textDocument, position, id, qualified, levels, kind,
                    hierarchy);

struct Out_cclsMember {
  Usr usr;
  std::string id;
  std::string_view name;
  std::string fieldName;
  Location location;
  // For unexpanded nodes, this is an upper bound because some entities may be
  // undefined. If it is 0, there are no members.
  int numChildren = 0;
  // Empty if the |levels| limit is reached.
  std::vector<Out_cclsMember> children;
};
MAKE_REFLECT_STRUCT(Out_cclsMember, id, name, fieldName, location, numChildren,
                    children);

bool Expand(MessageHandler *m, Out_cclsMember *entry, bool qualified,
            int levels, Kind memberKind);

// Add a field to |entry| which is a Func/Type.
void DoField(MessageHandler *m, Out_cclsMember *entry, const QueryVar &var,
             int64_t offset, bool qualified, int levels) {
  const QueryVar::Def *def1 = var.AnyDef();
  if (!def1)
    return;
  Out_cclsMember entry1;
  // With multiple inheritance, the offset is incorrect.
  if (offset >= 0) {
    if (offset / 8 < 10)
      entry1.fieldName += ' ';
    entry1.fieldName += std::to_string(offset / 8);
    if (offset % 8) {
      entry1.fieldName += '.';
      entry1.fieldName += std::to_string(offset % 8);
    }
    entry1.fieldName += ' ';
  }
  if (qualified)
    entry1.fieldName += def1->detailed_name;
  else {
    entry1.fieldName +=
        std::string_view(def1->detailed_name).substr(0, def1->qual_name_offset);
    entry1.fieldName += def1->Name(false);
  }
  if (def1->spell) {
    if (std::optional<Location> loc =
            GetLsLocation(m->db, m->wfiles, *def1->spell))
      entry1.location = *loc;
  }
  if (def1->type) {
    entry1.id = std::to_string(def1->type);
    entry1.usr = def1->type;
    if (Expand(m, &entry1, qualified, levels, Kind::Var))
      entry->children.push_back(std::move(entry1));
  } else {
    entry1.id = "0";
    entry1.usr = 0;
    entry->children.push_back(std::move(entry1));
  }
}

// Expand a type node by adding members recursively to it.
bool Expand(MessageHandler *m, Out_cclsMember *entry, bool qualified,
            int levels, Kind memberKind) {
  if (0 < entry->usr && entry->usr <= BuiltinType::LastKind) {
    entry->name = ClangBuiltinTypeName(int(entry->usr));
    return true;
  }
  const QueryType *type = &m->db->Type(entry->usr);
  const QueryType::Def *def = type->AnyDef();
  // builtin types have no declaration and empty |qualified|.
  if (!def)
    return false;
  entry->name = def->Name(qualified);
  std::unordered_set<Usr> seen;
  if (levels > 0) {
    std::vector<const QueryType *> stack;
    seen.insert(type->usr);
    stack.push_back(type);
    while (stack.size()) {
      type = stack.back();
      stack.pop_back();
      const auto *def = type->AnyDef();
      if (!def)
        continue;
      if (def->kind != SymbolKind::Namespace)
        for (Usr usr : def->bases) {
          auto &type1 = m->db->Type(usr);
          if (type1.def.size()) {
            seen.insert(type1.usr);
            stack.push_back(&type1);
          }
        }
      if (def->alias_of) {
        const QueryType::Def *def1 = m->db->Type(def->alias_of).AnyDef();
        Out_cclsMember entry1;
        entry1.id = std::to_string(def->alias_of);
        entry1.usr = def->alias_of;
        if (def1 && def1->spell) {
          // The declaration of target type.
          if (std::optional<Location> loc =
                  GetLsLocation(m->db, m->wfiles, *def1->spell))
            entry1.location = *loc;
        } else if (def->spell) {
          // Builtin types have no declaration but the typedef declaration
          // itself is useful.
          if (std::optional<Location> loc =
                  GetLsLocation(m->db, m->wfiles, *def->spell))
            entry1.location = *loc;
        }
        if (def1 && qualified)
          entry1.fieldName = def1->detailed_name;
        if (Expand(m, &entry1, qualified, levels - 1, memberKind)) {
          // For builtin types |name| is set.
          if (entry1.fieldName.empty())
            entry1.fieldName = std::string(entry1.name);
          entry->children.push_back(std::move(entry1));
        }
      } else if (memberKind == Kind::Func) {
        llvm::DenseSet<Usr, DenseMapInfoForUsr> seen1;
        for (auto &def : type->def)
          for (Usr usr : def.funcs)
            if (seen1.insert(usr).second) {
              QueryFunc &func1 = m->db->Func(usr);
              if (const QueryFunc::Def *def1 = func1.AnyDef()) {
                Out_cclsMember entry1;
                entry1.fieldName = def1->Name(false);
                if (def1->spell) {
                  if (auto loc = GetLsLocation(m->db, m->wfiles, *def1->spell))
                    entry1.location = *loc;
                } else if (func1.declarations.size()) {
                  if (auto loc = GetLsLocation(m->db, m->wfiles,
                                               func1.declarations[0]))
                    entry1.location = *loc;
                }
                entry->children.push_back(std::move(entry1));
              }
            }
      } else if (memberKind == Kind::Type) {
        llvm::DenseSet<Usr, DenseMapInfoForUsr> seen1;
        for (auto &def : type->def)
          for (Usr usr : def.types)
            if (seen1.insert(usr).second) {
              QueryType &type1 = m->db->Type(usr);
              if (const QueryType::Def *def1 = type1.AnyDef()) {
                Out_cclsMember entry1;
                entry1.fieldName = def1->Name(false);
                if (def1->spell) {
                  if (auto loc = GetLsLocation(m->db, m->wfiles, *def1->spell))
                    entry1.location = *loc;
                } else if (type1.declarations.size()) {
                  if (auto loc = GetLsLocation(m->db, m->wfiles,
                                               type1.declarations[0]))
                    entry1.location = *loc;
                }
                entry->children.push_back(std::move(entry1));
              }
            }
      } else {
        llvm::DenseSet<Usr, DenseMapInfoForUsr> seen1;
        for (auto &def : type->def)
          for (auto it : def.vars)
            if (seen1.insert(it.first).second) {
              QueryVar &var = m->db->Var(it.first);
              if (!var.def.empty())
                DoField(m, entry, var, it.second, qualified, levels - 1);
            }
      }
    }
    entry->numChildren = int(entry->children.size());
  } else
    entry->numChildren = def->alias_of ? 1 : int(def->vars.size());
  return true;
}

std::optional<Out_cclsMember> BuildInitial(MessageHandler *m, Kind kind,
                                           Usr root_usr, bool qualified,
                                           int levels, Kind memberKind) {
  switch (kind) {
  default:
    return {};
  case Kind::Func: {
    const auto *def = m->db->Func(root_usr).AnyDef();
    if (!def)
      return {};

    Out_cclsMember entry;
    // Not type, |id| is invalid.
    entry.name = def->Name(qualified);
    if (def->spell) {
      if (auto loc = GetLsLocation(m->db, m->wfiles, *def->spell))
        entry.location = *loc;
    }
    for (Usr usr : def->vars) {
      auto &var = m->db->Var(usr);
      if (var.def.size())
        DoField(m, &entry, var, -1, qualified, levels - 1);
    }
    return entry;
  }
  case Kind::Type: {
    const auto *def = m->db->Type(root_usr).AnyDef();
    if (!def)
      return {};

    Out_cclsMember entry;
    entry.id = std::to_string(root_usr);
    entry.usr = root_usr;
    if (def->spell) {
      if (auto loc = GetLsLocation(m->db, m->wfiles, *def->spell))
        entry.location = *loc;
    }
    Expand(m, &entry, qualified, levels, memberKind);
    return entry;
  }
  }
}
} // namespace

void MessageHandler::ccls_member(Reader &reader, ReplyOnce &reply) {
  Param param;
  Reflect(reader, param);
  std::optional<Out_cclsMember> result;
  if (param.id.size()) {
    try {
      param.usr = std::stoull(param.id);
    } catch (...) {
      return;
    }
    result.emplace();
    result->id = std::to_string(param.usr);
    result->usr = param.usr;
    // entry.name is empty as it is known by the client.
    if (!(db->HasType(param.usr) && Expand(this, &*result, param.qualified,
                                            param.levels, param.kind)))
      result.reset();
  } else {
    QueryFile *file = FindFile(reply, param.textDocument.uri.GetPath());
    if (!file)
      return;
    WorkingFile *wfile = wfiles->GetFileByFilename(file->def->path);
    for (SymbolRef sym :
         FindSymbolsAtLocation(wfile, file, param.position)) {
      switch (sym.kind) {
      case Kind::Func:
      case Kind::Type:
        result = BuildInitial(this, sym.kind, sym.usr, param.qualified,
                              param.levels, param.kind);
        break;
      case Kind::Var: {
        const QueryVar::Def *def = db->GetVar(sym).AnyDef();
        if (def && def->type)
          result = BuildInitial(this, Kind::Type, def->type, param.qualified,
                                param.levels, param.kind);
        break;
      }
      default:
        continue;
      }
      break;
    }
  }

  if (param.hierarchy)
    reply(result);
  else {
    auto out = FlattenHierarchy(result);
    reply(out);
  }
}
} // namespace ccls