// Copyright 2021 DeepMind Technologies Limited
//
// 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.


#ifndef MUJOCO_SRC_XML_XML_UTIL_H_
#define MUJOCO_SRC_XML_XML_UTIL_H_

#include <array>
#include <functional>
#include <optional>
#include <set>
#include <string>
#include <vector>
#include <sstream>

#include <mujoco/mujoco.h>
#include "user/user_util.h"
#include "tinyxml2.h"

// error string copy
void mjCopyError(char* dst, const char* src, int maxlen);

using tinyxml2::XMLElement;

XMLElement* FirstChildElement(XMLElement* e, const char* name = nullptr);
XMLElement* NextSiblingElement(XMLElement* e, const char* name = nullptr);

// XML Error info
class [[nodiscard]] mjXError {
 public:
  mjXError(const tinyxml2::XMLElement* elem = 0,
           const char* msg = 0,
           const char* str = 0,
           int pos = 0);
  ~mjXError() = default;

  char message[1000];             // error message
};


// max number of attribute fields in schema (plus 3)
#define mjXATTRNUM 36


// Custom XML file validation
class mjXSchema {
 public:
  mjXSchema(const char* schema[][mjXATTRNUM], unsigned nrow);

  std::string GetError();                         // return error
  void Print(std::stringstream& str, int level) const;      // print schema
  void PrintHTML(std::stringstream& str, int level, bool pad) const;

  bool NameMatch(tinyxml2::XMLElement* elem, int level);               // does name match
  tinyxml2::XMLElement* Check(tinyxml2::XMLElement* elem, int level);  // validator

 private:
  std::string name_;                  // element name
  char type_;                         // element type: '?', '!', '*', 'R'
  std::set<std::string> attr_;        // allowed attributes
  std::vector<mjXSchema> subschema_;  // allowed child elements

  int refcnt_ = 0;                    // refcount used for validation
  std::string error;                  // error from constructor or Check
};


// key(string) : value(int) map
struct _mjMap {
  const char* key;
  int value;
};
typedef struct _mjMap mjMap;


// XML read and write utility functions
class mjXUtil {
 public:
  mjXUtil() = default;
  virtual ~mjXUtil() = default;

  // compare two vectors
  template<typename T>
  static bool SameVector(const T* vec1, const T* vec2, int n);

  // find key in map, return value (-1: not found)
  static int FindKey(const mjMap* map, int mapsz, std::string key);

  // find value in map, return key ("": not found)
  static std::string FindValue(const mjMap* map, int mapsz, int value);

  // if attribute is present, return vector of numerical data
  template<typename T>
  static std::optional<std::vector<T>> ReadAttrVec(tinyxml2::XMLElement* elem,
                                                   const char* attr,
                                                   bool required = false);

  // if attribute is present, return attribute as a string
  static std::optional<std::string> ReadAttrStr(tinyxml2::XMLElement* elem,
                                                const char* attr,
                                                bool required = false);

  // if attribute is present, return attribute as a filename
  static std::optional<mujoco::user::FilePath>
      ReadAttrFile(tinyxml2::XMLElement* elem, const char* attr,
                   const mjVFS* vfs,
                   const mujoco::user::FilePath& dir = mujoco::user::FilePath(),
                   bool required = false);

  // if attribute is present, return numerical value of attribute
  template<typename T>
  static std::optional<T> ReadAttrNum(tinyxml2::XMLElement* elem,
                                      const char* attr,
                                      bool required = false);

  // if attribute is present, return array of numerical data
  // N should be small as data is allocated on the stack
  template<typename T, int N>
  static std::optional<std::array<T, N>> ReadAttrArr(tinyxml2::XMLElement* elem,
                                                     const char* attr,
                                                     bool required = false) {
    std::array<T, N> arr;
    int n = 0;
    if (!ReadAttrValues<T>(elem, attr, [&](int i, T num) { arr[i] = num; n++; }, N)) {
      throw mjXError(elem, "attribute '%s' has too much data", attr);
    }

    if (!n) {
      if (required) {
        throw mjXError(elem, "required attribute missing: '%s'", attr);
      } else {
        return std::nullopt;
      }
    }

    if (n < N) {
      throw mjXError(elem, "attribute '%s' does not have enough data", attr);
    }
    return arr;
  }

  // deprecated: use ReadAttrVec or ReadAttrArr
  template<typename T>
  static int ReadAttr(tinyxml2::XMLElement* elem, const char* attr, int len,
                      T* data, std::string& text,
                      bool required = false, bool exact = true);

  static int ReadQuat(tinyxml2::XMLElement* elem, const char* attr, double* data,
                      std::string& text, bool required = false);

  // deprecated: use ReadAttrVec
  static int ReadVector(tinyxml2::XMLElement* elem, const char* attr,
                        std::vector<double>& vec, std::string& text, bool required = false);

  // deprecated: use ReadAttrStr
  static bool ReadAttrTxt(tinyxml2::XMLElement* elem, const char* attr, std::string& text,
                          bool required = false);

  // deprecated: use ReadAttrNum
  static bool ReadAttrInt(tinyxml2::XMLElement* elem, const char* attr, int* data,
                          bool required = false);

  // write vector<float> to string
  static void Vector2String(std::string& txt, const std::vector<float>& vec, int ncol = 0);


  // find subelement with given name, make sure it is unique
  static tinyxml2::XMLElement* FindSubElem(tinyxml2::XMLElement* elem, std::string name,
                                           bool required = false);

  // find attribute, translate key, return int value
  static bool MapValue(tinyxml2::XMLElement* elem, const char* attr, int* data,
                       const mjMap* map, int mapSz, bool required = false);

  // write attribute- any type
  template<typename T>
  static void WriteAttr(tinyxml2::XMLElement* elem, std::string name, int n, const T* data,
                        const T* def = 0, bool trim = false);

  // write vector<double> attribute, with and without default
  static void WriteVector(tinyxml2::XMLElement* elem, std::string name,
                          const std::vector<double>& vec);
  static void WriteVector(tinyxml2::XMLElement* elem, std::string name,
                          const std::vector<double>& vec, const std::vector<double>& def);

  // write attribute- string
  static void WriteAttrTxt(tinyxml2::XMLElement* elem, std::string name, std::string value);

  // write attribute- single int
  static void WriteAttrInt(tinyxml2::XMLElement* elem, std::string name, int data, int def = -12345);

  // write attribute- keyword
  static void WriteAttrKey(tinyxml2::XMLElement* elem, std::string name,
                           const mjMap* map, int mapsz, int data, int def = -12345);

 private:
  template<typename T>
  static bool ReadAttrValues(tinyxml2::XMLElement* elem, const char* attr,
                             std::function<void (int, T)> push, int max = -1);
};

#endif  // MUJOCO_SRC_XML_XML_UTIL_H_