// Copyright 2017 Global Phasing Ltd.
//
// Utilities. Mostly for working with strings and vectors.

#ifndef GEMMI_UTIL_HPP_
#define GEMMI_UTIL_HPP_

#include <algorithm>  // for equal, find, remove_if
#include <cctype>     // for isspace
#include <cstring>    // for strncmp
#include <iterator>   // for begin, end, make_move_iterator
#include <string>
#include <vector>

namespace gemmi {

//   #####   string helpers   #####

inline void append_to_str(std::string& out, int v) { out += std::to_string(v); }
inline void append_to_str(std::string& out, size_t v) { out += std::to_string(v); }
template<typename T>
void append_to_str(std::string& out, const T& v) { out += v; }

inline void cat_to(std::string&) {}
template <typename T, typename... Args>
void cat_to(std::string& out, const T& value, Args const&... args) {
  append_to_str(out, value);
  cat_to(out, args...);
}
template <class... Args>
std::string cat(Args const&... args) {
  std::string out;
  cat_to(out, args...);
  return out;
}

inline bool starts_with(const std::string& str, const std::string& prefix) {
  size_t sl = prefix.length();
  return str.length() >= sl && str.compare(0, sl, prefix) == 0;
}

template<size_t N> bool starts_with(const char* a, const char (&b)[N]) {
  return std::strncmp(a, b, N-1) == 0;
}

inline bool ends_with(const std::string& str, const std::string& suffix) {
  size_t sl = suffix.length();
  return str.length() >= sl && str.compare(str.length() - sl, sl, suffix) == 0;
}

// can be faster than std::tolower() b/c it takes char not int
inline char lower(char c) {
  if (c >= 'A' && c <= 'Z')
    return c | 0x20;
  return c;
}

// works as expected only for a-zA-Z
inline char alpha_up(char c) { return c & ~0x20; }

inline std::string to_lower(std::string str) {
  for (char& c : str)
    if (c >= 'A' && c <= 'Z')
      c |= 0x20;
  return str;
}

inline std::string to_upper(std::string str) {
  for (char& c : str)
    if (c >= 'a' && c <= 'z')
      c &= ~0x20;
  return str;
}

// Case-insensitive comparisons. The second arg must be lowercase.

inline bool iequal(const std::string& str, const std::string& low) {
  return str.length() == low.length() &&
         std::equal(std::begin(low), std::end(low), str.begin(),
                    [](char c1, char c2) { return c1 == lower(c2); });
}

inline bool iequal_from(const std::string& str, size_t offset, const std::string& low) {
  return str.length() == low.length() + offset &&
         std::equal(std::begin(low), std::end(low), str.begin() + offset,
                    [](char c1, char c2) { return c1 == lower(c2); });
}

inline bool istarts_with(const std::string& str, const std::string& prefix) {
  return str.length() >= prefix.length() &&
         std::equal(std::begin(prefix), std::end(prefix), str.begin(),
                    [](char c1, char c2) { return c1 == lower(c2); });
}
inline bool iends_with(const std::string& str, const std::string& suffix) {
  size_t sl = suffix.length();
  return str.length() >= sl &&
         std::equal(std::begin(suffix), std::end(suffix), str.end() - sl,
                    [](char c1, char c2) { return c1 == lower(c2); });
}

inline bool giends_with(const std::string& str, const std::string& suffix) {
  return iends_with(str, suffix) || iends_with(str, suffix + ".gz");
}

inline std::string trim_str(const std::string& str) {
  const std::string ws = " \r\n\t";
  std::string::size_type first = str.find_first_not_of(ws);
  if (first == std::string::npos)
    return std::string{};
  std::string::size_type last = str.find_last_not_of(ws);
  return str.substr(first, last - first + 1);
}

inline std::string rtrim_str(const std::string& str) {
  std::string::size_type last = str.find_last_not_of(" \r\n\t");
  return str.substr(0, last == std::string::npos ? 0 : last + 1);
}

// end is after the last character of the string (typically \0)
inline const char* rtrim_cstr(const char* start, const char* end=nullptr) {
  if (!start)
    return nullptr;
  if (!end) {
    end = start;
    while (*end != '\0')
      ++end;
  }
  while (end > start && std::isspace(end[-1]))
    --end;
  return end;
}

namespace impl {
inline size_t length(char) { return 1; }
inline size_t length(const std::string& s) { return s.length(); }
}

// takes a single separator (usually char or string);
// may return empty fields
template<typename S>
void split_str_into(const std::string& str, S sep,
                    std::vector<std::string>& result) {
  std::size_t start = 0, end;
  while ((end = str.find(sep, start)) != std::string::npos) {
    result.emplace_back(str, start, end - start);
    start = end + impl::length(sep);
  }
  result.emplace_back(str, start);
}

template<typename S>
std::vector<std::string> split_str(const std::string& str, S sep) {
  std::vector<std::string> result;
  split_str_into(str, sep, result);
  return result;
}

// _multi variants takes multiple 1-char separators as a string;
// discards empty fields
inline void split_str_into_multi(const std::string& str, const char* seps,
                                 std::vector<std::string>& result) {
  std::size_t start = str.find_first_not_of(seps);
  while (start != std::string::npos) {
    std::size_t end = str.find_first_of(seps, start);
    result.emplace_back(str, start, end - start);
    start = str.find_first_not_of(seps, end);
  }
}

inline std::vector<std::string> split_str_multi(const std::string& str,
                                                const char* seps=" \t") {
  std::vector<std::string> result;
  split_str_into_multi(str, seps, result);
  return result;
}

template<typename T, typename S, typename F>
std::string join_str(T begin, T end, const S& sep, const F& getter) {
  std::string r;
  bool first = true;
  for (T i = begin; i != end; ++i) {
    if (!first)
      r += sep;
    r += getter(*i);
    first = false;
  }
  return r;
}

template<typename T, typename S>
std::string join_str(T begin, T end, const S& sep) {
  return join_str(begin, end, sep, [](const std::string& t) { return t; });
}

template<typename T, typename S, typename F>
std::string join_str(const T& iterable, const S& sep, const F& getter) {
  return join_str(iterable.begin(), iterable.end(), sep, getter);
}

template<typename T, typename S>
std::string join_str(const T& iterable, const S& sep) {
  return join_str(iterable.begin(), iterable.end(), sep);
}

template<typename T, typename S>
void string_append_sep(std::string& str, S sep, const T& item) {
  if (!str.empty())
    str += sep;
  str += item;
}

inline void replace_all(std::string &s,
                        const std::string &old, const std::string &new_) {
  std::string::size_type pos = 0;
  while ((pos = s.find(old, pos)) != std::string::npos) {
    s.replace(pos, old.size(), new_);
    pos += new_.size();
  }
}

// list is a comma separated string
inline bool is_in_list(const std::string& name, const std::string& list,
                       char sep=',') {
  if (name.length() >= list.length())
    return name == list;
  for (size_t start=0, end=0; end != std::string::npos; start=end+1) {
    end = list.find(sep, start);
    if (list.compare(start, end - start, name) == 0)
      return true;
  }
  return false;
}

//   #####   vector helpers   #####

template <class T>
bool in_vector(const T& x, const std::vector<T>& v) {
  return std::find(v.begin(), v.end(), x) != v.end();
}

template <typename F, typename T>
bool in_vector_f(F f, const std::vector<T>& v) {
  return std::find_if(v.begin(), v.end(), f) != v.end();
}

template <class T>
T* vector_end_ptr(std::vector<T>& v) { return v.data() + v.size(); }
template <class T>
const T* vector_end_ptr(const std::vector<T>& v) { return v.data() + v.size(); }

template <class T>
void vector_move_extend(std::vector<T>& dst, std::vector<T>&& src) {
  if (dst.empty())
    dst = std::move(src);
  else
    dst.insert(dst.end(), std::make_move_iterator(src.begin()),
                          std::make_move_iterator(src.end()));
}

// wrapper around the erase-remove idiom
template <class T, typename F>
void vector_remove_if(std::vector<T>& v, F&& condition) {
  v.erase(std::remove_if(v.begin(), v.end(), condition), v.end());
}


//   #####   other helpers   #####

// Numeric ID used for case-insensitive comparison of 4 letters.
// s must have 4 chars or 3 chars + NUL, ' ' and NUL are equivalent in s.
constexpr int ialpha4_id(const char* s) {
  return (s[0] << 24 | s[1] << 16 | s[2] << 8 | s[3]) & ~0x20202020;
}
// Numeric ID used for case-insensitive comparison of 3 letters.
constexpr int ialpha3_id(const char* s) {
  return (s[0] << 16 | s[1] << 8 | s[2]) & ~0x20202020;
}

} // namespace gemmi
#endif
