/*
 * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "utilities/debug.hpp"
#include "utilities/ostream.hpp"
#include "utilities/stringUtils.hpp"

int StringUtils::replace_no_expand(char* string, const char* from, const char* to) {
  int replace_count = 0;
  size_t from_len = strlen(from);
  size_t to_len = strlen(to);
  assert(from_len >= to_len, "must not expand input");

  for (char* dst = string; *dst && (dst = strstr(dst, from)) != NULL;) {
    char* left_over = dst + from_len;
    memmove(dst, to, to_len);                       // does not copy trailing 0 of <to>
    dst += to_len;                                  // skip over the replacement.
    memmove(dst, left_over, strlen(left_over) + 1); // copies the trailing 0 of <left_over>
    ++ replace_count;
  }

  return replace_count;
}

double StringUtils::similarity(const char* str1, size_t len1, const char* str2, size_t len2) {
  assert(str1 != NULL && str2 != NULL, "sanity");

  // filter out zero-length strings else we will underflow on len-1 below
  if (len1 == 0 || len2 == 0) {
    return 0.0;
  }

  size_t total = len1 + len2;
  size_t hit = 0;

  for (size_t i = 0; i < len1 - 1; i++) {
    for (size_t j = 0; j < len2 - 1; j++) {
      if ((str1[i] == str2[j]) && (str1[i+1] == str2[j+1])) {
        ++hit;
        break;
      }
    }
  }

  return 2.0 * (double) hit / (double) total;
}

class StringMatcher {
 public:
  typedef int getc_function_t(const char* &source, const char* limit);
  const getc_function_t* _pattern_getc;
  const getc_function_t* _string_getc;

  StringMatcher(getc_function_t pattern_getc,
                getc_function_t string_getc)
    : _pattern_getc(pattern_getc),
      _string_getc(string_getc)
  { }

  enum {  // special results from _pattern_getc
    string_match_comma  = -0x100 + ',',
    string_match_star   = -0x100 + '*',
    string_match_eos    = -0x100 + '\0'
  };

 private:
  const char*
  skip_anchor_word(const char* match,
                   const char* match_end,
                   int anchor_length,
                   const char* pattern,
                   const char* pattern_end) {
    assert(pattern < pattern_end && anchor_length > 0, "");
    const char* begp = pattern;
    int ch1 = _pattern_getc(begp, pattern_end);
    // note that begp is now advanced over ch1
    assert(ch1 > 0, "regular char only");
    const char* matchp = match;
    const char* limitp = match_end - anchor_length;
    while (matchp <= limitp) {
      int mch = _string_getc(matchp, match_end);
      if (mch == ch1) {
        const char* patp = begp;
        const char* anchorp = matchp;
        while (patp < pattern_end) {
          char ch = _pattern_getc(patp, pattern_end);
          char mch = _string_getc(anchorp, match_end);
          if (mch != ch) {
            anchorp = NULL;
            break;
          }
        }
        if (anchorp != NULL) {
          return anchorp;  // Found a full copy of the anchor.
        }
        // That did not work, so restart the search for ch1.
      }
    }
    return NULL;
  }

 public:
  bool string_match(const char* pattern,
                    const char* string) {
    return string_match(pattern, pattern + strlen(pattern),
                        string, string + strlen(string));
  }
  bool string_match(const char* pattern, const char* pattern_end,
                    const char* string, const char* string_end) {
    const char* patp = pattern;
    switch (_pattern_getc(patp, pattern_end)) {
    case string_match_eos:
      return false;  // Empty pattern is always false.
    case string_match_star:
      if (patp == pattern_end) {
        return true;   // Lone star pattern is always true.
      }
      break;
    }
    patp = pattern;  // Reset after lookahead.
    const char* matchp = string;  // NULL if failing
    for (;;) {
      int ch = _pattern_getc(patp, pattern_end);
      switch (ch) {
      case string_match_eos:
      case string_match_comma:
        // End of a list item; see if it's a match.
        if (matchp == string_end) {
          return true;
        }
        if (ch == string_match_comma) {
          // Get ready to match the next item.
          matchp = string;
          continue;
        }
        return false;  // End of all items.

      case string_match_star:
        if (matchp != NULL) {
          // Wildcard:  Parse out following anchor word and look for it.
          const char* begp = patp;
          const char* endp = patp;
          int anchor_len = 0;
          for (;;) {
            // get as many following regular characters as possible
            endp = patp;
            ch = _pattern_getc(patp, pattern_end);
            if (ch <= 0) {
              break;
            }
            anchor_len += 1;
          }
          // Anchor word [begp..endp) does not contain ch, so back up.
          // Now do an eager match to the anchor word, and commit to it.
          patp = endp;
          if (ch == string_match_eos ||
              ch == string_match_comma) {
            // Anchor word is at end of pattern, so treat it as a fixed pattern.
            const char* limitp = (matchp + strlen(matchp)) - anchor_len;
            matchp = limitp;
            patp = begp;
            // Resume normal scanning at the only possible match position.
            continue;
          }
          // Find a floating occurrence of the anchor and continue matching.
          // Note:  This is greedy; there is no backtrack here.  Good enough.
          matchp = skip_anchor_word(matchp, string_end, anchor_len, begp, endp);
        }
        continue;
      }
      // Normal character.
      if (matchp != NULL) {
        int mch = _string_getc(matchp, string_end);
        if (mch != ch) {
          matchp = NULL;
        }
      }
    }
  }
};

// Match a wildcarded class list to a proposed class name (in internal form).
// Commas or newlines separate multiple possible matches; stars are shell-style wildcards.
class ClassListMatcher : public StringMatcher {
 public:
  ClassListMatcher()
    : StringMatcher(pattern_list_getc, class_name_getc)
  { }

 private:
  static int pattern_list_getc(const char* &pattern_ptr,
                               const char* pattern_end) {
    if (pattern_ptr == pattern_end) {
      return string_match_eos;
    }
    int ch = (unsigned char) *pattern_ptr++;
    switch (ch) {
    case ' ': case '\t': case '\n': case '\r':
    case ',':
      // End of list item.
      for (;;) {
        switch (*pattern_ptr) {
        case ' ': case '\t': case '\n': case '\r':
        case ',':
          pattern_ptr += 1;  // Collapse multiple commas or spaces.
          continue;
        }
        break;
      }
      return string_match_comma;

    case '*':
      // Wildcard, matching any number of chars.
      while (*pattern_ptr == '*') {
        pattern_ptr += 1;  // Collapse multiple stars.
      }
      return string_match_star;

    case '.':
      ch = '/';   // Look for internal form of package separator
      break;

    case '\\':
      // Superquote in pattern escapes * , whitespace, and itself.
      if (pattern_ptr < pattern_end) {
        ch = (unsigned char) *pattern_ptr++;
      }
      break;
    }

    assert(ch > 0, "regular char only");
    return ch;
  }

  static int class_name_getc(const char* &name_ptr,
                             const char* name_end) {
    if (name_ptr == name_end) {
      return string_match_eos;
    }
    int ch = (unsigned char) *name_ptr++;
    if (ch == '.') {
      ch = '/';   // Normalize to internal form of package separator
    }
    return ch;  // plain character
  }
};

static bool class_list_match_sane();

bool StringUtils::class_list_match(const char* class_pattern_list,
                                   const char* class_name) {
  assert(class_list_match_sane(), "");
  if (class_pattern_list == NULL || class_name == NULL || class_name[0] == '\0')
    return false;
  ClassListMatcher clm;
  return clm.string_match(class_pattern_list, class_name);
}

#ifdef ASSERT
static void
class_list_match_sane(const char* pat, const char* str, bool result = true) {
  if (result) {
    assert(StringUtils::class_list_match(pat, str), "%s ~ %s", pat, str);
  } else {
    assert(!StringUtils::class_list_match(pat, str), "%s !~ %s", pat, str);
  }
}

static bool
class_list_match_sane() {
  static bool done = false;
  if (done)  return true;
  done = true;
  class_list_match_sane("foo", "foo");
  class_list_match_sane("foo,", "foo");
  class_list_match_sane(",foo,", "foo");
  class_list_match_sane("bar,foo", "foo");
  class_list_match_sane("bar,foo,", "foo");
  class_list_match_sane("*", "foo");
  class_list_match_sane("foo.bar", "foo/bar");
  class_list_match_sane("foo/bar", "foo.bar");
  class_list_match_sane("\\foo", "foo");
  class_list_match_sane("\\*foo", "*foo");
  const char* foo = "foo!";
  char buf[100], buf2[100];
  const int m = strlen(foo);
  for (int n = 0; n <= 1; n++) {
    for (int a = -1; a <= 1; a++) {
      for (int i = 0; i <= m; i++) {
        for (int j = i; j <= m; j++) {
          if (j == i && j > 0)  continue;
          for (int k = j; k <= m; k++) {
            if (k == j && k > i)  continue;
            for (int l = k; l <= m; l++) {
              if (l == k && l > j)  continue;
              char* bp = &buf[0];
              strncpy(bp, foo + 0, i - 0); bp += i - 0;
              *bp++ = '*';
              strncpy(bp, foo + j, k - j); bp += k - j;
              *bp++ = '*';
              strncpy(bp, foo + l, m - l); bp += m - l;
              if (n) {
                *bp++ = 'N';  // make it fail
              }
              *bp++ = '\0';
              if (a != 0) {
                if (a < 0) {
                  strcpy(buf2, buf);
                  strcat(buf, "X*, ");
                  strcat(buf, buf2);
                } else {
                  strcat(buf, ", Y");
                }
              }
              class_list_match_sane(buf, foo, !n);
            }
          }
        }
      }
    }
  }
  return true;
}
#endif //ASSERT