// Copyright 2004 and onwards Google Inc.
//
//

#include "gutil/strings/stringpiece.h"

// IWYU pragma: no_include <pstl/glue_algorithm_defs.h>

#include "common/logging.h"
#include <string.h>
#include <algorithm>
#include <climits>
#include <string>
#include <deque>
#include <ostream>

#include "gutil/stl_util.h"
#include "gutil/strings/memutil.h"

using std::copy;
using std::max;
using std::min;
using std::reverse;
using std::sort;
using std::swap;
using std::string;

std::ostream& operator<<(std::ostream& o, StringPiece piece) {
    o.write(piece.data(), piece.size());
    return o;
}

StringPiece::StringPiece(StringPiece x, int pos) : ptr_(x.ptr_ + pos), length_(x.length_ - pos) {
    DCHECK_LE(0, pos);
    DCHECK_LE(pos, x.length_);
}

StringPiece::StringPiece(StringPiece x, int pos, int len)
        : ptr_(x.ptr_ + pos), length_(min(len, x.length_ - pos)) {
    DCHECK_LE(0, pos);
    DCHECK_LE(pos, x.length_);
    DCHECK_GE(len, 0);
}

void StringPiece::CopyToString(string* target) const {
    STLAssignToString(target, ptr_, length_);
}

void StringPiece::AppendToString(string* target) const {
    STLAppendToString(target, ptr_, length_);
}

int StringPiece::copy(char* buf, size_type n, size_type pos) const {
    int ret = min(length_ - pos, n);
    memcpy(buf, ptr_ + pos, ret);
    return ret;
}

bool StringPiece::contains(StringPiece s) const {
    return find(s, 0) != npos;
}

int StringPiece::find(StringPiece s, size_type pos) const {
    if (length_ <= 0 || pos > static_cast<size_type>(length_)) {
        if (length_ == 0 && pos == 0 && s.length_ == 0) return 0;
        return npos;
    }
    const char* result = memmatch(ptr_ + pos, length_ - pos, s.ptr_, s.length_);
    return result ? result - ptr_ : npos;
}

int StringPiece::find(char c, size_type pos) const {
    if (length_ <= 0 || pos >= static_cast<size_type>(length_)) {
        return npos;
    }
    const char* result = static_cast<const char*>(memchr(ptr_ + pos, c, length_ - pos));
    return result != nullptr ? result - ptr_ : npos;
}

int StringPiece::rfind(StringPiece s, size_type pos) const {
    if (length_ < s.length_) return npos;
    const size_t ulen = length_;
    if (s.length_ == 0) return min(ulen, pos);

    const char* last = ptr_ + min(ulen - s.length_, pos) + s.length_;
    const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_);
    return result != last ? result - ptr_ : npos;
}

// Search range is [0..pos] inclusive.  If pos == npos, search everything.
int StringPiece::rfind(char c, size_type pos) const {
    // Note: memrchr() is not available on Windows.
    if (length_ <= 0) return npos;
    for (int i = min(pos, static_cast<size_type>(length_ - 1)); i >= 0; --i) {
        if (ptr_[i] == c) {
            return i;
        }
    }
    return npos;
}

// For each character in characters_wanted, sets the index corresponding
// to the ASCII code of that character to 1 in table.  This is used by
// the find_.*_of methods below to tell whether or not a character is in
// the lookup table in constant time.
// The argument `table' must be an array that is large enough to hold all
// the possible values of an unsigned char.  Thus it should be be declared
// as follows:
//   bool table[UCHAR_MAX + 1]
static inline void BuildLookupTable(StringPiece characters_wanted, bool* table) {
    const int length = characters_wanted.length();
    const char* const data = characters_wanted.data();
    for (int i = 0; i < length; ++i) {
        table[static_cast<unsigned char>(data[i])] = true;
    }
}

int StringPiece::find_first_of(StringPiece s, size_type pos) const {
    if (length_ <= 0 || s.length_ <= 0) {
        return npos;
    }
    // Avoid the cost of BuildLookupTable() for a single-character search.
    if (s.length_ == 1) return find_first_of(s.ptr_[0], pos);

    bool lookup[UCHAR_MAX + 1] = {false};
    BuildLookupTable(s, lookup);
    for (int i = pos; i < length_; ++i) {
        if (lookup[static_cast<unsigned char>(ptr_[i])]) {
            return i;
        }
    }
    return npos;
}

int StringPiece::find_first_not_of(StringPiece s, size_type pos) const {
    if (length_ <= 0) return npos;
    if (s.length_ <= 0) return 0;
    // Avoid the cost of BuildLookupTable() for a single-character search.
    if (s.length_ == 1) return find_first_not_of(s.ptr_[0], pos);

    bool lookup[UCHAR_MAX + 1] = {false};
    BuildLookupTable(s, lookup);
    for (int i = pos; i < length_; ++i) {
        if (!lookup[static_cast<unsigned char>(ptr_[i])]) {
            return i;
        }
    }
    return npos;
}

int StringPiece::find_first_not_of(char c, size_type pos) const {
    if (length_ <= 0) return npos;

    for (; pos < static_cast<size_type>(length_); ++pos) {
        if (ptr_[pos] != c) {
            return pos;
        }
    }
    return npos;
}

int StringPiece::find_last_of(StringPiece s, size_type pos) const {
    if (length_ <= 0 || s.length_ <= 0) return npos;
    // Avoid the cost of BuildLookupTable() for a single-character search.
    if (s.length_ == 1) return find_last_of(s.ptr_[0], pos);

    bool lookup[UCHAR_MAX + 1] = {false};
    BuildLookupTable(s, lookup);
    for (int i = min(pos, static_cast<size_type>(length_ - 1)); i >= 0; --i) {
        if (lookup[static_cast<unsigned char>(ptr_[i])]) {
            return i;
        }
    }
    return npos;
}

int StringPiece::find_last_not_of(StringPiece s, size_type pos) const {
    if (length_ <= 0) return npos;

    int i = min(pos, static_cast<size_type>(length_ - 1));
    if (s.length_ <= 0) return i;

    // Avoid the cost of BuildLookupTable() for a single-character search.
    if (s.length_ == 1) return find_last_not_of(s.ptr_[0], pos);

    bool lookup[UCHAR_MAX + 1] = {false};
    BuildLookupTable(s, lookup);
    for (; i >= 0; --i) {
        if (!lookup[static_cast<unsigned char>(ptr_[i])]) {
            return i;
        }
    }
    return npos;
}

int StringPiece::find_last_not_of(char c, size_type pos) const {
    if (length_ <= 0) return npos;

    for (int i = min(pos, static_cast<size_type>(length_ - 1)); i >= 0; --i) {
        if (ptr_[i] != c) {
            return i;
        }
    }
    return npos;
}

StringPiece StringPiece::substr(size_type pos, size_type n) const {
    if (pos > length_) pos = length_;
    if (n > length_ - pos) n = length_ - pos;
    return StringPiece(ptr_ + pos, n);
}

const StringPiece::size_type StringPiece::npos = size_type(-1);