/* SDSLib 2.0 -- A C dynamic strings library
 *
 * Copyright (c) 2006-2015, Redis Ltd.
 * Copyright (c) 2015, Oran Agra
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef __SDS_H
#define __SDS_H

#define SDS_MAX_PREALLOC (1024 * 1024)
extern const char *SDS_NOINIT;

#include <sys/types.h>
#include <stdarg.h>
#include <stdint.h>
#include <limits.h>

/* Constness:
 *
 * - 'const sds' means 'char * const'. It is a const-pointer to non-const content.
 * - 'const_sds' means 'const char *'. It is a non-const pointer to const content.
 * - 'const const_sds' means 'const char * const', const pointer and content. */

typedef char *sds;
typedef const char *const_sds;

/* Note: sdshdr5 is never used, we just access the flags byte directly.
 * However is here to document the layout of type 5 SDS strings. */
struct __attribute__((__packed__)) sdshdr5 {
    unsigned char flags; /* 3 lsb of type, and 5 msb of string length */
    char buf[];
};
struct __attribute__((__packed__)) sdshdr8 {
    uint8_t len;         /* used */
    uint8_t alloc;       /* excluding the header and null terminator */
    unsigned char flags; /* 3 lsb of type, 5 unused bits */
    char buf[];
};
struct __attribute__((__packed__)) sdshdr16 {
    uint16_t len;        /* used */
    uint16_t alloc;      /* excluding the header and null terminator */
    unsigned char flags; /* 3 lsb of type, 5 unused bits */
    char buf[];
};
struct __attribute__((__packed__)) sdshdr32 {
    uint32_t len;        /* used */
    uint32_t alloc;      /* excluding the header and null terminator */
    unsigned char flags; /* 3 lsb of type, 5 unused bits */
    char buf[];
};
struct __attribute__((__packed__)) sdshdr64 {
    uint64_t len;        /* used */
    uint64_t alloc;      /* excluding the header and null terminator */
    unsigned char flags; /* 3 lsb of type, 5 unused bits */
    char buf[];
};

#define SDS_TYPE_5 0
#define SDS_TYPE_8 1
#define SDS_TYPE_16 2
#define SDS_TYPE_32 3
#define SDS_TYPE_64 4
#define SDS_TYPE_MASK 7
#define SDS_TYPE_BITS 3
#define SDS_HDR_VAR(T, s) struct sdshdr##T *sh = (struct sdshdr##T *)((s) - (sizeof(struct sdshdr##T)))
#define SDS_HDR(T, s) ((struct sdshdr##T *)((s) - (sizeof(struct sdshdr##T))))
#define SDS_TYPE_5_LEN(f) ((unsigned char)(f) >> SDS_TYPE_BITS)

static inline unsigned char sdsType(const_sds s) {
    unsigned char flags = s[-1];
    return flags & SDS_TYPE_MASK;
}

/* Returns a user data bit stored in the SDS header by sdsSetAuxBit. The bit
 * index is 0-4. Returns 0 or 1. Always returns 0 for SDS_TYPE_5. */
static inline int sdsGetAuxBit(const_sds s, int bit) {
    unsigned char flags = s[-1];
    return sdsType(s) == SDS_TYPE_5 ? 0 : (flags >> (SDS_TYPE_BITS + bit) & 1U);
}

/* Stores a bit in an unused area in the SDS header, except for SDS_TYPE_5. The
 * bit index is 0-4. The value is 0 or 1. The aux bits are lost if the SDS is
 * auto-resized. This is only for special uses like immutable SDS embedded in
 * other structures. */
static inline void sdsSetAuxBit(sds s, int bit, int value) {
    if (sdsType(s) == SDS_TYPE_5) return;
    unsigned char flags = s[-1];
    if (value) {
        flags |= 1 << (SDS_TYPE_BITS + bit);
    } else {
        flags &= ~(1 << (SDS_TYPE_BITS + bit));
    }
    s[-1] = (char)flags;
}

/* The maximum length of a string that can be stored with the given SDS type. */
static inline size_t sdsTypeMaxSize(char type) {
    if (type == SDS_TYPE_5) return (1 << 5) - 1;
    if (type == SDS_TYPE_8) return (1 << 8) - 1;
    if (type == SDS_TYPE_16) return (1 << 16) - 1;
#if (LONG_MAX == LLONG_MAX)
    if (type == SDS_TYPE_32) return (1ll << 32) - 1;
#endif
    return -1; /* this is equivalent to the max SDS_TYPE_64 or SDS_TYPE_32 */
}

static inline size_t sdslen(const_sds s) {
    switch (sdsType(s)) {
    case SDS_TYPE_5: return SDS_TYPE_5_LEN(s[-1]);
    case SDS_TYPE_8: return SDS_HDR(8, s)->len;
    case SDS_TYPE_16: return SDS_HDR(16, s)->len;
    case SDS_TYPE_32: return SDS_HDR(32, s)->len;
    case SDS_TYPE_64: return SDS_HDR(64, s)->len;
    }
    return 0;
}

static inline size_t sdsavail(const_sds s) {
    unsigned char flags = s[-1];
    switch (flags & SDS_TYPE_MASK) {
    case SDS_TYPE_5: {
        return 0;
    }
    case SDS_TYPE_8: {
        SDS_HDR_VAR(8, s);
        return sh->alloc - sh->len;
    }
    case SDS_TYPE_16: {
        SDS_HDR_VAR(16, s);
        return sh->alloc - sh->len;
    }
    case SDS_TYPE_32: {
        SDS_HDR_VAR(32, s);
        return sh->alloc - sh->len;
    }
    case SDS_TYPE_64: {
        SDS_HDR_VAR(64, s);
        return sh->alloc - sh->len;
    }
    }
    return 0;
}

static inline void sdssetlen(sds s, size_t newlen) {
    unsigned char flags = s[-1];
    switch (flags & SDS_TYPE_MASK) {
    case SDS_TYPE_5: {
        unsigned char *fp = ((unsigned char *)s) - 1;
        *fp = SDS_TYPE_5 | (newlen << SDS_TYPE_BITS);
    } break;
    case SDS_TYPE_8: SDS_HDR(8, s)->len = newlen; break;
    case SDS_TYPE_16: SDS_HDR(16, s)->len = newlen; break;
    case SDS_TYPE_32: SDS_HDR(32, s)->len = newlen; break;
    case SDS_TYPE_64: SDS_HDR(64, s)->len = newlen; break;
    }
}

static inline void sdsinclen(sds s, size_t inc) {
    unsigned char flags = s[-1];
    switch (flags & SDS_TYPE_MASK) {
    case SDS_TYPE_5: {
        unsigned char *fp = ((unsigned char *)s) - 1;
        unsigned char newlen = SDS_TYPE_5_LEN(flags) + inc;
        *fp = SDS_TYPE_5 | (newlen << SDS_TYPE_BITS);
    } break;
    case SDS_TYPE_8: SDS_HDR(8, s)->len += inc; break;
    case SDS_TYPE_16: SDS_HDR(16, s)->len += inc; break;
    case SDS_TYPE_32: SDS_HDR(32, s)->len += inc; break;
    case SDS_TYPE_64: SDS_HDR(64, s)->len += inc; break;
    }
}

/* sdsalloc() = sdsavail() + sdslen() */
static inline size_t sdsalloc(const_sds s) {
    unsigned char flags = s[-1];
    switch (flags & SDS_TYPE_MASK) {
    case SDS_TYPE_5: return SDS_TYPE_5_LEN(flags);
    case SDS_TYPE_8: return SDS_HDR(8, s)->alloc;
    case SDS_TYPE_16: return SDS_HDR(16, s)->alloc;
    case SDS_TYPE_32: return SDS_HDR(32, s)->alloc;
    case SDS_TYPE_64: return SDS_HDR(64, s)->alloc;
    }
    return 0;
}

static inline void sdssetalloc(sds s, size_t newlen) {
    unsigned char flags = s[-1];
    switch (flags & SDS_TYPE_MASK) {
    case SDS_TYPE_5:
        /* Nothing to do, this type has no total allocation info. */
        break;
    case SDS_TYPE_8: SDS_HDR(8, s)->alloc = newlen; break;
    case SDS_TYPE_16: SDS_HDR(16, s)->alloc = newlen; break;
    case SDS_TYPE_32: SDS_HDR(32, s)->alloc = newlen; break;
    case SDS_TYPE_64: SDS_HDR(64, s)->alloc = newlen; break;
    }
}

sds sdsnewlen(const void *init, size_t initlen);
sds sdstrynewlen(const void *init, size_t initlen);
sds sdsnew(const char *init);
sds sdsempty(void);
sds sdsdup(const_sds s);
sds sdswrite(char *buf, size_t bufsize, char type, const char *init, size_t initlen);
void sdsfree(sds s);
void sdsfreeVoid(void *s);
sds sdsgrowzero(sds s, size_t len);
sds sdscatlen(sds s, const void *t, size_t len);
sds sdscat(sds s, const char *t);
sds sdscatsds(sds s, const_sds t);
sds sdscpylen(sds s, const char *t, size_t len);
sds sdscpy(sds s, const char *t);

sds sdscatvprintf(sds s, const char *fmt, va_list ap);
#ifdef __GNUC__
sds sdscatprintf(sds s, const char *fmt, ...) __attribute__((format(printf, 2, 3)));
#else
sds sdscatprintf(sds s, const char *fmt, ...);
#endif

sds sdscatfmt(sds s, char const *fmt, ...);
sds sdstrim(sds s, const char *cset);
void sdssubstr(sds s, size_t start, size_t len);
void sdsrange(sds s, ssize_t start, ssize_t end);
void sdsupdatelen(sds s);
void sdsclear(sds s);
int sdscmp(const_sds s1, const_sds s2);
sds *sdssplitlen(const char *s, ssize_t len, const char *sep, int seplen, int *count);
void sdsfreesplitres(sds *tokens, int count);
void sdstolower(sds s);
void sdstoupper(sds s);
sds sdsfromlonglong(long long value);
sds sdscatrepr(sds s, const char *p, size_t len);
sds *sdssplitargs(const char *line, int *argc);
sds *sdsnsplitargs(const char *line, size_t len, int *argc);
sds sdsmapchars(sds s, const char *from, const char *to, size_t setlen);
sds sdsjoin(char **argv, int argc, char *sep);
sds sdsjoinsds(sds *argv, int argc, const char *sep, size_t seplen);
int sdsneedsrepr(const_sds s);

/* Callback for sdstemplate. The function gets called by sdstemplate
 * every time a variable needs to be expanded. The variable name is
 * provided as variable, and the callback is expected to return a
 * substitution value. Returning a NULL indicates an error.
 */
typedef sds (*sdstemplate_callback_t)(const_sds variable, void *arg);
sds sdstemplate(const char *sds_template, sdstemplate_callback_t cb_func, void *cb_arg);

/* Low level functions exposed to the user API */
int sdsHdrSize(char type);
char sdsReqType(size_t string_size);
sds sdsMakeRoomFor(sds s, size_t addlen);
sds sdsMakeRoomForNonGreedy(sds s, size_t addlen);
void sdsIncrLen(sds s, ssize_t incr);
sds sdsRemoveFreeSpace(sds s, int would_regrow);
sds sdsResize(sds s, size_t size, int would_regrow);
size_t sdsAllocSize(const_sds s);
void *sdsAllocPtr(const_sds s);

/* Returns the minimum required size to store an sds string of the given length
 * and type. */
static inline size_t sdsReqSize(size_t len, char type) {
    return len + sdsHdrSize(type) + 1;
}

/* Export the allocator used by SDS to the program using SDS.
 * Sometimes the program SDS is linked to, may use a different set of
 * allocators, but may want to allocate or free things that SDS will
 * respectively free or allocate. */
void *sds_malloc(size_t size);
void *sds_realloc(void *ptr, size_t size);
void sds_free(void *ptr);

#endif
