/* SDSLib 2.0 -- A C dynamic strings library
 *
 * Copyright (c) 2006-Present, Redis Ltd.
 * All rights reserved.
 * 
 * Copyright (c) 2024-present, Valkey contributors.
 * All rights reserved. 
 *
 * Licensed under your choice of (a) the Redis Source Available License 2.0
 * (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
 * GNU Affero General Public License v3 (AGPLv3).
 */

#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>

typedef char *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 = (void*)((s)-(sizeof(struct sdshdr##T)));
#define SDS_HDR(T,s) ((struct sdshdr##T *)((s)-(sizeof(struct sdshdr##T))))
#define SDS_TYPE_5_LEN(s) (((unsigned char)(s[-1])) >> SDS_TYPE_BITS)

static inline unsigned char sdsType(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(sds s, int bit) {
    if (sdsType(s) == SDS_TYPE_5) 
        return 0;
    
    unsigned char flags = s[-1];
    return (flags & (1U << (SDS_TYPE_BITS + bit))) != 0U;
}

/* 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 |= 1U << (SDS_TYPE_BITS + bit);
    } else {
        flags &= ~(1U << (SDS_TYPE_BITS + bit));
    }
    s[-1] = (char)flags;
}

static inline size_t sdslen(const sds s) {
    switch (sdsType(s)) {
        case SDS_TYPE_5: return SDS_TYPE_5_LEN(s);
        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) {
    switch(sdsType(s)) {
        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) {
    switch(sdsType(s)) {
        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) {
    switch(sdsType(s)) {
        case SDS_TYPE_5:
            {
                unsigned char *fp = ((unsigned char*)s)-1;
                unsigned char newlen = SDS_TYPE_5_LEN(s)+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;
    }
}

/* Return the total size of the allocation of the specified sds string,
 * including:
 * 1) The sds header before the pointer.
 * 2) The string.
 * 3) The free buffer at the end if any.
 * 4) The implicit null term.
 */
static inline size_t sdsAllocSize(sds s) {
    switch(sdsType(s)) {
        case SDS_TYPE_5:
            return sizeof(struct sdshdr5) + SDS_TYPE_5_LEN(s) + 1;
        case SDS_TYPE_8:
            return sizeof(struct sdshdr8) + SDS_HDR(8,s)->alloc + 1;
        case SDS_TYPE_16:
            return sizeof(struct sdshdr16) + SDS_HDR(16,s)->alloc + 1;
        case SDS_TYPE_32:
            return sizeof(struct sdshdr32) + SDS_HDR(32,s)->alloc + 1;
        case SDS_TYPE_64:
            return sizeof(struct sdshdr64) + SDS_HDR(64,s)->alloc + 1;
    }
    return 0;
}

/* sdsalloc() = sdsavail() + sdslen() */
static inline size_t sdsalloc(const sds s) {
    switch(sdsType(s)) {
        case SDS_TYPE_5:
            return SDS_TYPE_5_LEN(s);
        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) {
    switch(sdsType(s)) {
        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;
    }
}

static inline int sdsHdrSize(char type) {
    switch(type&SDS_TYPE_MASK) {
        case SDS_TYPE_5:
            return sizeof(struct sdshdr5);
        case SDS_TYPE_8:
            return sizeof(struct sdshdr8);
        case SDS_TYPE_16:
            return sizeof(struct sdshdr16);
        case SDS_TYPE_32:
            return sizeof(struct sdshdr32);
        case SDS_TYPE_64:
            return sizeof(struct sdshdr64);
    }
    return 0;
}

sds sdsnewlen(const void *init, size_t initlen);
sds sdstrynewlen(const void *init, size_t initlen);
sds sdsnew(const char *init);
sds sdsnewplacement(char *buf, size_t bufsize, char type, const char *init, size_t initlen);

sds sdsempty(void);
sds sdsdup(const sds s);
void sdsfree(sds s);
void sdsfreegeneric(void *s);
void sdsfreeusable(sds s, size_t *usable);
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 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 *template, sdstemplate_callback_t cb_func, void *cb_arg);

/* Low level functions exposed to the user API */
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);
void *sdsAllocPtr(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);

#ifdef REDIS_TEST
int sdsTest(int argc, char *argv[], int flags);
#endif

#endif