#ifndef UC_DSTR_H_
#define UC_DSTR_H_

#include <stddef.h>
#include <stdarg.h>

#ifdef __cplusplus
extern "C" {
#endif

/**@file 
 * A managed C-string, using dynamically allocated memory for the string.
 *
 * The .str member might not always be nul terminated, and should not be 
 * accessed directly. Instead use uc_dstr_str() to retreive the managed string
 * which will always ensure the string is nul terminated
 *
 * Normally, let the DSTR manage the nul terminator as manually adding 
 * a nul byte and potintially adding more data to the DStr would append 
 * it after that nul terminator.
 */

/** Dynamic string struct. The user is responsible for managing
 * the struct Dstr memory, and the uc_dstr_ functions will manage
 * the memory held in .str.
 */
struct DStr {
    /** Length of the managed string.*/
    size_t len;

    //internal fields:
    size_t allocated;
    char *str;
};

#define UC_DSTR_INITIALIZER {0, 0, NULL}

/** Initialize a DStr.
 * Note that str->str will be NULL after initialization.
 * (However uc_dstr_str() will return a valid (empty) string.
 *
 */
void uc_dstr_init(struct DStr *str);

/** Initialize a DStr from an existing string
 *
 *  @return 0 on success (!= 0 if an allocation fail)
 */
int uc_dstr_init_str(struct DStr *str, const char *init);

/** Initialize a DStr from an existing string with a given length
 *
 *  @return 0 on success (!= 0 if an allocation fail)
 */
int uc_dstr_init_str_sz(struct DStr *str, const char *init, size_t len);

/** Destroy/free the string. 
 * (Frees str->str, not str itself)
 */
void uc_dstr_destroy(struct DStr *str);

/** Copy a DStr.
 *  The @dest string should not be an initialized string since it will be 
 *  initialized by uc_dstr_copy, and would cause a memory leak if it's already
 *  initialized.
 * 
 * @param dest destination string to copy to, must not contain an existing string
 * @param src DStr to copy
 *
 * @return 0 if success, != 0 if allocation fails
 */
int uc_dstr_copy(struct DStr *restrict dest, const struct DStr *restrict src);

/**
 * @return the available/unused tail bytes in the string.
 */
size_t uc_dstr_available(const struct DStr *str);

/** Ensure the DStr have room for least 'len' bytes,
 *  allocating room if needed. 
 *
 *  This includes the length of the existing string,
 *  to ensure e.g an additional 10 bytes can be appended,
 *  one would do uc_dstr_ensure(str, str->len + 10)
 *
 *  @return 0 on success (!= 0 if an allocation fail)
 */
int uc_dstr_ensure(struct DStr *str, size_t total);

/** Reset the DStr, setting its length to 0
 */
void uc_dstr_reset(struct DStr *str);

/** nul terminate the DStr */
void uc_dstr_terminate(struct DStr *str);

/** Retreive the managed string, the returned string
 * is always nul terminated. The DStr will still be managing
 * the returned char *.
 */
char *uc_dstr_str(struct DStr *str);

/** Reserve len bytes for appending to the dstr
 *  you must copy characters to all bytes in the [0-len) range of
 *  the returned pointer.
 *
 * @param len bytes to reseve
 * @return poiinter to the start of the data to append
 */
char *uc_dstr_put(struct DStr *str, size_t len);

/** Append a string, filtering out characters.
 * e.g. pass in the ctype.h isdigit as the is_x function
 * to append only the digits in the supplied string.
 *
 * @param s string to append
 * @param is_x ctype.h compatible function to use as a filter.
 * @return number of chars appended
 */
size_t uc_dstr_append_str_filter(struct DStr *str, const char *restrict s, int (*is_x)(int c));

/* Append a string of the give size.
 * (The nul terminator is not appended) 
 * 
 * @param s string to append
 * @param len bytes to append (not including the nul terminator) 
 * @return 0 on success (!= 0 if an allocation fail)
 */
int uc_dstr_append_str_sz(struct DStr *str, const char *restrict s, size_t len);

/* Append a string.
 * (The nul terminator is not appended) 
 *
 *  @return 0 on success (!= 0 if an allocation fail)
 */
int uc_dstr_append_str(struct DStr *str, const char *restrict s);

/* Append a single char.
 *
 *  @return 0 on success (!= 0 if an allocation fail)
 */
int uc_dstr_append_char(struct DStr *str, char c);

/* Make the DStr take ownership of the given dynamically allocated string.
 * Any existing string in the DStr is freed.
 */
void uc_dstr_own(struct DStr *str, char *restrict s);

/** Release the managed string.
 * The caller is now responsible for managing/free'ing the returned string.
 * The DStr is considered empty afterwards.
 *
 * @return The dynamically allocated string that was managed.
 */
char *uc_dstr_steal(struct DStr *str);

/** Swap the A and B DStr */
void uc_str_swap(struct DStr *restrict a, struct DStr *restrict b);

/** Replace all occurences in the DStr
 * (This may be used to replace any embedded nul bytes too)
 *
 * @param f char to find
 * @param r char to replace with
 */
size_t uc_dstr_replace(struct DStr *str, char f, char r);

/** Remove leading and trailing spaces in the DStr
 * Spaces are the ascii ones: " \t\r\v\t\n"
 */
void uc_dstr_trim(struct DStr *str);

/** Append formatted string (just as sprintf)*/
int uc_dstr_sprintf(struct DStr *str, const char *restrict fmt, ...) __attribute__((format(printf,2,3)));

/** va_list variant */
int uc_dstr_vsprintf(struct DStr *str, const char *restrict fmt, va_list ap_)__attribute__((format(printf,2,0)));

#ifdef __cplusplus
}
#endif

#endif