/**
 * @file shared.h
 * @author syxhe (https://t.me/syxhe)
 * @brief A collection of functions and macros shared between files, or without a better place
 * @version 0.1
 * @date 2025-06-09
 * 
 * @copyright Copyright (c) 2025
 * 
 */

#ifndef __VXGG_REWRITE___SHARED_H___3880294315821___
#define __VXGG_REWRITE___SHARED_H___3880294315821___ 1

#include <stddef.h>

typedef int (*gcallback)(void*);    //!< Generic callback signature
typedef void (*fcallback)(void*);   //!< free()-like callback signature

//! Get the size of a statically/vla defined array. Doesn't work on arrays allocated via `malloc()`
#define STATIC_ARRAY_LEN(arr) (sizeof((arr))/sizeof((arr)[0]))

//! Sets errno to `errval`, then returns `retval`. Defined as a macro because it is meant for use inside functions, not as a function itself
#define ERRRET(errval, retval) do {\
    errno = (errval);\
    return (retval);\
} while (0)

/// Defines how `x___alloc()` functions should exit. `___VXGG___XALLOC_EXIT_ON_ERROR___ > 0` calls `error()`, and thus functions
/// registered with `atexit()` and `on_exit()`. `___VXGG___XALLOC_EXIT_ON_ERROR___ <= 0` calls `abort()` on error. `x___alloc()` 
/// type functions will ALWAYS 'abort', doing otherwise defeats the purpose of the function type
#define ___VXGG___XALLOC_EXIT_ON_ERROR___ 1

/// Defines whether vxgg functions that can error print out a short warning of the error when one is encountered. 
/// `___VXGG___VERBOSE_ERRORS___ > 0` will print diagnostic error messages, and will do nothing otherwise
#define ___VXGG___VERBOSE_ERRORS___ 1

//! Macro to exit on an alloc error instead of doing the terrible nested if statement that was being used previously
#define XALLOC_EXIT(msg, ...) do {\
    if(!___VXGG___XALLOC_EXIT_ON_ERROR___)\
        abort();\
    if(!___VXGG___VERBOSE_ERRORS___)\
        exit(EXIT_FAILURE);\
    error(EXIT_FAILURE, errno, (msg)__VA_ARGS__);\
    exit(EXIT_FAILURE); /* Makes gcc happy */\
} while (0)


//! Holdover macro because I'm lazy. Used to call either malloc or xmalloc, but the xalloc functions were a bad idea, so I removed them
#define VALLOC(nmemb, size) malloc((nmemb) * (size))

//! Error macro that gcc will not complain about
#define ERROR(status, errnum, format, ...) do {error((status), (errnum), (format)__VA_ARGS__); exit((status));} while (0)
//! Spit out a warning using `error`
#define WARN(errnum, format, ...) do {error(0, (errnum), (format)__VA_ARGS__);} while (0)



/**
 * @brief Read the entire contents of a file descriptor into a malloc()'ed buffer
 * 
 * @param str Pointer to a string. Will be replaced with the malloc()'ed string
 * @param initsize The initial size of the malloc()'ed string
 * @param fd A file descriptor to read from
 * @return int Returns the size of the array on success, or -1 on error
 * @note The allocated buffer will expand and contract as necessary, but it's recommended to set `initsize` to some value close to or equal to the size of the file being read to reduce the number of resizes
 */
int rwbuf(char **str, unsigned long int initsize, int fd);

/**
 * @brief Write the entire contents of a buffer into a file descriptor
 * 
 * @param fd The file descriptor to write to
 * @param buf The buffer to write from
 * @param len The length of the buffer
 * @return int Returns 0 on success, -1 on error
 */
int wwbuf(int fd, const unsigned char *buf, int len);



/**
 * @brief `dirname()` reimplementation that returns a malloc()'ed string
 * 
 * @param path The filepath to be inspected
 * @return char* Returns a null-terminated string on success, or `null` on error
 */
char * vxdirname(const char * const path);



/**
 * @brief A locally defined structure designed for easier function cleanup
 * 
 */
typedef struct cl {
    fcallback *callbacks;   //!< An array of free()-like callbacks. Actual Type: fcallback callbacks[]
    void * *arguments;      //!< An array of void pointers. Actual Type: void *arguments[]
    int size;               //!< The size of each array
    int used;               //!< The current number of used elements in each array
} cleanup;

/**
 * @brief Initialize a cleanup object
 * 
 * @param loc The cleanup object to be initialized
 * @param callbacks An array of free()-like callbacks. Must be `size` elements long
 * @param arguments An array of void pointers. Must be `size` elements long
 * @param size The number of elements the callbacks and arguments array are long
 * @return int Returns 0 on success, -1 on error
 */
int cleanup_init(cleanup *loc, fcallback callbacks[], void *arguments[], int size);

/**
 * @brief Register a new callback and argument onto a cleanup stack
 * 
 * @param loc The cleanup object to modify
 * @param cb A free()-like callback to run
 * @param arg A piece of data for the callback to run
 * @return int Returns 0 on success, -1 on error
 */
int cleanup_register(cleanup *loc, fcallback cb, void *arg);

/**
 * @brief Conditionally register a callback and argument
 * 
 * @param loc The cleanup object to modify
 * @param cb A free()-like callback to run
 * @param arg A piece of data for the callback to run
 * @param flag Whether or not the register should take place. Will not run if `flag` is non-zero
 * @return int Returns 0 on success or skip, -1 on error
 */
int cleanup_cndregister(cleanup *loc, fcallback cb, void *arg, unsigned char flag);

/**
 * @brief Clear a cleanup object
 * @attention Does not free any registered callbacks or arguments, just marks them as available space
 * 
 * @param loc The cleanup object to modify
 * @return int Returns 0 on success, -1 on error
 */
int cleanup_clear(cleanup *loc);

/**
 * @brief Fires all the registered callbacks and arguments in a cleanup object in FIFO (stack) order
 * 
 * @param loc The cleanup object to fire
 * @return int Returns 0 on success, -1 on error
 */
int cleanup_fire(cleanup *loc);

/**
 * @brief Conditionally fires a cleanup object
 * 
 * @param loc The cleanup object in question
 * @param flag Whether the object should be fired. Will skip firing if non-zero
 * @return int Returns 0 on success, -1 on error
 */
int cleanup_cndfire(cleanup *loc, unsigned char flag);

/**
 * @brief Initializes a set of variables suitable for use in the cleanup macros
 * @param size The number of elements long each array should be
 */
#define cleanup_CREATE(size) \
cleanup __CLEANUP; \
fcallback __CLEANUP_FUNCS[(size)]; \
void *__CLEANUP_ARGS[(size)]; \
unsigned char __FLAG = 0; \
cleanup_init(&__CLEANUP, __CLEANUP_FUNCS, __CLEANUP_ARGS, (size))

//! Register a callback-argument pair using the local cleanup object
#define cleanup_REGISTER(cb, arg)       cleanup_register(&__CLEANUP, (cb), (arg))
//! Conditionally register a callback-argument pair using the local cleanup object
#define cleanup_CNDREGISTER(cb, arg)    cleanup_cndregister(&__CLEANUP, (cb), (arg), __FLAG)
//! Clean the local cleanup object
#define cleanup_CLEAR()                 cleanup_clear(&__CLEANUP)
//! Fire the local cleanup object
#define cleanup_FIRE()                  cleanup_fire(&__CLEANUP)
//! Conditionally fire the local cleanup object
#define cleanup_CNDFIRE()               cleanup_cndfire(&__CLEANUP, __FLAG)
//! Set the local cleanup flag to a non-zero number
#define cleanup_MARK()                  (__FLAG = 1)
//! Set the local cleanup flag to zero
#define cleanup_UNMARK()                (__FLAG = 0)
//! Check if the local cleanup flag is non-zero
#define cleanup_ERRORFLAGGED            (__FLAG != 0)
//! Conditionally execute some `code` if the local cleanup flag has not been marked
#define cleanup_CNDEXEC(code)           while(!cleanup_ERRORFLAGGED) {code; break;}

#endif