#include "buffer.h"

#include "logging.h"

#include <stdlib.h>

#include <limits.h>

#include <string.h>

typedef struct _flib_vector {

	void *data;

	size_t size;

	size_t capacity;

} _flib_vector;

flib_vector flib_vector_create() {

	flib_vector result = malloc(sizeof(_flib_vector));

	if(result == NULL) {

		return NULL;

	}

	result->data = malloc(16);

	if(result->data == NULL) {

		free(result);

		return NULL;

	}

	result->size = 0;

	result->capacity = 16;

	return result;

}

void flib_vector_destroy(flib_vector *vec) {

	if(vec && *vec) {

		free((*vec)->data);

		free(*vec);

		*vec = NULL;

	}

}

static void try_realloc(flib_vector vec, size_t newCapacity) {

	void *newData = realloc(vec->data, newCapacity);

	if(newData) {

		vec->data = newData;

		vec->capacity = newCapacity;

	}

}

static size_t getFreeCapacity(flib_vector vec) {

	return vec->capacity - vec->size;

}

int flib_vector_append(flib_vector vec, const void *data, size_t len) {

	if(getFreeCapacity(vec) < len) {

		// Resize exponentially for constant amortized time,

		// But at least by as much as we need of course,

		// and be extra careful with integer overflows...

		size_t extraCapacity = (vec->capacity)/2;

		size_t minExtraCapacity = len - getFreeCapacity(vec);

		if(extraCapacity < minExtraCapacity) {

			extraCapacity = minExtraCapacity;

		}

		if(extraCapacity <= SIZE_MAX - vec->capacity) {

			try_realloc(vec, vec->capacity+extraCapacity);

		}

		// Check if we were able to resize.

		// If not, try to allocate at least what we need...

		if(getFreeCapacity(vec) < len) {

			try_realloc(vec, vec->capacity+minExtraCapacity);

			// Still not working? Then we fail.

			if(getFreeCapacity(vec) < len) {

				return 0;

			}

		}

	}

	memmove(vec->data + vec->size, data, len);

	vec->size += len;

	return len;

}

flib_buffer flib_vector_as_buffer(flib_vector vec) {

	flib_buffer result = {vec->data, vec->size};

	return result;

}

flib_constbuffer flib_vector_as_constbuffer(flib_vector vec) {

	flib_constbuffer result = {vec->data, vec->size};

	return result;

}