#include "circle-buffer.h"

#include <stddef.h>	
#include <stdlib.h>

void CircleBufferInit(struct CircleBuffer* buffer, unsigned capacity) {
	buffer->data = malloc(capacity);
	buffer->capacity = capacity;
	buffer->size = 0;
	buffer->readPtr = buffer->data;
	buffer->writePtr = buffer->data;
}

void CircleBufferDeinit(struct CircleBuffer* buffer) {
	free(buffer->data);
	buffer->data = 0;
}

unsigned CircleBufferSize(const struct CircleBuffer* buffer) {
	return buffer->size;
}

int CircleBufferWrite8(struct CircleBuffer* buffer, int8_t value) {
	int8_t* data = buffer->writePtr;
	if (buffer->size + sizeof(int8_t) > buffer->capacity) {
		return 0;
	}
	*data = value;
	++data;
	size_t size = (int8_t*) data - (int8_t*) buffer->data;
	if (size < buffer->capacity) {
		buffer->writePtr = data;
	} else {
		buffer->writePtr = buffer->data;
	}
	buffer->size += sizeof(int8_t);
	return 1;
}

int CircleBufferWrite32(struct CircleBuffer* buffer, int32_t value) {
	int32_t* data = buffer->writePtr;
	if (buffer->size + sizeof(int32_t) > buffer->capacity) {
		return 0;
	}
	*data = value;
	++data;
	size_t size = (int8_t*) data - (int8_t*) buffer->data;
	if (size < buffer->capacity) {
		buffer->writePtr = data;
	} else {
		buffer->writePtr = buffer->data;
	}
	buffer->size += sizeof(int32_t);
	return 1;
}

int CircleBufferRead8(struct CircleBuffer* buffer, int8_t* value) {
	int8_t* data = buffer->readPtr;
	if (buffer->size < sizeof(int8_t)) {
		return 0;
	}
	*value = *data;
	++data;
	size_t size = (int8_t*) data - (int8_t*) buffer->data;
	if (size < buffer->capacity) {
		buffer->readPtr = data;
	} else {
		buffer->readPtr = buffer->data;
	}
	buffer->size -= sizeof(int8_t);
	return 1;
}

int CircleBufferRead32(struct CircleBuffer* buffer, int32_t* value) {
	int32_t* data = buffer->readPtr;
	if (buffer->size < sizeof(int32_t)) {
		return 0;
	}
	*value = *data;
	++data;
	size_t size = (int8_t*) data - (int8_t*) buffer->data;
	if (size < buffer->capacity) {
		buffer->readPtr = data;
	} else {
		buffer->readPtr = buffer->data;
	}
	buffer->size -= sizeof(int32_t);
	return 1;
}

int CircleBufferRead(struct CircleBuffer* buffer, void* output, size_t length) {
	int8_t* data = buffer->readPtr;
	if (buffer->size == 0) {
		return 0;
	}
	if (length > buffer->size) {
		length = buffer->size;
	}
	size_t remaining = buffer->capacity - ((int8_t*) data - (int8_t*) buffer->data);
	if (length <= remaining) {
		memcpy(output, data, length);
		if (length == remaining) {
			buffer->readPtr = buffer->data;
		} else {
			buffer->readPtr = (int8_t*) data + length;
		}
	} else {
		memcpy(output, data, remaining);
		memcpy((int8_t*) output + remaining, buffer->data, length - remaining);
		buffer->readPtr = (int8_t*) buffer->data + length - remaining;
	}

	buffer->size -= length;
	return length;
}