#include <blue/core/ringbuffer.h>
#include <stdlib.h>
#include <string.h>

#define BUF_LOCKED(buf)                                                            \
	(((buf)->r_flags & (B_RINGBUFFER_READ_LOCKED | B_RINGBUFFER_WRITE_LOCKED)) \
	 != 0)

struct b_ringbuffer *b_ringbuffer_create(size_t capacity)
{
	struct b_ringbuffer *buf = malloc(sizeof *buf);
	if (!buf) {
		return NULL;
	}

	void *p = malloc(capacity);
	if (!p) {
		free(buf);
		return NULL;
	}

	memset(buf, 0x0, sizeof *buf);

	buf->r_flags = B_RINGBUFFER_SELF_MALLOC | B_RINGBUFFER_BUFFER_MALLOC;
	buf->r_buf = p;
	buf->r_capacity = capacity;

	return buf;
}

struct b_ringbuffer *b_ringbuffer_create_with_buffer(void *ptr, size_t capacity)
{
	struct b_ringbuffer *buf = malloc(sizeof *buf);
	if (!buf) {
		return NULL;
	}

	memset(buf, 0x0, sizeof *buf);

	buf->r_flags = B_RINGBUFFER_SELF_MALLOC;
	buf->r_buf = ptr;
	buf->r_capacity = capacity;

	return buf;
}

enum b_status b_ringbuffer_init(struct b_ringbuffer *buf, size_t capacity)
{
	void *p = malloc(capacity);
	if (!p) {
		free(buf);
		return B_ERR_NO_MEMORY;
	}

	memset(buf, 0x0, sizeof *buf);

	buf->r_flags = B_RINGBUFFER_BUFFER_MALLOC;
	buf->r_buf = p;
	buf->r_capacity = capacity;

	return B_SUCCESS;
}

enum b_status b_ringbuffer_init_with_buffer(
	struct b_ringbuffer *buf, void *ptr, size_t capacity)
{
	memset(buf, 0x0, sizeof *buf);

	buf->r_flags = 0;
	buf->r_buf = ptr;
	buf->r_capacity = capacity;

	return B_SUCCESS;
}

enum b_status b_ringbuffer_reset(struct b_ringbuffer *buf)
{
	if (BUF_LOCKED(buf)) {
		return B_ERR_BUSY;
	}

	buf->r_read_ptr = buf->r_write_ptr = 0;

	return B_SUCCESS;
}

enum b_status b_ringbuffer_destroy(struct b_ringbuffer *buf)
{
	if (BUF_LOCKED(buf)) {
		return B_ERR_BUSY;
	}

	if (buf->r_flags & B_RINGBUFFER_BUFFER_MALLOC) {
		free(buf->r_buf);
	}

	if (buf->r_flags & B_RINGBUFFER_SELF_MALLOC) {
		free(buf);
	}

	return B_SUCCESS;
}

enum b_status b_ringbuffer_read(
	struct b_ringbuffer *buf, void *p, size_t count, size_t *nr_read)
{
	if (BUF_LOCKED(buf)) {
		return B_ERR_BUSY;
	}

	size_t r = 0;
	unsigned char *dest = p;
	size_t remaining = count;

	while (remaining > 0) {
		void *src;
		size_t available;
		enum b_status status
			= b_ringbuffer_open_read_buffer(buf, &src, &available);

		if (status == B_ERR_NO_DATA) {
			break;
		}

		if (!B_OK(status)) {
			return status;
		}

		size_t to_copy = remaining;
		if (to_copy > available) {
			to_copy = available;
		}

		memcpy(dest, src, to_copy);

		remaining -= to_copy;
		dest += to_copy;
		r += to_copy;

		b_ringbuffer_close_read_buffer(buf, &src, to_copy);
	}

	*nr_read = r;
	return B_SUCCESS;
}

enum b_status b_ringbuffer_write(
	struct b_ringbuffer *buf, const void *p, size_t count, size_t *nr_written)
{
	if (BUF_LOCKED(buf)) {
		return B_ERR_BUSY;
	}

	size_t w = 0;
	const unsigned char *src = p;
	size_t remaining = count;

	while (remaining > 0) {
		void *dest;
		size_t available;
		enum b_status status
			= b_ringbuffer_open_write_buffer(buf, &dest, &available);

		if (status == B_ERR_NO_SPACE) {
			break;
		}

		if (!B_OK(status)) {
			return status;
		}

		size_t to_copy = remaining;
		if (to_copy > available) {
			to_copy = available;
		}

		memcpy(dest, src, to_copy);

		remaining -= to_copy;
		src += to_copy;
		w += to_copy;

		b_ringbuffer_close_write_buffer(buf, &dest, to_copy);
	}

	*nr_written = w;
	return B_SUCCESS;
}

int b_ringbuffer_getc(struct b_ringbuffer *buf)
{
	size_t available = b_ringbuffer_available_data_remaining(buf);
	if (available == 0) {
		return -1;
	}

	char *p = buf->r_buf;
	char c = p[buf->r_read_ptr++];

	if (buf->r_read_ptr >= buf->r_capacity) {
		buf->r_read_ptr = 0;
	}

	return c;
}

enum b_status b_ringbuffer_putc(struct b_ringbuffer *buf, int c)
{
	size_t available = b_ringbuffer_write_capacity_remaining(buf);
	if (available == 0) {
		return B_ERR_NO_SPACE;
	}

	char *p = buf->r_buf;
	p[buf->r_write_ptr++] = c;

	if (buf->r_write_ptr >= buf->r_capacity) {
		buf->r_write_ptr = 0;
	}

	return c;
}

size_t b_ringbuffer_write_capacity_remaining(const struct b_ringbuffer *buf)
{
	if (buf->r_read_ptr > buf->r_write_ptr) {
		return buf->r_read_ptr - buf->r_write_ptr - 1;
	} else {
		return buf->r_capacity - buf->r_write_ptr + buf->r_read_ptr - 1;
	}
}

size_t b_ringbuffer_available_data_remaining(const struct b_ringbuffer *buf)
{
	if (buf->r_read_ptr < buf->r_write_ptr) {
		return buf->r_write_ptr - buf->r_read_ptr;
	} else if (buf->r_read_ptr > buf->r_write_ptr) {
		return buf->r_capacity - buf->r_read_ptr + buf->r_write_ptr;
	} else {
		return 0;
	}
}

enum b_status b_ringbuffer_open_read_buffer(
	struct b_ringbuffer *buf, void **ptr, size_t *length)
{
	if (BUF_LOCKED(buf)) {
		return B_ERR_BUSY;
	}

	size_t contiguous_capacity = 0;
	if (buf->r_read_ptr > buf->r_write_ptr) {
		contiguous_capacity = buf->r_capacity - buf->r_read_ptr;
	} else {
		contiguous_capacity = buf->r_write_ptr - buf->r_read_ptr;
	}

	if (contiguous_capacity == 0) {
		return B_ERR_NO_DATA;
	}

	buf->r_opened_buf = (char *)buf->r_buf + buf->r_read_ptr;
	buf->r_opened_capacity = contiguous_capacity;

	buf->r_flags |= B_RINGBUFFER_READ_LOCKED;
	*ptr = buf->r_opened_buf;
	*length = contiguous_capacity;

	return B_SUCCESS;
}

enum b_status b_ringbuffer_close_read_buffer(
	struct b_ringbuffer *buf, void **ptr, size_t nr_read)
{
	if (!(buf->r_flags & B_RINGBUFFER_READ_LOCKED)) {
		return B_ERR_BAD_STATE;
	}

	if (*ptr != buf->r_opened_buf) {
		return B_ERR_INVALID_ARGUMENT;
	}

	if (nr_read > buf->r_opened_capacity) {
		return B_ERR_INVALID_ARGUMENT;
	}

	buf->r_read_ptr += nr_read;
	if (buf->r_read_ptr >= buf->r_capacity) {
		buf->r_read_ptr = 0;
	}

	buf->r_opened_buf = NULL;
	buf->r_opened_capacity = 0;
	buf->r_flags &= ~B_RINGBUFFER_READ_LOCKED;

	return B_SUCCESS;
}

enum b_status b_ringbuffer_open_write_buffer(
	struct b_ringbuffer *buf, void **ptr, size_t *capacity)
{
	if (BUF_LOCKED(buf)) {
		return B_ERR_BUSY;
	}

	size_t contiguous_capacity = 0;
	if (buf->r_write_ptr >= buf->r_read_ptr) {
		contiguous_capacity = buf->r_capacity - buf->r_write_ptr - 1;

		if (buf->r_read_ptr > 0) {
			contiguous_capacity++;
		}
	} else {
		contiguous_capacity = buf->r_read_ptr - buf->r_write_ptr - 1;
	}

	if (contiguous_capacity == 0) {
		return B_ERR_NO_SPACE;
	}

	buf->r_opened_buf = (char *)buf->r_buf + buf->r_write_ptr;
	buf->r_opened_capacity = contiguous_capacity;

	buf->r_flags |= B_RINGBUFFER_WRITE_LOCKED;
	*ptr = buf->r_opened_buf;
	*capacity = contiguous_capacity;

	return B_SUCCESS;
}

enum b_status b_ringbuffer_close_write_buffer(
	struct b_ringbuffer *buf, void **ptr, size_t nr_written)
{
	if (!(buf->r_flags & B_RINGBUFFER_WRITE_LOCKED)) {
		return B_ERR_BAD_STATE;
	}

	if (*ptr != buf->r_opened_buf) {
		return B_ERR_INVALID_ARGUMENT;
	}

	if (nr_written > buf->r_opened_capacity) {
		return B_ERR_INVALID_ARGUMENT;
	}

	buf->r_write_ptr += nr_written;
	if (buf->r_write_ptr >= buf->r_capacity) {
		buf->r_write_ptr = 0;
	}

	buf->r_opened_buf = NULL;
	buf->r_opened_capacity = 0;
	buf->r_flags &= ~B_RINGBUFFER_WRITE_LOCKED;

	return B_SUCCESS;
}