#include "cstr.h"

/** DOC
 * @type function
 * @name string_length
 *
 * @param  char *str
 * @return u64
 *
 * @description
 * Computes the length of an `ASCII` cstr.
 */
u64 cstr_length(const char *str)
{
	const char *p = str;
	while (*p) ++p;
	return p - str;
}


/** DOC
 * @type function
 * @name cstr_compare
 *
 * @param  const char *a
 * @param  const char *b
 * @return u8
 *
 * @description
 * Compares two strings.
 * Returns 1 if a has a higher alphabethical value.
 * Returns -1 if a has a lower alphabethical value.
 * Returns 0 if strings are equal.
 */
i8 cstr_compare(const char *a, const char *b)
{
	while (*a && *b) {
		if (*a < *b)
			return -1;
		if (*a > *b)
			return 1;

		++a;
		++b;
	}

	if (*a < *b)
		return -1;
	if (*a > *b)
		return 1;

	return 0;
}


/** DOC
 * @type function
 * @name cstr_split
 *
 * @param  char *cstr
 * @param  char split
 * @return u64
 *
 * @description
 * Splits a string on every `split` char.
 * Returns the number of splits.
 * ``WARNING`` This function does replace all `split` char with `0`.
 *             The old string does not exist after calling this function.
 */
u64 cstr_split(char *cstr, char split)
{
	u64 splits = 1;

	while (*cstr) {
		if (*cstr == split) {
			*cstr = 0;
			++splits;
		}

		++cstr;
	}

	return splits;
}

/** DOC
 * @type function
 * @name cstr_split
 *
 * @param  char *cstr
 * @param  char split
 * @return u64
 *
 * @description
 * Splits a string on every `split` char.
 * Returns the number of splits.
 * ``WARNING`` This function does replace all `split` char with `0`.
 *             The old string does not exist after calling this function.
 */
u64 cstr_split_with_cancel(char *cstr, char split, char cancel)
{
	u64 splits = 1;
	u8 is_in_cancel = 0;

	while (*cstr) {
		if (*cstr == cancel) {
			is_in_cancel = !is_in_cancel;
		}

		if (*cstr == split && !is_in_cancel) {
			*cstr = 0;
			++splits;
		}

		++cstr;
	}

	return splits;
}


/** DOC
 * @type function
 * @name next_split
 * 
 * @param  const char *previous;
 * @return const char*
 *
 * @description
 * Returns the next split of a `split list` created by `cstr_split`.
 */
const char *next_split(const char *previous)
{
	while (*previous) ++previous;
	return previous + 1;
}


/** DOC
 * @type function
 * @name strip_front
 *
 * @param  char *cstr
 * @param  char strip
 * @return u64
 *
 * @description
 * Remove `strip` from front.
 */
u64 strip_front(char *cstr, char strip)
{
	char *front = cstr;

	while (*front && *front == strip) ++front;

	while (*front) {
		*cstr = *front;
		++cstr;
		++front;
	}

	while (*cstr) {
		*cstr = 0;
		++cstr;
	}

	return front - cstr;
}


/** DOC
 * @type function
 * @name strip_back
 *
 * @param  char *cstr
 * @param  char stip
 * @return u64
 *
 * @description
 * Removes `strip` char from back of the cstr.
 */
u64 strip_back(char *cstr, char strip)
{
	u64 diff = 0;

	while (*cstr) ++cstr;
	--cstr;

	while (*cstr == strip) {
		*cstr = 0;
		++diff;
	}

	return diff;
}

/** DOC
 * @type function
 * @name strip_cstr
 *
 * @param  char *cstr
 * @param  char strip
 * @return u64
 *
 * @description
 * Strips `strip` char from start and end of the string.
 */
u64 strip_cstr(char *cstr, char strip)
{
	return strip_front(cstr, strip) + strip_back(cstr, strip);
}


u64 number_of_lines(const char *cstr)
{
	u64 lines = 0;

	while (*cstr) {
		if (*cstr == '\n') ++lines;
		++cstr;
	}

	return lines;
}


substr_t getline(const char *cstr, u64 n)
{
	substr_t line;
	line.begin = (char *)cstr;
	line.end = line.begin;

	while (*line.end && *line.end != '\n') ++line.end;

	for (int i = 0; i < n; ++i)
		line = nextline(line);

	return line;
}


substr_t nextline(substr_t line)
{
	if (!(*line.end || *(line.end + 1))) {
		line.begin = 0;
		line.end = 0;
		return line;
	}

	line.begin = ++line.end;

	while (*line.end && *line.end != '\n') ++line.end;

	return line;
}

/* DOC
 * @type function
 * @name string_utf8_length
 *
 * @param  char *str
 * @return u64
 *
 * @description
 * Computes the length of a `UTF-8` cstr.
 */
u64 cstr_utf8_length(const char * str)
{
	const char *p = str;
	u64 length = 0;
	int a = 0;

	while (*p) {
		next_utf8(&p);
		++length;
	}

	return length;
}


/** DOC
 * @type function
 * @name next_utf8
 *
 * @param  char **c
 * @return u8
 *
 * @description
 * Set `c` to the next `UTF-8` char.
 * Returns the difference relative to `ASCII` chars.
 */
u8 next_utf8(const char **c)
{
	int a;

	switch (**c & 0xf0) {
		case 0xf0: a = 4; break;
		case 0xe0: a = 3; break;
		case 0xc0: a = 2; break;
		default:   a = 1; break;
	}

	*c += a;
	return a;
}

/** DOC
 * @type function
 * @name previous_utf8
 *
 * @param  char **c
 * @return u8
 *
 * @description
 * Set `c` to the previous `UTF-8` char.
 * Returns the difference relative to `ASCII` chars.
 */
u8 previous_utf8(const char **c)
{
	int a = 1;
	--(*c);

	while ((**c & 0xc0) == 0x80) {
		--(*c);
		++a;
	}

	return a;
}

/** DOC
 * @type function
 * @name u64_to_cstr
 *
 * @param u64  n
 * @param char *cstr
 * @param u64  length
 *
 * @description
 * Writes the string representation of `n` to the `cstr`.
 */
void u64_to_cstr(u64 n, char *cstr, u64 length)
{
	char *p = cstr + length - 1;
	u64 d = 0;
	int i = 0;

	for (;n && i < length; ++i) {
		*(p--) = (n % 10) + '0';
		n /= 10;
	}

	if (p == cstr + length - 1) {
		*(p--) = '0';
	}

	*p = 0;

	d = p - cstr + 1;

	for (i = 0; i < length - d; ++i)
		cstr[i] = cstr[i + d];
}

/** DOC
 * @type function
 * @name i64_to_cstr
 *
 * @param i64  n
 * @param char *cstr
 * @param u64  length
 *
 * @description
 * Writes the string representation of `n` to the `cstr`.
 */
void i64_to_cstr(i64 n, char *cstr, u64 length)
{
	if (n < 0) {
		*cstr = '-';
		n = -n;
		u64_to_cstr((u64)n, cstr + 1, length - 1);
	} else {
		u64_to_cstr((u64)n, cstr, length);
	}
}

/** DOC
 * @type function
 * @name cstr_to_u64
 *
 * @param  const char *cstr
 * @return u64
 *
 * @description
 * Parses an `u64` to cstr.
 */
u64 cstr_to_u64(const char *cstr)
{
	u64 n = 0;
	u64 e = 1;
	const char *p = cstr;

	while (*p) {
		if ((const unsigned char)(*p - '0') > 9)
			return 0;
		++p;
	}

	--p;

	while (p >= cstr) {
		n += (*p - '0') * e;
		e *= 10;
		--p;
	}

	return n;
}


/** DOC
 * @type function
 * @name cstr_to_i64
 */
i64 cstr_to_i64(const char *cstr)
{
	i64 n = 0;

	if (*cstr == '-') {
		n = (i64)cstr_to_u64(cstr + 1);
		n = -n;
	} else {
		n = (i64)cstr_to_u64(cstr);
	}

	return n;
}