#include <stddef.h>

#include "utf.h"
#include "str.h"

typedef struct Utf8Parser {
	String str;
} Utf8Parser;

bool Utf8ParserNextCodePoint(Utf8Parser *this, CodePoint *out_codepoint) {
	uitn8_t const flag_1_bytes = 0;
	uint8_t const mask_1_bytes = 1 << 7;

	uint8_t const flag_continuation = mask_1_bytes;
	uint8_t const mask_continuation = (1 << 7) | (1 << 6);

	uint8_t const flag_2_bytes = mask_continuation;
	uint8_t const mask_2_bytes = (1 << 7) | (1 << 6) | (1 << 5);

	uint8_t const flag_3_bytes = mask_2_bytes;
	uint8_t const mask_3_bytes = (1 << 7) | (1 << 6) | (1 << 5) | (1 << 4);

	uint8_t const flag_4_bytes = mask_3_bytes;
	uint8_t const mask_4_bytes = (1 << 7) | (1 << 6) | (1 << 5) | (1 << 4) | (1 << 3);

	if (this->str.size == 0) {
		*out_codepoint = 0;
		return false;
	}

	if ((this->str.buffer[0] & mask_1_bytes) == flag_1_bytes) {
		*out_codepoint = (CodePoint) str[0];
		bool ok = StringSub(this->str, 1, -1, &this->str);
		assert(ok && "has to be ok since the size is not 0");
		return ok;
	} else
}

// max must be less than or equal to the capacity of target.
bool CodePointsFromUtf8String(
	uint8_t const *str,
	CodePoint *target,
	int max
) {

	for (size_t i = 0; str[i] != '\0' && max > 0;) {
		if ((str[i] & mask_1_bytes) == flag_1_bytes) {
			*target = (CodePoint) str[i];

			target += 1;
			max -= 1;
			i += 1;
		} else
		if ((str[i] & mask_2_bytes) == flag_2_bytes) {
		} else
		if ((str[i] & mask_3_bytes) == flag_3_bytes) {
		} else
		if ((str[i] & mask_4_bytes) == flag_4_bytes) {
		} else {
			false;
		}
	}

	return true;
}