#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define DEFAULT_STRING_SIZE 32

typedef struct __string {
    char* Characters;
    int Length;
    int ByteCount;
    int Capacity;
} TString;

int GetGlyphByteWidth(const char* glyph);
void AppendGlyph(const char* glyph, TString* string);
void GetCharByIndex(int index, char characters[8], const TString* string);
TString* CreateString(void);

const unsigned char First = 0x70;
const unsigned char Teo = 0xE0;
const unsigned char Three = 0xF0;
const unsigned char Four = 0xF7;

int main(int argc, char** argv) {
    char glyph[10] = { 0 };
    char characters[8] = { 0 };

    int index = 2;
    TString* string = CreateString();
//0xF0 0xA0 0xBA 0x8C
    char* test = u8"\xE5\x87\x84";
    char* test2 = u8"\xE3\x81\x84";
    char* test4 = u8"\xF0\xA0\xBA\x8C";
    char* test5 = "B";
    char* test3 = " Just some\0 extra text";

    AppendGlyph(test, string);
    AppendGlyph(test2, string);
    AppendGlyph(test4, string);
    AppendGlyph(test5, string);

    GetCharByIndex(index, characters, string);
    GetCharByIndex(3, glyph, string);

    printf("From string index %d: '%s' (string length is %d)\n", index, characters, string->Length);
    printf("And one English character: '%s'\n", glyph);
    printf("Full string: '%s'\n", string->Characters);

    //fgets(glyph, 10, stdin);

    //glyph[strlen(glyph) - 1] = 0;

    //printf("Width %d byte(s).\n", GetGlyphByteWidth(glyph));
}

TString* CreateString(void) {
    TString* string = malloc(sizeof(TString));

    string->Characters = calloc(DEFAULT_STRING_SIZE, sizeof(char));

    string->Capacity = DEFAULT_STRING_SIZE;
    string->ByteCount = 0;
    string->Length = 0;

    return string;
}

void AppendGlyph(const char* glyph, TString* string) {
    int length = strlen(glyph);

    memcpy(&string->Characters[string->ByteCount], glyph, length);

    string->ByteCount += length;
    string->Length++;
}

void GetCharByIndex(int index, char characters[8], const TString* string) {
    int glyphCount = 0;

    for(int i = 0; i < string->ByteCount;) {
        if (glyphCount == index) {
            memcpy(characters, &string->Characters[i], GetGlyphByteWidth(&string->Characters[i]));
            return;
        }

        glyphCount++;
        i += GetGlyphByteWidth(&string->Characters[i]);
    }
}

int GetGlyphByteWidth(const char* glyph) {
    printf("Bytes for '%s': ", glyph);
    
    for(size_t i = 0; i < strlen(glyph); i++) {
        printf("%02X ", 0xFF & glyph[i]);
    }
    printf("\n");

    unsigned char result = *glyph & 0xFF;

    if ((*glyph & 0x80) == 0) {
        return 1;
    }
    else if ((*glyph & 0xE0) == 0xC0) {
        return 2;
    }
    else if ((*glyph & 0xF0) == 0xE0) {
        return 3;
    }
    else if ((*glyph & 0xF8) == 0xF0) {
        return 4;
    }

    fprintf(stderr, "Failed to get glyph %02X\n", 0xFF & *glyph);

    exit(-1);
}