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

/*
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * For more information, please refer to <http://unlicense.org/>
 *
 */

#define VERSION "0.45"

typedef struct {
    size_t position;
    size_t size;
    char *data;
} Buffer;

struct closeThings {
    bool Bold;
    bool Italics;
    bool Strikethrough;
    bool Monospace;
    bool Underline;
};

void reallocBuffer(Buffer *buffer) {
    buffer->size += 1024;
    buffer->data = realloc(buffer->data,buffer->size+1); /* Adding one ensures we always have a null terminator */
    if (!buffer->data) {
        printf("Error realloc-ing buffer!");
        exit(1);
    }
}


/* Yes I am not using most of these at the moment but I might in the future so they shall remain */
void checkBufSafety(Buffer *buffer) {
	if ((buffer->size < (buffer->position - 64)) || ((buffer->size - 64) < 0)) {
		reallocBuffer(buffer);
	}
}

void appendBufferToBuffer(Buffer *buffer, Buffer *dataBuffer) {
    for (size_t i = 0;i < dataBuffer->size;i++) {
        if (dataBuffer->data[i] == 0x00) break; /* stop on NULL */
        buffer->data[buffer->position] = dataBuffer->data[i];
        buffer->position++;
		checkBufSafety(buffer);
    }
}

void appendCharPToBuffer(char *string, Buffer *buffer) { 
	size_t stringLen = strlen(string);

	for (size_t i = 0;i < stringLen;i++) {
		checkBufSafety(buffer);
		buffer->data[buffer->position+i] = string[i];
		buffer->position++;
	}
}

void appendCharToBuffer(char character, Buffer *buffer) {
	buffer->data[buffer->position] = character;
	buffer->position++;
	checkBufSafety(buffer);
}

/* I'm gonna leave this as a define for now */
#define checkCloseAndPrint(thing,openTxt,closeTxt) \
	if (close->thing) { \
		fputs(closeTxt,stdout); \
		close->thing = 0; \
	} else { \
		fputs(openTxt,stdout); \
		close->thing = 1; \
	}

void getFormattingAndPrint(char character,struct closeThings *close) {
	int characterInt;
	int cont;
	switch (character) {
		case '\\':  /* character escaping */
			putc((char)fgetc(stdin),stdout);
			break;

		case '*': /* bold */
			checkCloseAndPrint(Bold,"<b>","</b>");
			break;

		case '/': /* italics */
			checkCloseAndPrint(Italics,"<i>","</i>");
			break;

		case '`': /* monospace */
			checkCloseAndPrint(Monospace,"<code>","</code>");
			break;

		case '~': /* strikethrough */
			checkCloseAndPrint(Strikethrough,"<del>","</del>");
			break;

		case '_': /* underline */
			checkCloseAndPrint(Underline,"<ins>","</ins>");
			break;

		case '\n': /* convert newlines */
			puts("<br>");
			break;
			
		case '[': /* links */
			;Buffer linkTxt;
			linkTxt.size = 1024;
			linkTxt.position = 0;
			linkTxt.data = calloc(linkTxt.size+1,sizeof(char));

			Buffer linkLoc;
			linkLoc.size = 1024;
			linkLoc.position = 0;
			linkLoc.data = calloc(linkLoc.size+1,sizeof(char));

			characterInt = '\n';
			cont = 0;

			while (1) {
				characterInt = fgetc(stdin);
		        character = (char)characterInt;
				if (characterInt == EOF) {
					puts("Stream ended before link text finished!");
					exit(1);
				}
				if (character == '\\') {
					cont = 1;
					continue;
				}
				if (cont) {
					cont = 0;
					checkBufSafety(&linkTxt);
					appendCharToBuffer(character,&linkTxt);
					continue;
				}

				checkBufSafety(&linkTxt);
				appendCharToBuffer(character,&linkTxt);
				if (character == ']') break;
			}
			linkTxt.data[--linkTxt.position] = 0;
			fgetc(stdin); /* Get past the '(' in the location */

			while (1) {
				characterInt = fgetc(stdin);
				character = (char)characterInt;
				if (characterInt == EOF) {
					puts("Stream ended before link location finished!");
					exit(1);
				}
				if (character == '\\') {
					cont = 1;
					continue;
				}
				if (cont) {
					cont = 0;
					checkBufSafety(&linkLoc);
					appendCharToBuffer(character,&linkLoc);
					continue;
				}

				checkBufSafety(&linkLoc);
				appendCharToBuffer(character,&linkLoc);
				if (character == ')') break;
			}
			linkLoc.data[--linkLoc.position] = 0;
			printf("<a href=\"%s\">%s</a>",linkLoc.data,linkTxt.data);

			free(linkLoc.data);
			free(linkTxt.data);
			break;

		case '{': /* images */
			;Buffer imgTxt;
			imgTxt.size = 1024;
			imgTxt.position = 0;
			imgTxt.data = calloc(imgTxt.size+1,sizeof(char));

			Buffer imgLoc;
			imgLoc.size = 1024;
			imgLoc.position = 0;
			imgLoc.data = calloc(imgLoc.size+1,sizeof(char));

			characterInt = '\n';
			cont = 0;

			while (1) {
				characterInt = fgetc(stdin);
		        character = (char)characterInt;
				if (characterInt == EOF) {
					puts("Stream ended before link text finished!");
					exit(1);
				}
				if (character == '\\') {
					cont = 1;
					continue;
				}
				if (cont) {
					cont = 0;
					checkBufSafety(&imgLoc);
					appendCharToBuffer(character,&imgLoc);
					continue;
				}

				checkBufSafety(&imgLoc);
				appendCharToBuffer(character,&imgLoc);
				if (character == '}') break;
			}
			imgLoc.data[--imgLoc.position] = 0;
			fgetc(stdin); /* Get past the '(' in the alt text */

			while (1) {
				characterInt = fgetc(stdin);
				character = (char)characterInt;
				if (characterInt == EOF) {
					puts("Stream ended before link location finished!");
					exit(1);
				}
				if (character == '\\') {
					cont = 1;
					continue;
				}
				if (cont) {
					cont = 0;
					checkBufSafety(&imgTxt);
					appendCharToBuffer(character,&imgTxt);
					continue;
				}

				checkBufSafety(&imgTxt);
				appendCharToBuffer(character,&imgTxt);
				if (character == ')') break;
			}
			imgTxt.data[--imgTxt.position] = 0;

		
			printf("<img alt=\"%s\" src=\"%s\">",imgTxt.data,imgLoc.data);

			free(imgTxt.data);
			free(imgLoc.data);

			break;

		default: /* it is a normal character print to stdout */
			putc(character,stdout);
			break;
	}
}

int main(int argc, char **argv) {
    (void)argv; /* this stops it from yelling at me :) */

    if (argc > 1) {
        fputs(
			"txtToHTML V"VERSION"\n" /* god I love the way C handles strings in the compiler */
	        "	Usage:\n"
	        "		cat coolthing.txt | txtToHTML > coolthing.html\n"
	        "	Special characters:\n"
	        "		* = bold\n"
	        "		/ = italic\n"
	        "		` = monospace\n"
	        "		~ = strikethrough\n"
	        "		_ = underline\n"
	        "		Markdown style links are available/\n"
			"		You can create images like so:\n"
			"			{https://image.location/img.gif}(Required alt text)\n"
			"		Alt text is required for images.\n"
	        "		you can escape any character with \\ and it will not be used for formatting\n",
			stderr);
        exit(1);
    }

    char character = 'a';
    int  characterInt = 'a';

    struct closeThings close  = {0,0,0,0,0}; /* Make sure it starts as zero so we do not get fucky shit */

    while (1) {
        characterInt = fgetc(stdin);
        character = (char)characterInt;
		if (characterInt == EOF) break;

		getFormattingAndPrint(character,&close);
    }
	puts("");
	fflush(stdout);

    return 0;
}