#include <stdio.h>
#include <getopt.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>

#define SBS_MIDDLE_LEFT_1920 480
#define SBS_MIDDLE_LEFT_3840 SBS_MIDDLE_LEFT_1920 * 2
#define SBS_MIDDLE_RIGHT_1920 1440
#define SBS_MIDDLE_RIGHT_3840 SBS_MIDDLE_RIGHT_1920 * 2
#define TB_MIDDLE_1920 960
#define TB_MIDDLE_3840 TB_MIDDLE_1920 * 2

static int fullres = 0;

static struct option long_options[] = {
	{ "input",	    required_argument,  0, 'i' },
	{ "output",	    required_argument,  0, 'o' },
	{ "3dmode",	    required_argument,  0, '3' },
	{ "3ddepth",	required_argument,  0, 'd' },
	{ "help",	    no_argument,        0, 'h' },
	{ "fullres",    no_argument,        &fullres, 1 },
	{ 0, 0, 0, 0 }
};

void show_help() {
	printf("srt2ass3D converts a SRT subtitle file to a ASS subtitle file for 3d viewing. Options are:\n");
	printf("\t--input,-i\t(required) Input file name\n");
	printf("\t--output,-o\t(required) Output file name\n");
	printf("\t--3dmode,-3\t(required) 3D Mode (SBS, TB)\n");
	printf("\t--3ddepth,-d\t(required) 3D Depth for the subtitles [-3, 3]\n");
	printf("\t--fullres\tSpecifies that the movie is a full resolution 3D movie (3840x1080 or 1920x2160)\n");
	printf("\t--help,-h\tThis help screen\n\n");
}

char* strreplace(const char *string, const char *substr, const char *replacement){
    char *tok = NULL;
    char *newstr = NULL;
    char *oldstr = NULL;
    char *head = NULL;

    /* if either substr or replacement is NULL, duplicate string a let caller handle it */
    if (substr == NULL || replacement == NULL)
        return strdup (string);

    newstr = strdup(string);
    head = newstr;
    while ((tok = strstr(head, substr))) {
        oldstr = newstr;
        newstr = malloc(strlen(oldstr) - strlen(substr) + strlen(replacement) + 1 );
        /*failed to alloc mem, free old string and return NULL */
        if (newstr == NULL) {
            free (oldstr);
            return NULL;
        }
        memcpy(newstr, oldstr, tok - oldstr);
        memcpy(newstr + (tok - oldstr), replacement, strlen(replacement));
        memcpy(newstr + (tok - oldstr) + strlen(replacement), tok + strlen(substr), strlen(oldstr) - strlen(substr) - (tok - oldstr));
        memset(newstr + strlen(oldstr) - strlen(substr) + strlen(replacement), 0, 1 );

        /* move back head right after the last replacement */
        head = newstr + (tok - oldstr) + strlen(replacement);
        free (oldstr);
    }
    return newstr;
}

char* replace_tags(char *text) {
	char *tmp1, *tmp2;

	tmp1 = strreplace(strreplace(text, "<i>", "{\\i1}"), "</i>", "{\\i0}");
	tmp2 = strreplace(strreplace(tmp1, "<b>", "{\\b1}"), "</b>", "{\\b0}");
	free(tmp1);
	return tmp2;
}

int main(int argc, char** argv) {
	int option_index;
	unsigned int c;
	char *input_name = NULL;
	char *output_name = NULL;
	int tb;
	short depth = 0;
	short valid_args = 0;

	while ((c = getopt_long(argc, argv, "i:o:3:d:h", long_options, &option_index)) != -1) {
		switch (c) {
            case 0: {
                if (long_options[option_index].flag != 0)
                    break;
            }
			case 'i': {
				input_name = malloc(sizeof(char) * strlen(optarg) + 1);
				strcpy(input_name, optarg);
				valid_args++;
				break;
			}
			case 'o': {
				output_name = malloc(sizeof(unsigned char) * strlen(optarg) + 1);
				strcpy(output_name, optarg);
				valid_args++;
				break;
			}
			case '3': {
				// If the argument is SBS then the result will be 0, and 0 == false, so TB = false.
				tb = strcasecmp("SBS", optarg);
				valid_args++;
				break;
			}
			case 'd': {
				depth = atoi(optarg);
				valid_args++;
				break;
			}
			case 'h': {
				show_help();
				return 0;
				break;
			}
		}
	}

	if (valid_args != 4) {
		if (input_name != NULL)
			free(input_name);
		if (output_name != NULL)
			free(output_name);
		show_help();
		return -1;
	}

    if (depth < -3 || depth > 3) {
        printf("Values of depth should be between -3 and 3\n");
        return -1;
	}

	FILE *inputf;
	FILE *outputf;
	inputf = fopen(input_name, "r");
	if (inputf == NULL) {
		printf("Error opening %s for reading: %s\n", input_name, strerror(errno));
		return -1;
	}
	outputf = fopen(output_name, "w");
	if (outputf == NULL) {
		printf("Error opening %s for writing: %s\n", output_name, strerror(errno));
		return -1;
	}

	printf("Input file: %s\nOutput file: %s\n3D type: %s\nDepth: %i\n\n",
		input_name, output_name, (tb ? "TB" : "SBS"), depth);

	// ASS headers
	fprintf(outputf, "[Script Info]\n");
	fprintf(outputf, "; Script generated by srt2ass3D 1.0\n");
	fprintf(outputf, "Title: %s\n", output_name);
	fprintf(outputf, "ScriptType: v4.00+\n");
	fprintf(outputf, "WrapStyle: 0\n");
	if (!fullres) {
        fprintf(outputf, "PlayResX: 1920\n");
        fprintf(outputf, "PlayResY: 1080\n");
	} else {
	    if (!tb) {
            fprintf(outputf, "PlayResX: 3840\n");
            fprintf(outputf, "PlayResY: 1080\n");
	    } else {
            fprintf(outputf, "PlayResX: 1920\n");
            fprintf(outputf, "PlayResY: 2160\n");
	    }
	}
	fprintf(outputf, "ScaledBorderAndShadow: yes\n\n");
	fprintf(outputf, "[V4+ Styles]\n");
	fprintf(outputf, "Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding\n");
	if (!tb)
        fprintf(outputf, "Style: 3D,Cube Modern Rounded Thin,60,&H00FFFFFF,&H000000FF,&H00000000,&H00000000,0,0,0,0,100,100,0,0,1,6,0,2,0,0,0,1\n\n");
    else
        fprintf(outputf, "Style: 3D,Cube Modern Rounded Short,60,&H00FFFFFF,&H000000FF,&H00000000,&H00000000,0,0,0,0,100,100,0,0,1,6,0,2,0,0,0,1\n\n");
	fprintf(outputf, "[Events]\n");
	fprintf(outputf, "Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text\n\n");

	short state = 0;
	char *line = malloc(sizeof(unsigned char) * 50);
	char *subtitle1 = malloc(sizeof(unsigned char) * 256);
	char *subtitle2 = malloc(sizeof(unsigned char) * 256);
	// read the input file and convert it
	while (fgets(line, 50, inputf) != NULL) {
		switch (state) {
			case 0: {
				// subtitle index expected
				strtol(line, (char **) NULL, 10);
				if (errno == EINVAL) {
					// Maybe the input format is wrong
					printf("Input file format is wrong\n");
					fclose(inputf);
					fclose(outputf);
					free(input_name);
					free(output_name);
					return -1;
				}
				state = 1;
				break;
			}
			case 1: {
				// start/end time expected
				unsigned short sh, sm, ss, sms;
				unsigned short eh, em, es, ems;
				int r = sscanf(line, "%hd:%hd:%hd,%hd --> %hd:%hd:%hd,%hd", &sh, &sm, &ss, &sms, &eh, &em, &es, &ems);
				if (r == 0) {
					// Maybe the input format is wrong
					printf("Input file format is wrong\n");
					fclose(inputf);
					fclose(outputf);
					free(input_name);
					free(output_name);
					return -1;
				}

				sprintf(subtitle1, "Dialogue: 0,%hd:%02hd:%02hd.%03hd,%hd:%02hd:%02hd.%03hd,3D,,0000,0000,0000,,",
					sh, sm, ss, sms, eh, em, es, ems);
				sprintf(subtitle2, "Dialogue: 0,%hd:%02hd:%02hd.%03hd,%hd:%02hd:%02hd.%03hd,3D,,0000,0000,0000,,",
					sh, sm, ss, sms, eh, em, es, ems);

				state = 2;
				break;
			}
			case 2: {
				// 1st line of the subtitle expected
				if (strlen(line) == 0) {
					// Maybe the input format is wrong
					printf("Input file format is wrong\n");
					fclose(inputf);
					fclose(outputf);
					free(input_name);
					free(output_name);
					return -1;
				}

                if (!tb) {
                    sprintf(subtitle1 + strlen(subtitle1), "{\\pos(%d,1060)}%s", (fullres == 0 ? SBS_MIDDLE_LEFT_1920 : SBS_MIDDLE_LEFT_3840) - depth, line);
                    sprintf(subtitle2 + strlen(subtitle2), "{\\pos(%d,1060)}%s", (fullres == 0 ? SBS_MIDDLE_RIGHT_1920 : SBS_MIDDLE_RIGHT_3840) + depth, line);
                } else {
                    sprintf(subtitle1 + strlen(subtitle1), "{\\pos(%d,1070)}%s", (fullres == 0 ? TB_MIDDLE_1920 : TB_MIDDLE_3840) - depth, line);
                    sprintf(subtitle2 + strlen(subtitle2), "{\\pos(%d,530)}%s", (fullres == 0 ? TB_MIDDLE_1920 : TB_MIDDLE_3840) + depth, line);
                }

				state = 3;
				break;
			}
			case 3: {
				// In this case, we can have a 2nd subtitle, or an empty line
				if (!isspace(*line)) {
					sprintf(subtitle1 + strlen(subtitle1) - 2, "\\N%s", line);
					sprintf(subtitle2 + strlen(subtitle2) - 2, "\\N%s", line);
				}

				fprintf(outputf, "%s", replace_tags(subtitle1));
				fprintf(outputf, "%s", replace_tags(subtitle2));

				state = (!isspace(*line) ? 4 : 0);
				break;
			}
			case 4: {
				// empty line expected
				if (!isspace(*line)) {
					// Maybe the input format is wrong
					printf("Input file format is wrong\n");
					fclose(inputf);
					fclose(outputf);
					free(input_name);
					free(output_name);
					return -1;
				}
				state = 0;
			}
		}
	}

	printf("Done\n");

	fclose(inputf);
	fclose(outputf);
	free(input_name);
	free(output_name);
	return 0;
}