#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <netdb.h>
#include <string.h>
#include <ctype.h>

int webclient(char* url, unsigned short jumps) {
	if (jumps > 5) {
		fprintf(stderr, "D'OH! Too many jumps, my legs hurts!\n");
		return 1;
	}

	if (strstr(url, "://") != NULL) {
		url = strstr(url, "://") + strlen("://");
	}

	char* parsedhost = url;
	char* parsedport = "80";
	char* parsedurl = "";
	char* parsedfile = "index.htm";
	unsigned int i = 0;
	while (url[i] != '\0') {
		if (url[i] == ':') {
			url[i] = '\0';
			parsedport = url + i + 1;
		}
		if (url[i] == '/') {
			url[i] = '\0';
			parsedurl = url + i + 1;
			i++;
			while (url[i] != '\0') {
				if (url[i] == '/') {
					parsedfile = url + i + 1;
				}
				i++;
			}
			break;
		}
		i++;
	}

	if (strlen(parsedurl) < 1) {
		parsedurl = "";
	}

	//printf("Host: %s\nPort: %s\nURL:  %s\nFile: %s\n", parsedhost, parsedport, parsedurl, parsedfile); //DEBUG

	int s = socket(PF_INET, SOCK_STREAM, 0);
	if (s < 0) {
		fprintf(stderr, "D'OH! Broken socket, call electrician.\n");
		return 1;
	}

	struct sockaddr_in sadr;
	bzero(&sadr, sizeof(sadr)); //radsi to vynulujem
	sadr.sin_family = AF_INET; //rodina
	struct hostent *host;
	if ((host = gethostbyname(parsedhost)) == NULL) {
		fprintf(stderr, "D'OH! Unknown host.\n");
		return 1;
	}
	memcpy(&sadr.sin_addr, host->h_addr, host->h_length); //adresa
	sadr.sin_port = htons(atoi(parsedport));

	if (connect(s, (struct sockaddr*) &sadr, sizeof(sadr)) < 0) {
		fprintf(stderr, "D'OH! Server is dead.\n");
		return 1;
	}
	printf("Connected!\n");

	printf("Negotiating...\n");
	char* get = NULL;
	if (parsedurl == NULL) {
		parsedurl = "";
	}
	//printf("Processing HTTP GET...\n");
	get = malloc((strlen("GET /") + strlen(parsedurl) + strlen(" HTTP/1.0\r\nHost: ") + strlen(parsedhost) + strlen("\r\n\r\n")) * sizeof(char));
	if (get == NULL) {
		fprintf(stderr, "D'OH! Malloc fail, buy more RAM!\n");
		return 1;
	}
	get[0] = '\0';
	strcat(get, "GET /");
	strcat(get, parsedurl);
	strcat(get, " HTTP/1.0\r\nHost: ");
	strcat(get, parsedhost);
	strcat(get, "\r\n\r\n");
	//printf("%s\n", get);
	if ((write(s, get, strlen(get))) <= 0) {
		fprintf(stderr, "D'OH! Can't write.\n");
		if (parsedurl != NULL) {
			free(get);
		}
		return 1;
	}
	if (parsedurl != NULL) {
		free(get);
	}

	printf("Reading...\n");
	char* header;
	unsigned int allocated = 1;
	unsigned int dumped = 0;
	header = malloc(allocated * sizeof(char));
	if (header == NULL) {
		fprintf(stderr, "D'OH! Malloc fail, buy me more memory!\n");
		return 1;
	}
	while (strstr(header, "\r\n\r\n") == NULL) {
		read(s, header + dumped, 1);
		dumped++;
		if (dumped >= allocated) {
			allocated *= 2;
			header = realloc(header, allocated);
			if (header == NULL) {
				fprintf(stderr, "D'OH! Realloc fail, buy me more memory!\n");
				return 1;
			}
		}
	}
	//printf("Header:\n%s", header);

	unsigned int response = atoi(header + 9);
	printf("Response: %d\n", response);

	char* location = NULL;
	if (response >= 300 && response < 400) {
		location = strstr(header, "Location: ") + strlen("Location: ");
		i = 0;
		while (location[i] != '\r') {
			i++;
		}
		location[i] = '\0';
		//printf("\nLocation: %s\n", location);
	}

	if (response == 200) {
		//printf("Socket -> %s...\n", parsedfile);
		printf("Downloading...\n");
		FILE* fp = fopen(parsedfile, "w");
		if (fp == NULL) {
			fprintf(stderr, "D'OH! I don't know where to write, buy me some paper!\n");
			free(header);
			return 1;
		}
		char socketchar[1];
		while (read(s, socketchar, 1) > 0) {
			fwrite(socketchar, sizeof(char), 1, fp);
		}
		fclose(fp);
	}
	if (response >= 300 && response < 400) {
		printf("Redirected...\n");
		webclient(location, ++jumps);
	}

	free(header);
	shutdown(s, 2);
	close(s);
	return 0;
}

int main(int argc, char* argv[]) {
	if (argc > 2) {
		fprintf(stderr, "D'OH! Too many parameters.\n");
		return 1;
	}

	if (argc == 1) {
		printf("USAGE: webclinet URL\n");
		return 0;
	}

	return webclient(argv[1], 0);
}