#include <fcntl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

void error(const char *msg) {
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[]) {
    if (argc < 2) {
        fprintf(stderr, "Usage: %s <port>\n", argv[0]);
        exit(1);
    }

    FILE *fptr;
    char response[8192];
    char html[8192];
    char xml[8192];
    char id[256];
    char val[256];
    char err[256];
    char field[256];
    char line[256];
    char *lines[256];

    int sockfd, newsockfd, portno, n;
    char buffer[1024];
    struct sockaddr_in serv_addr, cli_addr;
    socklen_t clilen;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        error("Unable to open socket");
    }

    bzero((char *)&serv_addr, sizeof(serv_addr));
    portno = atoi(argv[1]);

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);

    if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        error("Unable to bind");
    }

    listen(sockfd, 5);

    clilen = sizeof(cli_addr);

    while (1) {
        newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
        if (newsockfd < 0) {
            error("Unable to accept connection");
        }

        bzero(buffer, sizeof(buffer));
        n = read(newsockfd, buffer, sizeof(buffer) - 1);

        if (n < 0) {
            error("Failed to read");
        }

        printf("Request:\n%s\n", buffer);

        if (strncmp(buffer, "GET / ", 6) == 0) {
            fptr = fopen("index.html", "r");
            if (fptr == NULL) {
                fprintf(stderr, "Error opening view file\n");
                exit(1);
            }

            fread(html, 1, sizeof(html), fptr);
            fclose(fptr);

            snprintf(response, sizeof(response),
                     "HTTP/1.1 200 OK\r\n"
                     "Content-Length: %zu\r\n"
                     "Content-Type: text/html\r\n\r\n%s",
                     strlen(html), html);

            n = write(newsockfd, response, strlen(response));
            if (n < 0) {
                error("Failed to write");
            }
        } else if (strncmp(buffer, "GET /getTasks ", 10) == 0) {
            fptr = fopen("data.xml", "r");
            if (fptr == NULL) {
                fprintf(stderr, "Error opening data file\n");
                exit(1);
            }

            fread(xml, 1, sizeof(xml), fptr);
            fclose(fptr);

            snprintf(response, sizeof(response),
                     "HTTP/1.1 200 OK\r\n"
                     "Content-Length: %zu\r\n"
                     "Content-Type: text/xml\r\n\r\n%s",
                     strlen(xml), xml);

            n = write(newsockfd, response, strlen(response));
            if (n < 0) {
                error("Failed to write");
            }
        } else if (strncmp(buffer, "POST /postTask", 14) == 0) {
            char *start = strstr(buffer, "\"task\":\"");
            if (start == NULL) {
                fprintf(stderr, "Bad post string");
            } else {
                start += 8;
                int i = 0;
                while (*start != '\0' && *start != '\"') {
                    val[i++] = *start++;
                }
                val[i] = '\0';
                if (strcmp(val, "") == 0) {
                    strcpy(err,
                           "{\"error\":\"The field task is empty\", "
                           "\"field\":\"taskInput\"}");
                    snprintf(response, sizeof(response),
                             "HTTP/1.1 400 Bad Request\r\n"
                             "Content-Length: %zu\r\n"
                             "Content-Type: application/json\r\n\r\n%s",
                             strlen(err), err);
                    printf("%s", err);
                    n = write(newsockfd, response, strlen(response));
                    if (n < 0) {
                        error("Failed to write");
                    }
                } else {
                    fptr = fopen("data.xml", "r+");
                    if (fptr == NULL) {
                        fprintf(stderr, "Error opening data file\n");
                        exit(1);
                    }

                    int newId = 0;
                    while (fgets(line, sizeof(line), fptr) != NULL) {
                        if (strstr(line, "<id>") != NULL) {
                            char *idStart = strchr(line, '>') + 1;
                            char *idEnd = strchr(line, '<');
                            *idEnd = '\0';
                            int currentId = atoi(idStart);
                            if (currentId >= newId) {
                                newId = currentId + 1;
                            }
                        }
                    }

                    fseek(fptr, -9, SEEK_END);

                    fprintf(fptr,
                            "\r\n    <task>\r\n"
                            "        <id>%d</id>\r\n"
                            "        <value>%s</value>\r\n"
                            "    </task>\r\n</data>",
                            newId, val);

                    fclose(fptr);

                    strcpy(err, "{\"success\": 1}");
                    snprintf(response, sizeof(response),
                             "HTTP/1.1 200 OK\r\n"
                             "Content-Length: %zu\r\n"
                             "Content-Type: application/json\r\n\r\n%s",
                             strlen(err), err);

                    n = write(newsockfd, response, strlen(response));
                    if (n < 0) {
                        error("Failed to write");
                    }
                }
            }
        } else if (strncmp(buffer, "DELETE /delete ", 14) == 0) {
            char *start = strstr(buffer, "\"id\":\"");
            if (start == NULL) {
                fprintf(stderr, "Bad post string");
            } else {
                start += 6;
                int i = 0;
                while (*start != '\0' && *start != '\"') {
                    id[i++] = *start++;
                }
                id[i] = '\0';
                start = strstr(buffer, "\"task\":\"");
                if (start == NULL) {
                    fprintf(stderr, "Bad post string");
                } else {
                    start += 8;
                    int i = 0;
                    while (*start != '\0' && *start != '\"') {
                        val[i++] = *start++;
                    }
                    val[i] = '\0';
                    fptr = fopen("data.xml", "r+");
                    if (fptr == NULL) {
                        fprintf(stderr, "Error opening data file\n");
                        exit(1);
                    }
                    if (strcmp(val, "") == 0 || strcmp(id, "") == 0) {
                        strcpy(err,
                               "{\"error\":\"The field task is empty\", "
                               "\"field\":\"taskInput\"}");
                        snprintf(response, sizeof(response),
                                 "HTTP/1.1 400 Bad Request\r\n"
                                 "Content-Length: %zu\r\n"
                                 "Content-Type: application/json\r\n\r\n%s",
                                 strlen(err), err);
                        printf("%s", err);
                        n = write(newsockfd, response, strlen(response));
                        if (n < 0) {
                            error("Failed to write");
                        } else {
                            int lineIndex = 0;
                            while (fgets(line, sizeof(line), fptr) != NULL) {
                                lines[lineIndex] = strdup(line);
                                lineIndex++;
                                if (strstr(line, "<id>") != NULL) {
                                    char *idStart = strchr(line, '>') + 1;
                                    char *idEnd = strchr(line, '<');
                                    *idEnd = '\0';
                                    int currentId = atoi(idStart);
                                    if (currentId == atoi(id)) {
                                        lineIndex -= 2;
                                        fseek(fptr, 34 + strlen(val), SEEK_END);
                                    }
                                }
                            }
                            int lineSize = sizeof(lines) / sizeof(lines[0]);
                            printf("Line size:%i", lines[lineSize - 1]);
                        }
                    }
                }
            }
        }

        close(newsockfd);
    }

    close(sockfd);
    return 0;
}