#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <dirent.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <pthread.h>

#define PORT 8081
#define BUFFER_SIZE 512
#define MAX_PATH 512
#define ROOT_DIR "."

typedef struct handle_request_data {
    SSL *ssl;
    int socket;
    char *req;
} handle_request_data;

static const struct { const char *ext; const char *type; } mime_types[] = {
    {".html", "text/html"},
    {".css", "text/css"},
    {".js", "application/javascript"},
    {".jpg", "image/jpeg"},
    {".jpeg", "image/jpeg"},
    {".png", "image/png"},
    {NULL, "application/octet-stream"}
};

static const char *get_mime_type(const char *path) {
    const char *ext = strrchr(path, '.');
    if (!ext) return mime_types[0].type;
    for (int i = 0; mime_types[i].ext; i++) {
        if (!strcmp(ext, mime_types[i].ext)) return mime_types[i].type;
    }
    return mime_types[0].type;
}

static void send_response(SSL *ssl, const char *status, const char *type, const char *body, size_t len) {
    char buf[BUFFER_SIZE];
    int n = snprintf(buf, sizeof(buf), "HTTP/1.1 %s\r\nContent-Type: %s\r\nContent-Length: %zu\r\n\r\n", status, type, len);
    SSL_write(ssl, buf, n);
    if (len && body) SSL_write(ssl, body, len);
}

static void write_full(SSL *ssl, const char *data, size_t len) {
    while (len > 0) {
        int sent = SSL_write(ssl, data, len);
        if (sent <= 0) break;
        data += sent;
        len -= sent;
    }
}

static void list_files(SSL *ssl, char *directory) {
    char buf[8192] = "<html><head><title>File Server</title></head><body><h1>Files</h1><ul>";
    size_t pos = strlen(buf);
    DIR *dir = opendir(directory);
    if (!dir) {
        send_response(ssl, "500 Internal Server Error", "text/plain", "Cannot open directory", 20);
        return;
    }

    struct dirent *entry;
    while ((entry = readdir(dir)) && pos < sizeof(buf) - 100) {
        if (!strcmp(entry->d_name, ".")) continue;
        if (!strcmp(entry->d_name, "..") && !strcmp(directory, ROOT_DIR)) continue;
        char path[MAX_PATH];
        snprintf(path, sizeof(path), "%s/%s", directory, entry->d_name);
        pos += snprintf(buf + pos, sizeof(buf) - pos,
                        "<li><a href=\"/%s/%s\">%s</a></li>", directory, entry->d_name, entry->d_name);
    }
    closedir(dir);

    pos += snprintf(buf + pos, sizeof(buf) - pos, "</ul></body></html>");
    send_response(ssl, "200 OK", "text/html", buf, pos);
}

void *handle_request(void *param) {
    handle_request_data *param_data = (handle_request_data*)param;
    int client_sock = param_data->socket;
    SSL *ssl = param_data->ssl;
    char *req = param_data->req;
    char method[8], path[MAX_PATH-2], proto[8];
    if (sscanf(req, "%7s %127s %7s", method, path, proto) != 3) {
        send_response(ssl, "400 Bad Request", "text/plain", "Bad Request", 11);
        SSL_shutdown(ssl);
        SSL_free(ssl);
        close(client_sock);
        pthread_exit(0);
    }
    printf("%s %s %s\n", path, method, proto);

    if (strcmp(method, "GET")) {
        send_response(ssl, "405 Method Not Allowed", "text/plain", "Method Not Allowed", 18);
        SSL_shutdown(ssl);
        SSL_free(ssl);
        close(client_sock);
        pthread_exit(0);
    }

    if (strstr(path, "..")) {
        send_response(ssl, "403 Forbidden", "text/plain", "Forbidden", 9);
        SSL_shutdown(ssl);
        SSL_free(ssl);
        close(client_sock);
        pthread_exit(0);
    }

    if (!strcmp(path, "/favicon.ico")) {
        send_response(ssl, "204 No Content", "text/plain", NULL, 0);
        SSL_shutdown(ssl);
        SSL_free(ssl);
        close(client_sock);
        pthread_exit(0);
    }

    if (!strcmp(path, "/")) {
        list_files(ssl, ROOT_DIR);
        SSL_shutdown(ssl);
        SSL_free(ssl);
        close(client_sock);
        pthread_exit(0);
    }

    char file_path[MAX_PATH];
    snprintf(file_path, sizeof(file_path), "%s/%s", ROOT_DIR, path[0] == '/' ? path + 1 : path);
    if (file_path[0] == '.' && file_path[1] == '/') {
        for (int i = 2; i < MAX_PATH -1; i++) {
            file_path[i-2] = file_path[i];
        }
    }
    struct stat st;
    if (stat(file_path, &st) < 0 || S_ISDIR(st.st_mode)) {
        if (S_ISDIR(st.st_mode)) {
            list_files(ssl, file_path);
            SSL_shutdown(ssl);
            SSL_free(ssl);
            close(client_sock);
            pthread_exit(0);
        }
        send_response(ssl, st.st_mode ? "403 Forbidden" : "404 Not Found",
                      "text/plain", st.st_mode ? "Directory listing not allowed" : "Not Found",
                      st.st_mode ? 29 : 9);
        SSL_shutdown(ssl);
        SSL_free(ssl);
        close(client_sock);
        pthread_exit(0);
    }

    int fd = open(file_path, O_RDONLY);
    if (fd < 0) {
        send_response(ssl, "404 Not Found", "text/plain", "Not Found", 9);
        SSL_shutdown(ssl);
        SSL_free(ssl);
        close(client_sock);
        pthread_exit(0);
    }

    char buf[BUFFER_SIZE];
    int n = snprintf(buf, sizeof(buf), "HTTP/1.1 200 OK\r\nContent-Type: %s\r\nContent-Length: %lld\r\n\r\n",
                     get_mime_type(file_path), (long long)st.st_size);
    write_full(ssl, buf, n);

    char data[16384];
    off_t total_sent = 0;
    ssize_t bytes;
    while ((bytes = read(fd, data, sizeof(data))) > 0) {
        write_full(ssl, data, bytes);
        total_sent += bytes;
    }
    close(fd);

    if (total_sent != st.st_size) {
        send_response(ssl, "500 Internal Server Error", "text/plain", "Incomplete transfer", 18);
    }
    SSL_shutdown(ssl);
    SSL_free(ssl);
    close(client_sock);
    pthread_exit(0);
}

int main() {
    struct stat st;
    if (stat(ROOT_DIR, &st) < 0 || !S_ISDIR(st.st_mode)) return 1;

    SSL_load_error_strings();
    OpenSSL_add_ssl_algorithms();
    const SSL_METHOD *method = TLS_server_method();
    SSL_CTX *ctx = SSL_CTX_new(method);
    if (!ctx) return 1;

    if (SSL_CTX_use_certificate_file(ctx, "server.crt", SSL_FILETYPE_PEM) <= 0 ||
        SSL_CTX_use_PrivateKey_file(ctx, "server.key", SSL_FILETYPE_PEM) <= 0) {
        SSL_CTX_free(ctx);
        return 1;
    }

    int sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock < 0) {
        SSL_CTX_free(ctx);
        return 1;
    }

    int opt = 1;
    setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

    struct sockaddr_in addr = {
        .sin_family = AF_INET,
        .sin_addr.s_addr = INADDR_ANY,
        .sin_port = htons(PORT)
    };

    if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0 ||
        listen(sock, 5) < 0) {
        close(sock);
        SSL_CTX_free(ctx);
        return 1;
    }

    printf("Server started on https://localhost:%d\n", PORT);

    char buf[BUFFER_SIZE];
    struct sockaddr_in client;
    socklen_t len = sizeof(client);

    while (1) {
        int client_sock = accept(sock, (struct sockaddr *)&client, &len);
        if (client_sock < 0) continue;

        SSL *ssl = SSL_new(ctx);
        SSL_set_fd(ssl, client_sock);

        if (SSL_accept(ssl) <= 0) {
            SSL_free(ssl);
            close(client_sock);
            continue;
        }

        int n = SSL_read(ssl, buf, BUFFER_SIZE - 1);
        if (n > 0) {
            buf[n] = '\0';
            handle_request_data data;
            data.ssl = ssl;
            data.socket = client_sock;
            data.req = buf;
            pthread_t tid;
            pthread_attr_t attr;
            pthread_attr_init(&attr);
            pthread_create(&tid, &attr, handle_request, &data);
        }
    }

    close(sock);
    SSL_CTX_free(ctx);
    return 0;
}