#include "dbserver.h"

int get_nth_char_position(const char *s, int c, int n) {
    int charCount = 0;

    for (int i = 0; i < strlen(s); i++) {
        if (s[i] == c && (++charCount) == n) {
            return i;
        }
    }
    return -1;
}

int get_valid_number(char *rawNumber) {
    if (strlen(rawNumber) == 0) {
        return -1;
    }

    for (int i = 0; i < strlen(rawNumber); i++) {
        if (!isdigit(rawNumber[i])) {
            return -1;
        }
    }

    return atoi(rawNumber);
}

char *get_authkey_from_file(char *filePath) {
    FILE *fin = NULL;
    if ((fin = fopen(filePath, "r")) == NULL) {
        return NULL;
    }

    char *line = NULL;
    if ((line = read_line(fin)) == NULL) {
        return NULL;
    }

    fclose(fin);
    return line;
}

struct addrinfo *get_address_info(int port) {
    struct addrinfo *ai = 0;
    struct addrinfo hints;

    memset(&hints, 0, sizeof(struct addrinfo));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE;

    // Convert port to string for use in bind
    char portnum[6];
    sprintf(portnum, "%d", port);

    // Get the address info
    int err;
    if ((err = getaddrinfo(NULL, portnum, &hints, &ai))) {
        freeaddrinfo(ai);
        return NULL;
    }

    return ai;
}

int open_socket(int port) {
    struct addrinfo *ai = 0;
    if ((ai = get_address_info(port)) == NULL) {
        return -1;
    }

    // Bind socket to port
    int recvFd = socket(AF_INET, SOCK_STREAM, 0);

    // Reuse ports immediately
    int optionValue = 1;
    // clang-format off
    if (setsockopt(recvFd, SOL_SOCKET, SO_REUSEADDR, &optionValue,
            sizeof(int)) < 0) {
        // clang-format on
        freeaddrinfo(ai);
        return -1;
    }

    // Bind fd to socket
    if (bind(recvFd, (struct sockaddr *)ai->ai_addr, sizeof(struct sockaddr)) <
            0) {
        freeaddrinfo(ai);
        return -1;
    }
    freeaddrinfo(ai);

    // Backlogged if not being used right away
    if (listen(recvFd, MAX_BACKLOG) < 0) {
        return -1;
    }

    // Get port number and print to stdout
    struct sockaddr_in sin;
    socklen_t len = sizeof(sin);
    if (getsockname(recvFd, (struct sockaddr *)&sin, &len) == -1) {
        return -1;
    } else {
        fprintf(stderr, "%d\n", ntohs(sin.sin_port));
    }

    return recvFd;
}

void serverstats_init() {
    serverStats =
            (struct ServerStatistics *)malloc(sizeof(struct ServerStatistics));

    serverStats->currentConnections = 0;
    serverStats->completedConnections = 0;
    serverStats->authFails = 0;
    serverStats->gets = 0;
    serverStats->puts = 0;
    serverStats->deletes = 0;
    serverStats->connectionLock = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
}

int handle_listen(int port, int connections, char *authKey) {
    // Create a public (0) and private (1) stringstore
    StringStore *stringStores[2] = {NULL, NULL};
    stringStores[0] = stringstore_init();
    stringStores[1] = stringstore_init();

    struct sockaddr_in fromAddress = {0};
    socklen_t fromAddressSize = sizeof(fromAddress);

    int recvFd;
    if ((recvFd = open_socket(port)) < 0) {
        return EXIT_PORT_ERR;
    }

    while (1) {
        int fd = accept(
                recvFd, (struct sockaddr *)&fromAddress, &fromAddressSize);
        if (fd < 0) {
            return 1;
        }

        char hostname[NI_MAXHOST];
        int err;
        // clang-format off
        if ((err = getnameinfo((struct sockaddr *)&fromAddress,
                fromAddressSize, hostname, NI_MAXHOST, NULL, 0, 0))) {
            // clang-format on
            return 1;
        }

        struct ConnectionInfo ci;
        memset(&ci, 0, sizeof(struct ConnectionInfo));
        ci.fd = fd;
        ci.connections = connections;
        ci.authKey = authKey;
        ci.stringStores = stringStores;

        struct ConnectionInfo *ciPtr = malloc(sizeof(struct ConnectionInfo));
        *ciPtr = ci;

        pthread_t threadId;
        pthread_create(&threadId, NULL, handle_connection, ciPtr);
        pthread_detach(threadId);
    }

    free(stringStores[0]);
    free(stringStores[1]);
    close(recvFd);
    return 0;
}

char *process_response_get(char *key, StringStore *stringStore) {
    char *response = NULL;
    char *value = NULL;
    if ((value = (char *)stringstore_retrieve(stringStore, key)) == NULL) {
        response = construct_HTTP_response(404, "Not Found", NULL, NULL);
    } else {
        response = construct_HTTP_response(200, "OK", NULL, value);

        pthread_mutex_lock(&(serverStats->connectionLock));
        serverStats->gets += 1;
        pthread_mutex_unlock(&(serverStats->connectionLock));
    }

    return response;
}

char *process_response_put(char *key, char *value, StringStore *stringStore) {
    char *response = NULL;
    if (stringstore_add(stringStore, key, value) == 0) {
        response = construct_HTTP_response(
                500, "Internal Server Error", NULL, NULL);
    } else {
        response = construct_HTTP_response(200, "OK", NULL, NULL);

        pthread_mutex_lock(&(serverStats->connectionLock));
        serverStats->puts += 1;
        pthread_mutex_unlock(&(serverStats->connectionLock));
    }

    return response;
}

char *process_response_delete(char *key, StringStore *stringStore) {
    char *response = NULL;
    if (stringstore_delete(stringStore, key) == 0) {
        response = construct_HTTP_response(404, "Not Found", NULL, NULL);
    } else {
        response = construct_HTTP_response(200, "OK", NULL, NULL);

        pthread_mutex_lock(&(serverStats->connectionLock));
        serverStats->deletes += 1;
        pthread_mutex_unlock(&(serverStats->connectionLock));
    }

    return response;
}

int check_auth_key(HttpHeader **headers, char *authKey) {
    for (int i = 0; headers[i] != NULL; i++) {
        if (strcmp(headers[i]->name, "Authorization") == 0 &&
                strcmp(headers[i]->value, authKey) == 0) {
            return 1;
        }
    }
    return 0;
}

char *construct_response(
        struct RequestParams req, StringStore **stringStores) {
    char *response = NULL;

    // Default to public string store
    StringStore *stringStore = stringStores[0];

    if (req.path == NULL || req.key == NULL) {
        return NULL;
    }

    // If the client is trying to access a private path
    if (strcmp(req.path, PRIVATE_PATH) == 0) {
        if (!check_auth_key(req.headers, req.authKey)) {
            // Client failed to auth
            pthread_mutex_lock(&(serverStats->connectionLock));
            serverStats->authFails += 1;
            pthread_mutex_unlock(&(serverStats->connectionLock));

            return construct_HTTP_response(401, "Unauthorized", NULL, NULL);
        } else {
            stringStore = stringStores[1];
        }
    } else if (strcmp(req.path, PUBLIC_PATH) != 0) {
        return NULL;
    }

    if (strcmp(req.method, "GET") == 0) {
        response = process_response_get(req.key, stringStore);
    } else if (strcmp(req.method, "PUT") == 0) {
        response = process_response_put(req.key, req.value, stringStore);
    } else if (strcmp(req.method, "DELETE") == 0) {
        response = process_response_delete(req.key, stringStore);
    }
    return response;
}

int get_path_key(char *address, char **path, char **key) {
    int keyStartPos = get_nth_char_position(address, '/', 2) + 1;
    if (keyStartPos <= 0) {
        return 1;
    }

    *path = (char *)malloc(sizeof(char) * (keyStartPos + 1));
    strncpy(*path, address, keyStartPos);

    *key = (char *)malloc(
            sizeof(char) * ((strlen(address) - keyStartPos) + 1));
    strcpy(*key, &address[keyStartPos]);

    return 0;
}

struct RequestParams request_params_init() {
    struct RequestParams requestParams = {0};
    memset(&requestParams, 0, sizeof(struct RequestParams));
    requestParams.method = NULL;
    requestParams.path = NULL;
    requestParams.key = NULL;
    requestParams.value = NULL;
    requestParams.authKey = NULL;

    requestParams.headers = NULL;
    memset(&(requestParams.headers), 0, sizeof(HttpHeader *));

    return requestParams;
}

int handle_connection_request(
        FILE *recv, FILE *send, char *authKey, StringStore **stringStores) {
    struct RequestParams req = request_params_init();

    char *address = NULL;
    // clang-format off
    if (get_HTTP_request(recv, &(req.method), &address, &(req.headers),
            &(req.value)) == 1) {
        // clang-format on
        get_path_key(address, &(req.path), &(req.key));

        req.authKey = authKey;

        char *response = NULL;
        if ((response = construct_response(req, stringStores)) == NULL) {
            response = construct_HTTP_response(400, "Bad Request", NULL, NULL);
        }
        fprintf(send, response);
        fflush(send);

        // Will only need to free in this branch
        free(req.method);
        free(address);
        free(req.value);

        free(response);
        free(req.path);
        free(req.key);
        free_array_of_headers(req.headers);

        return 0;
    }

    return 1;
}

void handle_client_connection(
        int sendFd, char *authKey, StringStore **stringStores) {
    int recvFd = dup(sendFd);
    FILE *send = fdopen(sendFd, "w");
    FILE *recv = fdopen(recvFd, "r");

    // Loop until EOF or invalid response
    int err = 0;
    // clang-format off
    while ((err = handle_connection_request(
            recv, send, authKey, stringStores)) == 0) {
        // clang-format on
        ;
    }
    fclose(recv);
    fclose(send);

    close(recvFd);
}

void *handle_connection(void *ciPtr) {
    struct ConnectionInfo ci = *(struct ConnectionInfo *)ciPtr;
    free(ciPtr);

    // Lock connection count variable while updating
    pthread_mutex_lock(&(serverStats->connectionLock));
    serverStats->currentConnections += 1;
    pthread_mutex_unlock(&(serverStats->connectionLock));

    int illegalConnection = 0;
    if (serverStats->currentConnections <= ci.connections ||
            ci.connections == 0) {
        // if within the max connections
        handle_client_connection(ci.fd, ci.authKey, ci.stringStores);
    } else {
        // send them away
        write(ci.fd, UNAVALIABLE_RESPONSE, strlen(UNAVALIABLE_RESPONSE));
        illegalConnection = 1;
    }
    close(ci.fd);

    pthread_mutex_lock(&(serverStats->connectionLock));
    serverStats->currentConnections--;
    if (!illegalConnection) {
        serverStats->completedConnections++;
    }
    pthread_mutex_unlock(&(serverStats->connectionLock));
    return NULL;
}

void print_server_stats(int s) {
    fprintf(stderr,
            "Connected clients:%d\nCompleted clients:%d\nAuth "
            "failures:%d\nGET "
            "operations:%d\nPUT operations:%d\nDELETE operations:%d\n",
            serverStats->currentConnections, serverStats->completedConnections,
            serverStats->authFails, serverStats->gets, serverStats->puts,
            serverStats->deletes);
}

void setup_signal_handler(void) {
    struct sigaction sa;
    memset(&sa, 0, sizeof(sa));
    sa.sa_handler = print_server_stats;
    sa.sa_flags = SA_RESTART;

    sigaction(SIGHUP, &sa, 0);
}

int main(int argc, char *argv[]) {
    serverstats_init();
    setup_signal_handler();

    if (argc < 3 || argc > 4) {
        fprintf(stderr, PROGRAM_USAGE);
        exit(EXIT_ERR);
    }

    int connections = 0;
    if ((connections = get_valid_number(argv[2])) < 0) {
        fprintf(stderr, PROGRAM_USAGE);
        exit(EXIT_ERR);
    }

    int portnum = 0;
    if (argv[3] && strlen(argv[3]) > 0) {
        portnum = get_valid_number(argv[3]);
        if (portnum != 0 && (portnum < PORT_MIN || portnum > PORT_MAX)) {
            fprintf(stderr, PROGRAM_USAGE);
            exit(EXIT_ERR);
        }
    }

    char *authKey = get_authkey_from_file(argv[1]);
    if (authKey == NULL) {
        fprintf(stderr, "dbserver: unable to read authentication string\n");
        exit(EXIT_FILE_ERR);
    }

    int err;
    if ((err = handle_listen(portnum, connections, authKey)) > 0) {
        fprintf(stderr, "dbserver: unable to open socket for listening\n");
        free(authKey);
        exit(err);
    }

    free(authKey);
    free(serverStats);
}