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#include <stdlib.h>

#include <string.h>

#include <ctype.h>

#include <futex.h>

atomic_t fs_head_futex = FUTEX_INITIALIZER;

link_t fs_head;

/** Verify the VFS info structure.

 *

 * @param info      Info structure to be verified.

 *

 * @return      Non-zero if the info structure is sane, zero otherwise.

 */

static bool vfs_info_sane(vfs_info_t *info)

{

    int i;

    /*

     * Check if the name is non-empty and is composed solely of ASCII

     * characters [a-z]+[a-z0-9_-]*.

     */

    if (!islower(info->name[0])) {

        dprintf("The name doesn't start with a lowercase character.\n");

        return false;

    }

    for (i = 1; i < FS_NAME_MAXLEN; i++) {

        if (!(islower(info->name[i]) || isdigit(info->name[i])) &&

            (info->name[i] != '-') && (info->name[i] != '_')) {

            if (info->name[i] == '\0') {

                break;

            } else {

                dprintf("The name contains illegal "

                    "characters.\n");

                return false;

            }

        }

    }

    /*

     * Check if the FS implements mandatory VFS operations.

     */

    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_REGISTER)] != VFS_OP_DEFINED) {

        dprintf("Operation VFS_REGISTER not defined by the client.\n");

        return false;

    }

    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] != VFS_OP_DEFINED) {

        dprintf("Operation VFS_MOUNT not defined by the client.\n");

        return false;

    }

    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] != VFS_OP_DEFINED) {

        dprintf("Operation VFS_UNMOUNT not defined by the client.\n");

        return false;

    }

    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] != VFS_OP_DEFINED) {

        dprintf("Operation VFS_LOOKUP not defined by the client.\n");

        return false;

    }

    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_OPEN)] != VFS_OP_DEFINED) {

        dprintf("Operation VFS_OPEN not defined by the client.\n");

        return false;

    }

    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] != VFS_OP_DEFINED) {

        dprintf("Operation VFS_CLOSE not defined by the client.\n");

        return false;

    }

    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_READ)] != VFS_OP_DEFINED) {

        dprintf("Operation VFS_READ not defined by the client.\n");

        return false;

    }

    /*

     * Check if each operation is either not defined, defined or default.

     */

    for (i = VFS_FIRST; i < VFS_LAST; i++) {

        if ((info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_NULL) &&

            (info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_DEFAULT) &&

            (info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_DEFINED)) {

            dprintf("Operation info not understood.\n");

            return false;

        }

    }

    return true;

}

/** VFS_REGISTER protocol function.

 *

 * @param rid       Hash of the call with the request.

 * @param request   Call structure with the request.

 */

static void vfs_register(ipc_callid_t rid, ipc_call_t *request)

{

    ipc_callid_t callid;

    ipc_call_t call;

    int rc;

    size_t size;

    dprintf("Processing VFS_REGISTER request received from %p.\n",

        request->in_phone_hash);

    /*

     * The first call has to be IPC_M_DATA_SEND in which we receive the

     * VFS info structure from the client FS.

     */

    if (!ipc_data_receive(&callid, &call, NULL, &size)) {

        /*

         * The client doesn't obey the same protocol as we do.

         */

        dprintf("Receiving of VFS info failed.\n");

        ipc_answer_fast(callid, EINVAL, 0, 0);

        ipc_answer_fast(rid, EINVAL, 0, 0);

        return;

    }

    dprintf("VFS info received, size = %d\n", size);

    /*

     * We know the size of the VFS info structure. See if the client

     * understands this easy concept too.

     */

    if (size != sizeof(vfs_info_t)) {

        /*

         * The client is sending us something, which cannot be

         * the info structure.

         */

        dprintf("Received VFS info has bad size.\n");

        ipc_answer_fast(callid, EINVAL, 0, 0);

        ipc_answer_fast(rid, EINVAL, 0, 0);

        return;

    }

    fs_info_t *fs_info;

    /*

     * Allocate and initialize a buffer for the fs_info structure.

     */

    fs_info = (fs_info_t *) malloc(sizeof(fs_info_t));

    if (!fs_info) {

        dprintf("Could not allocate memory for FS info.\n");

        ipc_answer_fast(callid, ENOMEM, 0, 0);

        ipc_answer_fast(rid, ENOMEM, 0, 0);

        return;

    }

    link_initialize(&fs_info->fs_link);

    rc = ipc_data_deliver(callid, &call, &fs_info->vfs_info, size);

    if (rc != EOK) {

        dprintf("Failed to deliver the VFS info into our AS, rc=%d.\n",

            rc);

        free(fs_info);

        ipc_answer_fast(callid, rc, 0, 0);

        ipc_answer_fast(rid, rc, 0, 0);

        return;

    }

    dprintf("VFS info delivered.\n");

    if (!vfs_info_sane(&fs_info->vfs_info)) {

        free(fs_info);

        ipc_answer_fast(callid, EINVAL, 0, 0);

        ipc_answer_fast(rid, EINVAL, 0, 0);

        return;

    }

    futex_down(&fs_head_futex);

    /*

     * Check for duplicit registrations.

     */

    link_t *cur;

    for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {

        fs_info_t *fi = list_get_instance(cur, fs_info_t,

            fs_link);

        /* TODO: replace strcmp with strncmp once we have it */

        if (strcmp(fs_info->vfs_info.name, fi->vfs_info.name) == 0) {

            /*

             * We already register a fs like this.

             */

            dprintf("FS is already registered.\n");

            futex_up(&fs_head_futex);

            free(fs_info);

            ipc_answer_fast(callid, EEXISTS, 0, 0);

            ipc_answer_fast(rid, EEXISTS, 0, 0);

            return;

        }

    }

    /*

     * Add fs_info to the list of registered FS's.

     */

    dprintf("Adding FS into the registered list.\n");

    list_append(&fs_info->fs_link, &fs_head);

    /*

     * ACK receiving a properly formatted, non-duplicit vfs_info.

     */

    ipc_answer_fast(callid, EOK, 0, 0);

    /*

     * Now we want the client to send us the IPC_M_CONNECT_TO_ME call so

     * that a callback connection is created and we have a phone through

     * which to forward VFS requests to it.

     */

    callid = async_get_call(&call);

    if (IPC_GET_METHOD(call) != IPC_M_CONNECT_TO_ME) {

        dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));

        list_remove(&fs_info->fs_link);

        futex_up(&fs_head_futex);

        free(fs_info);

        ipc_answer_fast(callid, EINVAL, 0, 0);

        ipc_answer_fast(rid, EINVAL, 0, 0);

        return;

    }

    fs_info->phone = IPC_GET_ARG3(call);

    ipc_answer_fast(callid, EOK, 0, 0);

    dprintf("Callback connection to FS created.\n");

    futex_up(&fs_head_futex);

    /*

     * That was it. The FS has been registered.

     */

    ipc_answer_fast(rid, EOK, 0, 0);

    dprintf("\"%s\" filesystem successfully registered.\n",

        fs_info->vfs_info.name);

}