// Copyright (c) Vitaliy Filippov, 2019+
// License: VNPL-1.1 (see README.md for details)
//
// NFS proxy over VitastorKV database - CREATE, MKDIR, SYMLINK, MKNOD

#include <sys/time.h>

#include "str_util.h"
#include "nfs_proxy.h"
#include "nfs_kv.h"

void allocate_new_id(nfs_proxy_t *proxy, pool_id_t pool_id, std::function<void(int res, uint64_t new_id)> cb)
{
    auto & idgen = proxy->kvfs->idgen[pool_id];
    if (idgen.unallocated_ids.size())
    {
        auto new_id = idgen.unallocated_ids.back();
        idgen.unallocated_ids.pop_back();
        cb(0, INODE_WITH_POOL(pool_id, new_id));
        return;
    }
    else if (idgen.next_id <= idgen.allocated_id)
    {
        idgen.next_id++;
        cb(0, INODE_WITH_POOL(pool_id, idgen.next_id-1));
        return;
    }
    // FIXME: Maybe allow FS and block volumes to cohabitate in the same pool, but with different ID ranges
    else if (idgen.next_id >= ((uint64_t)1 << (64-POOL_ID_BITS)))
    {
        cb(-ENOSPC, 0);
        return;
    }
    proxy->db->get((pool_id ? "id"+std::to_string(pool_id) : "id"), [=](int res, const std::string & prev_str)
    {
        auto & idgen = proxy->kvfs->idgen[pool_id];
        if (res < 0 && res != -ENOENT)
        {
            cb(res, 0);
            return;
        }
        uint64_t prev_val = stoull_full(prev_str);
        if (prev_val >= ((uint64_t)1 << (64-POOL_ID_BITS)))
        {
            cb(-ENOSPC, 0);
            return;
        }
        if (prev_val < idgen.min_id)
        {
            prev_val = idgen.min_id;
        }
        uint64_t new_val = prev_val + proxy->kvfs->id_alloc_batch_size;
        if (new_val >= proxy->kvfs->fs_inode_count)
        {
            new_val = proxy->kvfs->fs_inode_count;
        }
        if (!pool_id && res == -ENOENT)
        {
            proxy->db->set("version", "1", [](int){});
        }
        proxy->db->set((pool_id ? "id"+std::to_string(pool_id) : "id"), std::to_string(new_val), [=](int res)
        {
            if (res == -EAGAIN)
            {
                // CAS failure - retry
                allocate_new_id(proxy, pool_id, cb);
            }
            else if (res < 0)
            {
                cb(res, 0);
            }
            else
            {
                auto & idgen = proxy->kvfs->idgen[pool_id];
                idgen.next_id = prev_val+2;
                idgen.allocated_id = new_val;
                cb(0, INODE_WITH_POOL(pool_id, prev_val+1));
            }
        }, [prev_val](int res, const std::string & value)
        {
            // FIXME: Allow to modify value from CAS callback? ("update" query)
            return res < 0 || stoull_full(value) == prev_val;
        });
    });
}

struct kv_create_state
{
    nfs_client_t *self = NULL;
    rpc_op_t *rop = NULL;
    bool exclusive = false;
    uint64_t verf = 0;
    uint64_t dir_ino = 0;
    std::string filename;
    // state
    int res = 0;
    pool_id_t pool_id = 0;
    uint64_t new_id = 0;
    json11::Json::object attrobj;
    json11::Json attrs;
    std::string direntry_text;
    uint64_t dup_ino = 0;
    std::function<void(int res)> cb;
};

static void kv_continue_create(kv_create_state *st, int state)
{
    if (state == 0)      {}
    else if (state == 1) goto resume_1;
    else if (state == 2) goto resume_2;
    else if (state == 3) goto resume_3;
    else if (state == 4) goto resume_4;
    else if (state == 5) goto resume_5;
    else if (state == 6) goto resume_6;
    if (st->self->parent->trace)
        fprintf(stderr, "[%d] CREATE %ju/%s ATTRS %s\n", st->self->nfs_fd, st->dir_ino, st->filename.c_str(), json11::Json(st->attrobj).dump().c_str());
    if (st->filename == "" || st->filename.find("/") != std::string::npos)
    {
        auto cb = std::move(st->cb);
        cb(-EINVAL);
        return;
    }
    st->attrobj["ctime"] = nfstime_now_str();
    if (st->attrobj.find("mtime") == st->attrobj.end())
        st->attrobj["mtime"] = st->attrobj["ctime"];
    if (st->rop->auth_sys.uid && st->attrobj.find("uid") == st->attrobj.end())
        st->attrobj["uid"] = (uint64_t)st->rop->auth_sys.uid;
    if (st->rop->auth_sys.gid && st->attrobj.find("gid") == st->attrobj.end())
        st->attrobj["gid"] = (uint64_t)st->rop->auth_sys.gid;
    st->attrs = std::move(st->attrobj);
    if (st->self->parent->enforce_perms)
    {
        // Check that the directory is actually a directory and is accessible
        kv_read_inode(st->self->parent, st->dir_ino, [st](int res, const std::string & value, json11::Json attrs)
        {
            st->res = res == 0 ? (attrs["type"].string_value() == "dir"
                ? (kv_is_accessible(st->rop->auth_sys, attrs, ACCESS3_MODIFY) ? 0 : -EACCES) : -ENOTDIR) : res;
            kv_continue_create(st, 6);
        }, true/*allow_cache*/);
        return;
resume_6:
        if (st->res < 0)
        {
            auto cb = std::move(st->cb);
            cb(st->res);
            return;
        }
    }
resume_1:
    // Generate inode ID
    // Directories and special files don't need pool
    st->pool_id = kv_map_type(st->attrs["type"].string_value()) == NF3REG
        ? st->self->parent->default_pool_id
        : 0;
    allocate_new_id(st->self->parent, st->pool_id, [st](int res, uint64_t new_id)
    {
        st->res = res;
        st->new_id = new_id;
        kv_continue_create(st, 2);
    });
    return;
resume_2:
    if (st->res < 0)
    {
        auto cb = std::move(st->cb);
        cb(st->res);
        return;
    }
    st->self->parent->kvfs->write_inode(st->new_id, st->attrs, false, [st](int res)
    {
        st->res = res;
        kv_continue_create(st, 3);
    }, [](int res, const std::string & value)
    {
        return res == -ENOENT;
    });
    return;
resume_3:
    if (st->res == -EAGAIN)
    {
        // Inode ID generator failure - retry
        goto resume_1;
    }
    if (st->res < 0)
    {
        auto cb = std::move(st->cb);
        cb(st->res);
        return;
    }
    {
        auto direntry = json11::Json::object{ { "ino", st->new_id } };
        if (st->attrs["type"].string_value() == "dir")
        {
            direntry["type"] = "dir";
        }
        st->direntry_text = json11::Json(direntry).dump().c_str();
    }
    // Set direntry
    st->dup_ino = 0;
    st->self->parent->db->set(kv_direntry_key(st->dir_ino, st->filename), st->direntry_text, [st](int res)
    {
        st->res = res;
        kv_continue_create(st, 4);
    }, [st](int res, const std::string & value)
    {
        // CAS compare - check that the key doesn't exist
        if (res == 0)
        {
            std::string err;
            auto direntry = json11::Json::parse(value, err);
            if (err != "")
            {
                fprintf(stderr, "Invalid JSON in direntry %s = %s: %s, overwriting\n",
                    kv_direntry_key(st->dir_ino, st->filename).c_str(), value.c_str(), err.c_str());
                return true;
            }
            if (st->exclusive && direntry["verf"].uint64_value() == st->verf)
            {
                st->dup_ino = direntry["ino"].uint64_value();
                return false;
            }
            return false;
        }
        return true;
    });
    return;
resume_4:
    if (st->res == -EAGAIN)
    {
        // Direntry already exists
        st->self->parent->db->del(kv_inode_key(st->new_id), [st](int res)
        {
            st->res = res;
            kv_continue_create(st, 5);
        });
        return;
resume_5:
        if (st->res < 0)
        {
            fprintf(stderr, "failed to delete duplicate inode %ju left from create %s (code %d)\n", st->new_id, strerror(-st->res), st->res);
        }
        else
        {
            auto & idgen = st->self->parent->kvfs->idgen[INODE_POOL(st->new_id)];
            idgen.unallocated_ids.push_back(INODE_NO_POOL(st->new_id));
        }
        if (st->dup_ino)
        {
            // Successfully created by the previous "exclusive" request
            st->new_id = st->dup_ino;
        }
        st->res = st->dup_ino ? 0 : -EEXIST;
    }
    if (!st->res)
    {
        st->self->parent->kvfs->touch_queue.insert(st->dir_ino);
    }
    auto cb = std::move(st->cb);
    cb(st->res);
}

static void kv_create_setattr(json11::Json::object & attrobj, sattr3 & sattr)
{
    if (sattr.mode.set_it)
        attrobj["mode"] = (uint64_t)sattr.mode.mode;
    if (sattr.uid.set_it)
        attrobj["uid"] = (uint64_t)sattr.uid.uid;
    if (sattr.gid.set_it)
        attrobj["gid"] = (uint64_t)sattr.gid.gid;
    if (sattr.atime.set_it)
        attrobj["atime"] = nfstime_to_str(sattr.atime.atime);
    if (sattr.mtime.set_it)
        attrobj["mtime"] = nfstime_to_str(sattr.mtime.mtime);
}

template<class T, class Tok> static void kv_create_reply(kv_create_state *st, int res)
{
    T *reply = (T*)st->rop->reply;
    if (res < 0)
    {
        *reply = (T){ .status = vitastor_nfs_map_err(-res) };
    }
    else
    {
        *reply = (T){
            .status = NFS3_OK,
            .resok = (Tok){
                .obj = {
                    .handle_follows = 1,
                    .handle = xdr_copy_string(st->rop->xdrs, kv_fh(st->new_id)),
                },
                .obj_attributes = {
                    .attributes_follow = 1,
                    .attributes = get_kv_attributes(st->self->parent, st->new_id, st->attrs),
                },
            },
        };
    }
    rpc_queue_reply(st->rop);
    delete st;
}

int kv_nfs3_create_proc(void *opaque, rpc_op_t *rop)
{
    kv_create_state *st = new kv_create_state;
    st->self = (nfs_client_t*)opaque;
    st->rop = rop;
    auto args = (CREATE3args*)rop->request;
    st->exclusive = args->how.mode == NFS_EXCLUSIVE;
    st->verf = st->exclusive ? *(uint64_t*)&args->how.verf : 0;
    st->dir_ino = kv_fh_inode(args->where.dir);
    st->filename = args->where.name;
    if (args->how.mode == NFS_EXCLUSIVE)
    {
        st->attrobj["verf"] = *(uint64_t*)&args->how.verf;
    }
    else if (args->how.mode == NFS_UNCHECKED)
    {
        kv_create_setattr(st->attrobj, args->how.obj_attributes);
        if (args->how.obj_attributes.size.set_it)
        {
            st->attrobj["size"] = (uint64_t)args->how.obj_attributes.size.size;
            st->attrobj["empty"] = true;
        }
    }
    st->cb = [st](int res) { kv_create_reply<CREATE3res, CREATE3resok>(st, res); };
    kv_continue_create(st, 0);
    return 1;
}

int kv_nfs3_mkdir_proc(void *opaque, rpc_op_t *rop)
{
    kv_create_state *st = new kv_create_state;
    st->self = (nfs_client_t*)opaque;
    st->rop = rop;
    auto args = (MKDIR3args*)rop->request;
    st->dir_ino = kv_fh_inode(args->where.dir);
    st->filename = args->where.name;
    st->attrobj["type"] = "dir";
    st->attrobj["parent_ino"] = st->dir_ino;
    kv_create_setattr(st->attrobj, args->attributes);
    st->cb = [st](int res) { kv_create_reply<MKDIR3res, MKDIR3resok>(st, res); };
    kv_continue_create(st, 0);
    return 1;
}

int kv_nfs3_symlink_proc(void *opaque, rpc_op_t *rop)
{
    kv_create_state *st = new kv_create_state;
    st->self = (nfs_client_t*)opaque;
    st->rop = rop;
    auto args = (SYMLINK3args*)rop->request;
    st->dir_ino = kv_fh_inode(args->where.dir);
    st->filename = args->where.name;
    st->attrobj["type"] = "link";
    st->attrobj["symlink"] = (std::string)args->symlink.symlink_data;
    kv_create_setattr(st->attrobj, args->symlink.symlink_attributes);
    st->cb = [st](int res) { kv_create_reply<SYMLINK3res, SYMLINK3resok>(st, res); };
    kv_continue_create(st, 0);
    return 1;
}

int kv_nfs3_mknod_proc(void *opaque, rpc_op_t *rop)
{
    kv_create_state *st = new kv_create_state;
    st->self = (nfs_client_t*)opaque;
    st->rop = rop;
    auto args = (MKNOD3args*)rop->request;
    st->dir_ino = kv_fh_inode(args->where.dir);
    st->filename = args->where.name;
    if (args->what.type == NF3CHR || args->what.type == NF3BLK)
    {
        st->attrobj["type"] = (args->what.type == NF3CHR ? "chr" : "blk");
        st->attrobj["major"] = (uint64_t)args->what.chr_device.spec.specdata1;
        st->attrobj["minor"] = (uint64_t)args->what.chr_device.spec.specdata2;
        kv_create_setattr(st->attrobj, args->what.chr_device.dev_attributes);
    }
    else if (args->what.type == NF3SOCK || args->what.type == NF3FIFO)
    {
        st->attrobj["type"] = (args->what.type == NF3SOCK ? "sock" : "fifo");
        kv_create_setattr(st->attrobj, args->what.sock_attributes);
    }
    else
    {
        *(MKNOD3res*)rop->reply = (MKNOD3res){ .status = NFS3ERR_INVAL };
        rpc_queue_reply(rop);
        delete st;
        return 0;
    }
    st->cb = [st](int res) { kv_create_reply<MKNOD3res, MKNOD3resok>(st, res); };
    kv_continue_create(st, 0);
    return 1;
}
