package rados

// #cgo LDFLAGS: -lrados
// #include <stdlib.h>
// #include <rados/librados.h>
import "C"

import "unsafe"
import "bytes"
import "reflect"

// ClusterStat represents Ceph cluster statistics.
type ClusterStat struct {
    Kb uint64
    Kb_used uint64
    Kb_avail uint64
    Num_objects uint64
}

// Conn is a connection handle to a Ceph cluster.
type Conn struct {
    cluster C.rados_t
}

// PingMonitor sends a ping to a monitor and returns the reply.
func (c *Conn) PingMonitor(id string) (string, error) {
    c_id := C.CString(id)
    defer C.free(unsafe.Pointer(c_id))

    var strlen C.size_t
    var strout *C.char

    ret := C.rados_ping_monitor(c.cluster, c_id, &strout, &strlen)
    defer C.rados_buffer_free(strout)

    if ret == 0 {
        reply := C.GoStringN(strout, (C.int)(strlen))
        return reply, nil
    } else {
        return "", RadosError(int(ret))
    }
}

// Connect establishes a connection to a RADOS cluster. It returns an error,
// if any.
func (c *Conn) Connect() error {
    ret := C.rados_connect(c.cluster)
    if ret == 0 {
        return nil
    } else {
        return RadosError(int(ret))
    }
}

// Shutdown disconnects from the cluster.
func (c *Conn) Shutdown() {
    C.rados_shutdown(c.cluster)
}

// ReadConfigFile configures the connection using a Ceph configuration file.
func (c *Conn) ReadConfigFile(path string) error {
    c_path := C.CString(path)
    defer C.free(unsafe.Pointer(c_path))
    ret := C.rados_conf_read_file(c.cluster, c_path)
    if ret == 0 {
        return nil
    } else {
        return RadosError(int(ret))
    }
}

// ReadDefaultConfigFile configures the connection using a Ceph configuration
// file located at default locations.
func (c *Conn) ReadDefaultConfigFile() error {
    ret := C.rados_conf_read_file(c.cluster, nil)
    if ret == 0 {
        return nil
    } else {
        return RadosError(int(ret))
    }
}

func (c *Conn) OpenIOContext(pool string) (*IOContext, error) {
    c_pool := C.CString(pool)
    defer C.free(unsafe.Pointer(c_pool))
    ioctx := &IOContext{}
    ret := C.rados_ioctx_create(c.cluster, c_pool, &ioctx.ioctx)
    if ret == 0 {
        return ioctx, nil
    } else {
        return nil, RadosError(int(ret))
    }
}

// ListPools returns the names of all existing pools.
func (c *Conn) ListPools() (names []string, err error) {
    buf := make([]byte, 4096)
    for {
        ret := int(C.rados_pool_list(c.cluster,
            (*C.char)(unsafe.Pointer(&buf[0])), C.size_t(len(buf))))
        if ret < 0 {
            return nil, RadosError(int(ret))
        }

        if ret > len(buf) {
            buf = make([]byte, ret)
            continue
        }

        tmp := bytes.SplitAfter(buf[:ret-1], []byte{0})
        for _, s := range tmp {
            if len(s) > 0 {
                name := C.GoString((*C.char)(unsafe.Pointer(&s[0])))
                names = append(names, name)
            }
        }

        return names, nil
    }
}

// SetConfigOption sets the value of the configuration option identified by
// the given name.
func (c *Conn) SetConfigOption(option, value string) error {
    c_opt, c_val := C.CString(option), C.CString(value)
    defer C.free(unsafe.Pointer(c_opt))
    defer C.free(unsafe.Pointer(c_val))
    ret := C.rados_conf_set(c.cluster, c_opt, c_val)
    if ret < 0 {
        return RadosError(int(ret))
    } else {
        return nil
    }
}

// GetConfigOption returns the value of the Ceph configuration option
// identified by the given name.
func (c *Conn) GetConfigOption(name string) (value string, err error) {
    buf := make([]byte, 4096)
    c_name := C.CString(name)
    defer C.free(unsafe.Pointer(c_name))
    ret := int(C.rados_conf_get(c.cluster, c_name,
        (*C.char)(unsafe.Pointer(&buf[0])), C.size_t(len(buf))))
    // FIXME: ret may be -ENAMETOOLONG if the buffer is not large enough. We
    // can handle this case, but we need a reliable way to test for
    // -ENAMETOOLONG constant. Will the syscall/Errno stuff in Go help?
    if ret == 0 {
        value = C.GoString((*C.char)(unsafe.Pointer(&buf[0])))
        return value, nil
    } else {
        return "", RadosError(ret)
    }
}

// WaitForLatestOSDMap blocks the caller until the latest OSD map has been
// retrieved.
func (c *Conn) WaitForLatestOSDMap() error {
    ret := C.rados_wait_for_latest_osdmap(c.cluster)
    if ret < 0 {
        return RadosError(int(ret))
    } else {
        return nil
    }
}

// GetClusterStat returns statistics about the cluster associated with the
// connection.
func (c *Conn) GetClusterStats() (stat ClusterStat, err error) {
    c_stat := C.struct_rados_cluster_stat_t{}
    ret := C.rados_cluster_stat(c.cluster, &c_stat)
    if ret < 0 {
        return ClusterStat{}, RadosError(int(ret))
    } else {
        return ClusterStat{
            Kb: uint64(c_stat.kb),
            Kb_used: uint64(c_stat.kb_used),
            Kb_avail: uint64(c_stat.kb_avail),
            Num_objects: uint64(c_stat.num_objects),
        }, nil
    }
}

// ParseCmdLineArgs configures the connection from command line arguments.
func (c *Conn) ParseCmdLineArgs(args []string) error {
    // add an empty element 0 -- Ceph treats the array as the actual contents
    // of argv and skips the first element (the executable name)
    argc := C.int(len(args) + 1)
    argv := make([]*C.char, argc)

    // make the first element a string just in case it is ever examined
    argv[0] = C.CString("placeholder")
    defer C.free(unsafe.Pointer(argv[0]))

    for i, arg := range args {
        argv[i+1] = C.CString(arg)
        defer C.free(unsafe.Pointer(argv[i+1]))
    }

    ret := C.rados_conf_parse_argv(c.cluster, argc, &argv[0])
    if ret < 0 {
        return RadosError(int(ret))
    } else {
        return nil
    }
}

// ParseDefaultConfigEnv configures the connection from the default Ceph
// environment variable(s).
func (c *Conn) ParseDefaultConfigEnv() error {
    ret := C.rados_conf_parse_env(c.cluster, nil)
    if ret == 0 {
        return nil
    } else {
        return RadosError(int(ret))
    }
}

// GetFSID returns the fsid of the cluster as a hexadecimal string. The fsid
// is a unique identifier of an entire Ceph cluster.
func (c *Conn) GetFSID() (fsid string, err error) {
    buf := make([]byte, 37)
    ret := int(C.rados_cluster_fsid(c.cluster,
        (*C.char)(unsafe.Pointer(&buf[0])), C.size_t(len(buf))))
    // FIXME: the success case isn't documented correctly in librados.h
    if ret == 36 {
        fsid = C.GoString((*C.char)(unsafe.Pointer(&buf[0])))
        return fsid, nil
    } else {
        return "", RadosError(int(ret))
    }
}

// GetInstanceID returns a globally unique identifier for the cluster
// connection instance.
func (c *Conn) GetInstanceID() uint64 {
    // FIXME: are there any error cases for this?
    return uint64(C.rados_get_instance_id(c.cluster))
}

// MakePool creates a new pool with default settings.
func (c *Conn) MakePool(name string) error {
    c_name :=C.CString(name)
    defer C.free(unsafe.Pointer(c_name))
    ret := int(C.rados_pool_create(c.cluster, c_name))
    if ret == 0 {
        return nil
    } else {
        return RadosError(ret)
    }
}

// DeletePool deletes a pool and all the data inside the pool.
func (c *Conn) DeletePool(name string) error {
    c_name :=C.CString(name)
    defer C.free(unsafe.Pointer(c_name))
    ret := int(C.rados_pool_delete(c.cluster, c_name))
    if ret == 0 {
        return nil
    } else {
        return RadosError(ret)
    }
}

// MonCommand sends a command to one of the monitors
func (c *Conn) MonCommand(args []byte) (buffer []byte, info string, err error) {
	argv := make([]*C.char, len(args))
	for i, _ := range args {
		argv[i] = (*C.char)(unsafe.Pointer(&args[i]))
	}

	var (
		outs, outbuf       *C.char
		outslen, outbuflen C.size_t
	)
	inbuf := C.CString("")
	defer C.free(unsafe.Pointer(inbuf))

	ret := C.rados_mon_command(c.cluster,
		&argv[0], C.size_t(len(args)),
		inbuf,       // inbuf
		C.size_t(0), // length inbuf
		&outbuf,     // actual data
		&outbuflen,  // len data
		&outs,       // report largenumber
		&outslen)

	if outslen > 0 {
		info = C.GoStringN(outs, C.int(outslen))
		//C.rados_buffer_free(outs)
		C.free(unsafe.Pointer(outs))
	}
	if outbuflen > 0 {
		length := int(outbuflen)
		hdr := reflect.SliceHeader{
			Data: uintptr(unsafe.Pointer(outbuf)),
			Len: length,
			Cap: length,
		}
		// now goSlice is a Go slice backed by the C array
		buffer = *(*[]byte)(unsafe.Pointer(&hdr))
	}
	if ret != 0 {
		err = RadosError(int(ret))
		return nil, info, err
		// info might contain hints as to why the error happened
	}

	return
}