package main

/*
#include <string.h>
typedef enum {
  PADDLE_ELEMENT_TYPE_INT32   = 0,
  PADDLE_ELEMENT_TYPE_UINT32  = 1,
  PADDLE_ELEMENT_TYPE_INT64   = 2,
  PADDLE_ELEMENT_TYPE_UINT64  = 3,
  PADDLE_ELEMENT_TYPE_FLOAT32 = 4,
  PADDLE_ELEMENT_TYPE_FLOAT64 = 5,
} paddle_element_type;

typedef struct {
  char*               name;
  paddle_element_type element_type;
  unsigned char*      content;
  int                 content_len;
} paddle_parameter, paddle_gradient;

typedef int paddle_pserver_client;
#define PSERVER_ERROR -1
#define PSERVER_OK 0
*/
import "C"

import (
	"log"
	"strings"
	"sync"
	"unsafe"

	"github.com/PaddlePaddle/Paddle/go/pserver"
)

var nullPtr = unsafe.Pointer(uintptr(0))
var mu sync.Mutex
var handleMap = make(map[C.paddle_pserver_client]*pserver.Client)
var curHandle C.paddle_pserver_client

func add(c *pserver.Client) C.paddle_pserver_client {
	mu.Lock()
	defer mu.Unlock()
	client := curHandle
	curHandle++
	handleMap[client] = c
	return client
}

func get(client C.paddle_pserver_client) *pserver.Client {
	mu.Lock()
	defer mu.Unlock()
	return handleMap[client]
}

func remove(client C.paddle_pserver_client) *pserver.Client {
	mu.Lock()
	defer mu.Unlock()
	h := handleMap[client]
	delete(handleMap, client)
	return h
}

func cArrayToSlice(p unsafe.Pointer, len int) []byte {
	if p == nullPtr {
		return nil
	}

	// create a Go clice backed by a C array, reference:
	// https://github.com/golang/go/wiki/cgo#turning-c-arrays-into-go-slices
	//
	// Go garbage collector will not interact with this data, need
	// to be freed properly.
	return (*[1 << 30]byte)(p)[:len:len]
}

type selector bool

func (s selector) Select() bool {
	return bool(s)
}

type lister []pserver.Server

func (l lister) List() []pserver.Server {
	return l
}

//export paddle_new_pserver_client
func paddle_new_pserver_client(addrs *C.char, selected int) C.paddle_pserver_client {
	a := C.GoString(addrs)
	as := strings.Split(a, ",")
	servers := make([]pserver.Server, len(as))
	for i := range as {
		servers[i].Index = i
		servers[i].Addr = as[i]
	}
	c := pserver.NewClient(lister(servers), len(as), selector(selected != 0))
	return add(c)
}

//export paddle_new_etcd_pserver_client
func paddle_new_etcd_pserver_client(etcd_addr *C.char) C.paddle_pserver_client {
	// TODO(helin): fault tolerant pserver client using etcd.
	panic("not implemented.")
}

//export paddle_pserver_client_release
func paddle_pserver_client_release(client C.paddle_pserver_client) {
	remove(client)
}

//export paddle_begin_init_params
func paddle_begin_init_params(client C.paddle_pserver_client) C.int {
	c := get(client)
	if selected := c.BeginInitParams(); selected {
		return 1
	}
	return C.PSERVER_OK
}

//export paddle_init_param
func paddle_init_param(client C.paddle_pserver_client, param C.paddle_parameter, param_config unsafe.Pointer, config_len C.int) C.int {
	et := pserver.ElementType(param.element_type)
	name := C.GoString(param.name)
	content := cArrayToSlice(unsafe.Pointer(param.content), int(param.content_len))
	pc := pserver.ParameterWithConfig{
		Param:  pserver.Parameter{Name: name, ElementType: et, Content: content},
		Config: cArrayToSlice(param_config, int(config_len)),
	}
	c := get(client)
	err := c.InitParam(pc)

	if err != nil {
		if err.Error() == pserver.AlreadyInitialized {
			log.Printf("parameter %s already initialized, treat paddle_init_param as sucessful.\n", name)
			return C.PSERVER_OK
		}
		log.Println(err)
		return C.PSERVER_ERROR
	}

	return C.PSERVER_OK
}

//export paddle_finish_init_params
func paddle_finish_init_params(client C.paddle_pserver_client) C.int {
	c := get(client)
	err := c.FinishInitParams()
	if err != nil {
		if err.Error() == pserver.AlreadyInitialized {
			log.Println("parameters already initialized, treat paddle_finish_init_params as sucessful.")
			return C.PSERVER_OK
		}

		log.Println(err)
		return C.PSERVER_ERROR
	}

	return C.PSERVER_OK
}

//export paddle_send_grads
func paddle_send_grads(client C.paddle_pserver_client, grads **C.paddle_gradient, total C.int) C.int {
	var gs []pserver.Gradient
	for i := 0; i < int(total); i++ {
		grad := *(**C.paddle_gradient)(unsafe.Pointer((uintptr(unsafe.Pointer(grads)) + uintptr(i)*unsafe.Sizeof(*grads))))
		et := pserver.ElementType(grad.element_type)
		name := C.GoString(grad.name)
		content := cArrayToSlice(unsafe.Pointer(grad.content), int(grad.content_len))
		gs = append(gs, pserver.Gradient{Name: name, ElementType: et, Content: content})
	}

	c := get(client)
	err := c.SendGrads(gs)
	if err != nil {
		log.Println(err)
		return C.PSERVER_ERROR
	}

	return C.PSERVER_OK
}

//export paddle_get_params
func paddle_get_params(client C.paddle_pserver_client, dst **C.paddle_parameter, total C.int) C.int {
	var ns []string
	for i := 0; i < int(total); i++ {
		param := *(**C.paddle_parameter)(unsafe.Pointer((uintptr(unsafe.Pointer(dst)) + uintptr(i)*unsafe.Sizeof(*dst))))
		ns = append(ns, C.GoString(param.name))
	}
	c := get(client)
	ps, err := c.GetParams(ns)
	if err != nil {
		log.Println(err)
		return C.PSERVER_ERROR
	}

	if len(ps) != len(ns) {
		pn := make([]string, len(ps))
		for i, p := range ps {
			pn[i] = p.Name
		}
		log.Printf("pserver returned wrong number of parameters. Requested: %s, returned: %s.\n", strings.Join(pn, ", "), strings.Join(ns, ", "))
		return C.PSERVER_ERROR
	}

	for i := range ps {
		if ns[i] != ps[i].Name {
			pn := make([]string, len(ps))
			for i, p := range ps {
				pn[i] = p.Name
			}
			log.Printf("pserver returned wrong parameters, or not in requested order. Requested: %s, returned: %s.\n", strings.Join(pn, ", "), strings.Join(ns, ", "))
			return C.PSERVER_ERROR
		}
	}

	for i := 0; i < int(total); i++ {
		p := ps[i]
		param := *(**C.paddle_parameter)(unsafe.Pointer((uintptr(unsafe.Pointer(dst)) + uintptr(i)*unsafe.Sizeof(*dst))))

		if unsafe.Pointer(param) == nullPtr {
			log.Println("must pre-allocate parameter.")
			return C.PSERVER_ERROR
		}

		if unsafe.Pointer(param.content) != nullPtr {
			if int(param.content_len) != len(p.Content) {
				log.Printf("the pre-allocated content len does not match parameter content len. Pre-allocated len: %d, returned len: %d", param.content_len, len(p.Content))
				return C.PSERVER_ERROR
			}
		}

		C.memcpy(unsafe.Pointer(param.content), unsafe.Pointer(&p.Content[0]), C.size_t(len(p.Content)))
		param.content_len = C.int(len(p.Content))
		param.element_type = C.paddle_element_type(p.ElementType)
	}

	return C.PSERVER_OK
}

//export paddle_save_model
func paddle_save_model(client C.paddle_pserver_client, path *C.char) C.int {
	p := C.GoString(path)
	c := get(client)
	err := c.Save(p)
	if err != nil {
		log.Println(err)
		return C.PSERVER_ERROR
	}

	return C.PSERVER_OK
}

func main() {} // Required but ignored