package main

import (
	"fmt"
	"time"

	"google.golang.org/protobuf/proto"
	pb "powerpod/gotool/pb"
)

// hostConn is the UART or BLE host transport used by CLI commands.
type hostConn interface {
	exchangePayload(payload []byte, cmdName string) ([]byte, error)
	exchange(cmdID byte, cmdName string) ([]byte, error)
	Close() error
}

// optional stream source (BLE only)
type hostStreamConn interface {
	hostConn
	// NextStreamTick waits for a BLE_STREAM_TICK payload (type byte + protobuf).
	NextStreamTick(timeout time.Duration) ([]byte, error)
}

func hostGetVersion(h hostConn) (*pb.VersionResponse, error) {
	payload, err := h.exchange(byte(pb.MessageType_VERSION), "VERSION")
	if err != nil {
		return nil, err
	}
	return decodeVersionPayload(payload)
}

func hostListClients(h hostConn) ([]*pb.ClientInfo, error) {
	payload, err := h.exchange(byte(pb.MessageType_CLIENT_INFO), "CLIENT_INFO")
	if err != nil {
		return nil, err
	}
	return decodeClientsPayload(payload)
}

func hostReadCacheStatus(h hostConn) (*pb.CacheStatusResponse, error) {
	payload, err := h.exchange(byte(pb.MessageType_CACHE_STATUS), "CACHE_STATUS")
	if err != nil {
		return nil, err
	}
	return decodeCacheStatusPayload(payload)
}

func hostAccelStream(h hostConn, req *pb.AccelStreamRequest) (*pb.AccelStreamResponse, error) {
	msg := &pb.UartMessage{
		Type: pb.MessageType_ACCEL_STREAM,
		Payload: &pb.UartMessage_AccelStreamRequest{
			AccelStreamRequest: req,
		},
	}
	body, err := proto.Marshal(msg)
	if err != nil {
		return nil, fmt.Errorf("encode: %w", err)
	}
	payload := append([]byte{byte(pb.MessageType_ACCEL_STREAM)}, body...)
	respPayload, err := h.exchangePayload(payload, "ACCEL_STREAM")
	if err != nil {
		return nil, err
	}
	var respMsg pb.UartMessage
	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
		return nil, fmt.Errorf("decode: %w", err)
	}
	r := respMsg.GetAccelStreamResponse()
	if r == nil {
		return nil, fmt.Errorf("missing accel_stream_response")
	}
	return r, nil
}

func hostFindMe(h hostConn, clientID uint32) error {
	msg := &pb.UartMessage{
		Type: pb.MessageType_FIND_ME,
		Payload: &pb.UartMessage_EspnowFindMeRequest{
			EspnowFindMeRequest: &pb.EspNowFindMeRequest{ClientId: clientID},
		},
	}
	body, err := proto.Marshal(msg)
	if err != nil {
		return fmt.Errorf("encode: %w", err)
	}
	payload := append([]byte{byte(pb.MessageType_FIND_ME)}, body...)
	respPayload, err := h.exchangePayload(payload, "FIND_ME")
	if err != nil {
		return err
	}
	var respMsg pb.UartMessage
	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
		return fmt.Errorf("decode: %w", err)
	}
	r := respMsg.GetEspnowFindMeResponse()
	if r == nil {
		return fmt.Errorf("missing espnow_find_me_response")
	}
	if !r.GetSuccess() {
		return fmt.Errorf("find-me rejected (client_id=%d)", r.GetClientId())
	}
	return nil
}

func hostRestart(h hostConn, clientID uint32) error {
	msg := &pb.UartMessage{
		Type: pb.MessageType_RESTART,
		Payload: &pb.UartMessage_RestartRequest{
			RestartRequest: &pb.RestartRequest{ClientId: clientID},
		},
	}
	body, err := proto.Marshal(msg)
	if err != nil {
		return fmt.Errorf("encode: %w", err)
	}
	payload := append([]byte{byte(pb.MessageType_RESTART)}, body...)
	respPayload, err := h.exchangePayload(payload, "RESTART")
	if err != nil {
		return err
	}
	var respMsg pb.UartMessage
	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
		return fmt.Errorf("decode: %w", err)
	}
	r := respMsg.GetRestartResponse()
	if r == nil {
		return fmt.Errorf("missing restart_response")
	}
	if !r.GetSuccess() {
		return fmt.Errorf("restart rejected (client_id=%d)", r.GetClientId())
	}
	return nil
}

func hostSetLogLevel(h hostConn, write bool, level uint32) (*pb.SetLogLevelResponse, error) {
	msg := &pb.UartMessage{
		Type: pb.MessageType_SET_LOG_LEVEL,
		Payload: &pb.UartMessage_SetLogLevelRequest{
			SetLogLevelRequest: &pb.SetLogLevelRequest{Write: write, Level: level},
		},
	}
	body, err := proto.Marshal(msg)
	if err != nil {
		return nil, fmt.Errorf("encode: %w", err)
	}
	payload := append([]byte{byte(pb.MessageType_SET_LOG_LEVEL)}, body...)
	respPayload, err := h.exchangePayload(payload, "SET_LOG_LEVEL")
	if err != nil {
		return nil, err
	}
	var respMsg pb.UartMessage
	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
		return nil, fmt.Errorf("decode: %w", err)
	}
	r := respMsg.GetSetLogLevelResponse()
	if r == nil {
		return nil, fmt.Errorf("missing set_log_level_response")
	}
	return r, nil
}

func hostInputSendMode(h hostConn, req *pb.InputSendModeRequest) (*pb.InputSendModeResponse, error) {
	msg := &pb.UartMessage{
		Type: pb.MessageType_INPUT_SEND_MODE,
		Payload: &pb.UartMessage_InputSendModeRequest{
			InputSendModeRequest: req,
		},
	}
	body, err := proto.Marshal(msg)
	if err != nil {
		return nil, fmt.Errorf("encode: %w", err)
	}
	payload := append([]byte{byte(pb.MessageType_INPUT_SEND_MODE)}, body...)
	respPayload, err := h.exchangePayload(payload, "INPUT_SEND_MODE")
	if err != nil {
		return nil, err
	}
	var respMsg pb.UartMessage
	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
		return nil, fmt.Errorf("decode: %w", err)
	}
	r := respMsg.GetInputSendModeResponse()
	if r == nil {
		return nil, fmt.Errorf("missing input_send_mode_response")
	}
	return r, nil
}

func hostLedRing(h hostConn, req *pb.LedRingProgressRequest) (*pb.LedRingProgressResponse, error) {
	msg := &pb.UartMessage{
		Type: pb.MessageType_LED_RING,
		Payload: &pb.UartMessage_LedRingProgressRequest{
			LedRingProgressRequest: req,
		},
	}
	body, err := proto.Marshal(msg)
	if err != nil {
		return nil, fmt.Errorf("encode: %w", err)
	}
	payload := append([]byte{byte(pb.MessageType_LED_RING)}, body...)
	respPayload, err := h.exchangePayload(payload, "LED_RING")
	if err != nil {
		return nil, err
	}
	var respMsg pb.UartMessage
	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
		return nil, fmt.Errorf("decode: %w", err)
	}
	r := respMsg.GetLedRingProgressResponse()
	if r == nil {
		return nil, fmt.Errorf("missing led_ring_progress_response")
	}
	return r, nil
}

func hostEchoPing(h hostConn, clientID uint32) (*EchoPingResult, error) {
	t0 := time.Now()
	timestampUs := uint64(t0.UnixMicro())
	req := &pb.EspNowEchoPingRequest{
		ClientId:    clientID,
		TimestampUs: timestampUs,
	}
	msg := &pb.UartMessage{
		Type: pb.MessageType_ESPNOW_ECHO_PING,
		Payload: &pb.UartMessage_EspnowEchoPingRequest{
			EspnowEchoPingRequest: req,
		},
	}
	body, err := proto.Marshal(msg)
	if err != nil {
		return nil, fmt.Errorf("encode: %w", err)
	}
	payload := append([]byte{byte(pb.MessageType_ESPNOW_ECHO_PING)}, body...)
	respPayload, err := h.exchangePayload(payload, "ESPNOW_ECHO_PING")
	if err != nil {
		return nil, err
	}
	rttMs := float64(time.Since(t0).Microseconds()) / 1000.0

	var respMsg pb.UartMessage
	if err := proto.Unmarshal(respPayload[1:], &respMsg); err != nil {
		return nil, fmt.Errorf("decode: %w", err)
	}
	r := respMsg.GetEspnowEchoPingResponse()
	if r == nil {
		return nil, fmt.Errorf("missing espnow_echo_ping_response")
	}
	if !r.GetSuccess() {
		return &EchoPingResult{
			Success:  false,
			ClientID: r.GetClientId(),
			RttMs:    rttMs,
		}, nil
	}
	if r.GetTimestampUs() != timestampUs {
		return nil, fmt.Errorf("timestamp mismatch: sent %d got %d", timestampUs, r.GetTimestampUs())
	}
	return &EchoPingResult{
		Success:     true,
		ClientID:    r.GetClientId(),
		TimestampUs: r.GetTimestampUs(),
		RttMs:       rttMs,
		EspRttUs:    r.GetEspRttUs(),
	}, nil
}