package service

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"
)

const (
	chanSuccessCode = 0
	chanErrorCode   = 9999
)

type chanSimKey struct {
	ChanKey string `json:"chanKey"`
	ICCID   string `json:"iccid"`
	IMSI    string `json:"imsi"`
	MSISDN  string `json:"msisdn"`
}

type chanRequest struct {
	SimKeys []chanSimKey    `json:"simKeys"`
	ReqData json.RawMessage `json:"reqData"`
}

type chanResponse[T any] struct {
	Code    int        `json:"code"`
	Message string     `json:"message"`
	SimKey  chanSimKey `json:"simKey"`
	ResData T          `json:"resData"`
}

type chanBasicInfo struct {
	ActiveDate string `json:"activeDate"`
	OpenDate   string `json:"openDate"`
	Remark     string `json:"remark"`
}

type chanSession struct {
	ApnID      string `json:"apnId"`
	Rat        string `json:"rat"`
	IPv4       string `json:"ipv4"`
	IPv6       string `json:"ipv6"`
	IPv6Prefix string `json:"ipv6Prefix"`
	Status     string `json:"status"`
	CreateTime string `json:"createTime"`
}

type chanCardStatus struct {
	CardStatus     int    `json:"cardStatus"`
	LastChangeDate string `json:"lastChangeDate"`
}

type chanIMEI struct {
	IMEI string `json:"imei"`
}

type chanUsage struct {
	DataUsage float64 `json:"dataUsage"`
}

type chanMonthlyUsage struct {
	DeadLine   string  `json:"deadLine"`
	DataAmount float64 `json:"dataAmount"`
}

type chanDailyUsage struct {
	QueryDate  string  `json:"queryDate"`
	DataAmount float64 `json:"dataAmount"`
}

type chanAPN struct {
	APNName string `json:"apnName"`
	Status  string `json:"status"`
}

type chanAPNList struct {
	APNList []chanAPN `json:"apnList"`
}

type chanOrder struct {
	OrderNum string `json:"orderNum"`
}

type chanBindStatus struct {
	BindStatus string `json:"bindStatus"`
}

type chanDeviceStatus struct {
	DeviceStatus string `json:"deviceStatus"`
}

type chanRegionLimitStatus struct {
	RegionLimitStatus string `json:"regionLimitStatus"`
}

type chanReqData struct {
	QueryDate string `json:"queryDate"`
	OperType  string `json:"operType"`
	APNName   string `json:"apnName"`
	TestType  *int   `json:"testType"`
}

func (s *Service) chanAPI(w http.ResponseWriter, r *http.Request) {
	path := strings.TrimPrefix(r.URL.Path, "/sim/")
	switch path {
	case "query/sim-basic-info":
		s.chanQueryBasicInfo(w, r)
	case "query/sim-session":
		s.chanQuerySession(w, r)
	case "query/sim-status", "query/sim-status-batch":
		s.chanQueryStatus(w, r)
	case "query/sim-card-bind-status":
		s.chanQueryBindStatus(w, r)
	case "query/sim-device-status":
		s.chanQueryDeviceStatus(w, r)
	case "query/sim-region-limit-status":
		s.chanQueryRegionLimitStatus(w, r)
	case "query/sim-imei":
		s.chanQueryIMEI(w, r)
	case "query/sim-datausage":
		s.chanQueryDataUsage(w, r)
	case "query/sim-datausage-monthly", "query/sim-datausage-monthly-batch":
		s.chanQueryMonthly(w, r)
	case "query/sim-datausage-daily", "query/sim-datausage-daily-batch":
		s.chanQueryDaily(w, r)
	case "query/sim-apn-info":
		s.chanQueryAPN(w, r)
	case "change/sim-status":
		s.chanChangeStatus(w, r)
	case "change/sim-apn":
		s.chanChangeAPN(w, r)
	default:
		writeJSON(w, http.StatusNotFound, map[string]string{"message": "unknown sim endpoint"})
	}
}

func parseChanRequest(r *http.Request) (chanRequest, error) {
	var req chanRequest
	if r.Method != http.MethodGet && r.Body != nil {
		body, err := io.ReadAll(io.LimitReader(r.Body, 2<<20))
		if err != nil {
			return req, err
		}
		if len(strings.TrimSpace(string(body))) > 0 {
			if err := json.Unmarshal(body, &req); err != nil {
				return req, fmt.Errorf("invalid JSON body: %w", err)
			}
		}
	}
	if len(req.SimKeys) == 0 {
		req.SimKeys = simKeysFromQuery(r.URL.Query())
	}
	if len(req.ReqData) == 0 {
		data := chanReqData{
			QueryDate: r.URL.Query().Get("queryDate"),
			OperType:  r.URL.Query().Get("operType"),
			APNName:   r.URL.Query().Get("apnName"),
		}
		if value := r.URL.Query().Get("testType"); value != "" {
			if parsed, err := strconv.Atoi(value); err == nil {
				data.TestType = &parsed
			}
		}
		if data.QueryDate != "" || data.OperType != "" || data.APNName != "" || data.TestType != nil {
			req.ReqData, _ = json.Marshal(data)
		}
	}
	return req, nil
}

func simKeysFromQuery(q url.Values) []chanSimKey {
	if raw := q.Get("simKeys"); raw != "" {
		var keys []chanSimKey
		if json.Unmarshal([]byte(raw), &keys) == nil {
			return keys
		}
	}
	var values []chanSimKey
	for _, item := range []struct {
		key  string
		name string
	}{
		{"iccids", "iccid"}, {"imsis", "imsi"}, {"msisdns", "msisdn"},
	} {
		for _, value := range splitIDs(q.Get(item.key)) {
			key := chanSimKey{}
			switch item.name {
			case "iccid":
				key.ICCID = value
			case "imsi":
				key.IMSI = value
			case "msisdn":
				key.MSISDN = value
			}
			values = append(values, key)
		}
	}
	if len(values) == 0 {
		key := chanSimKey{ICCID: q.Get("iccid"), IMSI: q.Get("imsi"), MSISDN: q.Get("msisdn")}
		if key.ICCID != "" || key.IMSI != "" || key.MSISDN != "" {
			values = append(values, key)
		}
	}
	return values
}

func splitIDs(raw string) []string {
	if raw == "" {
		return nil
	}
	raw = strings.ReplaceAll(raw, ",", "_")
	parts := strings.Split(raw, "_")
	values := make([]string, 0, len(parts))
	for _, part := range parts {
		if value := strings.TrimSpace(part); value != "" {
			values = append(values, value)
		}
	}
	return values
}

func decodeChanReqData(req chanRequest) chanReqData {
	var data chanReqData
	_ = json.Unmarshal(req.ReqData, &data)
	return data
}

func chanSuccess[T any](key chanSimKey, data T) chanResponse[T] {
	return chanResponse[T]{Code: chanSuccessCode, Message: "success", SimKey: key, ResData: data}
}

func chanFailure[T any](key chanSimKey, message string) chanResponse[T] {
	return chanResponse[T]{Code: chanErrorCode, Message: message, SimKey: key, ResData: *new(T)}
}

func writeChanResponses[T any](w http.ResponseWriter, responses []chanResponse[T]) {
	writeJSON(w, http.StatusOK, responses)
}

func (s *Service) chanCards(r *http.Request) (chanRequest, Store, error) {
	req, err := parseChanRequest(r)
	if err != nil {
		return req, Store{}, err
	}
	return req, s.store.Snapshot(), nil
}

func findChanCard(st Store, key chanSimKey) (SIMCard, bool) {
	if key.ICCID != "" {
		for _, card := range st.Cards {
			if card.ICCID == key.ICCID {
				return card, true
			}
		}
	}
	if key.IMSI != "" {
		for _, card := range st.Cards {
			if card.IMSI == key.IMSI {
				return card, true
			}
		}
	}
	if key.MSISDN != "" {
		for _, card := range st.Cards {
			if card.MSISDN == key.MSISDN {
				return card, true
			}
		}
	}
	return SIMCard{}, false
}

func chanRequestError[T any](w http.ResponseWriter, err error) {
	writeJSON(w, http.StatusBadRequest, []chanResponse[T]{{Code: chanErrorCode, Message: err.Error()}})
}

func (s *Service) chanQueryBasicInfo(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanBasicInfo](w, err)
		return
	}
	responses := make([]chanResponse[chanBasicInfo], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanBasicInfo](key, "card not found"))
			continue
		}
		responses = append(responses, chanSuccess(key, chanBasicInfo{ActiveDate: card.ActiveDate, OpenDate: card.OpenDate, Remark: card.Remark}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQuerySession(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanSession](w, err)
		return
	}
	responses := make([]chanResponse[chanSession], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanSession](key, "card not found"))
			continue
		}
		responses = append(responses, chanSuccess(key, chanSession{ApnID: primaryAPN(card).Name, Rat: card.RAT, IPv4: card.IP, IPv6: card.IPv6, IPv6Prefix: card.IPv6Prefix, Status: chanSessionStatus(card.SessionStatus), CreateTime: card.LastChangeDate}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryStatus(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanCardStatus](w, err)
		return
	}
	responses := make([]chanResponse[chanCardStatus], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanCardStatus](key, "card not found"))
			continue
		}
		status, _ := strconv.Atoi(card.CardStatus)
		responses = append(responses, chanSuccess(key, chanCardStatus{CardStatus: status, LastChangeDate: card.LastChangeDate}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryBindStatus(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanBindStatus](w, err)
		return
	}
	responses := make([]chanResponse[chanBindStatus], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanBindStatus](key, "card not found"))
			continue
		}
		responses = append(responses, chanSuccess(key, chanBindStatus{BindStatus: card.CardBindStatus}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryDeviceStatus(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanDeviceStatus](w, err)
		return
	}
	responses := make([]chanResponse[chanDeviceStatus], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanDeviceStatus](key, "card not found"))
			continue
		}
		responses = append(responses, chanSuccess(key, chanDeviceStatus{DeviceStatus: chanSessionStatus(card.OnOffStatus)}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryRegionLimitStatus(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanRegionLimitStatus](w, err)
		return
	}
	responses := make([]chanResponse[chanRegionLimitStatus], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanRegionLimitStatus](key, "card not found"))
			continue
		}
		responses = append(responses, chanSuccess(key, chanRegionLimitStatus{RegionLimitStatus: card.RegionLimitStatus}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryIMEI(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanIMEI](w, err)
		return
	}
	responses := make([]chanResponse[chanIMEI], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanIMEI](key, "card not found"))
			continue
		}
		responses = append(responses, chanSuccess(key, chanIMEI{IMEI: card.IMEI}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryDataUsage(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanUsage](w, err)
		return
	}
	responses := make([]chanResponse[chanUsage], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanUsage](key, "card not found"))
			continue
		}
		responses = append(responses, chanSuccess(key, chanUsage{DataUsage: card.MonthUsageKB / 1024}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryMonthly(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanMonthlyUsage](w, err)
		return
	}
	data := decodeChanReqData(req)
	responses := make([]chanResponse[chanMonthlyUsage], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanMonthlyUsage](key, "card not found"))
			continue
		}
		amount := card.MonthUsageKB
		if data.QueryDate != "" && len(data.QueryDate) == 6 && data.QueryDate != time.Now().Format("200601") {
			amount = card.MonthlyBaseKB
		}
		responses = append(responses, chanSuccess(key, chanMonthlyUsage{DeadLine: time.Now().AddDate(0, 0, -1).Format("20060102"), DataAmount: amount / 1024}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryDaily(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanDailyUsage](w, err)
		return
	}
	data := decodeChanReqData(req)
	queryDate := data.QueryDate
	if queryDate == "" {
		queryDate = r.URL.Query().Get("queryDate")
	}
	if queryDate == "" {
		queryDate = time.Now().Format("20060102")
	}
	responses := make([]chanResponse[chanDailyUsage], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanDailyUsage](key, "card not found"))
			continue
		}
		responses = append(responses, chanSuccess(key, chanDailyUsage{QueryDate: queryDate, DataAmount: card.DailyBaseKB / 1024}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanQueryAPN(w http.ResponseWriter, r *http.Request) {
	req, st, err := s.chanCards(r)
	if err != nil {
		chanRequestError[chanAPNList](w, err)
		return
	}
	responses := make([]chanResponse[chanAPNList], 0, len(req.SimKeys))
	for _, key := range req.SimKeys {
		card, ok := findChanCard(st, key)
		if !ok {
			responses = append(responses, chanFailure[chanAPNList](key, "card not found"))
			continue
		}
		apns := make([]chanAPN, 0, len(card.APNs))
		for _, apn := range card.APNs {
			apns = append(apns, chanAPN{APNName: apn.Name, Status: apn.Status})
		}
		responses = append(responses, chanSuccess(key, chanAPNList{APNList: apns}))
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanChangeStatus(w http.ResponseWriter, r *http.Request) {
	req, err := parseChanRequest(r)
	if err != nil {
		chanRequestError[chanOrder](w, err)
		return
	}
	data := decodeChanReqData(req)
	if data.OperType != "0" && data.OperType != "1" {
		responses := make([]chanResponse[chanOrder], 0, len(req.SimKeys))
		for _, key := range req.SimKeys {
			responses = append(responses, chanFailure[chanOrder](key, "unsupported operType, expected 0(stop) or 1(resume)"))
		}
		writeChanResponses(w, responses)
		return
	}
	responses := make([]chanResponse[chanOrder], 0, len(req.SimKeys))
	err = s.store.SaveMutation(func(st *Store) error {
		for _, key := range req.SimKeys {
			idx := findChanCardIndex(*st, key)
			if idx < 0 {
				responses = append(responses, chanFailure[chanOrder](key, "card not found"))
				continue
			}
			card := &st.Cards[idx]
			if data.OperType == "0" {
				card.CardStatus = "4"
			} else {
				card.CardStatus = "2"
			}
			card.LastChangeDate = time.Now().Format("2006-01-02 15:04:05")
			orderNum := "ORD" + time.Now().Format("20060102150405") + randomHex(3)
			st.Orders = append(st.Orders, Order{OrderNum: orderNum, MSISDN: card.MSISDN, ICCID: card.ICCID, IMSI: card.IMSI, Type: "sim-status", OperType: data.OperType, Status: "completed", CreatedAt: card.LastChangeDate})
			responses = append(responses, chanSuccess(key, chanOrder{OrderNum: orderNum}))
		}
		return nil
	})
	if err != nil {
		chanRequestError[chanOrder](w, err)
		return
	}
	writeChanResponses(w, responses)
}

func (s *Service) chanChangeAPN(w http.ResponseWriter, r *http.Request) {
	req, err := parseChanRequest(r)
	if err != nil {
		chanRequestError[chanOrder](w, err)
		return
	}
	data := decodeChanReqData(req)
	if data.APNName == "" || (data.OperType != "0" && data.OperType != "1") {
		responses := make([]chanResponse[chanOrder], 0, len(req.SimKeys))
		for _, key := range req.SimKeys {
			responses = append(responses, chanFailure[chanOrder](key, "apnName and operType are required"))
		}
		writeChanResponses(w, responses)
		return
	}
	responses := make([]chanResponse[chanOrder], 0, len(req.SimKeys))
	err = s.store.SaveMutation(func(st *Store) error {
		for _, key := range req.SimKeys {
			idx := findChanCardIndex(*st, key)
			if idx < 0 {
				responses = append(responses, chanFailure[chanOrder](key, "card not found"))
				continue
			}
			card := &st.Cards[idx]
			status := "0"
			if data.OperType == "0" {
				status = "1"
			}
			found := false
			for i := range card.APNs {
				if strings.EqualFold(card.APNs[i].Name, data.APNName) {
					card.APNs[i].Status = status
					found = true
				}
			}
			if !found {
				card.APNs = append(card.APNs, APN{Name: data.APNName, Status: status})
			}
			orderNum := "APN" + time.Now().Format("20060102150405") + randomHex(3)
			now := time.Now().Format("2006-01-02 15:04:05")
			st.Orders = append(st.Orders, Order{OrderNum: orderNum, MSISDN: card.MSISDN, ICCID: card.ICCID, IMSI: card.IMSI, Type: "sim-apn-function", OperType: data.OperType, APNName: data.APNName, Status: "completed", CreatedAt: now})
			responses = append(responses, chanSuccess(key, chanOrder{OrderNum: orderNum}))
		}
		return nil
	})
	if err != nil {
		chanRequestError[chanOrder](w, err)
		return
	}
	writeChanResponses(w, responses)
}

func findChanCardIndex(st Store, key chanSimKey) int {
	for i, card := range st.Cards {
		if (key.ICCID != "" && card.ICCID == key.ICCID) || (key.IMSI != "" && card.IMSI == key.IMSI) || (key.MSISDN != "" && card.MSISDN == key.MSISDN) {
			return i
		}
	}
	return -1
}

func chanSessionStatus(status string) string {
	switch strings.ToUpper(strings.TrimSpace(status)) {
	case "01", "1", "0", "ONLINE":
		return "0"
	case "00", "-1", "OFFLINE":
		return "-1"
	default:
		return "-2"
	}
}