package warningnotify

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"
	"unicode/utf8"

	"git.5iot.com/iotlcm-public/iotlcm-admin-svr/internal/consts"
	"git.5iot.com/iotlcm-public/iotlcm-admin-svr/internal/dao"
	"git.5iot.com/iotlcm-public/iotlcm-admin-svr/internal/library/cache"

	"github.com/gogf/gf/v2/frame/g"
	"github.com/gogf/gf/v2/os/gtime"
)

const (
	warningWechatAccessTokenURL = "https://api.weixin.qq.com/cgi-bin/token"
	warningWechatSendURL        = "https://api.weixin.qq.com/cgi-bin/message/subscribe/send"
	warningWechatDefaultPage    = "pages/message/index"
	warningWechatDefaultTimeout = 5 * time.Second
	warningWechatSentKeyPrefix  = "iotlcm:warning:wechat:sent"
	warningWechatMinSentTTL     = 24 * time.Hour
)

var warningWechatTokenMu sync.Mutex

type warningWechatConfig struct {
	Enabled    bool   `json:"enabled"`
	AppID      string `json:"appId"`
	AppSecret  string `json:"appSecret"`
	TemplateID string `json:"templateId"`
	Page       string `json:"page"`
	Timeout    string `json:"timeout"`
}

type warningWechatBinding struct {
	UserID int64  `orm:"user_id"`
	OpenID string `orm:"open_id"`
}

type warningWechatAccessTokenResponse struct {
	AccessToken string `json:"access_token"`
	ExpiresIn   int    `json:"expires_in"`
	ErrCode     int    `json:"errcode"`
	ErrMsg      string `json:"errmsg"`
}

type warningWechatSendResponse struct {
	ErrCode int    `json:"errcode"`
	ErrMsg  string `json:"errmsg"`
}

type warningWechatTemplateValue struct {
	Value string `json:"value"`
}

type warningWechatPayload struct {
	ToUser     string                                `json:"touser"`
	TemplateID string                                `json:"template_id"`
	Page       string                                `json:"page,omitempty"`
	Data       map[string]warningWechatTemplateValue `json:"data"`
}

func sendWarningWechat(ctx context.Context, batch Batch) error {
	cfg, ok := loadWarningWechatConfig(ctx)
	if !ok || !cfg.Enabled {
		g.Log().Infof(
			ctx,
			"WarningNotify wechat subscribe skipped, reason:%s, tenantId:%s, deptId:%d, category:%s, stage:%d, count:%d",
			wechatConfigSkipReason(ok, cfg),
			batch.TenantID,
			batch.DeptID,
			batch.Category,
			batch.WarnStage,
			len(batch.Items),
		)
		return nil
	}
	if strings.TrimSpace(cfg.AppID) == "" || strings.TrimSpace(cfg.AppSecret) == "" {
		g.Log().Warningf(ctx, "WarningNotify wechat subscribe skipped, reason:app credentials incomplete, tenantId:%s", batch.TenantID)
		return nil
	}

	deliveries := resolveTerminalPlatformDeliveries(ctx, batch)
	if len(deliveries) == 0 {
		g.Log().Infof(ctx, "WarningNotify wechat subscribe skipped, reason:no terminal recipients, tenantId:%s, count:%d", batch.TenantID, len(batch.Items))
		return nil
	}

	var sendErrs []string
	for _, delivery := range deliveries {
		if len(delivery.Group.UserIDs) == 0 || len(delivery.Batch.Items) == 0 {
			continue
		}
		userID := delivery.Group.UserIDs[0]
		bindings, err := queryWechatBindings(ctx, batch.TenantID, userID)
		if err != nil {
			sendErrs = append(sendErrs, fmt.Sprintf("userId=%d query binding: %v", userID, err))
			continue
		}
		if len(bindings) == 0 {
			g.Log().Infof(ctx, "WarningNotify wechat subscribe skipped, reason:no openid, tenantId:%s, userId:%d, count:%d", batch.TenantID, userID, len(delivery.Batch.Items))
			continue
		}

		acquired, sentKey, err := acquireWechatSendDedupe(ctx, delivery.Batch, userID)
		if err != nil {
			g.Log().Warningf(ctx, "WarningNotify wechat subscribe dedupe check failed, tenantId:%s, userId:%d, category:%s, stage:%d, count:%d, err:%+v",
				batch.TenantID, userID, delivery.Batch.Category, delivery.Batch.WarnStage, len(delivery.Batch.Items), err)
		} else if !acquired {
			g.Log().Infof(ctx, "WarningNotify wechat subscribe skipped, reason:duplicated, tenantId:%s, userId:%d, key:%s, category:%s, stage:%d, count:%d",
				batch.TenantID, userID, sentKey, delivery.Batch.Category, delivery.Batch.WarnStage, len(delivery.Batch.Items))
			continue
		}

		successCount := 0
		for _, binding := range bindings {
			templateID := wechatTemplateID(delivery.Batch.Items, cfg.TemplateID)
			if templateID == "" {
				sendErrs = append(sendErrs, fmt.Sprintf("userId=%d template id empty", userID))
				continue
			}
			payload := buildWechatPayload(delivery.Batch, binding.OpenID, templateID, cfg.Page)
			if err := sendWechatSubscription(ctx, cfg, payload); err != nil {
				sendErrs = append(sendErrs, fmt.Sprintf("userId=%d openid=%s: %v", userID, maskOpenID(binding.OpenID), err))
				g.Log().Errorf(ctx, "WarningNotify wechat subscribe failed, tenantId:%s, userId:%d, openid:%s, category:%s, stage:%d, count:%d, err:%+v",
					batch.TenantID, userID, maskOpenID(binding.OpenID), delivery.Batch.Category, delivery.Batch.WarnStage, len(delivery.Batch.Items), err)
				continue
			}
			g.Log().Infof(ctx, "WarningNotify wechat subscribe sent, tenantId:%s, userId:%d, openid:%s, category:%s, stage:%d, count:%d",
				batch.TenantID, userID, maskOpenID(binding.OpenID), delivery.Batch.Category, delivery.Batch.WarnStage, len(delivery.Batch.Items))
			successCount++
		}
		if acquired && successCount == 0 {
			releaseWechatSendDedupe(ctx, sentKey)
		}
	}

	if len(sendErrs) > 0 {
		return fmt.Errorf("wechat subscribe send completed with failures: %s", strings.Join(sendErrs, "; "))
	}
	return nil
}

func loadWarningWechatConfig(ctx context.Context) (warningWechatConfig, bool) {
	var cfg warningWechatConfig
	loaded := false
	value, err := g.Cfg().Get(ctx, "warning.wechat")
	if err == nil && !value.IsNil() {
		_ = value.Scan(&cfg)
		loaded = true
	}

	if envValue := strings.TrimSpace(os.Getenv("IOTLCM_WARNING_WECHAT_ENABLED")); envValue != "" {
		if enabled, parseErr := strconv.ParseBool(envValue); parseErr == nil {
			cfg.Enabled = enabled
			loaded = true
		}
	}
	loaded = applyWechatEnv(&cfg.AppID, "IOTLCM_WARNING_WECHAT_APP_ID") || loaded
	loaded = applyWechatEnv(&cfg.AppSecret, "IOTLCM_WARNING_WECHAT_APP_SECRET") || loaded
	loaded = applyWechatEnv(&cfg.TemplateID, "IOTLCM_WARNING_WECHAT_TEMPLATE_ID") || loaded
	loaded = applyWechatEnv(&cfg.Page, "IOTLCM_WARNING_WECHAT_PAGE") || loaded
	loaded = applyWechatEnv(&cfg.Timeout, "IOTLCM_WARNING_WECHAT_TIMEOUT") || loaded

	cfg.AppID = strings.TrimSpace(cfg.AppID)
	cfg.AppSecret = strings.TrimSpace(cfg.AppSecret)
	cfg.TemplateID = strings.TrimSpace(cfg.TemplateID)
	cfg.Page = strings.TrimSpace(cfg.Page)
	cfg.Timeout = strings.TrimSpace(cfg.Timeout)
	if cfg.TemplateID == "" {
		cfg.TemplateID = consts.WarningWechatTemplateIDDefault
	}
	if cfg.Page == "" {
		cfg.Page = warningWechatDefaultPage
	}
	return cfg, loaded
}

func applyWechatEnv(target *string, key string) bool {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return false
	}
	*target = value
	return true
}

func wechatConfigSkipReason(loaded bool, cfg warningWechatConfig) string {
	if !loaded {
		return "warning.wechat config not found"
	}
	if !cfg.Enabled {
		return "warning.wechat disabled"
	}
	if cfg.AppID == "" || cfg.AppSecret == "" {
		return "warning.wechat app credentials incomplete"
	}
	return "unknown"
}

func queryWechatBindings(ctx context.Context, tenantID string, userID int64) ([]warningWechatBinding, error) {
	if strings.TrimSpace(tenantID) == "" || userID <= 0 {
		return nil, nil
	}
	columns := dao.SysSocial.Columns()
	rows := make([]warningWechatBinding, 0)
	err := dao.SysSocial.Ctx(ctx).
		Fields(columns.UserId, columns.OpenId).
		Where(columns.TenantId, strings.TrimSpace(tenantID)).
		Where(columns.UserId, userID).
		Where(columns.Source, consts.SourceWechatMp).
		Where("open_id <> ?", "").
		OrderAsc(columns.Id).
		Scan(&rows)
	if err != nil {
		return nil, err
	}

	seen := make(map[string]struct{}, len(rows))
	result := make([]warningWechatBinding, 0, len(rows))
	for _, row := range rows {
		row.OpenID = strings.TrimSpace(row.OpenID)
		if row.OpenID == "" {
			continue
		}
		if _, exists := seen[row.OpenID]; exists {
			continue
		}
		seen[row.OpenID] = struct{}{}
		result = append(result, row)
	}
	return result, nil
}

func acquireWechatSendDedupe(ctx context.Context, batch Batch, userID int64) (bool, string, error) {
	key := wechatSendDedupeKey(batch, userID)
	if key == "" {
		return false, "", fmt.Errorf("wechat send dedupe key is empty")
	}
	ttl := wechatSendDedupeTTL(batch)
	ok, err := cache.Instance().SetIfNotExist(ctx, key, "1", ttl)
	return ok, key, err
}

func releaseWechatSendDedupe(ctx context.Context, key string) {
	key = strings.TrimSpace(key)
	if key == "" {
		return
	}
	_, _ = cache.Instance().Remove(ctx, key)
}

func wechatSendDedupeKey(batch Batch, userID int64) string {
	tenantID := strings.TrimSpace(batch.TenantID)
	if tenantID == "" || userID <= 0 {
		return ""
	}
	business := strings.TrimSpace(batch.Business)
	if business == "" {
		business = BusinessSimWarning
	}
	return fmt.Sprintf(
		"%s:%s:%d:%s:%s:%s",
		warningWechatSentKeyPrefix,
		tenantID,
		userID,
		wechatSafeKeyPart(business),
		wechatDedupeCategoryKey(batch),
		wechatDedupePeriodKey(batch),
	)
}

func wechatSendDedupeTTL(batch Batch) time.Duration {
	now := wechatBatchTime(batch)
	if wechatBatchHasTrafficKind(batch) {
		nextMonth := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location()).AddDate(0, 1, 0)
		if ttl := nextMonth.Sub(now); ttl > 0 {
			return ttl
		}
		return warningWechatMinSentTTL
	}
	if wechatBatchHasExpireKind(batch) {
		return 36 * time.Hour
	}
	return warningWechatMinSentTTL
}

func wechatDedupePeriodKey(batch Batch) string {
	now := wechatBatchTime(batch)
	if wechatBatchHasTrafficKind(batch) {
		return "m" + now.Format("200601")
	}
	if wechatBatchHasExpireKind(batch) {
		return fmt.Sprintf("d%s:s%d", now.Format("20060102"), batch.WarnStage)
	}
	return "d" + now.Format("20060102")
}

func wechatDedupeCategoryKey(batch Batch) string {
	switch wechatPrimaryKind(batch) {
	case "traffic_mb", "traffic_percent":
		return "card_traffic"
	case "pool_traffic_percent":
		return "flow_pool"
	case "expire_day":
		return "expire_day"
	case "expire_month":
		return "expire_month"
	}
	category := strings.TrimSpace(batch.Category)
	if category == "" {
		category = "warning"
	}
	return "cat_" + sha256Hex(category)
}

func wechatPrimaryKind(batch Batch) string {
	for _, item := range batch.Items {
		kind := strings.TrimSpace(item.Kind)
		if kind != "" {
			return kind
		}
	}
	return ""
}

func wechatBatchHasTrafficKind(batch Batch) bool {
	for _, item := range batch.Items {
		switch strings.TrimSpace(item.Kind) {
		case "traffic_mb", "traffic_percent", "pool_traffic_percent":
			return true
		}
	}
	return false
}

func wechatBatchHasExpireKind(batch Batch) bool {
	for _, item := range batch.Items {
		switch strings.TrimSpace(item.Kind) {
		case "expire_day", "expire_month":
			return true
		}
	}
	return false
}

func wechatBatchTime(batch Batch) time.Time {
	latest := latestEvent(batch.Items)
	if latest.WarnTime.IsZero() {
		return time.Now()
	}
	return latest.WarnTime
}

func wechatSafeKeyPart(value string) string {
	value = strings.TrimSpace(value)
	if value == "" {
		return "na"
	}
	var builder strings.Builder
	for _, r := range value {
		if r >= '0' && r <= '9' || r >= 'a' && r <= 'z' || r >= 'A' && r <= 'Z' || r == '_' || r == '-' {
			builder.WriteRune(r)
		}
	}
	if builder.Len() == 0 {
		return sha256Hex(value)
	}
	return strings.ToLower(builder.String())
}

func wechatTemplateID(items []Event, fallback string) string {
	for _, item := range items {
		if value := strings.TrimSpace(item.WxTemplateID); value != "" {
			return value
		}
	}
	return strings.TrimSpace(fallback)
}

func buildWechatPayload(batch Batch, openID string, templateID string, page string) warningWechatPayload {
	latest := latestEvent(batch.Items)
	return warningWechatPayload{
		ToUser:     strings.TrimSpace(openID),
		TemplateID: strings.TrimSpace(templateID),
		Page:       strings.TrimSpace(page),
		Data: map[string]warningWechatTemplateValue{
			"character_string6":  {Value: wechatCharacterString(wechatDeviceCharacterText(batch), 32)},
			"thing7":             {Value: truncateWechatText(wechatTypeText(batch), 20)},
			"thing9":             {Value: truncateWechatText(wechatReasonText(batch), 20)},
			"character_string32": {Value: wechatCharacterString(wechatValueText(batch), 32)},
			"time8":              {Value: wechatTimeText(latest)},
		},
	}
}

func latestEvent(items []Event) Event {
	var result Event
	for _, item := range items {
		if result.WarnTime.IsZero() || item.WarnTime.After(result.WarnTime) {
			result = item
		}
	}
	return result
}

func wechatDeviceText(batch Batch) string {
	if len(batch.Items) == 0 {
		return "--"
	}
	first := displayObjectCode(batch.Items[0])
	if len(batch.Items) == 1 {
		return first
	}
	return fmt.Sprintf("%s等%d张卡", first, len(batch.Items))
}

func wechatDeviceCharacterText(batch Batch) string {
	if len(batch.Items) == 0 {
		return "NA"
	}
	first := displayObjectCode(batch.Items[0])
	if len(batch.Items) == 1 {
		return first
	}
	return fmt.Sprintf("%sx%d", first, len(batch.Items))
}

func wechatTypeText(batch Batch) string {
	title := warningTitle(batch)
	if title == "" {
		title = "设备预警"
	}
	if len(batch.Items) > 1 {
		return fmt.Sprintf("%s，共%d张卡", title, len(batch.Items))
	}
	return title
}

func wechatReasonText(batch Batch) string {
	if len(batch.Items) == 1 {
		return emailWarningReason(batch.Items[0])
	}
	reason := fmt.Sprintf("共%d张卡触发预警，最高级别：%s", len(batch.Items), levelText(highestLevel(batch.Items)))
	if hasAffectOperation(batch.Items) {
		reason += "，涉及停机或断网"
	}
	return reason
}

func wechatValueText(batch Batch) string {
	if len(batch.Items) == 0 {
		return "NA"
	}
	item := batch.Items[0]
	unit := strings.TrimSpace(item.UnitText)
	switch unit {
	case "天":
		return fmt.Sprintf("%.0fd", item.Actual)
	case "月":
		return fmt.Sprintf("%.0fm", item.Actual)
	case "%":
		return fmt.Sprintf("%.2f%%", item.Actual)
	case "MB":
		if item.TotalFlowMB > 0 {
			return fmt.Sprintf("%.3f/%.3fMB", item.Actual, item.TotalFlowMB)
		}
		return fmt.Sprintf("%.3fMB", item.Actual)
	default:
		if unit == "" {
			return fmt.Sprintf("%.3f", item.Actual)
		}
		return fmt.Sprintf("%.3f%s", item.Actual, unit)
	}
}

func wechatTimeText(item Event) string {
	if item.WarnTime.IsZero() {
		return gtime.Now().Format("2006-01-02 15:04:05")
	}
	return item.WarnTime.Format("2006-01-02 15:04:05")
}

func sendWechatSubscription(ctx context.Context, cfg warningWechatConfig, payload warningWechatPayload) error {
	return sendWechatSubscriptionAttempt(ctx, cfg, payload, true)
}

type warningWechatAPIError struct {
	Code    int
	Message string
}

func (err *warningWechatAPIError) Error() string {
	return fmt.Sprintf("wechat subscribe code %d: %s", err.Code, err.Message)
}

func warningWechatTokenInvalid(code int) bool {
	return code == 40001 || code == 40014 || code == 42001
}

func sendWechatSubscriptionAttempt(ctx context.Context, cfg warningWechatConfig, payload warningWechatPayload, refreshToken bool) error {
	accessToken, err := warningWechatAccessToken(ctx, cfg)
	if err != nil {
		return err
	}
	query := url.Values{}
	query.Set("access_token", accessToken)
	body, err := json.Marshal(payload)
	if err != nil {
		return err
	}
	timeout := warningWechatTimeout(cfg)
	reqCtx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()
	req, err := http.NewRequestWithContext(reqCtx, http.MethodPost, warningWechatSendURL+"?"+query.Encode(), bytes.NewReader(body))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := (&http.Client{Timeout: timeout}).Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	var result warningWechatSendResponse
	if err = json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return err
	}
	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
		return fmt.Errorf("wechat subscribe http status %d: %s", resp.StatusCode, result.ErrMsg)
	}
	if result.ErrCode != 0 {
		if refreshToken && warningWechatTokenInvalid(result.ErrCode) {
			cacheKey := "iotlcm:warning:wechat:access_token:" + sha256Hex(cfg.AppID)
			if _, err = g.Redis().Do(ctx, "DEL", cacheKey); err != nil {
				return fmt.Errorf("invalidate wechat access token: %w", err)
			}
			return sendWechatSubscriptionAttempt(ctx, cfg, payload, false)
		}
		return &warningWechatAPIError{Code: result.ErrCode, Message: result.ErrMsg}
	}
	return nil
}

func warningWechatAccessToken(ctx context.Context, cfg warningWechatConfig) (string, error) {
	cacheKey := "iotlcm:warning:wechat:access_token:" + sha256Hex(cfg.AppID)
	if value, err := g.Redis().Get(ctx, cacheKey); err == nil && strings.TrimSpace(value.String()) != "" {
		return strings.TrimSpace(value.String()), nil
	}

	warningWechatTokenMu.Lock()
	defer warningWechatTokenMu.Unlock()
	if value, err := g.Redis().Get(ctx, cacheKey); err == nil && strings.TrimSpace(value.String()) != "" {
		return strings.TrimSpace(value.String()), nil
	}

	query := url.Values{}
	query.Set("grant_type", "client_credential")
	query.Set("appid", cfg.AppID)
	query.Set("secret", cfg.AppSecret)
	timeout := warningWechatTimeout(cfg)
	reqCtx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()
	req, err := http.NewRequestWithContext(reqCtx, http.MethodGet, warningWechatAccessTokenURL+"?"+query.Encode(), nil)
	if err != nil {
		return "", err
	}
	resp, err := (&http.Client{Timeout: timeout}).Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	var result warningWechatAccessTokenResponse
	if err = json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return "", err
	}
	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
		return "", fmt.Errorf("wechat access token http status %d: %s", resp.StatusCode, result.ErrMsg)
	}
	if result.ErrCode != 0 || strings.TrimSpace(result.AccessToken) == "" {
		return "", fmt.Errorf("wechat access token code %d: %s", result.ErrCode, result.ErrMsg)
	}

	ttl := result.ExpiresIn - 300
	if ttl <= 0 {
		ttl = 300
	}
	if _, err = g.Redis().Do(ctx, "SETEX", cacheKey, ttl, result.AccessToken); err != nil {
		g.Log().Warningf(ctx, "WarningNotify cache wechat access token failed, err:%+v", err)
	}
	return result.AccessToken, nil
}

func warningWechatTimeout(cfg warningWechatConfig) time.Duration {
	if value := strings.TrimSpace(cfg.Timeout); value != "" {
		if timeout, err := time.ParseDuration(value); err == nil && timeout > 0 {
			return timeout
		}
	}
	return warningWechatDefaultTimeout
}

func maskOpenID(value string) string {
	value = strings.TrimSpace(value)
	if value == "" {
		return ""
	}
	if utf8.RuneCountInString(value) <= 8 {
		return value
	}
	runes := []rune(value)
	return string(runes[:4]) + "..." + string(runes[len(runes)-4:])
}

func sha256Hex(value string) string {
	sum := sha256.Sum256([]byte(strings.TrimSpace(value)))
	return hex.EncodeToString(sum[:])[:16]
}

func truncateWechatText(value string, maxRunes int) string {
	value = strings.TrimSpace(value)
	if maxRunes <= 0 {
		return ""
	}
	runes := []rune(value)
	if len(runes) <= maxRunes {
		return value
	}
	return string(runes[:maxRunes-1]) + "…"
}

func wechatCharacterString(value string, maxRunes int) string {
	value = strings.TrimSpace(value)
	if value == "" || maxRunes <= 0 {
		return "NA"
	}
	var builder strings.Builder
	for _, r := range value {
		if r >= 33 && r <= 126 {
			builder.WriteRune(r)
		}
	}
	result := builder.String()
	if result == "" {
		return "NA"
	}
	runes := []rune(result)
	if len(runes) <= maxRunes {
		return result
	}
	return string(runes[:maxRunes])
}