package service

import (
	"context"
	"encoding/json"
	"strings"
	"sync"
	"time"

	"github.com/Tencent/WeKnora/internal/im"
	"github.com/Tencent/WeKnora/internal/im/wechat"
	"github.com/Tencent/WeKnora/internal/logger"
	"github.com/Tencent/WeKnora/internal/types"
	"github.com/google/uuid"
)

type digitalHumanChannels interface {
	InvalidateDeletedChannels([]string)
	ListChannelsByAgent(string, uint64) ([]im.IMChannel, error)
	GetChannelByIDAndTenant(string, uint64) (*im.IMChannel, error)
	CreateChannel(*im.IMChannel) error
	UpdateChannel(*im.IMChannel) error
	DeleteChannel(string, uint64) error
}

type digitalHumanQRProvider interface {
	GetLoginQRCode(context.Context) (*wechat.QRCodeResult, error)
	PollQRCodeStatus(context.Context, string) (*wechat.LoginResult, error)
}

type digitalHumanQRLogin struct {
	mu      sync.Mutex
	scope   types.DigitalHumanScope
	humanID string
	code    string
	expires time.Time
	channel *im.IMChannelSummary
}

type DigitalHumanWeChatStatus struct {
	Status  string               `json:"status"`
	Channel *im.IMChannelSummary `json:"channel,omitempty"`
}

// Personal WeChat credentials are scoped to the creator even for tenant admins.
func (s *DigitalHumanService) ownedHuman(ctx context.Context, id string) (*types.DigitalHumanDetail, types.DigitalHumanScope, error) {
	scope, err := digitalHumanScope(ctx)
	if err != nil {
		return nil, scope, err
	}
	human, err := s.repo.Get(ctx, scope, id)
	if err == nil && human.OwnerID != scope.OwnerID {
		return nil, scope, types.ErrDigitalHumanNotFound
	}
	return human, scope, err
}

func (s *DigitalHumanService) CheckOwner(ctx context.Context, id string) error {
	_, _, err := s.ownedHuman(ctx, id)
	return err
}

func (s *DigitalHumanService) WeChatChannels(ctx context.Context, id string) ([]im.IMChannelSummary, error) {
	human, scope, err := s.ownedHuman(ctx, id)
	if err != nil {
		return nil, err
	}
	channels, err := s.channels.ListChannelsByAgent(human.PrimaryAgentID, scope.TenantID)
	if err != nil {
		return nil, err
	}
	result := make([]im.IMChannelSummary, 0, len(channels))
	for _, channel := range channels {
		if channel.Platform == "wechat" {
			result = append(result, im.SummarizeIMChannel(channel))
		}
	}
	return result, nil
}

func (s *DigitalHumanService) WeChatQRCode(ctx context.Context, id string) (*wechat.QRCodeResult, error) {
	_, scope, err := s.ownedHuman(ctx, id)
	if err != nil {
		return nil, err
	}
	result, err := s.qr.GetLoginQRCode(ctx)
	if err != nil {
		logger.Errorf(ctx, "Digital human WeChat QR request failed: %v", err)
		return nil, digitalHumanInputError("微信二维码获取失败，请检查网络后重试")
	}
	if result == nil || result.QRCode == "" || result.QRCodeURL == "" {
		return nil, digitalHumanInputError("微信未返回有效二维码，请重试")
	}
	s.qrMu.Lock()
	defer s.qrMu.Unlock()
	if s.qrLogins == nil {
		s.qrLogins = make(map[string]*digitalHumanQRLogin)
	}
	for token, login := range s.qrLogins {
		if time.Now().After(login.expires) {
			delete(s.qrLogins, token)
		}
	}
	if len(s.qrLogins) >= 1024 {
		return nil, digitalHumanInputError("正在连接的微信账号较多，请稍后重试")
	}
	// The browser receives an owner-bound ticket, never an upstream polling token.
	token := uuid.NewString()
	s.qrLogins[token] = &digitalHumanQRLogin{scope: scope, humanID: id, code: result.QRCode, expires: time.Now().Add(5 * time.Minute)}
	return &wechat.QRCodeResult{QRCodeURL: result.QRCodeURL, QRCode: token}, nil
}

func (s *DigitalHumanService) WeChatPoll(ctx context.Context, id, ticket string) (*DigitalHumanWeChatStatus, error) {
	human, scope, err := s.ownedHuman(ctx, id)
	if err != nil {
		return nil, err
	}
	s.qrMu.Lock()
	login := s.qrLogins[ticket]
	s.qrMu.Unlock()
	if login == nil || login.scope != scope || login.humanID != id || time.Now().After(login.expires) {
		return nil, digitalHumanInputError("二维码不存在、已过期或不属于当前账号，请重新连接")
	}
	login.mu.Lock()
	defer login.mu.Unlock()
	if time.Now().After(login.expires) {
		return nil, digitalHumanInputError("二维码已过期，请重新连接")
	}
	if login.channel != nil {
		if _, err := s.ownedWeChatChannel(ctx, id, login.channel.ID); err != nil {
			return nil, err
		}
		return &DigitalHumanWeChatStatus{Status: "confirmed", Channel: login.channel}, nil
	}
	result, err := s.qr.PollQRCodeStatus(ctx, login.code)
	if err != nil {
		logger.Errorf(ctx, "Digital human WeChat status request failed: %v", err)
		return nil, digitalHumanInputError("微信连接状态获取失败，请重试")
	}
	if result == nil {
		return nil, digitalHumanInputError("微信未返回连接状态，请重试")
	}
	if result.Status != "confirmed" {
		return &DigitalHumanWeChatStatus{Status: result.Status}, nil
	}
	if result.BotToken == "" || result.ILinkBotID == "" {
		return nil, digitalHumanInputError("微信授权未返回完整凭证，请重新扫码")
	}
	// Recheck after the long poll in case the human was deleted while scanning.
	if err := s.CheckOwner(ctx, id); err != nil {
		return nil, err
	}
	credentials, _ := json.Marshal(map[string]string{
		"bot_token": result.BotToken, "ilink_bot_id": result.ILinkBotID,
		"ilink_user_id": result.ILinkUserID, "baseurl": result.BaseURL,
	})
	channel := &im.IMChannel{TenantID: scope.TenantID, AgentID: human.PrimaryAgentID,
		Platform: "wechat", Name: human.Name + " · 微信", Mode: "longpoll", OutputMode: "full", SessionMode: "user",
		Enabled: true, Credentials: types.JSON(credentials)}
	if err := s.channels.CreateChannel(channel); err != nil {
		logger.Errorf(ctx, "Digital human WeChat channel creation failed: %v", err)
		if strings.HasPrefix(err.Error(), "duplicate_bot:") {
			return nil, digitalHumanInputError("此微信账号已经连接，请先删除原连接或使用其他账号扫码")
		}
		return nil, digitalHumanInputError("微信已确认，但保存连接失败，请重试")
	}
	summary := im.SummarizeIMChannel(*channel)
	login.channel = &summary
	return &DigitalHumanWeChatStatus{Status: "confirmed", Channel: login.channel}, nil
}

func (s *DigitalHumanService) ownedWeChatChannel(ctx context.Context, humanID, channelID string) (*im.IMChannel, error) {
	human, scope, err := s.ownedHuman(ctx, humanID)
	if err != nil {
		return nil, err
	}
	channel, err := s.channels.GetChannelByIDAndTenant(channelID, scope.TenantID)
	if err != nil || channel == nil || channel.AgentID != human.PrimaryAgentID || channel.Platform != "wechat" {
		return nil, types.ErrDigitalHumanNotFound
	}
	return channel, nil
}

func (s *DigitalHumanService) DeleteWeChatChannel(ctx context.Context, humanID, channelID string) error {
	channel, err := s.ownedWeChatChannel(ctx, humanID, channelID)
	if err != nil {
		return err
	}
	return s.channels.DeleteChannel(channel.ID, channel.TenantID)
}

func (s *DigitalHumanService) SetWeChatChannelEnabled(ctx context.Context, humanID, channelID string, enabled bool) error {
	channel, err := s.ownedWeChatChannel(ctx, humanID, channelID)
	if err != nil {
		return err
	}
	channel.Enabled = enabled
	return s.channels.UpdateChannel(channel)
}