package service

import (
	"context"
	"fmt"
	"time"

	apperrors "with_you/internal/errors"
	"with_you/internal/model"
	"with_you/internal/repository"
)

type VerificationService interface {
	SubmitVerification(ctx context.Context, userID string, identity model.UserIdentity, realName, studentID, employeeID, department, proofMaterials string) (*model.VerificationRecord, error)
	GetVerificationStatus(ctx context.Context, userID string) (*VerificationStatusResponse, error)
	GetVerificationRecords(ctx context.Context, userID string, page, pageSize int) ([]*model.VerificationRecord, int64, error)
}

type VerificationStatusResponse struct {
	UserID             string                    `json:"user_id"`
	Identity           string                    `json:"identity"`
	VerificationStatus string                    `json:"verification_status"`
	HasPendingRequest  bool                      `json:"has_pending_request"`
	LatestRecord       *model.VerificationRecord `json:"latest_record,omitempty"`
}

type verificationServiceImpl struct {
	verificationRepo repository.VerificationRepository
	userRepo         repository.UserRepository
}

func NewVerificationService(
	verificationRepo repository.VerificationRepository,
	userRepo repository.UserRepository,
) VerificationService {
	return &verificationServiceImpl{
		verificationRepo: verificationRepo,
		userRepo:         userRepo,
	}
}

func (s *verificationServiceImpl) SubmitVerification(ctx context.Context, userID string, identity model.UserIdentity, realName, studentID, employeeID, department, proofMaterials string) (*model.VerificationRecord, error) {
	user, err := s.userRepo.GetByID(userID)
	if err != nil {
		return nil, apperrors.ErrUserNotFound
	}

	if user.VerificationStatus == model.VerificationStatusApproved {
		return nil, apperrors.ErrAlreadyVerified
	}

	existing, err := s.verificationRepo.GetPendingByUserID(userID)
	if err == nil && existing != nil {
		return nil, apperrors.ErrVerificationPending
	}

	record := &model.VerificationRecord{
		UserID:         userID,
		Identity:       identity,
		Status:         model.VerificationStatusPending,
		RealName:       realName,
		StudentID:      studentID,
		EmployeeID:     employeeID,
		Department:     department,
		ProofMaterials: proofMaterials,
	}

	if err := s.verificationRepo.Create(record); err != nil {
		return nil, fmt.Errorf("创建认证记录失败: %w", err)
	}

	user.VerificationStatus = model.VerificationStatusPending
	user.Identity = identity
	if err := s.userRepo.Update(user); err != nil {
		return nil, fmt.Errorf("更新用户状态失败: %w", err)
	}

	return record, nil
}

func (s *verificationServiceImpl) GetVerificationStatus(ctx context.Context, userID string) (*VerificationStatusResponse, error) {
	user, err := s.userRepo.GetByID(userID)
	if err != nil {
		return nil, apperrors.ErrUserNotFound
	}

	response := &VerificationStatusResponse{
		UserID:             userID,
		Identity:           string(user.Identity),
		VerificationStatus: string(user.VerificationStatus),
		HasPendingRequest:  false,
	}

	latestRecord, err := s.verificationRepo.GetLatestByUserID(userID)
	if err == nil && latestRecord != nil {
		response.LatestRecord = latestRecord
		response.HasPendingRequest = latestRecord.Status == model.VerificationStatusPending
	}

	return response, nil
}

func (s *verificationServiceImpl) GetVerificationRecords(ctx context.Context, userID string, page, pageSize int) ([]*model.VerificationRecord, int64, error) {
	return s.verificationRepo.GetRecordsByUserID(userID, page, pageSize)
}

type AdminVerificationService interface {
	ListVerifications(ctx context.Context, page, pageSize int, status, keyword string) ([]*model.VerificationRecord, int64, error)
	GetVerificationDetail(ctx context.Context, id string) (*model.VerificationRecord, error)
	ReviewVerification(ctx context.Context, reviewerID string, recordID string, approve bool, rejectReason string) (*model.VerificationRecord, error)
}

type adminVerificationServiceImpl struct {
	verificationRepo repository.VerificationRepository
	userRepo         repository.UserRepository
}

func NewAdminVerificationService(
	verificationRepo repository.VerificationRepository,
	userRepo repository.UserRepository,
) AdminVerificationService {
	return &adminVerificationServiceImpl{
		verificationRepo: verificationRepo,
		userRepo:         userRepo,
	}
}

func (s *adminVerificationServiceImpl) ListVerifications(ctx context.Context, page, pageSize int, status, keyword string) ([]*model.VerificationRecord, int64, error) {
	return s.verificationRepo.List(page, pageSize, status, keyword)
}

func (s *adminVerificationServiceImpl) GetVerificationDetail(ctx context.Context, id string) (*model.VerificationRecord, error) {
	return s.verificationRepo.GetByID(id)
}

func (s *adminVerificationServiceImpl) ReviewVerification(ctx context.Context, reviewerID string, recordID string, approve bool, rejectReason string) (*model.VerificationRecord, error) {
	record, err := s.verificationRepo.GetByID(recordID)
	if err != nil {
		return nil, apperrors.ErrVerificationNotFound
	}

	if record.Status != model.VerificationStatusPending {
		return nil, apperrors.ErrVerificationAlreadyHandled
	}

	if approve {
		record.Status = model.VerificationStatusApproved
	} else {
		record.Status = model.VerificationStatusRejected
		record.RejectReason = rejectReason
	}

	now := time.Now()
	record.ReviewedBy = &reviewerID
	record.ReviewedAt = &now

	if err := s.verificationRepo.Update(record); err != nil {
		return nil, fmt.Errorf("更新认证记录失败: %w", err)
	}

	user, err := s.userRepo.GetByID(record.UserID)
	if err != nil {
		return record, nil
	}

	if approve {
		user.VerificationStatus = model.VerificationStatusApproved
		user.Identity = record.Identity
	} else {
		user.VerificationStatus = model.VerificationStatusRejected
	}

	_ = s.userRepo.Update(user)

	return record, nil
}