package handlers

import (
	"context"
	"fmt"
	"time"

	"rag/file-system/internal/common"
	"rag/file-system/internal/domain/model"
	"rag/file-system/internal/domain/repository"
)

type GetShareInfoQuery struct {
	Token string
}

type DownloadShareQuery struct {
	Token    string
	Password string
}

type GetShareInfoHandler struct {
	ShareRepo    repository.ShareRepository
	FileMetaRepo repository.FileMetaRepository
}

func NewGetShareInfoHandler(shareRepo repository.ShareRepository, fileMetaRepo repository.FileMetaRepository) *GetShareInfoHandler {
	return &GetShareInfoHandler{ShareRepo: shareRepo, FileMetaRepo: fileMetaRepo}
}

func (h *GetShareInfoHandler) Handle(ctx context.Context, q GetShareInfoQuery) (*model.ShareInfo, error) {
	share, err := h.ShareRepo.GetByToken(ctx, q.Token)
	if err != nil {
		return nil, err
	}
	if share == nil {
		return nil, common.NewNotFoundError("分享链接不存在")
	}

	if share.ExpiresAt != nil && share.ExpiresAt.Before(time.Now()) {
		return nil, common.NewBusinessException("分享链接已过期")
	}

	if share.MaxDownloads != nil && share.DownloadCount >= *share.MaxDownloads {
		return nil, common.NewBusinessException("分享链接下载次数已达上限")
	}

	info := &model.ShareInfo{
		Token:        share.Token,
		ResourceType: share.ResourceType,
		HasPassword:  share.Password != nil,
		ExpiresAt:    share.ExpiresAt,
	}

	if share.ResourceType == "file" {
		file, err := h.FileMetaRepo.GetByID(ctx, share.ResourceID)
		if err != nil {
			return nil, err
		}
		if file != nil {
			info.FileName = file.Name
			info.FileSize = file.Size
		}
	}

	return info, nil
}

type DownloadShareHandler struct {
	ShareRepo    repository.ShareRepository
	FileMetaRepo repository.FileMetaRepository
	S3Repo       repository.FileRepository
}

func NewDownloadShareHandler(
	shareRepo repository.ShareRepository,
	fileMetaRepo repository.FileMetaRepository,
	s3Repo repository.FileRepository,
) *DownloadShareHandler {
	return &DownloadShareHandler{
		ShareRepo:    shareRepo,
		FileMetaRepo: fileMetaRepo,
		S3Repo:       s3Repo,
	}
}

func (h *DownloadShareHandler) Handle(ctx context.Context, q DownloadShareQuery) (string, error) {
	share, err := h.ShareRepo.GetByToken(ctx, q.Token)
	if err != nil {
		return "", err
	}
	if share == nil {
		return "", common.NewNotFoundError("分享链接不存在")
	}

	if share.ExpiresAt != nil && share.ExpiresAt.Before(time.Now()) {
		return "", common.NewBusinessException("分享链接已过期")
	}

	if share.MaxDownloads != nil && share.DownloadCount >= *share.MaxDownloads {
		return "", common.NewBusinessException("下载次数已达上限")
	}

	if share.Password != nil && *share.Password != "" {
		if q.Password == "" {
			return "", common.NewBusinessException("此分享需要密码")
		}
		if q.Password != *share.Password {
			return "", common.NewBusinessException("密码错误")
		}
	}

	if share.ResourceType != "file" {
		return "", common.NewBusinessException("仅支持文件分享下载")
	}

	file, err := h.FileMetaRepo.GetByID(ctx, share.ResourceID)
	if err != nil {
		return "", err
	}
	if file == nil {
		return "", common.NewNotFoundError("文件不存在")
	}

	presignedURL, err := h.S3Repo.GeneratePresignedURL(ctx, file.S3Bucket, file.S3Key, 5*time.Minute)
	if err != nil {
		return "", fmt.Errorf("failed to generate download URL: %w", err)
	}

	if err := h.ShareRepo.IncrementDownloadCount(ctx, q.Token); err != nil {
		common.Logger.Error("failed to increment download count", "token", q.Token, "error", err)
	}

	return presignedURL, nil
}