package endpoints

import (
	"file-system/internal/api/handlers"
	"file-system/internal/api/requests"
	"file-system/internal/api/validators"
	"file-system/internal/common"
	"file-system/internal/domain/repository"
	"file-system/internal/infrastructure/mediator"
	"io"
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
)

type FileEndpoint struct {
	Mediator             *mediator.Mediator
	UploadValidator      *validators.UploadFileValidator
	DownloadValidator    *validators.DownloadFileValidator
	NewFeaturesValidator *validators.NewFeaturesValidator
}

func NewFileEndpoint(m *mediator.Mediator, uv *validators.UploadFileValidator, dv *validators.DownloadFileValidator, nfv *validators.NewFeaturesValidator) *FileEndpoint {
	return &FileEndpoint{
		Mediator:             m,
		UploadValidator:      uv,
		DownloadValidator:    dv,
		NewFeaturesValidator: nfv,
	}
}

// UploadFile godoc
// @Summary      上传文件 (简单上传)
// @Description  上传小文件到指定的存储桶
// @Tags         文件操作
// @Accept       multipart/form-data
// @Produce      json
// @Param        bucket_name formData string true "存储桶名称"
// @Param        file formData file true "要上传的文件"
// @Success      200  {object}  map[string]string "上传成功消息"
// @Failure      400  {object}  map[string]string "参数错误"
// @Failure      500  {object}  map[string]string "服务器内部错误"
// @Router       /files/upload [post]
func (e *FileEndpoint) UploadFile(c *gin.Context) {
	var req requests.UploadFileRequest
	// 绑定参数
	if err := c.ShouldBind(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// 验证参数
	if err := e.UploadValidator.Validate(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// 打开文件流
	file, err := req.File.Open()
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to open file"})
		return
	}
	defer file.Close()

	// 构建 Command
	cmd := handlers.UploadFileCommand{
		BucketName: req.BucketName,
		FileName:   req.File.Filename,
		Data:       file,
	}

	// 调用 Mediator
	result, err := mediator.Send[handlers.UploadFileCommand, string](e.Mediator, c.Request.Context(), cmd)
	if err != nil {
		handleError(c, err)
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": result})
}

// DownloadFile godoc
// @Summary      下载文件
// @Description  从指定的存储桶下载文件
// @Tags         文件操作
// @Accept       json
// @Produce      octet-stream
// @Param        bucket_name query string true "存储桶名称"
// @Param        object_key query string true "对象键（文件名）"
// @Success      200  {file}    file "文件流"
// @Failure      400  {object}  map[string]string "参数错误"
// @Failure      500  {object}  map[string]string "服务器内部错误"
// @Router       /files/download [get]
func (e *FileEndpoint) DownloadFile(c *gin.Context) {
	var req requests.DownloadFileRequest
	if err := c.ShouldBind(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	if err := e.DownloadValidator.Validate(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	query := handlers.DownloadFileQuery{
		BucketName: req.BucketName,
		ObjectKey:  req.ObjectKey,
	}

	result, err := mediator.Send[handlers.DownloadFileQuery, io.ReadCloser](e.Mediator, c.Request.Context(), query)
	if err != nil {
		handleError(c, err)
		return
	}
	defer result.Close()

	c.Header("Content-Disposition", "attachment; filename="+req.ObjectKey)
	c.Header("Content-Type", "application/octet-stream")
	io.Copy(c.Writer, result)
}

// ListFiles godoc
// @Summary      文件列表 (分页)
// @Description  分页查询存储桶中的文件
// @Tags         文件操作
// @Accept       json
// @Produce      json
// @Param        bucket_name query string true "存储桶名称"
// @Param        prefix query string false "文件名前缀筛选"
// @Param        max_keys query int false "每页数量"
// @Param        token query string false "分页Token"
// @Success      200  {object}  repository.ListFilesResult
// @Failure      400  {object}  map[string]string
// @Failure      500  {object}  map[string]string
// @Router       /files/list [get]
func (e *FileEndpoint) ListFiles(c *gin.Context) {
	var req requests.ListFilesRequest
	if err := c.ShouldBind(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	if err := e.NewFeaturesValidator.ValidateListFiles(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	var token *string
	if req.Token != "" {
		token = &req.Token
	}

	query := handlers.ListFilesQuery{
		BucketName: req.BucketName,
		Prefix:     req.Prefix,
		MaxKeys:    req.MaxKeys,
		Token:      token,
	}

	result, err := mediator.Send[handlers.ListFilesQuery, *repository.ListFilesResult](e.Mediator, c.Request.Context(), query)
	if err != nil {
		handleError(c, err)
		return
	}
	c.JSON(http.StatusOK, result)
}

// GetPreviewURL godoc
// @Summary      获取预览链接
// @Description  生成文件的临时预览链接 (24小时有效)
// @Tags         文件操作
// @Accept       json
// @Produce      json
// @Param        bucket_name query string true "存储桶名称"
// @Param        object_key query string true "对象键"
// @Success      200  {object}  map[string]string
// @Failure      400  {object}  map[string]string
// @Failure      500  {object}  map[string]string
// @Router       /files/preview [get]
func (e *FileEndpoint) GetPreviewURL(c *gin.Context) {
	var req requests.GetFilePreviewRequest
	if err := c.ShouldBind(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	if err := e.NewFeaturesValidator.ValidatePreview(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	query := handlers.GetFilePreviewQuery{
		BucketName: req.BucketName,
		ObjectKey:  req.ObjectKey,
		Expiry:     24 * time.Hour,
	}

	result, err := mediator.Send[handlers.GetFilePreviewQuery, string](e.Mediator, c.Request.Context(), query)
	if err != nil {
		handleError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"url": result})
}

// InitMultipart godoc
// @Summary      初始化分片上传
// @Description  开始一个新的大文件分片上传任务
// @Tags         大文件上传
// @Accept       json
// @Produce      json
// @Param        request body requests.InitMultipartRequest true "请求参数"
// @Success      200  {object}  map[string]string "返回 upload_id"
// @Failure      400  {object}  map[string]string
// @Failure      500  {object}  map[string]string
// @Router       /files/multipart/init [post]
func (e *FileEndpoint) InitMultipart(c *gin.Context) {
	var req requests.InitMultipartRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if err := e.NewFeaturesValidator.ValidateInitMultipart(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	cmd := handlers.InitMultipartCommand{BucketName: req.BucketName, ObjectKey: req.ObjectKey}
	result, err := mediator.Send[handlers.InitMultipartCommand, string](e.Mediator, c.Request.Context(), cmd)
	if err != nil {
		handleError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"upload_id": result})
}

// UploadPart godoc
// @Summary      上传分片
// @Description  上传单个文件分片
// @Tags         大文件上传
// @Accept       multipart/form-data
// @Produce      json
// @Param        bucket_name formData string true "存储桶名称"
// @Param        object_key formData string true "对象键"
// @Param        upload_id formData string true "上传ID"
// @Param        part_number formData int true "分片序号 (从1开始)"
// @Param        file formData file true "分片文件数据"
// @Success      200  {object}  map[string]string "返回 ETag"
// @Failure      400  {object}  map[string]string
// @Failure      500  {object}  map[string]string
// @Router       /files/multipart/part [put]
func (e *FileEndpoint) UploadPart(c *gin.Context) {
	var req requests.UploadPartRequest
	if err := c.ShouldBind(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if err := e.NewFeaturesValidator.ValidateUploadPart(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	file, err := req.File.Open()
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to open part file"})
		return
	}
	defer file.Close()

	cmd := handlers.UploadPartCommand{
		BucketName: req.BucketName,
		ObjectKey:  req.ObjectKey,
		UploadId:   req.UploadId,
		PartNumber: req.PartNumber,
		Data:       file,
	}
	result, err := mediator.Send[handlers.UploadPartCommand, string](e.Mediator, c.Request.Context(), cmd)
	if err != nil {
		handleError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"etag": result})
}

// CompleteMultipart godoc
// @Summary      完成分片上传
// @Description  合并所有分片完成上传
// @Tags         大文件上传
// @Accept       json
// @Produce      json
// @Param        request body requests.CompleteMultipartRequest true "请求参数"
// @Success      200  {object}  map[string]string "返回文件位置"
// @Failure      400  {object}  map[string]string
// @Failure      500  {object}  map[string]string
// @Router       /files/multipart/complete [post]
func (e *FileEndpoint) CompleteMultipart(c *gin.Context) {
	var req requests.CompleteMultipartRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if err := e.NewFeaturesValidator.ValidateCompleteMultipart(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	cmd := handlers.CompleteMultipartCommand{
		BucketName: req.BucketName,
		ObjectKey:  req.ObjectKey,
		UploadId:   req.UploadId,
		Parts:      req.Parts,
	}
	result, err := mediator.Send[handlers.CompleteMultipartCommand, string](e.Mediator, c.Request.Context(), cmd)
	if err != nil {
		handleError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"location": result})
}

func handleError(c *gin.Context, err error) {
	if be, ok := err.(*common.BusinessException); ok {
		c.JSON(be.Code, gin.H{"error": be.Message})
	} else {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
	}
}