package handler

import (
	"context"
	"io"
	"strconv"

	"gcy_hpc_server/internal/model"
	"gcy_hpc_server/internal/server"
	"gcy_hpc_server/internal/service"

	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
)

type fileServiceProvider interface {
	ListFiles(ctx context.Context, folderID *int64, page, pageSize int, search string) ([]model.FileResponse, int64, error)
	GetFileMetadata(ctx context.Context, fileID int64) (*model.File, *model.FileBlob, error)
	DownloadFile(ctx context.Context, fileID int64, rangeHeader string) (io.ReadCloser, *model.File, *model.FileBlob, int64, int64, error)
	DeleteFile(ctx context.Context, fileID int64) error
}

type FileHandler struct {
	svc    fileServiceProvider
	logger *zap.Logger
}

func NewFileHandler(svc *service.FileService, logger *zap.Logger) *FileHandler {
	return &FileHandler{svc: svc, logger: logger}
}

func (h *FileHandler) ListFiles(c *gin.Context) {
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "10"))
	if page < 1 {
		page = 1
	}
	if pageSize < 1 {
		pageSize = 10
	}

	var folderID *int64
	if v := c.Query("folder_id"); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil {
			h.logger.Warn("invalid folder_id", zap.String("folder_id", v))
			server.BadRequest(c, "invalid folder_id")
			return
		}
		folderID = &id
	}

	search := c.Query("search")

	files, total, err := h.svc.ListFiles(c.Request.Context(), folderID, page, pageSize, search)
	if err != nil {
		h.logger.Error("failed to list files", zap.Error(err))
		server.InternalError(c, err.Error())
		return
	}

	server.OK(c, model.ListFilesResponse{
		Files:    files,
		Total:    total,
		Page:     page,
		PageSize: pageSize,
	})
}

func (h *FileHandler) GetFile(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		h.logger.Warn("invalid file id", zap.String("id", c.Param("id")))
		server.BadRequest(c, "invalid id")
		return
	}

	file, blob, err := h.svc.GetFileMetadata(c.Request.Context(), id)
	if err != nil {
		h.logger.Error("failed to get file", zap.Int64("id", id), zap.Error(err))
		server.InternalError(c, err.Error())
		return
	}

	resp := model.FileResponse{
		ID:        file.ID,
		Name:      file.Name,
		FolderID:  file.FolderID,
		Size:      blob.FileSize,
		MimeType:  blob.MimeType,
		SHA256:    file.BlobSHA256,
		CreatedAt: file.CreatedAt,
		UpdatedAt: file.UpdatedAt,
	}
	server.OK(c, resp)
}

func (h *FileHandler) DownloadFile(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		h.logger.Warn("invalid file id for download", zap.String("id", c.Param("id")))
		server.BadRequest(c, "invalid id")
		return
	}

	rangeHeader := c.GetHeader("Range")

	reader, file, blob, start, end, err := h.svc.DownloadFile(c.Request.Context(), id, rangeHeader)
	if err != nil {
		h.logger.Error("failed to download file", zap.Int64("id", id), zap.Error(err))
		server.InternalError(c, err.Error())
		return
	}

	if rangeHeader != "" {
		server.StreamRange(c, reader, start, end, blob.FileSize, blob.MimeType)
	} else {
		server.StreamFile(c, reader, file.Name, blob.FileSize, blob.MimeType)
	}
}

func (h *FileHandler) DeleteFile(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		h.logger.Warn("invalid file id for delete", zap.String("id", c.Param("id")))
		server.BadRequest(c, "invalid id")
		return
	}

	if err := h.svc.DeleteFile(c.Request.Context(), id); err != nil {
		h.logger.Error("failed to delete file", zap.Int64("id", id), zap.Error(err))
		server.InternalError(c, err.Error())
		return
	}

	h.logger.Info("file deleted", zap.Int64("id", id))
	server.OK(c, gin.H{"message": "file deleted"})
}