package avatar

import (
	"errors"
	"net/http"

	"github.com/gin-gonic/gin"

	"galo/internal/auth"
	"galo/internal/httpx"
	"galo/internal/photos"
)

// avatarCacheControl is safe to cache aggressively because the URL carries an
// opaque per-generation version segment: replacing the avatar changes the URL.
const avatarCacheControl = "private, max-age=31536000, immutable"

type Handler struct {
	svc *Service
}

func NewHandler(svc *Service) *Handler { return &Handler{svc: svc} }

// Upload installs or replaces the authenticated user's avatar from a multipart
// "file" field and returns the updated self profile.
func (h *Handler) Upload(c *gin.Context) {
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, h.svc.MaxUploadBytes())
	fileHeader, err := c.FormFile("file")
	if err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) {
			httpx.RespondError(c, httpx.NewError(http.StatusRequestEntityTooLarge, "file_too_large",
				"avatar exceeds the maximum upload size"))
			return
		}
		httpx.RespondError(c, httpx.BadRequest("invalid_request", "file is required"))
		return
	}
	f, err := fileHeader.Open()
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	defer f.Close()

	u, err := h.svc.SetAvatar(c.Request.Context(), auth.UserID(c), f)
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"user": u.Self()})
}

// Remove resets the avatar to the default placeholder and returns the updated
// self profile.
func (h *Handler) Remove(c *gin.Context) {
	u, err := h.svc.RemoveAvatar(c.Request.Context(), auth.UserID(c))
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"user": u.Self()})
}

// Serve streams the user's avatar. The version segment only busts caches; the
// current generation is always served.
func (h *Handler) Serve(c *gin.Context) {
	large := c.Query("size") == "large"
	data, err := h.svc.AvatarImage(c.Request.Context(), c.Param("userID"), large)
	if err != nil {
		if errors.Is(err, photos.ErrObjectNotFound) {
			httpx.RespondError(c, httpx.NotFound("avatar_not_found", "avatar not found"))
			return
		}
		httpx.RespondError(c, err)
		return
	}
	c.Header("Cache-Control", avatarCacheControl)
	c.Data(http.StatusOK, "image/webp", data)
}