package controller

import (
	"net/http"

	"github.com/QuantumNous/new-api/common"
	"github.com/gin-gonic/gin"
)

// etagVersionPublicContent namespaces the public-content ETag; bump it when
// the JSON envelope served by serveRevalidatedJSON changes shape.
const etagVersionPublicContent = "public-content:v1"

type publicContentResponse struct {
	Success bool   `json:"success"`
	Message string `json:"message"`
	Data    string `json:"data"`
}

// serveRevalidatedJSON writes public content as JSON with a weak
// content-derived ETag and answers conditional requests with 304 Not
// Modified. The ETag is a weak validator derived from the content, so it is
// stable across replicas and JSON encodings, and a new one is issued when
// the content changes. Cache-Control: no-cache forces revalidation before
// reuse, so an admin edit takes effect on the next request; Vary:
// Accept-Encoding keeps the gzip and identity encodings apart in shared
// caches.
func serveRevalidatedJSON(c *gin.Context, content string) {
	body, err := common.Marshal(publicContentResponse{
		Success: true,
		Message: "",
		Data:    content,
	})
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{
			"success": false,
			"message": err.Error(),
		})
		return
	}

	etag := common.ETagFor(etagVersionPublicContent, content)

	c.Header("ETag", etag)
	c.Header("Cache-Control", "no-cache")
	c.Header("Vary", "Accept-Encoding")

	if common.ETagMatches(c.GetHeader("If-None-Match"), etag) {
		c.Status(http.StatusNotModified)
		return
	}

	c.Data(http.StatusOK, "application/json; charset=utf-8", body)
}