package server

import (
	"errors"
	"mime"
	"net/http"
	"net/url"
	"strconv"
	"strings"

	"cmbuyer/admin/internal/taskdetail"
	"cmbuyer/admin/internal/transport/webui"

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

const detailViewHeader = "X-CMBuyer-View"
const detailVaryHeader = "X-CMBuyer-View, Accept, Sec-Fetch-Site"

func taskDetailPage(options Options) gin.HandlerFunc {
	return func(context *gin.Context) {
		context.Header("Vary", detailVaryHeader)
		if !options.Sessions.IsAuthenticated(context.Request) {
			context.Redirect(http.StatusSeeOther, "/login?return_to="+url.QueryEscape(context.Request.URL.RequestURI()))
			return
		}
		view := context.GetHeader(detailViewHeader)
		if view != "" && view != "drawer" {
			context.Status(http.StatusBadRequest)
			return
		}
		if view == "drawer" {
			if context.GetHeader("Sec-Fetch-Site") != "same-origin" {
				context.Status(http.StatusForbidden)
				return
			}
			if !acceptsHTML(context.GetHeader("Accept")) {
				context.Status(http.StatusNotAcceptable)
				return
			}
		}
		detail, err := options.TaskDetails.Get(context.Request.Context(), context.Param("id"))
		if errors.Is(err, taskdetail.ErrNotFound) {
			context.Status(http.StatusNotFound)
			return
		}
		if err != nil {
			context.Status(http.StatusInternalServerError)
			return
		}
		context.Header("Content-Type", "text/html; charset=utf-8")
		context.Status(http.StatusOK)
		data := webui.TaskDetailData{Detail: detail}
		if view == "drawer" {
			if err := webui.RenderTaskDetailFragment(context.Writer, data); err != nil {
				_ = context.Error(err)
			}
			return
		}
		if err := webui.RenderTaskDetailPage(context.Writer, data); err != nil {
			_ = context.Error(err)
		}
	}
}

func acceptsHTML(header string) bool {
	for _, value := range strings.Split(header, ",") {
		mediaType, parameters, err := mime.ParseMediaType(strings.TrimSpace(value))
		if err != nil || !strings.EqualFold(mediaType, "text/html") {
			continue
		}
		quality := 1.0
		if rawQuality, exists := parameters["q"]; exists {
			quality, err = strconv.ParseFloat(rawQuality, 64)
			if err != nil || quality < 0 || quality > 1 {
				continue
			}
		}
		if quality > 0 {
			return true
		}
	}
	return false
}