package handler

import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"path"
	"show-rss/src/feeds"
	"slices"
	"text/template"
)

var dir = func() string {
	if v := os.Getenv("UI_D"); v != "" {
		return v
	}
	return "./src/cmd/server/handler/testdata"
}()

func (h Handler) ui(w http.ResponseWriter, r *http.Request) error {
	fs := http.FileServer(http.Dir(dir))
	if path.Base(r.URL.Path) == "ui" {
		return h.uiIndex(w, r)
	}
	http.StripPrefix("/experimental/ui", fs).ServeHTTP(w, r)
	return nil
}

func (h Handler) uiIndex(w http.ResponseWriter, r *http.Request) error {
	ctx := r.Context()

	b, _ := os.ReadFile(path.Join(dir, "index.tmpl"))

	tmpl := template.New(r.URL.Path).Funcs(template.FuncMap{
		"feeds": func() ([]feeds.Feed, error) {
			all := []feeds.Feed{}
			err := feeds.ForEach(ctx, func(f feeds.Feed) error {
				all = append(all, f)
				return ctx.Err()
			})
			return all, err
		},
		"feedsVersionFields": func() []string {
			b, _ := json.Marshal(feeds.Version{})
			var m map[string]any
			json.Unmarshal(b, &m)
			ks := make([]string, 0, len(m))
			for k := range m {
				ks = append(ks, k)
			}
			slices.Sort(ks)
			return ks
		},
		"namespan": func(k string, v any) string {
			return fmt.Sprintf("<span name=%q>%s</span>", k, v)
		},
	})

	tmpl, err := tmpl.Parse(string(b))
	if err != nil {
		return err
	}

	return tmpl.Execute(w, nil)
}