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// Package ui serves the embedded client and operator frontends.
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package ui
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import (
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	"embed"
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	"fmt"
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	"io/fs"
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	"net/http"
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	"strings"
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)
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//go:embed all:dist
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var output embed.FS
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func page(name string) http.Handler {
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	body, err := output.ReadFile("dist/" + name + "/index.html")
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	if err != nil {
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		panic(fmt.Errorf("read %s UI (run make ui): %w", name, err))
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	}
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	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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		if r.Method != http.MethodGet && r.Method != http.MethodHead {
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			w.Header().Set("Allow", "GET, HEAD")
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			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
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			return
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		}
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		w.Header().Set("Content-Type", "text/html; charset=utf-8")
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		w.Header().Set("Cache-Control", "no-cache")
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		if r.Method != http.MethodHead {
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			w.Write(body)
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		}
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	})
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}
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func ClientPage() http.Handler   { return page("client") }
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func OperatorPage() http.Handler { return page("operator") }
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// Assets serves common build assets relative to /ui/ or /_internal/ui/.
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// The caller strips its prefix and applies the interface's access controls.
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func Assets() http.Handler {
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	files, err := fs.Sub(output, "dist")
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	if err != nil {
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		panic(err)
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	}
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	server := http.FileServerFS(files)
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	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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		name := strings.TrimPrefix(r.URL.Path, "/")
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		if !fs.ValidPath(name) || strings.HasSuffix(name, "/") ||
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			(!strings.HasPrefix(name, "assets/") && !strings.HasPrefix(name, "fonts/")) {
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			http.NotFound(w, r)
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			return
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		}
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		if r.Method != http.MethodGet && r.Method != http.MethodHead {
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			w.Header().Set("Allow", "GET, HEAD")
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			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
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			return
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		}
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		w.Header().Set("Cache-Control", "private, max-age=31536000, immutable")
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		server.ServeHTTP(w, r)
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	})
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}