package middleware

import (
	"net/http"
	"strings"
)

// HeaderBool reads portal-proxy boolean headers.
// Contract: "1", "true", "yes" and "on" are true; everything else is false.
func HeaderBool(r *http.Request, name string) bool {
	switch strings.ToLower(strings.TrimSpace(r.Header.Get(name))) {
	case "1", "true", "yes", "on":
		return true
	default:
		return false
	}
}

// HeaderCSV returns a trimmed non-empty CSV list from a portal-proxy header.
func HeaderCSV(r *http.Request, name string) []string {
	raw := strings.TrimSpace(r.Header.Get(name))
	if raw == "" {
		return nil
	}
	parts := strings.Split(raw, ",")
	out := make([]string, 0, len(parts))
	for _, part := range parts {
		if v := strings.TrimSpace(part); v != "" {
			out = append(out, v)
		}
	}
	return out
}

// HeaderScope returns a lower-cased scope constrained to allowed values.
// The fallback is returned when the header is empty or unknown.
func HeaderScope(r *http.Request, name, fallback string, allowed ...string) string {
	value := strings.ToLower(strings.TrimSpace(r.Header.Get(name)))
	for _, option := range allowed {
		if value == strings.ToLower(strings.TrimSpace(option)) {
			return value
		}
	}
	return fallback
}