package http

import (
	"context"
	"net/http"
	"net/netip"
	"strings"

	"tug/internal/platform/origin"
)

type Client = origin.Client

func WithClient(ctx context.Context, c Client) context.Context {
	return origin.With(ctx, c)
}

func ClientOf(ctx context.Context) Client {
	return origin.Of(ctx)
}

func forwardedClient(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		next.ServeHTTP(w, r.WithContext(WithClient(r.Context(), Client{Addr: lastForwarded(r.Header), UserAgent: r.UserAgent()})))
	})
}

func lastForwarded(h http.Header) netip.Addr {
	lines := h.Values("X-Forwarded-For")
	if len(lines) == 0 {
		return netip.Addr{}
	}
	last := lines[len(lines)-1]
	return parseForwarded(strings.Trim(last[strings.LastIndexByte(last, ',')+1:], " \t"))
}

func parseForwarded(s string) netip.Addr {
	if a, err := netip.ParseAddr(s); err == nil {
		return a.WithZone("").Unmap()
	}
	if ap, err := netip.ParseAddrPort(s); err == nil {
		return ap.Addr().WithZone("").Unmap()
	}
	if inner, ok := strings.CutPrefix(s, "["); ok {
		if inner, ok = strings.CutSuffix(inner, "]"); ok {
			if a, err := netip.ParseAddr(inner); err == nil && a.Is6() {
				return a.WithZone("").Unmap()
			}
		}
	}
	return netip.Addr{}
}