// Package httpclient provides shared HTTP client helpers used across the
// monorepo: client IP extraction, CORS middleware, and related utilities.
package httpclient

import (
	"net"
	"net/http"
	"strings"
)

// ClientIP extracts the best-effort client IP from a request by checking
// common reverse-proxy and CDN headers in priority order, falling back to
// the TCP remote address when no header is present. It does NOT respect
// query-parameter overrides (those belong at the handler level — see
// slask-finder/cmd/stores for the ?ip= debug pattern).
//
// Priority order: CF-Connecting-IP → X-Real-IP → X-Forwarded-For (first
// entry) → RemoteAddr (with port stripped when present).
func ClientIP(r *http.Request) string {
	for _, h := range []string{"CF-Connecting-IP", "X-Real-IP", "X-Forwarded-For"} {
		v := r.Header.Get(h)
		if v == "" {
			continue
		}
		// X-Forwarded-For may be a comma-separated list; take the first.
		if h == "X-Forwarded-For" {
			if i := strings.IndexByte(v, ','); i >= 0 {
				v = v[:i]
			}
		}
		return strings.TrimSpace(v)
	}
	// Fall back to the TCP remote address, stripping the port when present.
	if host, _, err := net.SplitHostPort(r.RemoteAddr); err == nil {
		return host
	}
	return r.RemoteAddr
}