package edge

import (
	"encoding/json"
	"io"
	"net"
	"net/http"
	"net/http/httptest"
	"net/url"
	"testing"
	"time"

	"github.com/carlosframework/platform/internal/geo"
	"github.com/carlosframework/platform/internal/geoip"
	"github.com/carlosframework/platform/internal/registry"
	"github.com/carlosframework/platform/internal/release"
)

// tunnelGeoScene is a hub edge routing demo.example over a real tunnelclient
// connection to a remote box whose own Edge serves the app (geoip spec §8.4,
// D2). It returns the hub, the remote edge, and a request func.
func tunnelGeoScene(t *testing.T) (hub, remote *Edge, get func() map[string]string) {
	t.Helper()
	hubReg := tunnelRoute(t, registry.Route{Host: "demo.example", Kind: "instance", Status: "ready", Tunnel: "pi-box"})
	hub, err := New(hubReg, nil)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(hub.probers.Stop)
	srv := httptest.NewServer(hub)
	t.Cleanup(srv.Close)
	u, _ := url.Parse(srv.URL)
	th := NewTunnelHub(u.Hostname(), map[string]string{"pi-box": "sekrit"})
	hub.EnableTunnels(th)
	if err := hub.Reload(); err != nil {
		t.Fatal(err)
	}
	remote = geoEdge(t, "demo.example") // the remote box's own edge, geo-echo backend
	stop := startFakeRemoteHost(t, srv.URL, "pi-box", "sekrit", remote)
	t.Cleanup(stop)
	waitForTunnelState(t, th, "pi-box", "connected", e2eReconnectBound)
	get = func() map[string]string {
		t.Helper()
		req, _ := http.NewRequest("GET", srv.URL+"/", nil)
		req.Host = "demo.example"
		req.Header.Set(geoip.HeaderCountry, "KP") // a forgery at the hub's door
		resp, err := http.DefaultClient.Do(req)
		if err != nil {
			t.Fatal(err)
		}
		defer resp.Body.Close()
		b, _ := io.ReadAll(resp.Body)
		got := map[string]string{}
		if err := json.Unmarshal(b, &got); err != nil {
			t.Fatalf("remote app body %q: %v", b, err)
		}
		return got
	}
	return hub, remote, get
}

func TestTunnelDeliversTheHubsAnswerAndTheRemoteNeverLooksUp(t *testing.T) {
	hub, remote, get := tunnelGeoScene(t)
	hubSpy, remoteSpy := spyGeo(hub, "GB"), spyGeo(remote, "XX")
	h := get()
	if h[geoip.HeaderCountry] != "GB" || h[geoip.HeaderSource] != "TestDB-GB" {
		t.Fatalf("remote app saw %v, want the hub's GB answer", h)
	}
	if _, leaked := h[geoip.HeaderHop]; leaked {
		t.Fatal("X-Carlos-Hop-Geo reached the remote app")
	}
	if hubSpy.Load() != 1 || remoteSpy.Load() != 0 {
		t.Fatalf("lookups hub=%d remote=%d, want 1 and 0 (ingress computes)", hubSpy.Load(), remoteSpy.Load())
	}
}

// A miss at the hub crosses as a miss: the remote app gets no headers and
// the remote does not look up for itself.
func TestTunnelCarriesAMissAsAMiss(t *testing.T) {
	hub, remote, get := tunnelGeoScene(t)
	remoteSpy := spyGeo(remote, "XX")
	hub.geoLookup = func(_ net.IP) geo.Snapshot { return geo.Snapshot{Loaded: true, Source: "TestDB"} }
	if h := get(); len(h) != 0 {
		t.Fatalf("a hub miss reached the remote app as %v", h)
	}
	if remoteSpy.Load() != 0 {
		t.Fatal("the remote looked up after the hub missed")
	}
}

// Spec §9, codex R4-1/R5: one analytics observation per served response.
// The hub observes every tunnelled response (fresh or from its own cache)
// with its own geo answer; the remote observes none of them.
func TestTunnelledPageviewsAreCountedOnceAtTheHub(t *testing.T) {
	hubReg := tunnelRoute(t, registry.Route{Host: "demo.example", Kind: "instance", Status: "ready", Tunnel: "pi-box", App: "web"})
	hub, err := New(hubReg, nil)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(hub.probers.Stop)
	hub.EnableCache(NewCache(DefaultCacheMaxEntries, DefaultCacheMaxBodyBytes))
	srv := httptest.NewServer(hub)
	t.Cleanup(srv.Close)
	u, _ := url.Parse(srv.URL)
	th := NewTunnelHub(u.Hostname(), map[string]string{"pi-box": "sekrit"})
	hub.EnableTunnels(th)
	if err := hub.Reload(); err != nil {
		t.Fatal(err)
	}

	page := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		if r.URL.Path == "/cached" {
			w.Header().Set("Cache-Control", "public, max-age=60")
		}
		w.Write([]byte("<h1>hi</h1>"))
	}))
	t.Cleanup(page.Close)
	remoteReg := openReg(t)
	if err := remoteReg.Upsert(registry.Route{Host: "demo.example", Kind: "service", Addr: page.Listener.Addr().String(), Status: "ready", App: "web"}); err != nil {
		t.Fatal(err)
	}
	remote, err := New(remoteReg, nil)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(remote.probers.Stop)
	stop := startFakeRemoteHost(t, srv.URL, "pi-box", "sekrit", remote)
	t.Cleanup(stop)
	waitForTunnelState(t, th, "pi-box", "connected", e2eReconnectBound)

	hubM, remoteM := &memAnalytics{}, &memAnalytics{}
	on := map[string]bool{release.OpsAccount + "/web": true}
	hub.EnableAnalytics(hubM)
	hub.SetAnalyticsOn(on)
	remote.EnableAnalytics(remoteM)
	remote.SetAnalyticsOn(on)
	spyGeo(hub, "GB")
	spyGeo(remote, "XX")

	get := func(path string) {
		req, _ := http.NewRequest("GET", srv.URL+path, nil)
		req.Host = "demo.example"
		req.Header.Set("User-Agent", "Mozilla/5.0")
		resp, err := http.DefaultClient.Do(req)
		if err != nil {
			t.Fatal(err)
		}
		io.Copy(io.Discard, resp.Body)
		resp.Body.Close()
	}
	get("/fresh")
	get("/cached")
	get("/cached") // the hub's cache answers; the remote never sees it

	deadline := time.Now().Add(2 * time.Second)
	for len(hubM.snap()) < 3 && time.Now().Before(deadline) {
		time.Sleep(10 * time.Millisecond) // the observer runs in a defer after the response
	}
	if n := len(remoteM.snap()); n != 0 {
		t.Fatalf("the remote observed %d tunnelled responses, want 0", n)
	}
	obs := hubM.snap()
	if len(obs) != 3 {
		t.Fatalf("the hub observed %d responses, want 3 (one per served response)", len(obs))
	}
	for _, o := range obs {
		if o.Country != "GB" || o.GeoState != "hit" || o.GeoSource != "TestDB-GB" {
			t.Fatalf("hub observation %+v, want its own GB answer", o)
		}
	}
}