package main

import (
	"crypto/tls"
	"encoding/json"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"testing"

	"github.com/novox/mesh-controller/internal/broker"
)

// behind is a workload the proxy can send to, and a table routing one public name and one
// internal-only name to it, with the mesh's machines as the membership would issue them.
func behind(t *testing.T, mesh ...string) *table {
	t.Helper()
	workload := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, "the workload")
	}))
	t.Cleanup(workload.Close)
	at, _ := url.Parse(workload.URL)
	host, port, _ := net.SplitHostPort(at.Host)

	routes, public, err := routesFrom(write(t, fmt.Sprintf(`{"given":[
	  {"from":"app","node":"anchor","at":%q,
	   "values":{"name":"app.example","internal-name":"app.anchor.internal","port":%s}},
	  {"from":"admin","node":"anchor","at":%q,
	   "values":{"internal-name":"admin.anchor.internal","port":%s}}
	]}`, host, port, host, port)))
	if err != nil {
		t.Fatal(err)
	}
	held := newTable()
	inside, err := sourcesOf(mesh)
	if err != nil {
		t.Fatal(err)
	}
	held.setInside(inside)
	held.set(routes, public)
	return held
}

// askFrom is what the proxy answers a request for host coming from remote.
func askFrom(held *table, host, remote string) (int, string) {
	r := httptest.NewRequest(http.MethodGet, "http://"+host+"/", nil)
	r.RemoteAddr = remote
	w := httptest.NewRecorder()
	handler(held).ServeHTTP(w, r)
	return w.Code, w.Body.String()
}

// **An internal-only name is served to the private network and to nobody else** (novox/hq ADR
// 0138, issue 191). The proxy answers public names on the same listeners, so without this a name
// being internal kept nobody out: a request from the internet only had to carry it.
func TestAnInternalOnlyNameIsServedOnlyInsideThePrivateNetwork(t *testing.T) {
	held := behind(t, "10.10.0.1", "10.10.0.7")

	if code, body := askFrom(held, "admin.anchor.internal", "10.10.0.7:51000"); code != http.StatusOK ||
		body != "the workload" {
		t.Errorf("a request from the private network was not served: %d %q", code, body)
	}
	if code, body := askFrom(held, "admin.anchor.internal", "127.0.0.1:51000"); code != http.StatusOK {
		t.Errorf("a request from the machine itself was not served: %d %q", code, body)
	}

	code, body := askFrom(held, "admin.anchor.internal", "203.0.113.9:51000")
	if code != http.StatusNotFound {
		t.Fatalf("a request from outside the private network reached an internal-only name: %d %q",
			code, body)
	}
	// Answered as a name never routed, and the list of what is served does not name it either —
	// otherwise the refusal would tell an outsider exactly what to ask for from inside.
	if strings.Contains(strings.SplitN(body, "\n", 2)[1], "admin.anchor.internal") {
		t.Errorf("the refusal names the internal-only route to an outsider: %q", body)
	}
	if !strings.Contains(body, "app.example") {
		t.Errorf("the refusal stopped listing the public names: %q", body)
	}
}

// The internal name of a route that also has a public one is internal too: served inside, and to
// an outsider only under the public name. Nothing is lost — the outsider has the public name — and a
// name stays one thing whichever route it came from.
func TestAnInternalAliasOfAPublicRouteIsServedInsideOnly(t *testing.T) {
	held := behind(t, "10.10.0.1", "10.10.0.7")
	if code, body := askFrom(held, "app.anchor.internal", "10.10.0.7:51000"); code != http.StatusOK {
		t.Errorf("the internal alias stopped answering the private network: %d %q", code, body)
	}
	if code, _ := askFrom(held, "app.anchor.internal", "203.0.113.9:51000"); code != http.StatusNotFound {
		t.Errorf("the internal alias was served to an outsider: %d", code)
	}
	if code, _ := askFrom(held, "app.example", "203.0.113.9:51000"); code != http.StatusOK {
		t.Errorf("the public name was refused to an outsider: %d", code)
	}
}

// Before a membership has said who the mesh is, only the machine itself is inside — refused to
// everyone else, never served to everyone.
func TestUntilTheMeshIsIssuedAnInternalOnlyNameIsServedToTheMachineAlone(t *testing.T) {
	held := behind(t)
	if code, _ := askFrom(held, "admin.anchor.internal", "10.10.0.7:51000"); code != http.StatusNotFound {
		t.Errorf("an internal-only name was served with no private network said: %d", code)
	}
	if code, _ := askFrom(held, "admin.anchor.internal", "[::1]:51000"); code != http.StatusOK {
		t.Errorf("an internal-only name was refused to the machine itself: %d", code)
	}
}

type from struct {
	net.Conn
	remote net.Addr
}

func (c from) RemoteAddr() net.Addr { return c.remote }

// The handshake refuses an internal-only name to an outsider too: the certificate would name it,
// and serving it would answer the question the routing refuses to.
func TestTheHandshakeRefusesAnInternalOnlyNameToAnOutsider(t *testing.T) {
	held := behind(t, "10.10.0.1", "10.10.0.7")
	served := &tls.Certificate{}
	pick := certificateFor(held, func(*tls.ClientHelloInfo) (*tls.Certificate, error) { return served, nil }, nil)
	hello := func(name, remote string) *tls.ClientHelloInfo {
		addr, _ := net.ResolveTCPAddr("tcp", remote)
		return &tls.ClientHelloInfo{ServerName: name, Conn: from{remote: addr}}
	}

	if _, err := pick(hello("admin.anchor.internal", "203.0.113.9:443")); err == nil {
		t.Error("an outsider was handed a certificate for an internal-only name")
	}
	if got, err := pick(hello("admin.anchor.internal", "10.10.0.7:443")); err != nil || got != served {
		t.Errorf("a client on the private network was refused: %v", err)
	}
	if got, err := pick(hello("app.example", "203.0.113.9:443")); err != nil || got != served {
		t.Errorf("a public name was refused to an outsider: %v", err)
	}
}

// The mesh is issued as machines' addresses; a range is read as well. One that does not parse is
// refused rather than skipped, so a typo never quietly narrows or widens who is inside.
func TestTheMeshIsReadAsAddressesAndRanges(t *testing.T) {
	if _, err := sourcesOf([]string{"10.10.0.1", "not-an-address"}); err == nil {
		t.Error("an entry that is not an address was accepted")
	}
	inside, err := sourcesOf([]string{"10.10.0.1", "fd00::1", "10.20.0.0/24"})
	if err != nil {
		t.Fatal(err)
	}
	for remote, want := range map[string]bool{
		"10.10.0.1:1":          true,
		"[::ffff:10.10.0.1]:1": true,
		"[fd00::1]:1":          true,
		"10.20.0.200:1":        true,
		"10.10.0.2:1":          false,
		"192.168.1.10:1":       false,
		"not-an-address":       false,
	} {
		if inside.holds(remote) != want {
			t.Errorf("%s inside the mesh: got %v, want %v", remote, !want, want)
		}
	}
}

// What the mesh issues is what is served: the routes in the membership, internal names to the
// machines it names (novox/hq ADR 0167).
func TestAMembershipIsServedAsIssued(t *testing.T) {
	held := newTable()
	took := applyMembership(broker.Membership{
		Receives: map[string]json.RawMessage{"route": json.RawMessage(`[
		  {"from":"admin","node":"anchor","at":"anchor.internal",
		   "values":{"internal-name":"admin.anchor.internal","port":8080}}]`)},
		Mesh: []string{"10.10.0.7"},
	}, held)
	if !took {
		t.Fatal("a membership carrying routes was not applied")
	}
	if code, _ := askFrom(held, "admin.anchor.internal", "10.10.0.7:1"); code == http.StatusNotFound {
		t.Error("a machine the membership names was refused the internal-only route")
	}
	if code, _ := askFrom(held, "admin.anchor.internal", "10.10.0.9:1"); code != http.StatusNotFound {
		t.Errorf("a machine the membership does not name was served the internal-only route: %d", code)
	}
}

// A membership that says nothing about routes is one from a controller that does not issue them,
// and changes nothing: the file stays the source rather than every route being withdrawn.
func TestAMembershipWithoutRoutesLeavesTheFileServing(t *testing.T) {
	held := behind(t, "10.10.0.7")
	before := held.names()
	if applyMembership(broker.Membership{Mesh: []string{"10.10.0.7"}}, held) {
		t.Error("a membership without routes was taken as the source of routes")
	}
	if got := held.names(); strings.Join(got, ",") != strings.Join(before, ",") {
		t.Errorf("a membership without routes changed what is served: %v, was %v", got, before)
	}
	if applyMembership(broker.Membership{
		Receives: map[string]json.RawMessage{"route": json.RawMessage(`[]`)},
		Mesh:     []string{"not-an-address"},
	}, held) {
		t.Error("a membership whose mesh cannot be read was applied")
	}
}