package main

import (
	"context"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func write(t *testing.T, body string) string {
	t.Helper()
	path := filepath.Join(t.TempDir(), "routes.json")
	if err := os.WriteFile(path, []byte(body), 0o644); err != nil {
		t.Fatal(err)
	}
	return path
}

// plain is the table an ordinary set of routes makes: one host, one target, no policy.
func plain(routes map[string]string) map[string][]rule {
	out := map[string][]rule{}
	for host, target := range routes {
		out[host] = []rule{{target: target}}
	}
	return out
}

// allPublic is every host in a routes map, ACME-eligible — the ordinary case for a test with no
// internal-name alias of its own to distinguish.
func allPublic(routes map[string][]rule) map[string]bool {
	out := map[string]bool{}
	for host := range routes {
		out[host] = true
	}
	return out
}

// targetOf is where a host's first matching rule sends a request.
func targetOf(routes map[string][]rule, host string) string {
	if rules := routes[host]; len(rules) > 0 {
		return rules[0].target
	}
	return ""
}

// A route is a grant: the consumer supplies a target, and where that machine is comes from the
// mesh rather than from a naming convention the proxy has to know.
func TestARouteGoesToWhereTheMeshSaysTheConsumerIs(t *testing.T) {
	routes, _, err := routesFrom(write(t, `{"contributions":1,"requirement":"route","given":[
	  {"from":"app","node":"laptop","at":"laptop.internal","values":{"name":"App.Example","port":8080}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	// Lower-cased, because a Host header is not case-sensitive and a route that only answers the
	// spelling in the manifest answers half the requests made to it.
	if targetOf(routes, "app.example") != "http://laptop.internal:8080" {
		t.Fatalf("the route does not point at the consumer: %v", routes)
	}
}

// A route with an internal-name alias is reachable under both hostnames, pointed at the same
// target — the same convenience a predecessor proxy gave for reaching a service over the VPN
// without a public TLS round trip.
func TestARouteWithAnInternalNameIsReachableUnderBoth(t *testing.T) {
	routes, public, err := routesFrom(write(t, `{"given":[
	  {"from":"app","node":"anchor","at":"anchor.internal",
	   "values":{"name":"app.example","internal-name":"app.anchor.internal","port":8080}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	if targetOf(routes, "app.example") != "http://anchor.internal:8080" {
		t.Fatalf("the public name does not point at the consumer: %v", routes)
	}
	if targetOf(routes, "app.anchor.internal") != "http://anchor.internal:8080" {
		t.Fatalf("the internal alias does not point at the same consumer: %v", routes)
	}
	if !public["app.example"] {
		t.Errorf("the public name is not eligible for a certificate: %v", public)
	}
	if public["app.anchor.internal"] {
		t.Errorf("the internal alias is eligible for a certificate no public CA could ever issue: %v",
			public)
	}
}

// A route with no internal-name composed gets no second host — the ordinary case, unchanged.
func TestARouteWithNoInternalNameGetsNoAlias(t *testing.T) {
	routes, _, err := routesFrom(write(t, `{"given":[
	  {"from":"app","node":"anchor","values":{"name":"app.example","port":8080}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	if len(routes) != 1 {
		t.Fatalf("a route with no internal-name grew a second host: %v", routes)
	}
}

// A workload beside the proxy is ordinary, and reaching it over loopback is both correct and the
// only thing that works when there is no private network.
func TestAConsumerOnTheProxysOwnMachineIsReachedOverLoopback(t *testing.T) {
	routes, _, err := routesFrom(write(t, `{"given":[
	  {"from":"app","node":"anchor","values":{"name":"app.example","port":9000}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	if targetOf(routes, "app.example") != "http://127.0.0.1:9000" {
		t.Fatalf("a workload on this machine was not reachable: %v", routes)
	}
}

// Skipped rather than served wrongly. A route with no port would proxy to :0.
func TestAContributionMissingWhatARouteNeedsIsSkipped(t *testing.T) {
	routes, _, err := routesFrom(write(t, `{"given":[
	  {"from":"a","node":"n","at":"n.internal","values":{"name":"no-port.example"}},
	  {"from":"b","node":"n","at":"n.internal","values":{"port":8080}},
	  {"from":"c","node":"n","at":"n.internal","values":{"name":"fine.example","port":8080}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	if len(routes) != 1 || targetOf(routes, "fine.example") == "" {
		t.Fatalf("an unusable contribution was served: %v", routes)
	}
}

// A route may name a target reached over https, for a backend that terminates its own TLS — the
// shape Mailu's webmail front needs, which this proxy reaches as a plain workload otherwise.
func TestARouteMayTargetHttps(t *testing.T) {
	routes, _, err := routesFrom(write(t, `{"given":[
	  {"from":"mail","node":"anchor","at":"anchor.internal",
	   "values":{"name":"mail.example","port":7443,"scheme":"https","insecure":true}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	if targetOf(routes, "mail.example") != "https://anchor.internal:7443" {
		t.Fatalf("an https target was not built as one: %v", routes)
	}
	if !routes["mail.example"][0].insecure {
		t.Fatal("insecure was declared and not carried onto the rule")
	}
}

// A scheme that is neither http nor https is refused rather than guessed at.
func TestARouteWithAnUnknownSchemeIsSkipped(t *testing.T) {
	routes, _, err := routesFrom(write(t, `{"given":[
	  {"from":"a","node":"n","at":"n.internal","values":{"name":"bad.example","port":80,"scheme":"ftp"}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	if len(routes) != 0 {
		t.Fatalf("a route with an unusable scheme was served: %v", routes)
	}
}

// End to end: a backend terminating TLS with a certificate nothing would ordinarily trust is still
// reached when the route declared `insecure`, and the response comes back through unmodified.
func TestTheProxyReachesAnInsecureHttpsBackend(t *testing.T) {
	workload := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write([]byte("the workload, over its own TLS"))
	}))
	defer workload.Close()
	target := strings.TrimPrefix(workload.URL, "https://")

	held := newTable()
	routes := map[string][]rule{"mail.example": {{target: "https://" + target, insecure: true}}}
	held.set(routes, allPublic(routes))

	proxy := httptest.NewServer(handler(held))
	defer proxy.Close()

	asked, err := http.NewRequest(http.MethodGet, proxy.URL, nil)
	if err != nil {
		t.Fatal(err)
	}
	asked.Host = "mail.example"
	answer, err := http.DefaultClient.Do(asked)
	if err != nil {
		t.Fatal(err)
	}
	defer answer.Body.Close()
	if answer.StatusCode != http.StatusOK {
		t.Fatalf("an insecure https backend was not reached: %d", answer.StatusCode)
	}
}

// End to end through the proxy itself: a request for the name reaches the workload, and a name
// nobody asked for is refused in a way that says what IS served.
func TestTheProxyReachesTheWorkloadAndNamesWhatItServes(t *testing.T) {
	workload := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write([]byte("the workload"))
	}))
	defer workload.Close()
	target := strings.TrimPrefix(workload.URL, "http://")
	host, port, _ := strings.Cut(target, ":")

	held := newTable()
	held.set(plain(map[string]string{"app.example": "http://" + host + ":" + port}), allPublic(plain(map[string]string{"app.example": "http://" + host + ":" + port})))

	proxy := httptest.NewServer(handler(held))
	defer proxy.Close()

	asked, err := http.NewRequest(http.MethodGet, proxy.URL, nil)
	if err != nil {
		t.Fatal(err)
	}
	asked.Host = "app.example"
	answer, err := http.DefaultClient.Do(asked)
	if err != nil {
		t.Fatal(err)
	}
	defer answer.Body.Close()
	if answer.StatusCode != http.StatusOK {
		t.Fatalf("a request for a served name got %d", answer.StatusCode)
	}

	// And a name that is not served says which are — a route withdrawn and a name that never
	// existed are different things, and a bare 404 makes an operator go and read the mesh.
	other, _ := http.NewRequest(http.MethodGet, proxy.URL, nil)
	other.Host = "nobody.example"
	refused, err := http.DefaultClient.Do(other)
	if err != nil {
		t.Fatal(err)
	}
	defer refused.Body.Close()
	if refused.StatusCode != http.StatusNotFound {
		t.Fatalf("a name nobody asked for got %d", refused.StatusCode)
	}
	body := make([]byte, 256)
	n, _ := refused.Body.Read(body)
	if !strings.Contains(string(body[:n]), "app.example") {
		t.Fatalf("the refusal does not say what is served: %s", body[:n])
	}
}

// The file is the whole truth about who has a route, so the table replaces rather than merges.
//
// Merging would keep serving a name whose module was unassigned — the stale-route fault
// 08-connectivity lists as open, reintroduced one level down. A stale public name pointing at
// nothing fails more visibly than a stale grant, which is exactly why it must not survive.
func TestWithdrawingARouteStopsServingIt(t *testing.T) {
	held := newTable()
	initial := plain(map[string]string{
		"going.example":   "http://a.internal:80",
		"staying.example": "http://b.internal:80",
	})
	held.set(initial, allPublic(initial))
	held.set(plain(map[string]string{"staying.example": "http://b.internal:80"}), allPublic(plain(map[string]string{"staying.example": "http://b.internal:80"})))

	if _, still := held.find("going.example", "/"); still {
		t.Fatal("a route whose module was unassigned is still served")
	}
	if _, kept := held.find("staying.example", "/"); !kept {
		t.Fatal("withdrawing one route took another with it")
	}
}

// A Host header carries a port and the name does not.
func TestARequestNamingAPortStillFindsItsRoute(t *testing.T) {
	held := newTable()
	held.set(plain(map[string]string{"app.example": "http://a.internal:8080"}), allPublic(plain(map[string]string{"app.example": "http://a.internal:8080"})))
	if _, found := held.find("app.example:8080", "/"); !found {
		t.Fatal("a request to app.example:8080 did not find the route for app.example")
	}
}

// Defends novox/hq 04-ISSUES/004: issuance targets staging unless something says otherwise.
//
// The failure this guards is not a broken proxy. It is a working one that quietly spends a
// production quota which does not replenish for a week, on exactly the work most likely to
// iterate.
func TestTheIssuerIsStagingUnlessNamed(t *testing.T) {
	t.Setenv("ACME_DIRECTORY", "")
	if got := issuer(); !strings.Contains(got, "staging") {
		t.Fatalf("with nothing set the issuer is %q, and a default that spends production quota "+
			"is a default nobody chose", got)
	}

	t.Setenv("ACME_DIRECTORY", "https://acme-v02.api.letsencrypt.org/directory")
	if got := issuer(); strings.Contains(got, "staging") {
		t.Fatalf("an issuer was named explicitly and %q was used instead", got)
	}
}

// A certificate is only ever asked for on a name the mesh routes here.
//
// **Without this, anything that can reach the port spends the quota.** A scan sending arbitrary
// names, or one misconfigured client, becomes a stream of failed orders against the account's
// rate limit — and the proxy would look healthy throughout.
func TestNoCertificateIsAskedForOnAnUnroutedName(t *testing.T) {
	held := newTable()
	held.set(plain(map[string]string{"photos.example": "http://127.0.0.1:8080"}), allPublic(plain(map[string]string{"photos.example": "http://127.0.0.1:8080"})))
	policy := onlyWhatTheMeshSaid(held)

	if err := policy(context.Background(), "photos.example"); err != nil {
		t.Errorf("a name the mesh routes here was refused a certificate: %v", err)
	}
	for _, name := range []string{"unknown.example", "", "photos.example.evil"} {
		if err := policy(context.Background(), name); err == nil {
			t.Errorf("a certificate would be ordered for %q, which the mesh never mentioned", name)
		}
	}
}

// A certificate is asked for on a route's public name, never on its internal-network alias — no
// public CA can validate a private name, and asking anyway would only spend the account's rate
// limit on an order that can never succeed.
func TestNoCertificateIsAskedForOnAnInternalAlias(t *testing.T) {
	routes, public, err := routesFrom(write(t, `{"given":[
	  {"from":"app","node":"anchor","at":"anchor.internal",
	   "values":{"name":"app.example","internal-name":"app.anchor.internal","port":8080}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	held := newTable()
	held.set(routes, public)
	policy := onlyWhatTheMeshSaid(held)

	if err := policy(context.Background(), "app.example"); err != nil {
		t.Errorf("the route's public name was refused a certificate: %v", err)
	}
	if err := policy(context.Background(), "app.anchor.internal"); err == nil {
		t.Error("a certificate was ordered for the internal alias, which no public CA can validate")
	}
}

// A certificate is asked of the *internal* authority only for a name that is routed here and is
// not a route's own public name — the internal-network alias, never the route it accompanies.
func TestTheInternalAuthorityOnlyCertifiesInternalOnlyAliases(t *testing.T) {
	routes, public, err := routesFrom(write(t, `{"given":[
	  {"from":"app","node":"anchor","at":"anchor.internal",
	   "values":{"name":"app.example","internal-name":"app.anchor.internal","port":8080}}
	]}`))
	if err != nil {
		t.Fatal(err)
	}
	held := newTable()
	held.set(routes, public)
	policy := onlyInternalNamesTheMeshSaid(held)

	if err := policy(context.Background(), "app.anchor.internal"); err != nil {
		t.Errorf("the internal alias was refused by its own authority: %v", err)
	}
	if err := policy(context.Background(), "app.example"); err == nil {
		t.Error("the internal authority certified a route's public name, which the public authority already covers")
	}
	if err := policy(context.Background(), "unrouted.internal"); err == nil {
		t.Error("the internal authority certified a name nobody routed here")
	}
}

// A route withdrawn stops being certifiable, without the proxy restarting.
func TestWithdrawingARouteWithdrawsItsCertificate(t *testing.T) {
	held := newTable()
	held.set(plain(map[string]string{"photos.example": "http://127.0.0.1:8080"}), allPublic(plain(map[string]string{"photos.example": "http://127.0.0.1:8080"})))
	policy := onlyWhatTheMeshSaid(held)
	if err := policy(context.Background(), "photos.example"); err != nil {
		t.Fatal(err)
	}

	held.set(nil, nil)
	if err := policy(context.Background(), "photos.example"); err == nil {
		t.Fatal("a withdrawn route can still order certificates, so the policy read a copy taken " +
			"once rather than what is served now")
	}
}