package agent

import (
	"encoding/base64"
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"strconv"
	"strings"
	"testing"
)

const (
	oauthPath           = "kubernetes/namespace/repospawner/default/oauth-credentials"
	oauthClientID       = "mediamark-client-id"
	existingClientSec   = "existing-client-secret-from-authentik"
	existingCookieSec   = "existing-cookie-secret-value-abcdefghij"
	oauthExtraKeyValue  = "extra-key-secret-value"
	oauthVaultClientTok = "s.vaulttoken"
)

// oauthVaultStub is a KV-v2 stand-in that actually stores what is written, so
// read-modify-write behaviour can be asserted end to end.
type oauthVaultStub struct {
	data        map[string]any
	exists      bool
	version     int
	readStatus  int
	writeStatus int
	writes      []map[string]any
}

func newOAuthVaultStub() *oauthVaultStub {
	return &oauthVaultStub{readStatus: http.StatusOK, writeStatus: http.StatusOK}
}

// seed makes the path exist with the given fields at version 1.
func (v *oauthVaultStub) seed(data map[string]any) *oauthVaultStub {
	v.data = data
	v.exists = true
	v.version = 1
	return v
}

func (v *oauthVaultStub) server(t *testing.T) *httptest.Server {
	t.Helper()
	mux := http.NewServeMux()
	mux.HandleFunc("/v1/auth/approle/login", func(w http.ResponseWriter, r *http.Request) {
		var body map[string]string
		_ = json.NewDecoder(r.Body).Decode(&body)
		if _, ok := body["secret_id"]; ok {
			t.Errorf("secret_id must not be sent")
		}
		_, _ = io.WriteString(w, `{"auth":{"client_token":"`+oauthVaultClientTok+`"}}`)
	})
	mux.HandleFunc("/v1/kv/data/"+oauthPath, func(w http.ResponseWriter, r *http.Request) {
		if got := r.Header.Get("X-Vault-Token"); got != oauthVaultClientTok {
			t.Errorf("X-Vault-Token = %q, want %q", got, oauthVaultClientTok)
		}
		switch r.Method {
		case http.MethodGet:
			if v.readStatus != http.StatusOK {
				w.WriteHeader(v.readStatus)
				_, _ = io.WriteString(w, `{"errors":["permission denied"]}`)
				return
			}
			if !v.exists {
				w.WriteHeader(http.StatusNotFound)
				_, _ = io.WriteString(w, `{"errors":[]}`)
				return
			}
			payload, _ := json.Marshal(map[string]any{
				"data": map[string]any{"data": v.data, "metadata": map[string]any{"version": v.version}},
			})
			_, _ = w.Write(payload)
		case http.MethodPost:
			if v.writeStatus != http.StatusOK {
				w.WriteHeader(v.writeStatus)
				_, _ = io.WriteString(w, `{"errors":["permission denied"]}`)
				return
			}
			var body struct {
				Data map[string]any `json:"data"`
			}
			_ = json.NewDecoder(r.Body).Decode(&body)
			v.writes = append(v.writes, body.Data)
			v.data = body.Data
			v.exists = true
			v.version++
			_, _ = io.WriteString(w, `{"data":{"version":`+strconv.Itoa(v.version)+`}}`)
		default:
			t.Errorf("unexpected method %s", r.Method)
		}
	})
	srv := httptest.NewServer(mux)
	t.Cleanup(srv.Close)
	return srv
}

func oauthOpts(vaultURL string) SeedOAuthOptions {
	return SeedOAuthOptions{
		VaultAddr: vaultURL,
		RoleID:    "role-xyz",
		KVMount:   DefaultKVMount,
		Path:      oauthPath,
		ClientID:  oauthClientID,
	}
}

// actions flattens a result into key -> action for order-independent asserts.
func actions(res SeedOAuthResult) map[string]string {
	m := make(map[string]string, len(res.Keys))
	for _, k := range res.Keys {
		m[k.Name] = k.Action
	}
	return m
}

func stringField(t *testing.T, data map[string]any, key string) string {
	t.Helper()
	s, ok := data[key].(string)
	if !ok {
		t.Fatalf("written %s = %v, want a string", key, data[key])
	}
	return s
}

// assertDecodesTo32 fails unless the value is base64 of exactly 32 bytes, which
// is what oauth2-proxy requires of a cookie secret.
func assertDecodesTo32(t *testing.T, enc *base64.Encoding, value, name string) {
	t.Helper()
	raw, err := enc.DecodeString(value)
	if err != nil {
		t.Fatalf("%s is not valid base64: %v", name, err)
	}
	if len(raw) != oauthSecretBytes {
		t.Errorf("%s decodes to %d bytes, want %d", name, len(raw), oauthSecretBytes)
	}
}

func TestSeedOAuthFreshCreate(t *testing.T) {
	v := newOAuthVaultStub()
	res, err := SeedOAuth(oauthOpts(v.server(t).URL))
	if err != nil {
		t.Fatalf("SeedOAuth: %v", err)
	}
	if !res.Changed || res.Version != 1 {
		t.Errorf("Changed=%v Version=%d, want a first write at version 1", res.Changed, res.Version)
	}
	for key, want := range map[string]string{
		OAuthClientIDKey:     ActionCreated,
		OAuthClientSecretKey: ActionCreated,
		OAuthCookieSecretKey: ActionCreated,
	} {
		if got := actions(res)[key]; got != want {
			t.Errorf("%s action = %q, want %q", key, got, want)
		}
	}
	if len(v.writes) != 1 {
		t.Fatalf("%d writes, want exactly 1", len(v.writes))
	}
	w := v.writes[0]
	if got := stringField(t, w, OAuthClientIDKey); got != oauthClientID {
		t.Errorf("written client_id = %q, want %q", got, oauthClientID)
	}
	assertDecodesTo32(t, base64.StdEncoding, stringField(t, w, OAuthClientSecretKey), OAuthClientSecretKey)
	assertDecodesTo32(t, base64.RawURLEncoding, stringField(t, w, OAuthCookieSecretKey), OAuthCookieSecretKey)
}

// The mediamark case: a client_secret already issued by Authentik must survive
// while the missing keys are filled in.
func TestSeedOAuthPreservesExistingClientSecret(t *testing.T) {
	v := newOAuthVaultStub().seed(map[string]any{OAuthClientSecretKey: existingClientSec})
	res, err := SeedOAuth(oauthOpts(v.server(t).URL))
	if err != nil {
		t.Fatalf("SeedOAuth: %v", err)
	}
	got := actions(res)
	for key, want := range map[string]string{
		OAuthClientIDKey:     ActionCreated,
		OAuthClientSecretKey: ActionKept,
		OAuthCookieSecretKey: ActionCreated,
	} {
		if got[key] != want {
			t.Errorf("%s action = %q, want %q", key, got[key], want)
		}
	}
	if len(v.writes) != 1 {
		t.Fatalf("%d writes, want exactly 1", len(v.writes))
	}
	if s := stringField(t, v.writes[0], OAuthClientSecretKey); s != existingClientSec {
		t.Errorf("client_secret was replaced, want the existing value kept")
	}
}

func TestSeedOAuthPreservesOtherKeys(t *testing.T) {
	v := newOAuthVaultStub().seed(map[string]any{
		OAuthClientIDKey:     oauthClientID,
		OAuthClientSecretKey: existingClientSec,
		"redirect_url":       "https://mediamark.unkin.net/oauth2/callback",
		"extra":              oauthExtraKeyValue,
	})
	res, err := SeedOAuth(oauthOpts(v.server(t).URL))
	if err != nil {
		t.Fatalf("SeedOAuth: %v", err)
	}
	got := actions(res)
	for _, key := range []string{"redirect_url", "extra"} {
		if got[key] != ActionPreserved {
			t.Errorf("%s action = %q, want %q", key, got[key], ActionPreserved)
		}
	}
	if len(v.writes) != 1 {
		t.Fatalf("%d writes, want exactly 1", len(v.writes))
	}
	w := v.writes[0]
	if stringField(t, w, "extra") != oauthExtraKeyValue {
		t.Errorf("extra key was not written back unchanged")
	}
	if stringField(t, w, "redirect_url") != "https://mediamark.unkin.net/oauth2/callback" {
		t.Errorf("redirect_url was not written back unchanged")
	}
}

func TestSeedOAuthRotateRegenerates(t *testing.T) {
	v := newOAuthVaultStub().seed(map[string]any{
		OAuthClientIDKey:     oauthClientID,
		OAuthClientSecretKey: existingClientSec,
		OAuthCookieSecretKey: existingCookieSec,
	})
	o := oauthOpts(v.server(t).URL)
	o.Rotate = true

	res, err := SeedOAuth(o)
	if err != nil {
		t.Fatalf("SeedOAuth: %v", err)
	}
	got := actions(res)
	for key, want := range map[string]string{
		OAuthClientIDKey:     ActionKept,
		OAuthClientSecretKey: ActionRotated,
		OAuthCookieSecretKey: ActionRotated,
	} {
		if got[key] != want {
			t.Errorf("%s action = %q, want %q", key, got[key], want)
		}
	}
	if len(v.writes) != 1 {
		t.Fatalf("%d writes, want exactly 1", len(v.writes))
	}
	w := v.writes[0]
	if stringField(t, w, OAuthClientSecretKey) == existingClientSec {
		t.Errorf("client_secret unchanged under --rotate")
	}
	if stringField(t, w, OAuthCookieSecretKey) == existingCookieSec {
		t.Errorf("cookie_secret unchanged under --rotate")
	}
	assertDecodesTo32(t, base64.RawURLEncoding, stringField(t, w, OAuthCookieSecretKey), OAuthCookieSecretKey)
}

// A complete, correct secret must not produce a new KV version.
func TestSeedOAuthIdempotentWritesNothing(t *testing.T) {
	v := newOAuthVaultStub()
	url := v.server(t).URL
	if _, err := SeedOAuth(oauthOpts(url)); err != nil {
		t.Fatalf("first SeedOAuth: %v", err)
	}
	res, err := SeedOAuth(oauthOpts(url))
	if err != nil {
		t.Fatalf("second SeedOAuth: %v", err)
	}
	if res.Changed || res.Version != 0 {
		t.Errorf("Changed=%v Version=%d, want an unchanged result", res.Changed, res.Version)
	}
	if len(v.writes) != 1 {
		t.Errorf("%d writes, want the second run to write nothing", len(v.writes))
	}
	for _, k := range res.Keys {
		if k.Action != ActionKept {
			t.Errorf("%s action = %q, want %q", k.Name, k.Action, ActionKept)
		}
	}
}

func TestSeedOAuthClientIDUpdated(t *testing.T) {
	v := newOAuthVaultStub().seed(map[string]any{
		OAuthClientIDKey:     "stale-client-id",
		OAuthClientSecretKey: existingClientSec,
		OAuthCookieSecretKey: existingCookieSec,
	})
	res, err := SeedOAuth(oauthOpts(v.server(t).URL))
	if err != nil {
		t.Fatalf("SeedOAuth: %v", err)
	}
	if got := actions(res)[OAuthClientIDKey]; got != ActionUpdated {
		t.Errorf("client_id action = %q, want %q", got, ActionUpdated)
	}
	if len(v.writes) != 1 || stringField(t, v.writes[0], OAuthClientIDKey) != oauthClientID {
		t.Errorf("writes = %v, want the new client_id written", v.writes)
	}
}

func TestSeedOAuthLoginFailure(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/v1/auth/approle/login", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusBadRequest)
		_, _ = io.WriteString(w, `{"errors":["invalid role ID"]}`)
	})
	vs := httptest.NewServer(mux)
	defer vs.Close()

	_, err := SeedOAuth(oauthOpts(vs.URL))
	if err == nil {
		t.Fatal("SeedOAuth() = nil, want an approle login error")
	}
	if !strings.Contains(err.Error(), "approle login failed") {
		t.Errorf("error = %v, want it to name the approle login", err)
	}
}

func TestSeedOAuthReadDenied(t *testing.T) {
	v := newOAuthVaultStub()
	v.readStatus = http.StatusForbidden

	_, err := SeedOAuth(oauthOpts(v.server(t).URL))
	if err == nil {
		t.Fatal("SeedOAuth() = nil, want a KV read error")
	}
	msg := err.Error()
	if !strings.Contains(msg, oauthPath) || !strings.Contains(msg, "policy") {
		t.Errorf("error = %v, want it to name the path and point at the policy", err)
	}
	if len(v.writes) != 0 {
		t.Errorf("wrote %v, want no write when the read is denied", v.writes)
	}
}

func TestSeedOAuthWriteDenied(t *testing.T) {
	v := newOAuthVaultStub()
	v.writeStatus = http.StatusForbidden

	_, err := SeedOAuth(oauthOpts(v.server(t).URL))
	if err == nil {
		t.Fatal("SeedOAuth() = nil, want a KV write error")
	}
	msg := err.Error()
	if !strings.Contains(msg, oauthPath) || !strings.Contains(msg, "create/update") {
		t.Errorf("error = %v, want it to name the path and the missing capability", err)
	}
}

// A missing path is normal (first seed), not a not-found error.
func TestSeedOAuthMissingPathIsNotAnError(t *testing.T) {
	v := newOAuthVaultStub()
	if _, err := SeedOAuth(oauthOpts(v.server(t).URL)); err != nil {
		t.Fatalf("SeedOAuth on a missing path: %v", err)
	}
}

func TestSeedOAuthRequiresPathAndClientID(t *testing.T) {
	v := newOAuthVaultStub()
	url := v.server(t).URL
	for name, mutate := range map[string]func(*SeedOAuthOptions){
		"no path":      func(o *SeedOAuthOptions) { o.Path = "" },
		"no client id": func(o *SeedOAuthOptions) { o.ClientID = "" },
	} {
		t.Run(name, func(t *testing.T) {
			o := oauthOpts(url)
			mutate(&o)
			if _, err := SeedOAuth(o); err == nil {
				t.Fatal("SeedOAuth() = nil, want a required-input error")
			}
		})
	}
}

// No failure path may leak stored or generated secret material.
func TestSeedOAuthErrorsNeverLeakSecrets(t *testing.T) {
	cases := map[string]func(*oauthVaultStub){
		"read denied":  func(v *oauthVaultStub) { v.readStatus = http.StatusForbidden },
		"write denied": func(v *oauthVaultStub) { v.writeStatus = http.StatusForbidden },
		"read error":   func(v *oauthVaultStub) { v.readStatus = http.StatusInternalServerError },
		"write error":  func(v *oauthVaultStub) { v.writeStatus = http.StatusInternalServerError },
	}
	for name, mutate := range cases {
		t.Run(name, func(t *testing.T) {
			v := newOAuthVaultStub().seed(map[string]any{
				OAuthClientSecretKey: existingClientSec,
				OAuthCookieSecretKey: existingCookieSec,
				"extra":              oauthExtraKeyValue,
			})
			mutate(v)
			_, err := SeedOAuth(oauthOpts(v.server(t).URL))
			if err == nil {
				t.Fatal("SeedOAuth() = nil, want an error")
			}
			for _, secret := range []string{existingClientSec, existingCookieSec, oauthExtraKeyValue} {
				if strings.Contains(err.Error(), secret) {
					t.Errorf("error %q leaks a secret", err)
				}
			}
		})
	}
}

// The successful result carries key names and a version, never values.
func TestSeedOAuthResultNeverCarriesSecrets(t *testing.T) {
	v := newOAuthVaultStub().seed(map[string]any{OAuthClientSecretKey: existingClientSec})
	res, err := SeedOAuth(oauthOpts(v.server(t).URL))
	if err != nil {
		t.Fatalf("SeedOAuth: %v", err)
	}
	rendered := strings.Join(append(res.KeyNames(), res.Path, res.KVMount), " ")
	written := v.writes[0]
	for _, key := range []string{OAuthClientSecretKey, OAuthCookieSecretKey} {
		if value := stringField(t, written, key); strings.Contains(rendered, value) {
			t.Errorf("result leaks the %s value", key)
		}
	}
}