package token

import (
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"github.com/golang-jwt/jwt/v5"
)

// The plain-text guidance sent with a 401 has to name a host `docker login`
// can actually handshake against. /auth/token answers on the UI domain (that
// is where the WWW-Authenticate realm points) as well as on every registry
// domain, and the UI domain refuses /v2/* outright, so the guidance must name
// the resolved registry service rather than echoing the request's own host.
func TestSendAuthError_NamesRegistryDomainNotRequestHost(t *testing.T) {
	keyPath := getSharedTestKey(t)

	tests := []struct {
		name string
		// services declared on the handler; the issuer's service is the first.
		services []string
		// host the request arrives on.
		host string
		// service parameter the client echoes back, if any.
		requested string
		// registry_domains as configured, before normalization. Empty leaves
		// the display list unset, which is the pre-existing behaviour.
		displayNames []string

		wantLogin  string   // hostname step 2 must name
		wantAbsent []string // hostnames step 2 must not name
	}{
		{
			// seamark-shaped: UI on seamark.dev, registry on seamark.cr. A
			// client following the realm lands on the UI host.
			name:       "split domain, request on the UI host",
			services:   []string{"seamark.cr"},
			host:       "seamark.dev",
			wantLogin:  "seamark.cr",
			wantAbsent: []string{"docker login seamark.dev"},
		},
		{
			name:      "split domain, request on the registry host",
			services:  []string{"seamark.cr"},
			host:      "seamark.cr",
			wantLogin: "seamark.cr",
		},
		{
			// Multiple front doors: the guidance follows the service the
			// client is authenticating against, not the primary.
			name:       "secondary registry domain via ?service=",
			services:   []string{"seamark.cr", "buoy.cr"},
			host:       "seamark.dev",
			requested:  "buoy.cr",
			wantLogin:  "buoy.cr",
			wantAbsent: []string{"docker login seamark.dev"},
		},
		{
			// ?service= is client-influenced, so an unconfigured value falls
			// back to the primary registry domain, never to r.Host.
			name:       "unconfigured ?service= falls back to the primary",
			services:   []string{"seamark.cr"},
			host:       "seamark.dev",
			requested:  "evil.example",
			wantLogin:  "seamark.cr",
			wantAbsent: []string{"docker login seamark.dev", "evil.example"},
		},
		{
			// Single-domain deployment (the dev stack): the UI host is the
			// registry domain, and the printed hostname is still correct.
			name:      "single domain, UI host is the registry domain",
			services:  []string{"localhost"},
			host:      "localhost:5000",
			wantLogin: "localhost",
		},
		{
			// The dev stack as actually configured: registry_domains is
			// ["127.0.0.1:5000"], which normalizes to the audience "127.0.0.1".
			// The command has to keep the port or it dials the wrong place.
			name:         "dev stack keeps the configured port",
			services:     []string{"127.0.0.1"},
			displayNames: []string{"127.0.0.1:5000"},
			host:         "127.0.0.1:5000",
			wantLogin:    "127.0.0.1:5000",
			wantAbsent:   []string{"docker login 127.0.0.1\n"},
		},
		{
			// Production shape: port-free domains print exactly as before.
			name:         "production domain unchanged by the display list",
			services:     []string{"seamark.cr"},
			displayNames: []string{"seamark.cr"},
			host:         "seamark.dev",
			wantLogin:    "seamark.cr",
			wantAbsent:   []string{"docker login seamark.dev"},
		},
		{
			// The checked-in seamark deployment fronts three registry domains.
			// The guidance must name the one the client is authenticating
			// against, resolved back to its own configured entry.
			name:         "multi-domain picks the entry the service came from",
			services:     []string{"buoy.cr", "bouy.cr", "seamark.cr"},
			displayNames: []string{"buoy.cr", "bouy.cr", "seamark.cr"},
			host:         "seamark.dev",
			requested:    "seamark.cr",
			wantLogin:    "seamark.cr",
			wantAbsent:   []string{"docker login buoy.cr", "docker login bouy.cr"},
		},
		{
			// Same, with ports: each normalized service maps back to its own
			// configured entry, not to the primary's.
			name:         "multi-domain with ports maps each service to its own entry",
			services:     []string{"127.0.0.1", "localhost"},
			displayNames: []string{"127.0.0.1:5000", "localhost:5001"},
			host:         "127.0.0.1:5000",
			requested:    "localhost:5001",
			wantLogin:    "localhost:5001",
			wantAbsent:   []string{"docker login 127.0.0.1"},
		},
		{
			// Two configured entries that normalize to the same host: first
			// wins, matching deriveServices' first-wins dedupe.
			name:         "colliding entries print the first configured form",
			services:     []string{"atcr.io"},
			displayNames: []string{"atcr.io:443", "atcr.io"},
			host:         "atcr.io",
			wantLogin:    "atcr.io:443",
		},
		{
			// A service with no configured entry (the issuer's fallback on a
			// deployment whose display list does not cover it) prints the
			// normalized name, exactly as before this existed.
			name:         "service absent from the display list falls back to normalized",
			services:     []string{"seamark.cr"},
			displayNames: []string{"buoy.cr:8443"},
			host:         "seamark.dev",
			wantLogin:    "seamark.cr",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			issuer, err := NewIssuer(keyPath, "atcr.io", tt.services[0], 15*time.Minute)
			if err != nil {
				t.Fatalf("NewIssuer() error = %v", err)
			}
			handler := NewHandler(issuer, nil)
			handler.SetServices(tt.services)
			handler.SetServiceDisplayNames(tt.displayNames)

			// A push-only scope with no credentials has no anonymous
			// component, so it draws the plain-text challenge.
			target := "/auth/token?scope=repository:bob.bsky.social/myapp:push"
			if tt.requested != "" {
				target += "&service=" + tt.requested
			}
			req := httptest.NewRequest(http.MethodGet, target, nil)
			req.Host = tt.host

			w := httptest.NewRecorder()
			handler.ServeHTTP(w, req)

			if w.Code != http.StatusUnauthorized {
				t.Fatalf("status = %d, want %d. Body: %s", w.Code, http.StatusUnauthorized, w.Body.String())
			}

			body := w.Body.String()
			want := "docker login " + tt.wantLogin
			if !strings.Contains(body, want) {
				t.Errorf("guidance does not contain %q.\nBody:\n%s", want, body)
			}
			for _, absent := range tt.wantAbsent {
				if strings.Contains(body, absent) {
					t.Errorf("guidance contains %q, which cannot serve /v2/.\nBody:\n%s", absent, body)
				}
			}

			// Step 1 stays on the request's own base URL: the install page
			// lives on the UI domain and registry domains redirect there.
			if wantInstall := getBaseURL(req) + "/install"; !strings.Contains(body, wantInstall) {
				t.Errorf("guidance does not contain install URL %q.\nBody:\n%s", wantInstall, body)
			}
		})
	}
}

// A handler whose issuer has no service configured has no registry domain to
// name, so it drops the docker login step rather than printing a host that
// cannot work.
func TestSendAuthError_NoServiceOmitsDockerLoginStep(t *testing.T) {
	keyPath := getSharedTestKey(t)

	issuer, err := NewIssuer(keyPath, "atcr.io", "", 15*time.Minute)
	if err != nil {
		t.Fatalf("NewIssuer() error = %v", err)
	}
	handler := NewHandler(issuer, nil)

	req := httptest.NewRequest(http.MethodGet, "/auth/token?scope=repository:bob.bsky.social/myapp:push", nil)
	req.Host = "seamark.dev"

	w := httptest.NewRecorder()
	handler.ServeHTTP(w, req)

	if w.Code != http.StatusUnauthorized {
		t.Fatalf("status = %d, want %d", w.Code, http.StatusUnauthorized)
	}
	if body := w.Body.String(); strings.Contains(body, "docker login") {
		t.Errorf("guidance names a docker login host with no service configured.\nBody:\n%s", body)
	}
}

// The display list must not leak into the JWT. Audiences stay on the
// normalized, port-stripped service, because that is what the registry
// compares against the port-stripped r.Host it routes on.
func TestServiceDisplayNames_DoNotChangeTokenAudience(t *testing.T) {
	keyPath := getSharedTestKey(t)

	tests := []struct {
		name         string
		services     []string
		displayNames []string
		host         string
		requested    string
		wantAudience string
	}{
		{
			name:         "dev stack",
			services:     []string{"127.0.0.1"},
			displayNames: []string{"127.0.0.1:5000"},
			host:         "127.0.0.1:5000",
			wantAudience: "127.0.0.1",
		},
		{
			name:         "dev stack, service echoed back with its port",
			services:     []string{"127.0.0.1"},
			displayNames: []string{"127.0.0.1:5000"},
			host:         "127.0.0.1:5000",
			requested:    "127.0.0.1:5000",
			wantAudience: "127.0.0.1",
		},
		{
			name:         "multi-domain with ports",
			services:     []string{"127.0.0.1", "localhost"},
			displayNames: []string{"127.0.0.1:5000", "localhost:5001"},
			host:         "127.0.0.1:5000",
			requested:    "localhost:5001",
			wantAudience: "localhost",
		},
		{
			name:         "production shape",
			services:     []string{"seamark.cr", "buoy.cr"},
			displayNames: []string{"seamark.cr", "buoy.cr"},
			host:         "seamark.dev",
			requested:    "buoy.cr",
			wantAudience: "buoy.cr",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			issuer, err := NewIssuer(keyPath, "atcr.io", tt.services[0], 15*time.Minute)
			if err != nil {
				t.Fatalf("NewIssuer() error = %v", err)
			}
			handler := NewHandler(issuer, nil)
			handler.SetServices(tt.services)
			handler.SetServiceDisplayNames(tt.displayNames)

			// An anonymous pull actually mints a token, so the audience is
			// observable end to end rather than through resolveService alone.
			target := "/auth/token?scope=repository:bob.bsky.social/myapp:pull"
			if tt.requested != "" {
				target += "&service=" + tt.requested
			}
			req := httptest.NewRequest(http.MethodGet, target, nil)
			req.Host = tt.host

			w := httptest.NewRecorder()
			handler.ServeHTTP(w, req)

			if w.Code != http.StatusOK {
				t.Fatalf("status = %d, want %d. Body: %s", w.Code, http.StatusOK, w.Body.String())
			}

			claims := parseTokenClaims(t, decodeToken(t, w), issuer)
			if len(claims.Audience) != 1 || claims.Audience[0] != tt.wantAudience {
				t.Errorf("audience = %v, want [%q]", claims.Audience, tt.wantAudience)
			}

			// And the resolved service key itself, which is what routing and
			// the access controller compare against.
			if got := handler.resolveService(req, tt.requested); got != tt.wantAudience {
				t.Errorf("resolveService() = %q, want %q", got, tt.wantAudience)
			}
		})
	}
}

// parseTokenClaims verifies the JWT against the issuer's own key and returns
// its claims.
func parseTokenClaims(t *testing.T, tokenString string, issuer *Issuer) *Claims {
	t.Helper()
	parsed, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(*jwt.Token) (any, error) {
		return issuer.publicKey, nil
	})
	if err != nil {
		t.Fatalf("parse token: %v", err)
	}
	claims, ok := parsed.Claims.(*Claims)
	if !ok {
		t.Fatalf("claims type = %T, want *Claims", parsed.Claims)
	}
	return claims
}