// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause

package certs

import (
	"context"
	"errors"
	"fmt"
	"log"
	"syscall"
	"testing"
	"time"

	"tailscale.com/ipn"
	"tailscale.com/kube/localclient"
	"tailscale.com/tailcfg"
)

// TestEnsureCertLoops tests that the certManager correctly starts and stops
// update loops for certs when the serve config changes. It tracks goroutine
// count and uses that as a validator that the expected number of cert loops are
// running.
func TestEnsureCertLoops(t *testing.T) {
	tests := []struct {
		name              string
		initialConfig     *ipn.ServeConfig
		updatedConfig     *ipn.ServeConfig
		initialGoroutines int64 // after initial serve config is applied
		updatedGoroutines int64 // after updated serve config is applied
		wantErr           bool
	}{
		{
			name:              "empty_serve_config",
			initialConfig:     &ipn.ServeConfig{},
			initialGoroutines: 0,
		},
		{
			name:              "nil_serve_config",
			initialConfig:     nil,
			initialGoroutines: 0,
			wantErr:           true,
		},
		{
			name:          "empty_to_one_service",
			initialConfig: &ipn.ServeConfig{},
			updatedConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
						},
					},
				},
			},
			initialGoroutines: 0,
			updatedGoroutines: 1,
		},
		{
			name: "single_service",
			initialConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
						},
					},
				},
			},
			initialGoroutines: 1,
		},
		{
			name: "multiple_services",
			initialConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
						},
					},
					"svc:my-other-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-other-app.tailnetxyz.ts.net:443": {},
						},
					},
				},
			},
			initialGoroutines: 2, // one loop per domain across all services
		},
		{
			name: "ignore_non_https_ports",
			initialConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
							"my-app.tailnetxyz.ts.net:80":  {},
						},
					},
				},
			},
			initialGoroutines: 1, // only one loop for the 443 endpoint
		},
		{
			name: "remove_domain",
			initialConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
						},
					},
					"svc:my-other-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-other-app.tailnetxyz.ts.net:443": {},
						},
					},
				},
			},
			updatedConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
						},
					},
				},
			},
			initialGoroutines: 2, // initially two loops (one per service)
			updatedGoroutines: 1, // one loop after removing service2
		},
		{
			name: "tcp_terminate_tls",
			initialConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-apiserver": {
						TCP: map[uint16]*ipn.TCPPortHandler{
							443: {
								TCPForward:   "localhost:80",
								TerminateTLS: "my-apiserver.tailnetxyz.ts.net",
							},
						},
					},
				},
			},
			initialGoroutines: 1,
		},
		{
			name: "tcp_terminate_tls_and_web",
			initialConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-apiserver": {
						TCP: map[uint16]*ipn.TCPPortHandler{
							443: {
								TCPForward:   "localhost:80",
								TerminateTLS: "my-apiserver.tailnetxyz.ts.net",
							},
						},
					},
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
						},
					},
				},
			},
			initialGoroutines: 2,
		},
		{
			name: "add_domain",
			initialConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
						},
					},
				},
			},
			updatedConfig: &ipn.ServeConfig{
				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
					"svc:my-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-app.tailnetxyz.ts.net:443": {},
						},
					},
					"svc:my-other-app": {
						Web: map[ipn.HostPort]*ipn.WebServerConfig{
							"my-other-app.tailnetxyz.ts.net:443": {},
						},
					},
				},
			},
			initialGoroutines: 1,
			updatedGoroutines: 2,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			ctx, cancel := context.WithCancel(context.Background())
			defer cancel()

			notifyChan := make(chan ipn.Notify)
			go func() {
				// SelfChange wakes the cert manager; cert domains are
				// then fetched via FakeLocalClient.CertDomainsResult.
				for {
					notifyChan <- ipn.Notify{
						SelfChange: &tailcfg.Node{StableID: "test"},
					}
				}
			}()
			cm := &CertManager{
				lc: &localclient.FakeLocalClient{
					FakeIPNBusWatcher: localclient.FakeIPNBusWatcher{
						NotifyChan: notifyChan,
					},
					CertDomainsResult: []string{
						"my-app.tailnetxyz.ts.net",
						"my-other-app.tailnetxyz.ts.net",
						"my-apiserver.tailnetxyz.ts.net",
					},
				},
				logf:      log.Printf,
				certLoops: make(map[string]context.CancelFunc),
			}

			allDone := make(chan bool, 1)
			defer cm.tracker.AddDoneCallback(func() {
				cm.mu.Lock()
				defer cm.mu.Unlock()
				if cm.tracker.RunningGoroutines() > 0 {
					return
				}
				select {
				case allDone <- true:
				default:
				}
			})()

			err := cm.EnsureCertLoops(ctx, tt.initialConfig)
			if (err != nil) != tt.wantErr {
				t.Fatalf("ensureCertLoops() error = %v", err)
			}

			if got := cm.tracker.RunningGoroutines(); got != tt.initialGoroutines {
				t.Errorf("after initial config: got %d running goroutines, want %d", got, tt.initialGoroutines)
			}

			if tt.updatedConfig != nil {
				if err := cm.EnsureCertLoops(ctx, tt.updatedConfig); err != nil {
					t.Fatalf("ensureCertLoops() error on update = %v", err)
				}

				// Although starting goroutines and cancelling
				// the context happens in the main goroutine, it
				// the actual goroutine exit when a context is
				// cancelled does not- so wait for a bit for the
				// running goroutine count to reach the expected
				// number.
				deadline := time.After(5 * time.Second)
				for {
					if got := cm.tracker.RunningGoroutines(); got == tt.updatedGoroutines {
						break
					}
					select {
					case <-deadline:
						t.Fatalf("timed out waiting for goroutine count to reach %d, currently at %d",
							tt.updatedGoroutines, cm.tracker.RunningGoroutines())
					case <-time.After(10 * time.Millisecond):
						continue
					}
				}
			}

			if tt.updatedGoroutines == 0 {
				return // no goroutines to wait for
			}
			// cancel context to make goroutines exit
			cancel()
			select {
			case <-time.After(5 * time.Second):
				t.Fatal("timed out waiting for goroutine to finish")
			case <-allDone:
			}
		})
	}
}

func TestIsTransientCertErr(t *testing.T) {
	tests := []struct {
		name string
		err  error
		want bool
	}{
		{"nil", nil, false},
		{"deadline", context.DeadlineExceeded, true},
		{"canceled", context.Canceled, true},
		{"wrapped_deadline", fmt.Errorf("wrap: %w", context.DeadlineExceeded), true},
		{"connrefused", fmt.Errorf("dial: %w", syscall.ECONNREFUSED), true},
		{"connreset", fmt.Errorf("read: %w", syscall.ECONNRESET), true},
		{"random", errors.New("badNonce"), false},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := isTransientCertErr(tt.err); got != tt.want {
				t.Errorf("isTransientCertErr(%v) = %v, want %v", tt.err, got, tt.want)
			}
		})
	}
}

func TestNextRetryInterval(t *testing.T) {
	const normal = 24 * time.Hour
	tests := []struct {
		name         string
		err          error
		retryAfter   time.Duration
		startCount   int
		wantCount    int
		wantInterval time.Duration
	}{
		{"success", nil, 0, 5, 0, normal},
		{"transient_no_advance", context.DeadlineExceeded, 0, 3, 3, retrySchedule[0]},
		{"rate_limit_with_hint", errors.New("rate limited"), 17 * time.Minute, 0, 1, 17 * time.Minute},
		{"rate_limit_no_hint", errors.New("rate limited"), 0, 0, 1, retrySchedule[0]},
		{"other_advances", errors.New("badNonce"), 0, 0, 1, retrySchedule[0]},
		{"other_clamps", errors.New("badNonce"), 0, len(retrySchedule) + 3, len(retrySchedule) + 4, retrySchedule[len(retrySchedule)-1]},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			c := tt.startCount
			got := nextRetryInterval(tt.err, &c, normal, tt.retryAfter)
			if c != tt.wantCount {
				t.Errorf("retryCount = %d, want %d", c, tt.wantCount)
			}
			if got != tt.wantInterval {
				t.Errorf("interval = %v, want %v", got, tt.wantInterval)
			}
		})
	}
}