package gcp

import (
	"context"
	"errors"
	"net/http"
	"net/http/httptest"
	"net/url"
	"sync"
	"syscall"
	"testing"

	compute "cloud.google.com/go/compute/apiv1"
	"cloud.google.com/go/compute/apiv1/computepb"
	"google.golang.org/api/googleapi"
	"google.golang.org/api/option"
	"google.golang.org/protobuf/proto"

	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
)

func TestCheck_reachable(t *testing.T) {
	t.Parallel()
	api := &fakeAPI{}
	p := newTestProvider(api)

	got := p.Check(context.Background())

	if len(got) != 1 {
		t.Fatalf("Check() returned %d targets, want 1", len(got))
	}
	ts := got[0]
	if !ts.Ready || ts.Reason != provider.ReasonReachable || ts.Message != "" {
		t.Errorf("Check() = %+v, want ready and Reachable", ts)
	}
	if ts.Name != "my-project" || ts.Address != "compute.googleapis.com" {
		t.Errorf("target = %q at %q, want my-project at compute.googleapis.com", ts.Name, ts.Address)
	}
	want := &computepb.AggregatedListInstancesRequest{
		Project:              "my-project",
		Filter:               proto.String("labels.proxy-operator-managed = true"),
		MaxResults:           proto.Uint32(1),
		ReturnPartialSuccess: proto.Bool(true),
	}
	if !proto.Equal(api.probeReq, want) {
		t.Errorf("probe request = %v, want %v", api.probeReq, want)
	}
}

func TestCheck_failureReasons(t *testing.T) {
	t.Parallel()
	ended, cancel := context.WithCancel(context.Background())
	cancel()

	tests := []struct {
		name string
		ctx  context.Context
		err  error
		want string
	}{
		{"unauthorized", context.Background(), gerr(401), provider.ReasonUnauthorized},
		{"forbidden", context.Background(), gerr(403, "forbidden"), provider.ReasonForbidden},
		{"api disabled", context.Background(), gerr(403, "accessNotConfigured"), provider.ReasonForbidden},
		{"server error", context.Background(), gerr(500), provider.ReasonAPIError},
		{"deadline", context.Background(), &url.Error{
			Op: "Get", URL: "https://compute.googleapis.com/", Err: context.DeadlineExceeded,
		}, provider.ReasonTimeout},
		{"context ended", ended, context.Canceled, provider.ReasonTimeout},
		{"connection refused", context.Background(), &url.Error{
			Op: "Get", URL: "https://compute.googleapis.com/", Err: syscall.ECONNREFUSED,
		}, provider.ReasonUnreachable},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			p := newTestProvider(&fakeAPI{probeErr: tc.err})

			got := p.Check(tc.ctx)

			if len(got) != 1 {
				t.Fatalf("Check() returned %d targets, want 1", len(got))
			}
			if got[0].Ready || got[0].Reason != tc.want || got[0].Message != tc.err.Error() {
				t.Errorf("Check() = %+v, want not ready, reason %s, message %q", got[0], tc.want, tc.err.Error())
			}
		})
	}
}

// TestRealInstances_Probe runs the real SDK client against a local server,
// since the point of Probe is how many requests the SDK makes.
func TestRealInstances_Probe(t *testing.T) {
	t.Parallel()
	tests := []struct {
		name     string
		status   int
		body     string
		wantCode int
	}{
		{
			name:   "fetches only the first page",
			status: http.StatusOK,
			body:   `{"items":{"zones/europe-west1-b":{"instances":[{"name":"proxy-a"}]}},"nextPageToken":"page-2"}`,
		},
		{
			name:   "empty project",
			status: http.StatusOK,
			body:   `{}`,
		},
		{
			name:     "api error keeps its status",
			status:   http.StatusForbidden,
			body:     `{"error":{"code":403,"message":"Compute Engine API has not been used","errors":[{"reason":"accessNotConfigured"}]}}`,
			wantCode: http.StatusForbidden,
		},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			var (
				mu   sync.Mutex
				reqs []*url.URL
			)
			srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				mu.Lock()
				reqs = append(reqs, r.URL)
				mu.Unlock()
				w.Header().Set("Content-Type", "application/json")
				w.WriteHeader(tc.status)
				_, _ = w.Write([]byte(tc.body))
			}))
			t.Cleanup(srv.Close)
			ctx := context.Background()
			c, err := compute.NewInstancesRESTClient(ctx, option.WithEndpoint(srv.URL), option.WithoutAuthentication())
			if err != nil {
				t.Fatalf("NewInstancesRESTClient: %v", err)
			}
			t.Cleanup(func() { _ = c.Close() })

			err = (&realInstances{client: c}).Probe(ctx, &computepb.AggregatedListInstancesRequest{
				Project:    "my-project",
				MaxResults: proto.Uint32(1),
			})

			var gerr *googleapi.Error
			switch {
			case tc.wantCode == 0 && err != nil:
				t.Fatalf("Probe() = %v, want nil", err)
			case tc.wantCode != 0 && (!errors.As(err, &gerr) || gerr.Code != tc.wantCode):
				t.Fatalf("Probe() = %v, want a googleapi error with code %d", err, tc.wantCode)
			}
			mu.Lock()
			defer mu.Unlock()
			if len(reqs) != 1 {
				t.Fatalf("server saw %d requests, want 1", len(reqs))
			}
			if got := reqs[0].Query().Get("maxResults"); got != "1" {
				t.Errorf("maxResults = %q, want 1", got)
			}
			if want := "/compute/v1/projects/my-project/aggregated/instances"; reqs[0].Path != want {
				t.Errorf("path = %q, want %q", reqs[0].Path, want)
			}
		})
	}
}