package api_test

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/v10networks/nmon/internal/api"
	"github.com/v10networks/nmon/internal/clock"
	"github.com/v10networks/nmon/internal/fixturegen"
	"github.com/v10networks/nmon/internal/poller"
	"github.com/v10networks/nmon/internal/selfmon"
	"github.com/v10networks/nmon/internal/simagent"
	"github.com/v10networks/nmon/internal/store"
	"github.com/v10networks/nmon/internal/testutil"
	"github.com/v10networks/nmon/internal/ulid"
	"github.com/v10networks/nmon/internal/vmsup"
)

// querier is the fake metric store. fn, when set, answers every query;
// otherwise body does. Every query is recorded.
type querier struct {
	mu                sync.Mutex
	body              []byte
	err               error
	fn                func(store, expr string, from, to time.Time, step time.Duration) ([]byte, error)
	q                 string
	ts, from, to      time.Time
	step              time.Duration
	instant, rangeCnt int
	calls             []call
}

type call struct {
	store, expr string
	from, to    time.Time
	step        time.Duration
}

func (q *querier) Query(_ context.Context, st, expr string, ts time.Time) ([]byte, error) {
	q.mu.Lock()
	q.instant++
	q.q, q.ts = expr, ts
	q.calls = append(q.calls, call{store: st, expr: expr, from: ts, to: ts})
	fn, body, err := q.fn, q.body, q.err
	q.mu.Unlock()
	if fn != nil {
		return fn(st, expr, ts, ts, 0)
	}
	return body, err
}

func (q *querier) QueryRange(_ context.Context, st, expr string, from, to time.Time, step time.Duration) ([]byte, error) {
	q.mu.Lock()
	q.rangeCnt++
	q.q, q.from, q.to, q.step = expr, from, to, step
	q.calls = append(q.calls, call{store: st, expr: expr, from: from, to: to, step: step})
	fn, body, err := q.fn, q.body, q.err
	q.mu.Unlock()
	if fn != nil {
		return fn(st, expr, from, to, step)
	}
	return body, err
}

// queries returns a copy of the recorded queries.
func (q *querier) queries() []call {
	q.mu.Lock()
	defer q.mu.Unlock()
	return append([]call(nil), q.calls...)
}

type refresher struct{ n atomic.Int32 }

func (r *refresher) Refresh() { r.n.Add(1) }

type env struct {
	clk *clock.Fake
	h   http.Handler
	st  store.Store
	q   *querier
	ref *refresher
	reg *selfmon.Registry

	afterID atomic.Int64
	status  []poller.DeviceStatus
}

func newEnv(t *testing.T, port int) *env { return newEnvDeps(t, port, nil) }

// newEnvDeps is newEnv with a chance to change the API's dependencies.
func newEnvDeps(t *testing.T, port int, mutate func(*api.Deps)) *env {
	clk := clock.NewFake(time.Date(2026, 10, 22, 12, 0, 0, 0, time.UTC))
	e := &env{clk: clk, st: testutil.OpenStore(t, clk), q: &querier{body: []byte(`{"status":"success","data":{"resultType":"vector","result":[]}}`)},
		ref: &refresher{}, reg: selfmon.New()}
	d := api.Deps{Store: e.st, Querier: e.q, Poller: e.ref, Clock: clk, Registry: e.reg, SNMPPort: port,
		DiscoveryTimeout: 3 * time.Second,
		PollerStatus:     func() []poller.DeviceStatus { return e.status },
		AfterDiscover:    func(id int64) { e.afterID.Store(id) }}
	if mutate != nil {
		mutate(&d)
	}
	e.h = api.New(d)
	return e
}

func (e *env) do(method, path, body string) *httptest.ResponseRecorder {
	req := httptest.NewRequest(method, path, strings.NewReader(body))
	if body != "" {
		req.Header.Set("Content-Type", "application/json")
	}
	rec := httptest.NewRecorder()
	e.h.ServeHTTP(rec, req)
	return rec
}

func isProblem(t *testing.T, rec *httptest.ResponseRecorder, status int) {
	t.Helper()
	if rec.Code != status {
		t.Fatalf("status %d, want %d: %s", rec.Code, status, rec.Body)
	}
	if ct := rec.Header().Get("Content-Type"); !strings.HasPrefix(ct, "application/problem+json") {
		t.Fatalf("content type %q, want problem+json: %s", ct, rec.Body)
	}
	var p struct {
		Title  string `json:"title"`
		Status int    `json:"status"`
	}
	if err := json.Unmarshal(rec.Body.Bytes(), &p); err != nil || p.Status != status || p.Title == "" {
		t.Fatalf("problem body %s (%v)", rec.Body, err)
	}
}

const community = "s3cr3t-comm-xyz"

func TestAddAndGetDevice(t *testing.T) {
	a := testutil.StartAgent(t, simagent.Config{
		Recording: fixturegen.Generic(fixturegen.Options{Ports: 8, SysName: "edge1", HCCounters: true}), Community: community,
	})
	e := newEnv(t, int(a.Addr().Port()))
	body := fmt.Sprintf(`{"name":"Edge One","addresses":["::1"],"site":"yyz","role":"edge","snmp":{"version":"v2c","community":%q}}`, community)
	rec := e.do("POST", "/api/v1/devices", body)
	if rec.Code != http.StatusCreated {
		t.Fatalf("POST: %d %s", rec.Code, rec.Body)
	}
	if e.ref.n.Load() != 1 {
		t.Error("poller not refreshed")
	}
	var created api.DeviceView
	if err := json.Unmarshal(rec.Body.Bytes(), &created); err != nil {
		t.Fatal(err)
	}
	if created.Slug == "" || created.Name != "Edge One" || created.Site != "yyz" || created.SysName != "edge1" ||
		created.MgmtIP != "::1" || created.SNMPVersion != "v2c" || len(created.Interfaces) != 8 {
		t.Fatalf("created: %+v", created)
	}

	get := e.do("GET", "/api/v1/devices/"+created.Slug, "")
	if get.Code != 200 {
		t.Fatalf("GET: %d %s", get.Code, get.Body)
	}
	for _, r := range []*httptest.ResponseRecorder{rec, get} {
		if strings.Contains(r.Body.String(), community) {
			t.Fatalf("response contains the community: %s", r.Body)
		}
		var m map[string]json.RawMessage
		if err := json.Unmarshal(r.Body.Bytes(), &m); err != nil {
			t.Fatal(err)
		}
		for _, k := range []string{"id", "snmp_credential_id", "community", "device_id"} {
			if _, ok := m[k]; ok {
				t.Errorf("device response has key %q", k)
			}
		}
	}
	var got api.DeviceView
	if err := json.Unmarshal(get.Body.Bytes(), &got); err != nil {
		t.Fatal(err)
	}
	for _, i := range got.Interfaces {
		if !ulid.Valid(i.ID) {
			t.Errorf("interface id %q", i.ID)
		}
		if i.FirstSeen.Location() != time.UTC {
			t.Errorf("timestamp not UTC: %v", i.FirstSeen)
		}
	}
	if !strings.Contains(get.Body.String(), `"created_at":"2026-10-22T12:00:00Z"`) {
		t.Errorf("created_at is not RFC 3339 UTC: %s", get.Body)
	}
	// the secret is in the store, encrypted, and decrypts for the poller
	d, _ := e.st.GetDeviceBySlug(context.Background(), created.Slug)
	c, err := e.st.GetCredential(context.Background(), *d.SNMPCredentialID)
	if err != nil || c.Community != community {
		t.Fatalf("stored credential: %+v %v", c, err)
	}
}

func TestAddDeviceRejections(t *testing.T) {
	e := newEnv(t, 1) // nothing listens on UDP 1
	for name, tc := range map[string]struct {
		body   string
		status int
	}{
		"no snmp for network": {`{"name":"x","addresses":["::1"]}`, 422},
		"bad address":         {`{"name":"x","addresses":["nope"],"snmp":{"version":"v2c","community":"c"}}`, 422},
		"no community":        {`{"name":"x","addresses":["::1"],"snmp":{"version":"v2c"}}`, 422},
		"bad version":         {`{"name":"x","addresses":["::1"],"snmp":{"version":"v9","community":"c"}}`, 422},
		"no addresses":        {`{"name":"x","addresses":[],"snmp":{"version":"v2c","community":"c"}}`, 422},
		"unreachable":         {`{"name":"x","addresses":["::1"],"snmp":{"version":"v2c","community":"c"}}`, 502},
	} {
		t.Run(name, func(t *testing.T) { isProblem(t, e.do("POST", "/api/v1/devices", tc.body), tc.status) })
	}
	if _, n, err := e.st.ListDevices(context.Background(), store.DeviceFilter{}, store.Page{}); err != nil || n != 0 {
		t.Fatalf("rejected requests stored %d devices (%v)", n, err)
	}
	if e.ref.n.Load() != 0 {
		t.Error("poller refreshed for a rejected device")
	}
	// a device without SNMP is fine
	rec := e.do("POST", "/api/v1/devices", `{"name":"vm1","kind":"vm","addresses":["192.0.2.7"]}`)
	if rec.Code != 201 {
		t.Fatalf("vm: %d %s", rec.Code, rec.Body)
	}
}

func TestProblemDetails(t *testing.T) {
	e := newEnv(t, 0)
	isProblem(t, e.do("GET", "/api/v1/devices/no-such-device", ""), 404)
	isProblem(t, e.do("GET", "/api/v1/nothing", ""), 404)
	rec := e.do("DELETE", "/api/v1/query", "")
	isProblem(t, rec, 405)
	isProblem(t, e.do("GET", "/api/v1/query", ""), 422) // missing q
}

func TestOpenAPIDocsAndMetrics(t *testing.T) {
	e := newEnv(t, 0)
	e.reg.Counter("nmon_test_total", "device", "d1").Add(3)
	rec := e.do("GET", "/openapi.json", "")
	var spec struct {
		Paths map[string]map[string]any `json:"paths"`
	}
	if rec.Code != 200 || json.Unmarshal(rec.Body.Bytes(), &spec) != nil {
		t.Fatalf("openapi.json: %d %s", rec.Code, rec.Body)
	}
	for _, p := range []string{"/api/v1/devices", "/api/v1/devices/{slug}", "/api/v1/query", "/api/v1/query_range", "/metrics"} {
		if spec.Paths[p] == nil {
			t.Errorf("openapi.json lacks %s", p)
		}
	}
	if d := e.do("GET", "/docs", ""); d.Code != 200 || !strings.Contains(d.Header().Get("Content-Type"), "text/html") {
		t.Errorf("/docs: %d %s", d.Code, d.Header().Get("Content-Type"))
	}
	m := e.do("GET", "/metrics", "")
	if m.Code != 200 || !strings.Contains(m.Body.String(), `nmon_test_total{device="d1"} 3`) {
		t.Errorf("/metrics: %d %s", m.Code, m.Body)
	}
}

func seriesBody(n int) []byte {
	var b bytes.Buffer
	b.WriteString(`{"status":"success","data":{"resultType":"vector","result":[`)
	for i := 0; i < n; i++ {
		if i > 0 {
			b.WriteByte(',')
		}
		b.WriteString(`{"metric":{},"value":[1,"1"]}`)
	}
	b.WriteString(`]}}`)
	return b.Bytes()
}

func TestQueryProxy(t *testing.T) {
	e := newEnv(t, 0)
	e.q.body = seriesBody(3)
	rec := e.do("GET", "/api/v1/query?q=ifHCInOctets&time=2026-10-22T12:00:00Z", "")
	if rec.Code != 200 || !bytes.Equal(rec.Body.Bytes(), e.q.body) || rec.Header().Get("Content-Type") != "application/json" {
		t.Fatalf("passthrough: %d %s", rec.Code, rec.Body)
	}
	if e.q.q != "ifHCInOctets" || !e.q.ts.Equal(time.Date(2026, 10, 22, 12, 0, 0, 0, time.UTC)) {
		t.Errorf("forwarded %q at %v", e.q.q, e.q.ts)
	}
	e.do("GET", "/api/v1/query?q=up&time=1700000000.5", "")
	if e.q.ts.UnixMilli() != 1700000000500 {
		t.Errorf("unix time parsed as %v", e.q.ts)
	}
	isProblem(t, e.do("GET", "/api/v1/query?q=up&time=yesterday", ""), 422)

	rec = e.do("GET", "/api/v1/query_range?q=up&from=1700000000&to=1700003600&step=30s", "")
	if rec.Code != 200 || e.q.step != 30*time.Second || e.q.to.Sub(e.q.from) != time.Hour {
		t.Fatalf("range: %d %s step=%v", rec.Code, rec.Body, e.q.step)
	}
	isProblem(t, e.do("GET", "/api/v1/query_range?q=up", ""), 422) // step required
	isProblem(t, e.do("GET", "/api/v1/query_range?q=up&step=0", ""), 422)

	e.q.body = seriesBody(api.MaxSeries)
	if rec := e.do("GET", "/api/v1/query?q=x", ""); rec.Code != 200 {
		t.Fatalf("exactly %d series must pass: %d", api.MaxSeries, rec.Code)
	}
	e.q.body = seriesBody(api.MaxSeries + 1)
	isProblem(t, e.do("GET", "/api/v1/query?q=x", ""), 422)
	isProblem(t, e.do("GET", "/api/v1/query_range?q=x&step=1m", ""), 422)

	e.q.err = fmt.Errorf("%w: hot", vmsup.ErrStoreDown)
	isProblem(t, e.do("GET", "/api/v1/query?q=x", ""), 503)
	e.q.err = errors.New("vmsup: hot store: 422 Unprocessable Entity: cannot parse")
	isProblem(t, e.do("GET", "/api/v1/query?q=x", ""), 422)
	e.q.err = errors.New("connection reset")
	isProblem(t, e.do("GET", "/api/v1/query?q=x", ""), 502)
}

func TestDocsAreSelfHosted(t *testing.T) {
	e := newEnv(t, 0)
	page := e.do("GET", "/docs", "")
	if page.Code != 200 || strings.Contains(page.Body.String(), "http") && strings.Contains(page.Body.String(), "unpkg") ||
		!strings.Contains(page.Body.String(), "/docs/assets/swagger-ui-bundle.js") {
		t.Fatalf("/docs: %d %s", page.Code, page.Body)
	}
	for path, ct := range map[string]string{"/docs/assets/swagger-ui-bundle.js": "javascript", "/docs/assets/swagger-ui.css": "css", "/docs/assets/init.js": "javascript"} {
		rec := e.do("GET", path, "")
		if rec.Code != 200 || rec.Body.Len() < 50 || !strings.Contains(rec.Header().Get("Content-Type"), ct) {
			t.Errorf("%s: %d %s %d bytes", path, rec.Code, rec.Header().Get("Content-Type"), rec.Body.Len())
		}
	}
	if !strings.Contains(e.do("GET", "/docs/assets/init.js", "").Body.String(), "/openapi.json") {
		t.Error("the page must load the spec from this server")
	}
	if rec := e.do("GET", "/openapi.json", ""); rec.Code != 200 || !strings.Contains(rec.Body.String(), `"openapi":"3.1.0"`) {
		t.Errorf("openapi.json: %d", rec.Code)
	}
}