// Package meshtest raises what the controller would, for tests against a real bus: the ASSIGNMENTS
// and EVENTS streams, memberships issued by hand, and a fixture's path.
//
// **The packages share one bus, so run them one at a time: `go test -p 1 ./...`.** Each test raises
// the streams afresh, and the console discovers every runtime that announces itself on the bus
// (novox/hq ADR 0197) — a runtime from another package's test is, correctly, found.
package meshtest

import (
	"encoding/json"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
	"time"

	"github.com/nats-io/nats.go"

	"github.com/novox/mesh-tools/node-tools/internal/bus"
)

// URL is the test bus, or the test is skipped.
func URL(t *testing.T) string {
	t.Helper()
	url := os.Getenv("MESH_TEST_NATS")
	if url == "" {
		t.Skip("MESH_TEST_NATS unset")
	}
	return url
}

// Mesh is the controller's job, done by hand.
type Mesh struct {
	nc *nats.Conn
	js nats.JetStreamContext
}

// New raises the streams afresh.
func New(t *testing.T) *Mesh {
	t.Helper()
	nc, err := nats.Connect(URL(t))
	if err != nil {
		t.Fatal(err)
	}
	js, _ := nc.JetStream()
	for _, s := range []string{"ASSIGNMENTS", "EVENTS"} {
		_ = js.DeleteStream(s)
	}
	if _, err := js.AddStream(&nats.StreamConfig{Name: "ASSIGNMENTS", Subjects: []string{"mesh.assignment.>"},
		MaxMsgsPerSubject: 1, AllowDirect: true}); err != nil {
		t.Fatal(err)
	}
	if _, err := js.AddStream(&nats.StreamConfig{Name: "EVENTS", Subjects: []string{"mesh.mod.*.event.>"}}); err != nil {
		t.Fatal(err)
	}
	t.Cleanup(nc.Close)
	return &Mesh{nc: nc, js: js}
}

// Issue publishes a membership.
func (m *Mesh) Issue(t *testing.T, mem bus.Membership) {
	t.Helper()
	body, _ := json.Marshal(mem)
	if _, err := m.js.Publish(bus.MembershipSubject(mem.Node, mem.Module), body); err != nil {
		t.Fatal(err)
	}
}

// NextEvent is the subject the next event under a pattern lands on.
func (m *Mesh) NextEvent(t *testing.T, pattern string) <-chan string {
	t.Helper()
	ch := make(chan string, 1)
	sub, err := m.nc.Subscribe(pattern, func(msg *nats.Msg) {
		select {
		case ch <- msg.Subject:
		default:
		}
	})
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = sub.Unsubscribe() })
	_ = m.nc.Flush()
	return ch
}

// MembershipOf is a membership as the controller issues one on a machine.
func MembershipOf(module, node string, plain bool, seats map[string][]string) bus.Membership {
	own := "mesh.mod." + module
	serves := []bus.Served{{Subject: own + ".tool.{tool}." + node}}
	if plain {
		serves = append(serves, bus.Served{Subject: own + ".tool.{tool}", Queue: "serve." + module})
	}
	var verbs []bus.SeatVerb
	for seat, vs := range seats {
		for _, v := range vs {
			verbs = append(verbs, bus.SeatVerb{Seat: seat, Verb: v, Subject: "mesh.seat." + seat + ".tool." + v + "." + node})
		}
	}
	return bus.Membership{Node: node, Module: module, Serves: serves, Seats: verbs,
		Emits: own + ".event.{event}", Tools: own + ".tool.tools"}
}

// Fixture is a path in node-tools/test/fixtures, which these tests share with the TypeScript ones.
func Fixture(name string) string {
	_, here, _, _ := runtime.Caller(0)
	return filepath.Join(filepath.Dir(here), "..", "..", "test", "fixtures", name)
}

// Until retries while the bus answers "no responders" — something not yet served.
func Until(t *testing.T, try func() error) {
	t.Helper()
	var err error
	for i := 0; i < 50; i++ {
		if err = try(); err == nil {
			return
		}
		time.Sleep(100 * time.Millisecond)
	}
	t.Fatal(err)
}

// Logs collects what the runtime says.
type Logs struct{ lines []string }

// Logf is a logger that keeps the lines.
func (l *Logs) Logf(format string, args ...any) {
	l.lines = append(l.lines, sprintf(format, args...))
}

// Has says whether a line contains every fragment.
func (l *Logs) Has(fragments ...string) bool {
	for _, line := range l.lines {
		all := true
		for _, f := range fragments {
			all = all && strings.Contains(line, f)
		}
		if all {
			return true
		}
	}
	return false
}

// All is every line.
func (l *Logs) All() string { return strings.Join(l.lines, "\n") }

// Consumer makes a module's durable consumer on a machine as the controller does: pull, on the
// EVENTS stream, filtered to what the module consumes, with a short ack wait so a test sees a
// redelivery in seconds rather than the mesh's minutes.
func (m *Mesh) Consumer(t *testing.T, node, module string, filters []string, ackWait time.Duration) {
	t.Helper()
	cfg := &nats.ConsumerConfig{Durable: node + "_" + module, AckPolicy: nats.AckExplicitPolicy,
		AckWait: ackWait, MaxDeliver: 10, DeliverPolicy: nats.DeliverNewPolicy}
	if len(filters) == 1 {
		cfg.FilterSubject = filters[0]
	} else {
		cfg.FilterSubjects = filters
	}
	if _, err := m.js.AddConsumer("EVENTS", cfg); err != nil {
		t.Fatal(err)
	}
}

// Emit publishes an event as a module would, into the EVENTS stream.
func (m *Mesh) Emit(t *testing.T, subject string, body any) {
	t.Helper()
	data, _ := json.Marshal(body)
	if _, err := m.js.Publish(subject, data); err != nil {
		t.Fatal(err)
	}
}

// Pending is what a module's consumer still holds: delivered and not acknowledged, and not yet
// delivered.
func (m *Mesh) Pending(t *testing.T, node, module string) (ackPending, notDelivered uint64) {
	t.Helper()
	info, err := m.js.ConsumerInfo("EVENTS", node+"_"+module)
	if err != nil {
		t.Fatal(err)
	}
	return uint64(info.NumAckPending), info.NumPending
}

// Bucket makes a module's state afresh as the controller does from the catalogue (novox/hq ADR 0202),
// and answers it for writing what is there before a bundle starts.
func (m *Mesh) Bucket(t *testing.T, name string) nats.KeyValue {
	t.Helper()
	_ = m.js.DeleteKeyValue(name)
	kv, err := m.js.CreateKeyValue(&nats.KeyValueConfig{Bucket: name, History: 1, MaxValueSize: 256 * 1024})
	if err != nil {
		t.Fatal(err)
	}
	return kv
}