package bus_test

import (
	"encoding/base64"
	"encoding/json"
	"testing"

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

	"git.novox.be/novox/mesh-sdk/go/buscalls"
	mt "github.com/novox/mesh-tools/node-tools/internal/meshtest"
)

// Design 47 G A-249, §681: the runner asks a chunked verb with a call token of its own, receives the chunks the answer counts
// (each acknowledged before the next) and answers the verb's own answer with the whole file, so the asker receives none.
func TestAChunkedSeatAnswerIsReceivedByTheRunnerAndHandedWhole(t *testing.T) {
	url := mt.URL(t)
	holder := dial(t, url, "mesh-delivery-indexer", "anchor", "")
	asker := dial(t, url, "mesh-build-go", "anchor", "")
	raw, err := nats.Connect(url)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(raw.Close)
	file := make([]byte, buscalls.SeatChunkBytes*2+5)
	for i := range file {
		file[i] = byte(i)
	}
	// the holder's process: answers the count, then sends each chunk and waits for its acknowledgement
	stop, err := holder.Handle("seat:mesh-catalog.input", func(body json.RawMessage) (any, error) {
		var in struct{ Call, Digest string }
		if err := json.Unmarshal(body, &in); err != nil || in.Call == "" {
			t.Errorf("the verb was asked with no call token: %s (%v)", body, err)
			return nil, err
		}
		send := buscalls.SeatChunks{Seat: "mesh-catalog", Verb: "input", Call: in.Call}
		go func() {
			for n := int64(1); n <= 3; n++ {
				end := min(int64(len(file)), n*buscalls.SeatChunkBytes)
				data, _ := json.Marshal(buscalls.SeatChunk{N: n, Of: 3, Data: file[(n-1)*buscalls.SeatChunkBytes : end]})
				ackSub, _ := raw.SubscribeSync(send.Ack(n))
				_ = raw.Flush()
				if err := raw.Publish(send.Chunk(n), data); err != nil {
					return
				}
				m, err := ackSub.NextMsg(buscalls.SeatAckWithin)
				if err != nil {
					t.Errorf("chunk %d not acknowledged: %v", n, err)
					return
				}
				_ = m.Respond([]byte("{}"))
			}
		}()
		return map[string]any{"digest": in.Digest, "chunks": 3}, nil
	})
	if err != nil {
		t.Fatal(err)
	}
	defer stop()
	holder.Flush() // the bus holds the verb's subscription before it is asked: the asker is another connection
	got, err := asker.AskAsChunked("mesh-build-go", "seat:mesh-catalog.input", map[string]any{"digest": "d1"})
	if err != nil {
		t.Fatal(err)
	}
	var ans struct {
		Digest string `json:"digest"`
		Chunks int    `json:"chunks"`
		File   string `json:"file"`
	}
	if err := json.Unmarshal(got.Result, &ans); err != nil || ans.Digest != "d1" || ans.Chunks != 3 {
		t.Fatalf("the answer %s: %v", got.Result, err)
	}
	if body, err := base64.StdEncoding.DecodeString(ans.File); err != nil || string(body) != string(file) {
		t.Errorf("the file handed is %d bytes, want the %d sent: %v", len(body), len(file), err)
	}
	// Design 47 G A-257, A-254: a bundle answers a chunked verb with the whole file in the member `file`; the runner that serves the
	// verb sends the file in chunks (each acknowledged before the next) and answers the count, so the bundle sends none, and the asker
	// of one node's verb receives it whole.
	t.Run("ABundlesChunkedAnswerIsSentByTheRunner", func(t *testing.T) {
		url := mt.URL(t)
		holder := dial(t, url, "mesh-build-go", "anchor", "")
		asker := dial(t, url, "mesh-delivery-indexer", "anchor", "")
		file := make([]byte, buscalls.SeatChunkBytes*2+7)
		for i := range file {
			file[i] = byte(i * 7)
		}
		stop, err := holder.Handle("seat:node-build-go.output@anchor", func(body json.RawMessage) (any, error) {
			answer := map[string]any{"ask": "a1", "file": base64.StdEncoding.EncodeToString(file)}
			return holder.AnswerChunked("node-build-go", "output", body, answer)
		})
		if err != nil {
			t.Fatal(err)
		}
		defer stop()
		holder.Flush() // the bus holds the verb's subscription before it is asked: the asker is another connection
		got, err := asker.AskAsChunked("mesh-delivery-indexer", "seat:node-build-go.output@anchor", map[string]any{"ask": "a1"})
		if err != nil {
			t.Fatal(err)
		}
		var ans struct {
			Ask    string `json:"ask"`
			Chunks int    `json:"chunks"`
			File   string `json:"file"`
		}
		if err := json.Unmarshal(got.Result, &ans); err != nil || ans.Ask != "a1" || ans.Chunks != 3 {
			t.Fatalf("the answer %s: %v", got.Result, err)
		}
		if body, err := base64.StdEncoding.DecodeString(ans.File); err != nil || string(body) != string(file) {
			t.Errorf("the file handed is %d bytes, want the %d sent: %v", len(body), len(file), err)
		}
		// an answer with no file is the verb's own: no chunks are sent
		plain, err := holder.AnswerChunked("node-build-go", "output", json.RawMessage(`{"call":"c"}`), map[string]any{"ask": "x", "chunks": 0})
		if m, _ := plain.(map[string]any); err != nil || m["chunks"] != 0 {
			t.Fatalf("an answer with no file was %v, %v", plain, err)
		}
	})
}