package launch

import (
	"encoding/json"
	"errors"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"
	"time"
)

// puttingBundle asks the capability words, and once they are answered with put-sessions sends the one chunk of a put
// session, as mesh-sdk's bundle does; it then ends, which closes its channel.
const puttingBundle = `#!/bin/sh
while IFS= read -r line; do
  id=$(printf '%s' "$line" | sed -n 's/.*"id":\([0-9]*\)[,}].*/\1/p')
  case "$line" in
    *'"method":"initialize"'*) printf '{"jsonrpc":"2.0","id":%s,"result":{}}\n' "$id" ;;
    *'"method":"tools/list"'*) printf '{"jsonrpc":"2.0","id":%s,"result":{"tools":[]}}\n' "$id"
       printf '{"jsonrpc":"2.0","id":"w1","method":"mesh/capabilities","params":{}}\n' ;;
    *'"id":"w1"'**put-sessions*) printf '{"jsonrpc":"2.0","id":"p1","method":"mesh/objects.put-chunk","params":{"objects":"o","name":"n","call":"c","seq":1,"last":true,"data":"aGk="}}\n' ;;
    *'"id":"p1"'*) exit 0 ;;
  esac
done
`

type sessionBus struct {
	subscribing
	mu      sync.Mutex
	chunks  []string
	dropped chan struct{}
}

func (b *sessionBus) CapabilityWords() []string { return []string{"put-sessions"} }
func (b *sessionBus) BusState(method string, params json.RawMessage) (json.RawMessage, error) {
	b.mu.Lock()
	b.chunks = append(b.chunks, method+" "+string(params))
	b.mu.Unlock()
	return json.RawMessage(`{"name":"n"}`), nil
}
func (b *sessionBus) DropSessions() { close(b.dropped) }

// Design 47 G §576, §518: a bundle reads the runner's capability words with mesh/capabilities, then runs its put session
// through the runner's put-chunk, and the sessions of its channel are dropped when the channel closes.
func TestABundleReadsTheCapabilityWordsRunsAPutSessionAndItsChannelsClosingDropsThem(t *testing.T) {
	dir := t.TempDir()
	entry := filepath.Join(dir, "bundle")
	if err := os.WriteFile(entry, []byte(puttingBundle), 0o755); err != nil {
		t.Fatal(err)
	}
	b := &sessionBus{dropped: make(chan struct{})}
	l, err := Start("putter", entry, os.Environ(), b, func(string, ...any) {})
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(l.Stop)
	select {
	case <-b.dropped:
	case <-time.After(5 * time.Second):
		t.Fatal("the bundle's sessions were not dropped when its channel closed")
	}
	b.mu.Lock()
	defer b.mu.Unlock()
	if len(b.chunks) != 1 || !strings.HasPrefix(b.chunks[0], "mesh/objects.put-chunk ") || !strings.Contains(b.chunks[0], `"seq":1`) {
		t.Fatalf("the runner took %v", b.chunks)
	}
}

// findingBundle asks, as mesh-sdk's finding writer does, a publish with ack that the bus takes, one it refuses, and a
// subscription for new messages; each answer it gets is written to $FINDING_OUT, and it ends after the subscription's.
const findingBundle = `#!/bin/sh
while IFS= read -r line; do
  id=$(printf '%s' "$line" | sed -n 's/.*"id":\([0-9]*\)[,}].*/\1/p')
  case "$line" in
    *'"method":"initialize"'*) printf '{"jsonrpc":"2.0","id":%s,"result":{}}\n' "$id" ;;
    *'"method":"tools/list"'*) printf '{"jsonrpc":"2.0","id":%s,"result":{"tools":[]}}\n' "$id"
       printf '{"jsonrpc":"2.0","id":"a1","method":"mesh/publish","params":{"key":"taken","ack":true,"body":{}}}\n' ;;
    *'"id":"a1"'*) printf '%s\n' "$line" >>"$FINDING_OUT"
       printf '{"jsonrpc":"2.0","id":"a2","method":"mesh/publish","params":{"key":"refused","ack":true,"body":{}}}\n' ;;
    *'"id":"a2"'*) printf '%s\n' "$line" >>"$FINDING_OUT"
       printf '{"jsonrpc":"2.0","id":"s1","method":"mesh/subscribe","params":{"pattern":"mesh-conditions.findings-asked","deliver":"new"}}\n' ;;
    *'"id":"s1"'*) printf '%s\n' "$line" >>"$FINDING_OUT"; exit 0 ;;
  esac
done
`

type findingBus struct {
	subscribing
	mu      sync.Mutex
	pattern string
	stopped chan struct{}
}

func (b *findingBus) PublishAcked(params json.RawMessage) (uint64, error) {
	if strings.Contains(string(params), `"refused"`) {
		return 0, errors.New("the bus refused it")
	}
	return 42, nil
}

func (b *findingBus) SubscribeNew(pattern string, _ func(json.RawMessage) error) (func(), error) {
	b.mu.Lock()
	b.pattern = pattern
	b.mu.Unlock()
	return func() { close(b.stopped) }, nil
}

// Design 47 G §559: `mesh/publish` with `ack` is answered with its sequence once the bus acknowledged it, or `{error}`;
// `mesh/subscribe` with `deliver: new` makes a subscription for new messages that ends with the bundle's channel.
func TestAPublishWithAckIsAnsweredWithItsSequenceAndASubscriptionForNewMessagesEndsWithTheChannel(t *testing.T) {
	dir := t.TempDir()
	entry, out := filepath.Join(dir, "bundle"), filepath.Join(dir, "out")
	if err := os.WriteFile(entry, []byte(findingBundle), 0o755); err != nil {
		t.Fatal(err)
	}
	b := &findingBus{stopped: make(chan struct{})}
	l, err := Start("writer", entry, append(os.Environ(), "FINDING_OUT="+out), b, func(string, ...any) {})
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(l.Stop)
	select {
	case <-b.stopped:
	case <-time.After(5 * time.Second):
		t.Fatal("the subscription for new messages was not ended with the bundle's channel")
	}
	got, _ := os.ReadFile(out)
	for _, want := range []string{`"sequence":42`, `"error":"the bus refused it"`} {
		if !strings.Contains(string(got), want) {
			t.Errorf("the bundle was answered %s, want it to hold %s", got, want)
		}
	}
	b.mu.Lock()
	defer b.mu.Unlock()
	if b.pattern != "mesh-conditions.findings-asked" {
		t.Errorf("the subscription was made for %q", b.pattern)
	}
	if len(b.published) != 0 {
		t.Errorf("a publish with ack went the unacknowledged way: %v", b.published)
	}
}