package selfcompose

import (
	"context"
	"encoding/json"
	"errors"
	"strings"
	"sync"
	"testing"

	"git.novox.be/novox/mesh-contracts/go/clients/nodeengineclient"
	"git.novox.be/novox/mesh-contracts/go/seats/meshmoduleassigner"
	nodeengine "git.novox.be/novox/mesh-contracts/go/seats/nodeengine"
	"git.novox.be/novox/mesh-delivery/contracts/go/clients/meshcatalogclient"
	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshcatalog"
	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshwants"
	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds"
	"github.com/novox/mesh-host/internal/agent"
	"github.com/novox/mesh-host/internal/buckets"
	"github.com/novox/mesh-host/internal/buckets/bucketstest"
	"github.com/novox/mesh-host/internal/compositions"
)

// Design 47 G §421, §683, §698 (the lead's answers A-47, A-50): the node-engine reads the entry its want names by the
// fingerprint, through its own calls of the seat mesh-catalog's verb entry, and reads neither the indexer's states nor the
// builder's; a want whose entry the catalog half holds none of is held, its have saying entry-missing and naming the
// fingerprint; the entries and wants it composes from are kept in its composition state, written before the composition that
// uses them and read at its start before anything is asked; a want removed takes its kept want and entry away.
func composeFromEntries(t *testing.T) {
	b := newFakeBus()
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	fp := meshcatalogclient.SourcePrefix2 + strings.Repeat("a", 64)
	ghost := meshcatalogclient.SourcePrefix2 + strings.Repeat("b", 64)
	var manifest map[string]any
	if err := json.Unmarshal([]byte(lemurs), &manifest); err != nil {
		t.Fatal(err)
	}
	entry := meshcatalog.CatalogEntry{Module: "lemurs", Fp: fp, Manifest: manifest, Repository: "novox/x", Commit: "c",
		ManifestDigest: meshcatalogclient.ManifestDigest([]byte(lemurs))}
	var mu sync.Mutex
	var asked []string
	ask := func(_ context.Context, seat, verb string, args any) (json.RawMessage, error) {
		in := args.(meshcatalog.EntryInput)
		mu.Lock()
		asked = append(asked, in.Fingerprint)
		mu.Unlock()
		if seat != "mesh-catalog" || verb != "entry" {
			t.Errorf("asked %s.%s", seat, verb)
		}
		if in.Fingerprint != fp {
			return nil, errors.New("no entry of fingerprint " + in.Fingerprint + " is kept")
		}
		return json.Marshal(meshcatalog.EntryAnswer{Entry: entry})
	}
	state := &fakeComposed{kv: map[string]ComposedEntry{}}
	var held map[string]string
	env := b.env()
	env.Entry, env.ComposedState = EntryCall(ask), state
	env.Refused = func(_ string, h map[string]string) { mu.Lock(); held = h; mu.Unlock() }
	c := New(env)
	out, err := c.Watch(ctx, "n1.>")
	if err != nil {
		t.Fatal(err)
	}
	place := assignedValues(t, meshmoduleassigner.Assignments{Node: "n1", Decided: meshmoduleassigner.NodeDecided{Hub: true, Address: "10.77.0.1"},
		Modules: []meshmoduleassigner.PlacedModule{{Module: "lemurs"}, {Module: "ghost"}}})
	have, _ := nodeengineclient.EncodeHaveNode(nodeengine.HaveByNodeNodeValue{Record: &nodeengine.NodeRecord{Node: "n1", TunnelKey: "k", SealingKey: "sk", Capabilities: []string{"systemd"}}})
	nodeWant, _ := bucketstest.NodeWant(meshwants.WantsByWantNodeNodeValue{Self: true})
	b.putAssigned(t, place)
	b.put(t, buckets.Have, "n1.node", have)
	b.put(t, buckets.Wants, "want.n1.node", nodeWant)
	for module, w := range map[string]meshwants.WantsByWantNodeModuleValue{"lemurs": {Fp: fp, Self: true}, "ghost": {Fp: ghost, Self: true}} {
		raw, _ := bucketstest.Want(w)
		b.put(t, buckets.Wants, "want.n1."+module, raw)
	}
	for _, bucket := range []string{buckets.Wants, buckets.Assignments, buckets.Have, ResolvedBucket} {
		b.send(bucket, agent.Update{Caught: true})
	}
	lemursKey, _ := compositions.Key("n1", "lemurs", fp)
	handed := map[string]bool{}
	for !handed[lemursKey] {
		handed[next(t, out).Key] = true
	}
	// Neither the indexer's states nor the builder's are watched or read.
	b.mu.Lock()
	for _, r := range b.reads {
		if r[0] == buckets.Modules || r[0] == buckets.Manifests || r[0] == buckets.Verdicts || r[0] == builds.BuilderBuildsBucket {
			t.Errorf("the node-engine read %s of %s", r[1], r[0])
		}
	}
	b.mu.Unlock()
	// A want whose entry the half holds none of is held, saying entry-missing and the fingerprint; the rest is composed.
	mu.Lock()
	why := held["ghost"]
	mu.Unlock()
	if !strings.HasPrefix(why, agent.EntryMissing) || !strings.Contains(why, ghost) || held["lemurs"] != "" {
		t.Errorf("held %q, want ghost held with %s naming %s", held, agent.EntryMissing, ghost)
	}
	// Each entry and want it composes from is kept in the composition state before the composition that uses them.
	state.mu.Lock()
	_, hasEntry := state.kv[entryKey(fp)]
	_, hasWant := state.kv["want.lemurs"]
	state.mu.Unlock()
	if !hasEntry || !hasWant {
		t.Errorf("the composition state holds entry %v and want %v of lemurs: %v", hasEntry, hasWant, state.written())
	}
	// The seat's first-views lists them.
	_, entries, wants := c.FirstViews()
	if len(entries) < 2 || len(wants) != 2 {
		t.Errorf("first-views lists %v and %v", entries, wants)
	}
	// A restart reads what is kept before it asks anything: lemurs's entry is not asked again.
	mu.Lock()
	asked = nil
	mu.Unlock()
	env2 := b.env()
	env2.Entry, env2.ComposedState = EntryCall(ask), state
	c2 := New(env2)
	if _, err := c2.Watch(ctx, "n1.>"); err != nil {
		t.Fatal(err)
	}
	c2.mu.Lock()
	kept, keptWant := c2.keptEnt[fp], c2.wants["lemurs"].Fp
	c2.mu.Unlock()
	if kept.entry.Module != "lemurs" || keptWant != fp {
		t.Errorf("a restart read entry %q and want %q from the state", kept.entry.Module, keptWant)
	}
	// A want removed takes its kept want and entry away.
	raw, _ := bucketstest.Want(meshwants.WantsByWantNodeModuleValue{Fp: fp, Removed: true})
	b.put(t, buckets.Wants, "want.n1.lemurs", raw)
	for range 20 {
		state.mu.Lock()
		_, hasWant = state.kv["want.lemurs"]
		_, hasEntry = state.kv[entryKey(fp)]
		state.mu.Unlock()
		if !hasWant && !hasEntry {
			break
		}
		next(t, out)
	}
	if hasWant || hasEntry {
		t.Errorf("a removed want left its kept want %v and entry %v", hasWant, hasEntry)
	}
}