package build

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"sync"
	"testing"
	"time"

	"git.novox.be/novox/mesh-sdk/go/catalogue"
	"git.novox.be/novox/mesh-sdk/go/delivery"
)

// buildModules simulates the two build modules on the nodes: a long tool answers a step and key at once and writes the
// step's end into the steps (as mesh-build-go and mesh-build-node do), with a digest by node and artifact, or a failure.
type buildModules struct {
	mu      sync.Mutex
	n       int
	calls   []call
	steps   *fakeSteps
	digests map[string]string // `<node>/<artifact>` -> digest; the default is `digest`
	fails   map[string]string // `<node>/<tool>` -> the reason the step fails with
	// hold, when set before the builds start, blocks every call until it is closed; entered is sent to as a call arrives.
	hold    chan struct{}
	entered chan struct{}
}

func newBuildModules() *buildModules {
	return &buildModules{steps: &fakeSteps{steps: map[string]delivery.Step{}}, digests: map[string]string{}, fails: map[string]string{}}
}

func (b *buildModules) CallOn(node, key string, body any) (json.RawMessage, error) {
	if b.hold != nil {
		select {
		case b.entered <- struct{}{}:
		default:
		}
		<-b.hold
	}
	b.mu.Lock()
	defer b.mu.Unlock()
	b.calls = append(b.calls, call{node, key, body})
	b.n++
	id := fmt.Sprintf("s%d", b.n)
	module, tool, _ := strings.Cut(key, ".")
	args, _ := body.(map[string]any)
	step := delivery.Step{ID: id, Tool: tool, Node: node, State: delivery.StepPassed}
	if reason, ok := b.fails[node+"/"+tool]; ok {
		step.State, step.Reason = delivery.StepFailed, reason
	} else if strings.HasSuffix(tool, "_fetch") {
		step.Result = json.RawMessage(`{"workspace":"w-` + node + `"}`)
	} else {
		d := digest
		if v, ok := b.digests[node+"/"+fmt.Sprint(args["artifact"])]; ok {
			d = v
		}
		step.Result = json.RawMessage(`{"digest":"` + d + `"}`)
	}
	sk, _ := delivery.StepKey(node, id)
	b.steps.mu.Lock()
	b.steps.steps[module+"/"+sk] = step
	b.steps.mu.Unlock()
	return json.RawMessage(`{"step":"` + id + `","key":"` + sk + `","state":"running"}`), nil
}

func (b *buildModules) callsOf(tool string) (out []call) {
	b.mu.Lock()
	defer b.mu.Unlock()
	for _, c := range b.calls {
		if strings.HasSuffix(c.key, "."+tool) {
			out = append(out, c)
		}
	}
	return out
}

type fakeManifests struct {
	byDigest map[string]catalogue.Manifest
}

func (f *fakeManifests) Manifest(_ context.Context, d string) (catalogue.Manifest, error) {
	m, ok := f.byDigest[d]
	if !ok {
		return catalogue.Manifest{}, fmt.Errorf("manifests.%s is not there", d)
	}
	return m, nil
}

func mdigest(c byte) string { return hex64(c) }

type rig struct {
	b     *Builder
	st    *memStore
	bm    *buildModules
	tools *ToolchainSet
	pres  *PresenceSet
	mf    *fakeManifests
	key   string
}

func newRig(t *testing.T, artifacts ...catalogue.Artifact) *rig {
	t.Helper()
	r := &rig{st: newMem(), bm: newBuildModules(), tools: &ToolchainSet{}, pres: &PresenceSet{}, mf: &fakeManifests{byDigest: map[string]catalogue.Manifest{mdigest('a'): {Module: "m", Build: &catalogue.Build{Artifacts: artifacts}}}}}
	for _, n := range []string{"ace", "novox"} {
		r.tools.Put(GoBuildModule, n+".go", tcValue(t, "go", "go1.27.1"), false)
		r.tools.Put(NodeBuildModule, n+".typescript", tcValue(t, "typescript", "tsc5"), false)
		r.pres.Put(n, presenceValue(t, true), false)
	}
	r.b = &Builder{
		Claimer: Claimer{Store: r.st, By: "novox.builder"}, Runner: Runner{Caller: r.bm, Steps: r.bm.steps, Bound: time.Second},
		Toolchains: r.tools, Presence: r.pres, Manifests: r.mf, Nodes: 2, Logf: t.Logf,
	}
	var err error
	if r.key, err = delivery.BuilderBuildKey("m", fp1); err != nil {
		t.Fatal(err)
	}
	return r
}

// agreedToolchains are what the rig's nodes report, and so what a fingerprint computed now names.
var agreedToolchains = map[string]delivery.ToolchainUsed{"go": {Version: "go1.27.1", Recipe: "1"}, "typescript": {Version: "tsc5", Recipe: "1"}}

func moduleValue(t *testing.T, path string) []byte { return moduleValueWith(t, path, agreedToolchains) }

func moduleValueWith(t *testing.T, path string, toolchains map[string]delivery.ToolchainUsed) []byte {
	t.Helper()
	data, err := delivery.EncodeModule(delivery.Module{Repository: "novox/mesh-catalog", Commit: "7a74cee83f88e6585a5511c3cc53bdf0f5303d20", FP: "src1:" + hex64('f'), FP2: fp1, Manifest: mdigest('a'), Path: path, Toolchains: toolchains})
	if err != nil {
		t.Fatal(err)
	}
	return data
}

func (r *rig) consider(t *testing.T, path string) delivery.BuilderBuild {
	t.Helper()
	r.b.Module(context.Background(), "m", moduleValue(t, path))
	r.b.Wait()
	if _, ok := r.st.vals[r.key]; !ok {
		t.Fatal("no build key was written")
	}
	return valueOf(t, r.st, r.key)
}

var (
	goBundle  = catalogue.Artifact{Name: "tool", Kind: "bundle", Language: "go"}
	tsBundle  = catalogue.Artifact{Name: "web", Kind: "bundle", Language: "typescript"}
	archiveA  = catalogue.Artifact{Name: "files", Kind: "archive"}
	imageArt  = catalogue.Artifact{Name: "img", Kind: "image"}
	manifestD = mdigest('a')
)

func TestABundleAndAnArchiveAreBuiltOnTwoNodesAndDoneWhenTheDigestsAgree(t *testing.T) { // 1607/AC7, ADR 0478 clauses 1, 4
	r := newRig(t, goBundle, archiveA, tsBundle)
	v := r.consider(t, "modules/m")
	if v.State != delivery.BuildDone || v.By != "novox.builder" || v.Manifest != manifestD || len(v.Artifacts) != 3 {
		t.Fatalf("build = %+v, want done by novox.builder with three artifacts", v)
	}
	for i, want := range []string{"files", "tool", "web"} {
		if a := v.Artifacts[i]; a.Name != want || a.Digest != digest || a.Reference != "" {
			t.Errorf("artifact %d = %+v, want %s with the digest and no reference (ADR 0478 clause 6)", i, a, want)
		}
	}
	if v.Artifacts[0].Kind != "archive" || v.Artifacts[1].Kind != "bundle" {
		t.Errorf("kinds = %+v", v.Artifacts)
	}
	if got := v.Toolchains["go"]; got.Version != "go1.27.1" || got.Recipe != "1" {
		t.Errorf("toolchains = %+v, want go and typescript named", v.Toolchains)
	}
	if got := v.Toolchains["typescript"]; got.Version != "tsc5" {
		t.Errorf("toolchains = %+v", v.Toolchains)
	}
	// Two fetches per build module, one on each node; every build names the module's directory.
	if n := len(r.bm.callsOf("build_go_fetch")); n != 2 {
		t.Errorf("%d go fetches, want one per node", n)
	}
	if n := len(r.bm.callsOf("build_go_build")); n != 4 { // tool and files, each on two nodes
		t.Errorf("%d go builds, want 4", n)
	}
	if n := len(r.bm.callsOf("build_node_build")); n != 2 {
		t.Errorf("%d node builds, want 2", n)
	}
	c := r.bm.callsOf("build_go_build")[0]
	if args := c.body.(map[string]any); args["module"] != "modules/m" || !strings.HasPrefix(fmt.Sprint(args["workspace"]), "w-") {
		t.Errorf("build args = %+v, want the module's path and the fetch's workspace", args)
	}
	f := r.bm.callsOf("build_go_fetch")[0].body.(map[string]any)
	if f["repository"] != "novox/mesh-catalog" || f["commit"] != "7a74cee83f88e6585a5511c3cc53bdf0f5303d20" {
		t.Errorf("fetch args = %+v", f)
	}
}

func TestDifferingDigestsFailTheBuildNamingBothNodes(t *testing.T) { // 1607/AC4, ADR 0478 clause 4
	r := newRig(t, goBundle)
	r.bm.digests["ace/tool"] = "sha256:" + hex64('9')
	v := r.consider(t, "modules/m")
	if v.State != delivery.BuildFailed || !strings.Contains(v.Error, "ace") || !strings.Contains(v.Error, "novox") || !strings.Contains(v.Error, digest) || !strings.Contains(v.Error, hex64('9')) {
		t.Errorf("build = %+v, want failed naming both nodes and both digests", v)
	}
}

func TestOneQualifyingNodeBuildsOnceAndTheKeySaysSo(t *testing.T) { // 1607/AC4, ADR 0478 clause 4
	r := newRig(t, goBundle)
	r.tools.Put(GoBuildModule, "ace.go", nil, true)
	v := r.consider(t, "modules/m")
	if v.State != delivery.BuildDone || !strings.Contains(v.Step, "one node") || !strings.Contains(v.Step, "novox") {
		t.Errorf("build = %+v, want done with its step saying one node, novox", v)
	}
	if n := len(r.bm.callsOf("build_go_build")); n != 1 {
		t.Errorf("%d builds, want one", n)
	}
}

func TestAFailingStepFailsTheBuildWithItsReasonAndNodeAndIsTriedAgainAsANewRevision(t *testing.T) { // 1607/AC7, ADR 0429 clause 18
	r := newRig(t, goBundle)
	r.bm.fails["ace/build_go_build"] = "go build of tool: undefined: x"
	v := r.consider(t, "modules/m")
	if v.State != delivery.BuildFailed || !strings.Contains(v.Error, "ace") || !strings.Contains(v.Error, "undefined: x") {
		t.Fatalf("build = %+v, want failed with the node and the reason", v)
	}
	rev := r.st.revs[r.key]
	delete(r.bm.fails, "ace/build_go_build")
	v = r.consider(t, "modules/m")
	if v.State != delivery.BuildDone || r.st.revs[r.key] <= rev {
		t.Errorf("build = %+v at revision %d (was %d), want done as a new revision of the same key", v, r.st.revs[r.key], rev)
	}
}

func TestAModuleWithAnImageGetsARefusedKeyNeverBuiltAgain(t *testing.T) { // 1607/AC2, ADR 0478 clause 2
	r := newRig(t, archiveA, imageArt)
	v := r.consider(t, "modules/m")
	if v.State != delivery.BuildFailed || !strings.HasPrefix(v.Error, RefusedPrefix) || !strings.Contains(v.Error, "image") || !strings.Contains(v.Error, "build-agent") {
		t.Fatalf("build = %+v, want failed 'refused kind: image' naming build-agent", v)
	}
	if len(r.bm.calls) != 0 {
		t.Errorf("%d calls, want none for a refused kind", len(r.bm.calls))
	}
	writes := r.st.writes
	r.consider(t, "modules/m")
	if r.st.writes != writes {
		t.Errorf("a refused key was written again (%d writes, was %d)", r.st.writes, writes)
	}
}

func TestAModuleKeyWithNoPathFailsNamingThatReason(t *testing.T) { // 1607/AC8, ADR 0478 clause 8
	r := newRig(t, goBundle)
	v := r.consider(t, "")
	if v.State != delivery.BuildFailed || !strings.Contains(v.Error, "path") || len(r.bm.calls) != 0 {
		t.Errorf("build = %+v with %d calls, want failed naming the missing path and nothing called", v, len(r.bm.calls))
	}
}

func TestAnUnreadableManifestFailsTheBuild(t *testing.T) {
	r := newRig(t, goBundle)
	delete(r.mf.byDigest, mdigest('a'))
	v := r.consider(t, "modules/m")
	if v.State != delivery.BuildFailed || !strings.Contains(v.Error, "manifest") {
		t.Errorf("build = %+v, want failed naming the manifest", v)
	}
}

func TestAModuleWithNoFingerprintOrNoArtifactIsNotBuilt(t *testing.T) { // 1607/AC2
	r := newRig(t)
	r.b.Module(context.Background(), "m", moduleValue(t, "modules/m"))
	data, _ := delivery.EncodeModule(delivery.Module{Repository: "novox/r", Commit: "c", FP: "src1:" + hex64('f'), None2: "toolchain not yet reported"})
	r.b.Module(context.Background(), "n", data)
	r.b.Wait()
	if len(r.st.vals) != 0 {
		t.Errorf("keys %v were written: a module with no new-form fingerprint or no artifact has nothing to build", r.st.vals)
	}
}

func TestAKeyTheBuilderLeftBuildingIsBuiltAtStartAndDoneKeysAreNotBuiltTwice(t *testing.T) { // 1607/AC3, AC7
	r := newRig(t, goBundle)
	seed(t, r.st, delivery.BuilderBuild{State: delivery.BuildBuilding, By: "novox.builder", Manifest: manifestD})
	if v := r.consider(t, "modules/m"); v.State != delivery.BuildDone {
		t.Fatalf("build = %+v, want the builder's own building key built", v)
	}
	calls := len(r.bm.calls)
	r.b.Module(context.Background(), "m", moduleValue(t, "modules/m"))
	r.b.Reconsider(context.Background())
	r.b.Wait()
	if len(r.bm.calls) != calls {
		t.Errorf("a done key was built again (%d calls, was %d)", len(r.bm.calls), calls)
	}
}

// Two instances that start together on one key: the second finds the key building and takes it over (ADR 0478 clause 6:
// a key found building at start is taken over, whoever holds it), so both may build; the key is written once, by the one
// whose compare-and-set comes first, and the other's write is refused, never overwriting it.
func TestTwoInstancesStartingTogetherEndWithOneDoneKey(t *testing.T) { // 1607/AC7, review round 4
	r := newRig(t, goBundle)
	other := &Builder{Claimer: Claimer{Store: r.st, By: "ace.builder"}, Runner: r.b.Runner, Toolchains: r.tools, Presence: r.pres, Manifests: r.mf, Nodes: 2, Logf: t.Logf}
	value := moduleValue(t, "modules/m")
	var wg sync.WaitGroup
	for _, b := range []*Builder{r.b, other} {
		wg.Add(1)
		go func() { defer wg.Done(); b.Module(context.Background(), "m", value); b.Wait() }()
	}
	wg.Wait()
	if v := valueOf(t, r.st, r.key); v.State != delivery.BuildDone || len(v.Artifacts) != 1 {
		t.Errorf("build = %+v, want one done key", v)
	}
	if n := len(r.bm.callsOf("build_go_build")); n < 2 || n%2 != 0 {
		t.Errorf("%d builds, want two for each instance that built", n)
	}
}

func TestAModulesValueThatArrivesWhileItsKeyIsBeingBuiltIsLookedAtAgainWhenItEnds(t *testing.T) { // 1607/AC6 (no event is dropped, no timer)
	r := newRig(t, goBundle)
	r.bm.fails["ace/build_go_build"] = "go build of tool: boom"
	r.bm.hold, r.bm.entered = make(chan struct{}), make(chan struct{}, 8)
	value := moduleValue(t, "modules/m")
	r.b.Module(context.Background(), "m", value)
	<-r.bm.entered // the first build is under way
	r.b.Module(context.Background(), "m", value)
	r.b.Reconsider(context.Background())
	delete(r.bm.fails, "ace/build_go_build") // what the event is about: the build can succeed now
	close(r.bm.hold)
	r.b.Wait()
	if v := valueOf(t, r.st, r.key); v.State != delivery.BuildDone {
		t.Errorf("build = %+v, want the failed key built again as a new revision after the first build ended", v)
	}
}

func TestAKeyIsBuiltOnlyWithTheToolchainItsFingerprintNamesAndNothingIsWrittenOtherwise(t *testing.T) { // 1615/AC4
	r := newRig(t, goBundle)
	old := map[string]delivery.ToolchainUsed{"go": {Version: "go1.26.0", Recipe: "1"}}
	r.b.Module(context.Background(), "m", moduleValueWith(t, "modules/m", old))
	r.b.Wait()
	if len(r.st.vals) != 0 || len(r.bm.calls) != 0 {
		t.Errorf("keys %v and %d calls for a fingerprint of go1.26.0 while the nodes agree on go1.27.1, want neither", r.st.vals, len(r.bm.calls))
	}
	// A recipe that differs is a different toolchain too, and a value that names none (written before) is not built.
	r.b.Module(context.Background(), "m", moduleValueWith(t, "modules/m", map[string]delivery.ToolchainUsed{"go": {Version: "go1.27.1", Recipe: "0"}}))
	r.b.Module(context.Background(), "m", moduleValueWith(t, "modules/m", nil))
	r.b.Wait()
	if len(r.st.vals) != 0 || len(r.bm.calls) != 0 {
		t.Errorf("keys %v and %d calls for a recipe that differs or a value that names no toolchain", r.st.vals, len(r.bm.calls))
	}
	// The toolchain moves under a key that is not built yet: the old fingerprint stays unbuilt, the new one builds.
	r.tools.Put(GoBuildModule, "ace.go", tcValue(t, "go", "go1.27.2"), false)
	r.tools.Put(GoBuildModule, "novox.go", tcValue(t, "go", "go1.27.2"), false)
	r.b.Reconsider(context.Background())
	r.b.Wait()
	if len(r.st.vals) != 0 {
		t.Errorf("keys %v: the old fingerprint was built with the new toolchain", r.st.vals)
	}
	r.b.Module(context.Background(), "m", moduleValueWith(t, "modules/m", map[string]delivery.ToolchainUsed{"go": {Version: "go1.27.2", Recipe: "1"}}))
	r.b.Wait()
	if v := valueOf(t, r.st, r.key); v.State != delivery.BuildDone || v.Toolchains["go"].Version != "go1.27.2" {
		t.Errorf("build = %+v, want done with go1.27.2", v)
	}
}

func TestNodesTheyDisagreeOnLeaveTheKeyUnwritten(t *testing.T) { // 1615/AC4
	r := newRig(t, goBundle)
	r.tools.Put(GoBuildModule, "ace.go", tcValue(t, "go", "go1.26.0"), false)
	r.b.Module(context.Background(), "m", moduleValue(t, "modules/m"))
	r.b.Wait()
	if len(r.st.vals) != 0 || len(r.bm.calls) != 0 {
		t.Errorf("keys %v and %d calls while the nodes disagree", r.st.vals, len(r.bm.calls))
	}
}

func TestARootModulesPathIsDotAndIsGivenToTheBuildTools(t *testing.T) { // 1615/AC4
	r := newRig(t, goBundle)
	if v := r.consider(t, delivery.RootPath); v.State != delivery.BuildDone {
		t.Fatalf("build = %+v, want done for a root module", v)
	}
	if args := r.bm.callsOf("build_go_build")[0].body.(map[string]any); args["module"] != "." {
		t.Errorf("build args = %+v, want module \".\"", args)
	}
}

func TestANodeThatIsNotOnlineIsNotChosenAndComingBackWakesTheBuild(t *testing.T) { // 1607 review 3
	r := newRig(t, goBundle)
	r.tools.Put(GoBuildModule, "g14.go", tcValue(t, "go", "go1.27.1"), false) // a laptop that reports its toolchain and sleeps
	v := r.consider(t, "modules/m")
	if v.State != delivery.BuildDone {
		t.Fatalf("build = %+v", v)
	}
	for _, c := range r.bm.calls {
		if c.node == "g14" {
			t.Errorf("a call went to g14, which is not online: %+v", c)
		}
	}
	// With no node online the key fails naming why; a node coming online builds it as a new revision.
	r2 := newRig(t, goBundle)
	r2.pres.Put("ace", nil, true)
	r2.pres.Put("novox", nil, true)
	if v := r2.consider(t, "modules/m"); v.State != delivery.BuildFailed || !strings.Contains(v.Error, "online") {
		t.Fatalf("build = %+v, want failed because no node is online", v)
	}
	r2.pres.Put("ace", presenceValue(t, true), false)
	r2.b.Reconsider(context.Background())
	r2.b.Wait()
	if v := valueOf(t, r2.st, r2.key); v.State != delivery.BuildDone {
		t.Errorf("build = %+v, want done once a node is online", v)
	}
}