package index

import (
	"context"
	"reflect"
	"strings"
	"testing"
	"time"

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

// The fixtures here are mesh-catalog a67f0196's manifests (testdata, captured from that commit) with the module renamed (and,
// where a test needs one, a build.on entry added as the controller's own test has it, standing_on_test.go:22): the manifest
// parser, not a hand-written manifest, reads them.

func renamed(t *testing.T, from, to string) string {
	t.Helper()
	raw := catalogueManifest(t, from)
	out := strings.Replace(raw, `"module": "`+from+`"`, `"module": "`+to+`"`, 1)
	if out == raw {
		t.Fatalf("%s's manifest has no module line", from)
	}
	return out
}

func standingOn(t *testing.T, raw, base string) string {
	t.Helper()
	out := strings.Replace(raw, `"build": {`, `"build": {
    "on": [{"arg": "RUNTIME_BASE", "module": "`+base+`", "artifact": "runtime"}],`, 1)
	if out == raw {
		t.Fatal("the manifest has no build")
	}
	return out
}

const buildAgentRepo = "novox/mesh-controller"

type mod struct {
	name, manifest string
}

// merged applies one merge of the catalogue carrying these modules (every one a Go bundle's go.sum, a TypeScript bundle's
// package-lock.json) and returns the indexer.
func newFormIndexer(t *testing.T, mods ...mod) (*Indexer, *memStore) {
	t.Helper()
	ix, store, f := newFormIndexerUnmerged(t, mods...)
	if err := ix.Apply(context.Background(), f); err != nil {
		t.Fatal(err)
	}
	// build-agent's value of today's form, from a merge of the controller (modules.build-agent holds its fingerprint).
	if err := ix.Apply(context.Background(), mergedMsg(buildAgentRepo, map[string]string{"modules/build-agent": "agent-tree-1"})); err != nil {
		t.Fatal(err)
	}
	return ix, store
}

// newFormIndexerUnmerged is the indexer and the catalogue merge of these modules, not yet applied.
func newFormIndexerUnmerged(t *testing.T, mods ...mod) (*Indexer, *memStore, delivery.Forge) {
	t.Helper()
	var recs [][2]any
	trees, manifests := map[string]string{}, map[string]string{}
	locks := map[string]map[string]string{}
	for i, m := range mods {
		dir := "modules/" + m.name
		recs = append(recs, rec(t, "build-"+m.name, m.name, catalogueRepo, dir, "main", "", "2026-10-19T09:00:00Z", aInputs))
		trees[dir], manifests[dir] = "tree-"+m.name, m.manifest
		locks[dir] = map[string]string{"go.sum": avahiGoSum, "package-lock.json": strings.Repeat("c", 63) + string(rune('a'+i))}
	}
	recs = append(recs, rec(t, "build-agent-1", "build-agent", buildAgentRepo, "modules/build-agent", "main", "", "2026-10-19T09:00:00Z", aInputs))
	ix, store, _ := manifestsIndexer(t, recs...)
	return ix, store, withManifests(mergedMsg(catalogueRepo, trees), manifests, locks)
}

// toolchainValue is a toolchains value as the build module's writer encodes it (mesh-sdk go/delivery EncodeToolchain).
func toolchainValue(t *testing.T, language, version, recipe string) []byte {
	t.Helper()
	b, err := delivery.EncodeToolchain(delivery.Toolchain{Language: language, Version: version, Recipe: recipe, At: time.Now()})
	if err != nil {
		t.Fatal(err)
	}
	return b
}

func reportToolchain(t *testing.T, ix *Indexer, module, node, language, version string) {
	t.Helper()
	key, err := delivery.ToolchainKey(node, language)
	if err != nil {
		t.Fatal(err)
	}
	if err := ix.ApplyToolchain(context.Background(), module, key, toolchainValue(t, language, version, "1"), false); err != nil {
		t.Fatal(err)
	}
}

func TestAgreedToolchainChangesAGoModulesReasonWithNoMerge(t *testing.T) { // 1444/AC5
	ix, mods := newFormIndexer(t, mod{"avahi", catalogueManifest(t, "avahi")})
	if m, _ := moduleOf(t, mods, "avahi"); m.None2 != delivery.ToolchainNoReport {
		t.Fatalf("before: none2 = %q", m.None2)
	}
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1")
	reportToolchain(t, ix, "mesh-build-go", "ace", "go", "go1.27.1")
	m, _ := moduleOf(t, mods, "avahi")
	if m.None2 != None2Builder || m.FP2 != "" {
		t.Errorf("none2 = %q fp2 = %q, want none2 %q", m.None2, m.FP2, None2Builder)
	}
}

func TestNodesReportingDifferentVersionsLeaveTheReasonNamingBoth(t *testing.T) { // 1444/AC6
	ix, mods := newFormIndexer(t, mod{"avahi", catalogueManifest(t, "avahi")})
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1")
	reportToolchain(t, ix, "mesh-build-go", "ace", "go", "go1.26.0")
	m, _ := moduleOf(t, mods, "avahi")
	if !strings.Contains(m.None2, "builders disagree") || !strings.Contains(m.None2, "go1.27.1") || !strings.Contains(m.None2, "go1.26.0") {
		t.Errorf("none2 = %q, want 'builders disagree' naming both versions", m.None2)
	}
}

// builderModules are the builder, a base, a module on the base (named so that it is stored before its base) and a module
// whose base is a TypeScript module with no toolchain reported.
func builderModules(t *testing.T) []mod {
	return []mod{
		{"mesh-delivery-builder", renamed(t, "avahi", "mesh-delivery-builder")},
		{"mesh-tools", renamed(t, "avahi", "mesh-tools")},
		{"avahi", standingOn(t, catalogueManifest(t, "avahi"), "mesh-tools")},
		{"other", standingOn(t, renamed(t, "avahi", "other"), "ts-base")},
		{"ts-base", renamed(t, "audit-logger", "ts-base")},
	}
}

func goInputs(t *testing.T, ix *Indexer, mods *memStore, module, builder string, bases ...string) delivery.SourceInputs2 {
	t.Helper()
	return delivery.SourceInputs2{Module: module, Tree: "tree-" + module, Builder: builder, Bases: bases,
		Locks:      map[string]string{"tools": avahiGoSum},
		Toolchains: map[string]delivery.Toolchain2{"tools": {Language: "go", Version: "go1.27.1", Recipe: "1"}}}
}

func fp2(t *testing.T, in delivery.SourceInputs2) string {
	t.Helper()
	fp, none := delivery.SourceFingerprint2(in)
	if none != "" {
		t.Fatal(none)
	}
	return fp
}

func TestBasesAndTheBuilderAreComputedBeforeTheModulesTakingThem(t *testing.T) { // 1444/AC7, AC8
	ix, mods := newFormIndexer(t, builderModules(t)...)
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1")
	agent, _ := moduleOf(t, mods, "build-agent")
	if agent.FP == "" {
		t.Fatalf("build-agent has no fingerprint of today's form: %+v", agent)
	}
	builderFP := fp2(t, goInputs(t, ix, mods, "mesh-delivery-builder", agent.FP))
	toolsFP := fp2(t, goInputs(t, ix, mods, "mesh-tools", builderFP))
	want := map[string]string{"mesh-delivery-builder": builderFP, "mesh-tools": toolsFP, "avahi": fp2(t, goInputs(t, ix, mods, "avahi", builderFP, toolsFP))}
	for name, fp := range want {
		if m, _ := moduleOf(t, mods, name); m.FP2 != fp || m.None2 != "" {
			t.Errorf("%s: fp2 = %q none2 = %q, want %s", name, m.FP2, m.None2, fp)
		}
	}
	if m, _ := moduleOf(t, mods, "other"); m.FP2 != "" || !strings.Contains(m.None2, "ts-base") || !strings.Contains(m.None2, "base") {
		t.Errorf("other: fp2 = %q none2 = %q, want none2 naming the base ts-base", m.FP2, m.None2)
	}
	// 1444/AC8: build-agent changes at a merge of the controller; the builder's value moves with it, and so do the modules built by it.
	if err := ix.Apply(context.Background(), mergedMsg(buildAgentRepo, map[string]string{"modules/build-agent": "agent-tree-2"})); err != nil {
		t.Fatal(err)
	}
	moved, _ := moduleOf(t, mods, "build-agent")
	if moved.FP == agent.FP {
		t.Fatal("build-agent's fingerprint did not change")
	}
	newBuilder := fp2(t, goInputs(t, ix, mods, "mesh-delivery-builder", moved.FP))
	if m, _ := moduleOf(t, mods, "mesh-delivery-builder"); m.FP2 != newBuilder || newBuilder == builderFP {
		t.Errorf("builder: fp2 = %q, want %s (was %s)", m.FP2, newBuilder, builderFP)
	}
	if m, _ := moduleOf(t, mods, "mesh-tools"); m.FP2 != fp2(t, goInputs(t, ix, mods, "mesh-tools", newBuilder)) {
		t.Errorf("mesh-tools did not follow the builder: %+v", m)
	}
}

func TestAToolchainEntryChangedToTheSameValuesWritesNothing(t *testing.T) { // 1444/AC9
	ix, mods := newFormIndexer(t, builderModules(t)...)
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1")
	before := mods.writes
	time.Sleep(2 * time.Millisecond)
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1") // the same version and recipe, a later time
	if mods.writes != before {
		t.Errorf("modules written %d times after the same values, want none", mods.writes-before)
	}
}

func TestModulesThatStandOnEachOtherAreNamedAsACycle(t *testing.T) { // 1444 (the indexer has no graph: a cycle is a reason)
	ix, mods := newFormIndexer(t,
		mod{"aa", standingOn(t, renamed(t, "avahi", "aa"), "bb")},
		mod{"bb", standingOn(t, renamed(t, "avahi", "bb"), "aa")})
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1")
	for _, name := range []string{"aa", "bb"} {
		if m, _ := moduleOf(t, mods, name); m.FP2 != "" || !strings.Contains(m.None2, "cycle") {
			t.Errorf("%s: fp2 = %q none2 = %q, want a reason naming the cycle", name, m.FP2, m.None2)
		}
	}
}

func TestAMergeWritesEachModuleOnceWithItsFinalValueAndAReplayWritesNothing(t *testing.T) { // 1444 (review finding 8)
	ctx := context.Background()
	ix, mods, f := newFormIndexerUnmerged(t, mod{"avahi", catalogueManifest(t, "avahi")})
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1") // agreed before the merge is heard
	if err := ix.Apply(ctx, f); err != nil {
		t.Fatal(err)
	}
	m, _ := moduleOf(t, mods, "avahi")
	if mods.writes != 1 || m.None2 != None2Builder {
		t.Errorf("writes = %d none2 = %q after one merge, want one write with %q", mods.writes, m.None2, None2Builder)
	}
	if err := ix.Apply(ctx, f); err != nil {
		t.Fatal(err)
	}
	if mods.writes != 1 {
		t.Errorf("writes = %d after the same merge again, want still 1", mods.writes)
	}
}

func TestAMergeKeepsAFingerprintTheModuleStillHas(t *testing.T) { // 1444 (review finding 8: a merge never blanks FP2)
	ctx := context.Background()
	ix, mods := newFormIndexer(t, builderModules(t)...)
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1")
	before, _ := moduleOf(t, mods, "mesh-tools")
	if before.FP2 == "" {
		t.Fatalf("mesh-tools has no fp2: %+v", before)
	}
	w := mods.writes
	// the same catalogue merged again at a later commit: nothing moved
	_, _, f := newFormIndexerUnmerged(t, builderModules(t)...)
	if err := ix.Apply(ctx, f); err != nil {
		t.Fatal(err)
	}
	if after, _ := moduleOf(t, mods, "mesh-tools"); after.FP2 != before.FP2 || mods.writes != w {
		t.Errorf("fp2 = %q (was %q), writes %d more", after.FP2, before.FP2, mods.writes-w)
	}
}

func TestAModuleKeepsTheToolchainsItsFingerprintWasComputedWith(t *testing.T) { // 1615/AC3
	ix, mods := newFormIndexer(t, builderModules(t)...)
	if m, _ := moduleOf(t, mods, "avahi"); m.Toolchains != nil {
		t.Fatalf("before a toolchain is reported: toolchains = %+v, want none", m.Toolchains)
	}
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1")
	m, _ := moduleOf(t, mods, "avahi")
	want := map[string]delivery.ToolchainUsed{"go": {Version: "go1.27.1", Recipe: "1"}}
	if m.FP2 == "" || !reflect.DeepEqual(m.Toolchains, want) {
		t.Fatalf("avahi: fp2 %q toolchains %+v, want %+v", m.FP2, m.Toolchains, want)
	}
	if o, _ := moduleOf(t, mods, "other"); o.FP2 != "" || o.Toolchains != nil {
		t.Errorf("a module with no fingerprint carries toolchains %+v", o.Toolchains)
	}
	// An upgrade moves the fingerprint and the toolchains together, with no merge.
	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.2")
	n, _ := moduleOf(t, mods, "avahi")
	if n.FP2 == m.FP2 || n.Toolchains["go"].Version != "go1.27.2" {
		t.Errorf("after the upgrade: fp2 %q (was %q) toolchains %+v, want the new version with the new fingerprint", n.FP2, m.FP2, n.Toolchains)
	}
	// Nodes that disagree leave no fingerprint and no toolchains.
	reportToolchain(t, ix, "mesh-build-go", "ace", "go", "go1.26.0")
	if d, _ := moduleOf(t, mods, "avahi"); d.FP2 != "" || d.Toolchains != nil {
		t.Errorf("disagreeing nodes: fp2 %q toolchains %+v, want neither", d.FP2, d.Toolchains)
	}
}