package engine

import (
	"strings"
	"testing"

	"gitea.maximumdirect.net/eric/ConfigKit/internal/document"
)

func parseIdentifiedInheritanceSequence(t *testing.T, sourceID, input string) *document.Node {
	t.Helper()
	var indented strings.Builder
	indented.WriteString("jobs:\n")
	for _, line := range strings.Split(strings.TrimSuffix(input, "\n"), "\n") {
		indented.WriteString("  ")
		indented.WriteString(line)
		indented.WriteByte('\n')
	}
	root := parseItemPolicyDocument(t, sourceID, indented.String())
	sequence, found := documentAtPath(root, Keys("jobs"))
	if !found || sequence.Kind != document.Sequence {
		t.Fatalf("identified sequence missing from test document: %#v", root)
	}
	return sequence
}

func TestIdentifiedInheritanceGraphSchedulesForwardReferencesInPlace(t *testing.T) {
	sequence := parseIdentifiedInheritanceSequence(t, "identified-graph", `- id: 2
  tenant: acme
  extends: {id: 1.0, tenant: acme}
- id: 1e0
  tenant: acme
  extends: {id: 0, tenant: acme}
- id: 0
  tenant: acme
- id: 3
  tenant: acme
  extends: null
`)
	path := Keys("jobs")
	graph, diagnostics := analyzeIdentifiedInheritanceGraph(sequence, path, []string{"tenant", "id"})
	if len(diagnostics) != 0 {
		t.Fatalf("analyze identified graph: %#v", diagnostics)
	}
	if len(graph.edges) != 2 {
		t.Fatalf("edges = %#v, want the two links in the inheritance chain", graph.edges)
	}
	order, diagnostics := graph.schedule()
	if len(diagnostics) != 0 {
		t.Fatalf("schedule identified graph: %#v", diagnostics)
	}
	if len(order) != 4 || order[0] != 2 || order[1] != 1 || order[2] != 0 {
		t.Fatalf("schedule = %v, want the forward parent chain before its children", order)
	}
	if graph.nodes[0].path.String() != "/jobs/0" || graph.nodes[0].item != sequence.Sequence[0] ||
		!graph.nodes[3].cancelled || len(graph.nodes[3].directivePath.segments) == 0 {
		t.Fatalf("graph nodes changed authored positions or cancellation: %#v", graph.nodes)
	}
	if _, found := graph.byIdentity[graph.nodes[1].tuple]; !found {
		t.Fatal("identity index does not contain the parent record")
	}
}

func TestIdentifiedInheritanceScopeAdapterReusesTemplateExecution(t *testing.T) {
	sequence := parseIdentifiedInheritanceSequence(t, "identified-scope", `- id: child-a
  tenant: team-a
  extends: {id: parent-a, tenant: team-a}
  settings: {child: a}
- id: parent-a
  tenant: team-a
  settings: {parent: a}
- id: child-b
  tenant: team-b
  extends: {id: parent-b, tenant: team-b}
  settings: {child: b}
- id: parent-b
  tenant: team-b
  settings: {parent: b}
`)
	path := Keys("jobs")
	graph, diagnostics := analyzeIdentifiedInheritanceGraph(sequence, path, []string{"tenant", "id"})
	if len(diagnostics) != 0 {
		t.Fatalf("analyze identified graph: %#v", diagnostics)
	}
	policies := collectionPolicyScope{}
	policies.set(path.Index(1).Key("steps"), collectionPolicy{
		identityFields: []string{"step-id"}, identityPresent: true,
	})
	result, diagnostics := applyIdentifiedInheritanceTemplates(graph, defaultProjectionLimits(), nil, policies, sequencePolicy{})
	if len(diagnostics) != 0 {
		t.Fatalf("apply identified templates: %#v", diagnostics)
	}
	if got := len(result.root.Sequence); got != 4 {
		t.Fatalf("result sequence length = %d, want 4", got)
	}
	for index, want := range []string{"child-a", "parent-a", "child-b", "parent-b"} {
		id, found := documentAtPath(result.root.Sequence[index], Path{}.Key("id"))
		if !found || id.Text != want {
			t.Fatalf("result identity at index %d = %#v, found %t; want %q", index, id, found, want)
		}
	}
	for index, want := range []string{"a", "b"} {
		value, found := documentAtPath(result.root.Sequence[index*2], Path{}.Key("settings").Key("parent"))
		if !found || value.Text != want {
			t.Fatalf("inherited value at record %d = %#v, found %t; want %q", index*2, value, found, want)
		}
	}
	if len(result.transfers) != 2 || result.transfers[0].from.String() != "/jobs/1" || result.transfers[0].to.String() != "/jobs/0" ||
		result.transfers[1].from.String() != "/jobs/3" || result.transfers[1].to.String() != "/jobs/2" {
		t.Fatalf("record transfers = %#v, want independent transfers at authored positions", result.transfers)
	}
	if len(result.controls) != 2 || result.controls[0].path.String() != "/jobs/0/extends" || result.controls[1].path.String() != "/jobs/2/extends" {
		t.Fatalf("relationship controls = %#v, want paths from child positions", result.controls)
	}
	if len(result.operations) != 4 || result.operations[1].transfer == nil || result.operations[1].transfer.to.String() != "/jobs/0" ||
		result.operations[3].transfer == nil || result.operations[3].transfer.to.String() != "/jobs/2" {
		t.Fatalf("relationship history operations = %#v, want transfer evidence at child positions", result.operations)
	}
	if _, found := result.origins[path.Index(0).Key("id").String()]; !found {
		t.Fatal("resolved sequence output did not retain the child identity origin path")
	}
	projectedPolicy, found := result.collectionPolicies.at(path.Index(0).Key("steps"))
	if !found || !projectedPolicy.identityPresent || len(projectedPolicy.identityFields) != 1 || projectedPolicy.identityFields[0] != "step-id" {
		t.Fatalf("inherited nested collection policy = %#v, found %t", projectedPolicy, found)
	}
	adapter := identifiedSequenceInheritanceScope{graph: graph, policies: policies}
	fields := adapter.templates()[0].identityFields
	if len(fields) != 2 || fields[0] != "id" || fields[1] != "tenant" {
		t.Fatalf("payload identity fields = %v, want [id tenant]", fields)
	}
	templates := adapter.templates()
	parentPolicy, found := templates[1].collectionPolicies.at(Keys("steps"))
	if !found || len(parentPolicy.identityFields) != 1 || parentPolicy.identityFields[0] != "step-id" {
		t.Fatalf("parent nested policy = %#v, found %t", parentPolicy, found)
	}
	if _, found := templates[0].collectionPolicies.at(Keys("steps")); found {
		t.Fatal("nested policy from one record leaked into a sibling template")
	}
	parentPolicy.identityFields[0] = "changed"
	templates[1].collectionPolicies.set(Keys("steps"), parentPolicy)
	reused, found := adapter.templates()[1].collectionPolicies.at(Keys("steps"))
	if !found || len(reused.identityFields) != 1 || reused.identityFields[0] != "step-id" {
		t.Fatal("reusing the adapter observed a mutation to a prior template snapshot")
	}
	if sequence.Sequence[0].Mapping[0].Value.Text != "child-a" {
		t.Fatal("executing the sequence adapter mutated its source scope")
	}
}

func TestIdentifiedInheritanceResolvesNestedCollectionsAtEachDestination(t *testing.T) {
	root := parseItemPolicyDocument(t, "identified-nested", `jobs:
  - id: child
    extends: {id: parent}
  - id: parent
    extends: {id: base}
    steps:
      - id: child-step
        extends: {id: parent-step}
        value: child-value
      - id: parent-step
        value: parent-value
  - id: base
    steps:
      - id: base-step
        value: base-value
`)
	identity := collectionPolicy{identityFields: []string{"id"}, identityPresent: true}
	policies := collectionPolicyScope{}
	policies.set(Keys("jobs"), identity)
	for index := 0; index < 3; index++ {
		policies.set(Keys("jobs").Index(index).Key("steps"), identity)
	}
	expanded, diagnostics := expandInheritanceWithCollectionRules(root, nil, policies, sequencePolicy{}, defaultProjectionLimits())
	if len(diagnostics) != 0 {
		t.Fatalf("expand nested identified inheritance: %#v", diagnostics)
	}
	steps, found := documentAtPath(expanded.root, Keys("jobs").Index(0).Key("steps"))
	if !found || steps.Kind != document.Sequence || len(steps.Sequence) != 3 {
		t.Fatalf("child nested steps = %#v, found %t", steps, found)
	}
	for index, want := range []string{"base-step", "child-step", "parent-step"} {
		id, exists := documentAtPath(steps.Sequence[index], Keys("id"))
		if !exists || id.Text != want {
			t.Fatalf("child step %d identity = %#v, found %t; want %q", index, id, exists, want)
		}
	}
	value, found := documentAtPath(steps.Sequence[1], Keys("value"))
	if !found || value.Text != "child-value" {
		t.Fatalf("nested record inheritance = %#v, found %t", value, found)
	}
	if containsInheritanceDirective(expanded.root) {
		t.Fatal("a nested record relationship remained after destination-local expansion")
	}
	childIdentity, found := expanded.origins["/jobs/0/id"]
	if !found || len(childIdentity.Locations) == 0 || childIdentity.Locations[0].SourceID != "identified-nested" {
		t.Fatalf("child identity origin = %#v, found %t", childIdentity, found)
	}
	if _, found := expanded.origins["/jobs/0/steps/1/value"]; !found {
		t.Fatal("nested inherited value did not retain its destination origin")
	}
}

func TestIdentifiedInheritanceRespectsOutputNodeBudget(t *testing.T) {
	root := parseItemPolicyDocument(t, "identified-budget", `jobs:
  - id: child
    extends: {id: parent}
  - id: parent
    value: inherited
`)
	policies := collectionPolicyScope{}
	policies.set(Keys("jobs"), collectionPolicy{identityFields: []string{"id"}, identityPresent: true})
	baseline, diagnostics := expandInheritanceWithCollectionRules(root, nil, policies, sequencePolicy{}, defaultProjectionLimits())
	if len(diagnostics) != 0 {
		t.Fatalf("unbounded identified inheritance: %#v", diagnostics)
	}
	outputNodes, within := inheritanceLowerBoundCount(baseline.root, -1)
	if !within || outputNodes < 2 {
		t.Fatalf("identified output node count = %d, within %t", outputNodes, within)
	}
	limits := defaultProjectionLimits()
	limits.nodes = outputNodes
	if result, diagnostics := expandInheritanceWithCollectionRules(root, nil, policies, sequencePolicy{}, limits); result == nil || len(diagnostics) != 0 {
		t.Fatalf("at output-node boundary: result = %#v, diagnostics = %#v", result, diagnostics)
	}
	limits.nodes = outputNodes - 1
	if result, diagnostics := expandInheritanceWithCollectionRules(root, nil, policies, sequencePolicy{}, limits); result != nil ||
		len(diagnostics) != 1 || diagnostics[0].Code != CodeSchemaProjectionLimit {
		t.Fatalf("below output-node boundary: result = %#v, diagnostics = %#v", result, diagnostics)
	}
}

func TestIdentifiedInheritanceRequiresChildIdentityBeforeParentLookup(t *testing.T) {
	sequence := parseIdentifiedInheritanceSequence(t, "missing-child-field", `- id: child
  extends: {id: parent, tenant: acme}
- id: parent
  tenant: acme
`)
	_, diagnostics := analyzeIdentifiedInheritanceGraph(sequence, Keys("jobs"), []string{"id", "tenant"})
	if len(diagnostics) != 1 || diagnostics[0].Code != CodeSequenceInvalid || diagnostics[0].Path.String() != "/jobs/0/tenant" {
		t.Fatalf("missing child identity diagnostics = %#v", diagnostics)
	}
}

func TestIdentifiedInheritanceRejectsMalformedAndMissingReferences(t *testing.T) {
	tests := []struct {
		name     string
		value    string
		wantCode Code
	}{
		{name: "string shorthand", value: "extends: parent\n", wantCode: CodeInheritanceInvalid},
		{name: "sequence shorthand", value: "extends: [{id: parent, tenant: acme}]\n", wantCode: CodeInheritanceInvalid},
		{name: "missing component", value: "extends: {id: parent}\n", wantCode: CodeInheritanceInvalid},
		{name: "extra component", value: "extends: {id: parent, tenant: acme, extra: value}\n", wantCode: CodeInheritanceInvalid},
		{name: "mapping component", value: "extends: {id: {nested: value}, tenant: acme}\n", wantCode: CodeInheritanceInvalid},
		{name: "missing parent", value: "extends: {id: missing, tenant: acme}\n", wantCode: CodeInheritanceMissing},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			sequence := parseIdentifiedInheritanceSequence(t, "bad-reference", "- id: child\n  tenant: acme\n  "+test.value)
			_, diagnostics := analyzeIdentifiedInheritanceGraph(sequence, Keys("jobs"), []string{"id", "tenant"})
			if len(diagnostics) != 1 || diagnostics[0].Code != test.wantCode || diagnostics[0].Path.String() != "/jobs/0/extends" && diagnostics[0].Code != CodeInheritanceInvalid {
				t.Fatalf("diagnostics = %#v", diagnostics)
			}
			if diagnostics[0].Code == CodeInheritanceMissing && diagnostics[0].Path.String() != "/jobs/0/extends" {
				t.Fatalf("missing-parent path = %s", diagnostics[0].Path)
			}
		})
	}
}

func TestIdentifiedInheritanceGraphFindsSelfAndLongerCycles(t *testing.T) {
	for _, input := range []string{
		`- id: self
  tenant: acme
  extends: {id: self, tenant: acme}
`,
		`- id: alpha
  tenant: acme
  extends: {id: beta, tenant: acme}
- id: beta
  tenant: acme
  extends: {id: gamma, tenant: acme}
- id: gamma
  tenant: acme
  extends: {id: alpha, tenant: acme}
`,
	} {
		graph, diagnostics := analyzeIdentifiedInheritanceGraph(parseIdentifiedInheritanceSequence(t, "cycle", input), Keys("jobs"), []string{"id", "tenant"})
		if len(diagnostics) != 0 {
			t.Fatalf("analyze cycle graph: %#v", diagnostics)
		}
		_, diagnostics = graph.schedule()
		if len(diagnostics) != 1 || diagnostics[0].Code != CodeInheritanceCycle || diagnostics[0].Path.String() == "" {
			t.Fatalf("cycle diagnostics = %#v", diagnostics)
		}
		if diagnostics[0].Primary == nil || diagnostics[0].Primary.SourceID != "cycle" {
			t.Fatalf("cycle primary location = %#v", diagnostics[0].Primary)
		}
	}
}

func TestIdentifiedInheritanceScopesCannotReferenceOtherCollections(t *testing.T) {
	other := parseIdentifiedInheritanceSequence(t, "other-collection", `- id: parent
  tenant: acme
`)
	_, diagnostics := analyzeIdentifiedInheritanceGraph(other, Keys("other"), []string{"id", "tenant"})
	if len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	first := parseIdentifiedInheritanceSequence(t, "first-collection", `- id: child
  tenant: acme
  extends: {id: parent, tenant: acme}
`)
	_, diagnostics = analyzeIdentifiedInheritanceGraph(first, Keys("first"), []string{"id", "tenant"})
	if len(diagnostics) != 1 || diagnostics[0].Code != CodeInheritanceMissing {
		t.Fatalf("cross-collection reference diagnostics = %#v", diagnostics)
	}
}

func TestIdentifiedInheritanceAcceptsStrictlyComposedParentReference(t *testing.T) {
	left := parseCompositionDocument(t, "reference-left", "extends: {id: parent}\n")
	right := parseCompositionDocument(t, "reference-right", "extends: {tenant: acme}\n")
	reference, diagnostics := composeDocuments(left, right)
	if len(diagnostics) != 0 {
		t.Fatalf("compose disjoint reference helpers: %#v", diagnostics)
	}
	child, diagnostics := composeDocuments(parseCompositionDocument(t, "child-fields", "id: child\ntenant: acme\n"), reference.root)
	if len(diagnostics) != 0 {
		t.Fatalf("compose child fields and reference: %#v", diagnostics)
	}
	parent := parseCompositionDocument(t, "parent", "id: parent\ntenant: acme\n")
	sequence := &document.Node{Kind: document.Sequence, Sequence: []*document.Node{child.root, parent}}
	graph, diagnostics := analyzeIdentifiedInheritanceGraph(sequence, Keys("jobs"), []string{"id", "tenant"})
	if len(diagnostics) != 0 {
		t.Fatalf("analyze composed reference: %#v", diagnostics)
	}
	if len(graph.edges) != 1 || graph.edges[0] != (dependencyEdge{prerequisite: 1, dependent: 0}) {
		t.Fatalf("composed reference edge = %#v", graph.edges)
	}

	_, diagnostics = composeDocuments(
		parseCompositionDocument(t, "overlap-a", "extends: {id: first}\n"),
		parseCompositionDocument(t, "overlap-b", "extends: {id: second}\n"),
	)
	if len(diagnostics) != 1 || diagnostics[0].Code != CodeComposeConflict {
		t.Fatalf("overlapping reference fields should conflict during strict composition: %#v", diagnostics)
	}
}

func TestIdentifiedInheritanceValidatesOnlySurvivingRelationships(t *testing.T) {
	lower := parseIdentifiedInheritanceSequence(t, "superseded", `- id: shared
  extends: {id: absent, tenant: acme}
`)
	higher := parseIdentifiedInheritanceSequence(t, "cancelled", `- id: shared
  extends: null
`)
	resolution := collectionPolicyResolution{
		operation: sequenceModeUpsert, effectiveIdentityFields: []string{"id"},
	}
	combined, diagnostics := combineSequence(lower, higher, resolution, sequenceCombinationContext{destination: Keys("jobs")})
	if len(diagnostics) != 0 {
		t.Fatalf("combine surviving reference: %#v", diagnostics)
	}
	graph, diagnostics := analyzeIdentifiedInheritanceGraph(combined.value, Keys("jobs"), []string{"id"})
	if len(diagnostics) != 0 || len(graph.edges) != 0 || !graph.nodes[0].cancelled {
		t.Fatalf("superseded missing reference was validated: graph=%#v diagnostics=%#v", graph, diagnostics)
	}
}