package engine

import (
	"reflect"
	"testing"

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

func TestInheritanceGraphSchedulesDirectRelationshipsAndAppliesTemplates(t *testing.T) {
	root := parseCompositionDocument(t, "schedule", `
child:
  extends: base
  own: child-value
base:
  inherited: base-value
cleared:
  extends: null
  own: cleared-value
scalar: kept
`)
	original := document.Clone(root)
	graph, diagnostics := analyzeInheritanceGraph(root, Path{})
	if len(diagnostics) != 0 {
		t.Fatalf("analyze diagnostics = %#v", diagnostics)
	}
	if len(graph.edges) != 1 {
		t.Fatalf("edges = %#v, want one direct parent edge", graph.edges)
	}
	order, diagnostics := graph.schedule()
	if len(diagnostics) != 0 {
		t.Fatalf("schedule diagnostics = %#v", diagnostics)
	}
	orderNames := make([]string, len(order))
	for i, index := range order {
		orderNames[i] = graph.nodes[index].name
	}
	if want := []string{"base", "child", "cleared"}; !reflect.DeepEqual(orderNames, want) {
		t.Fatalf("mapping schedule = %v, want %v", orderNames, want)
	}

	result, diagnostics := applyInheritanceTemplates(graph, order, defaultProjectionLimits(), nil)
	if len(diagnostics) != 0 {
		t.Fatalf("apply diagnostics = %#v", diagnostics)
	}
	if !reflect.DeepEqual(root, original) {
		t.Fatal("applying templates mutated the input mapping")
	}
	if len(result.controls) != 2 || result.controls[0].path.String() != "/child/extends" || result.controls[0].cancelled ||
		result.controls[1].path.String() != "/cleared/extends" || !result.controls[1].cancelled {
		t.Fatalf("controls = %#v, want scheduled ordinary and null relationships", result.controls)
	}
	if len(result.transfers) != 1 || result.transfers[0].from.String() != "/base" || result.transfers[0].to.String() != "/child" {
		t.Fatalf("transfers = %#v, want the direct parent transfer", result.transfers)
	}
	if got, want := result.root.Mapping[0].Key, "child"; got != want {
		t.Fatalf("root order begins with %q, want %q", got, want)
	}
	child := result.root.Mapping[0].Value
	inherited, found := documentAtPath(child, Path{}.Key("inherited"))
	if !found || inherited.Text != "base-value" {
		t.Fatalf("inherited value = %#v, found %t", inherited, found)
	}
	childValue, found := documentAtPath(child, Path{}.Key("own"))
	if !found || childValue.Text != "child-value" {
		t.Fatalf("child value = %#v, found %t", childValue, found)
	}
	cleared := result.root.Mapping[2].Value
	clearedValue, found := documentAtPath(cleared, Path{}.Key("own"))
	if !found || clearedValue.Text != "cleared-value" {
		t.Fatalf("null relationship value = %#v, found %t", clearedValue, found)
	}
	if _, found := inheritanceDirective(cleared); found {
		t.Fatal("null relationship directive remained in the template")
	}

	child.Mapping[0].Value.Text = "changed-result"
	inherited, found = documentAtPath(root.Mapping[1].Value, Path{}.Key("inherited"))
	if !found || inherited.Text != "base-value" {
		t.Fatalf("mutating result changed input: inherited value = %#v, found %t", inherited, found)
	}
}

func TestInheritanceGraphReportsCycleAtAuthoredRelationship(t *testing.T) {
	root := parseCompositionDocument(t, "cycle-source", `alpha:
  extends: beta
beta:
  extends: alpha
`)
	graph, diagnostics := analyzeInheritanceGraph(root, Path{})
	if len(diagnostics) != 0 {
		t.Fatalf("analyze diagnostics = %#v", diagnostics)
	}
	_, diagnostics = graph.schedule()
	if len(diagnostics) != 1 || diagnostics[0].Code != CodeInheritanceCycle {
		t.Fatalf("cycle diagnostics = %#v", diagnostics)
	}
	diagnostic := diagnostics[0]
	if diagnostic.Primary == nil || diagnostic.Primary.SourceID != "cycle-source" {
		t.Fatalf("cycle primary = %#v, want authored source", diagnostic.Primary)
	}
	if diagnostic.Primary.Line != 4 {
		t.Fatalf("cycle primary line = %d, want line 4", diagnostic.Primary.Line)
	}
	if len(diagnostic.Related) != 1 || diagnostic.Related[0].SourceID != "cycle-source" {
		t.Fatalf("cycle related sites = %#v, want the referenced mapping", diagnostic.Related)
	}
	if diagnostic.Message != "sibling inheritance contains a cycle" {
		t.Fatalf("cycle message exposes unexpected details: %q", diagnostic.Message)
	}
}

func TestInheritanceGraphValidatesRelationshipKinds(t *testing.T) {
	tests := []struct {
		name string
		text string
		code Code
	}{
		{name: "missing sibling", text: "child:\n  extends: absent\n", code: CodeInheritanceMissing},
		{name: "non-mapping sibling", text: "base: scalar\nchild:\n  extends: base\n", code: CodeInheritanceInvalid},
		{name: "invalid relationship", text: "child:\n  extends: 3\n", code: CodeInheritanceInvalid},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			root := parseCompositionDocument(t, "invalid", test.text)
			_, diagnostics := analyzeInheritanceGraph(root, Path{})
			if len(diagnostics) != 1 || diagnostics[0].Code != test.code {
				t.Fatalf("diagnostics = %#v, want code %q", diagnostics, test.code)
			}
			if diagnostics[0].Primary == nil || diagnostics[0].Primary.SourceID != "invalid" {
				t.Fatalf("primary site = %#v, want authored declaration", diagnostics[0].Primary)
			}
		})
	}
}