package engine

import (
	"reflect"
	"strconv"
	"strings"
	"testing"

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

func TestSiblingInheritanceResolvesReferencesAndKeepsInputs(t *testing.T) {
	tests := []struct {
		name, input string
		path        Path
		text        string
		transfers   int
		controls    int
	}{
		{
			name: "forward reference", input: "child: {extends: parent, value: own}\nparent: {value: parent, kept: preserved}\n",
			path: Keys("child", "kept"), text: "preserved", transfers: 1, controls: 1,
		},
		{
			name: "backward reference", input: "parent: {value: parent, kept: preserved}\nchild: {extends: parent, value: own}\n",
			path: Keys("child", "value"), text: "own", transfers: 1, controls: 1,
		},
		{
			name: "chain and shared parent", input: "last: {extends: middle, enabled: false}\nfirst: {value: original}\nmiddle: {extends: first, extra: middle}\nother: {extends: first}\n",
			path: Keys("last", "value"), text: "original", transfers: 3, controls: 3,
		},
		{
			name: "exact empty sibling name", input: "child: {extends: \"\"}\n\"\": {value: empty}\n",
			path: Keys("child", "value"), text: "empty", transfers: 1, controls: 1,
		},
		{
			name: "exact unusual sibling name", input: "child: {extends: \"a/b~c\"}\n\"a/b~c\": {value: unusual}\n",
			path: Keys("child", "value"), text: "unusual", transfers: 1, controls: 1,
		},
		{
			name: "null cancellation", input: "child: {extends: null, value: own}\nparent: {value: parent}\n",
			path: Keys("child", "value"), text: "own", controls: 1,
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			input := parseCompositionDocument(t, "source-1", test.input)
			before := document.Clone(input)
			result, diagnostics := expandSiblingDefinitions(input, Path{})
			if len(diagnostics) != 0 {
				t.Fatalf("diagnostics = %#v", diagnostics)
			}
			if len(result.transfers) != test.transfers || len(result.controls) != test.controls {
				t.Fatalf("evidence = %#v, %#v", result.transfers, result.controls)
			}
			node, found := documentAtPath(result.root, test.path)
			if !found || node.Text != test.text {
				t.Fatalf("%s = %#v, %v", test.path.String(), node, found)
			}
			if _, found := documentAtPath(result.root, Keys("child", inheritanceKey)); found {
				t.Fatal("child directive remained in expanded payload")
			}
			if !reflect.DeepEqual(input, before) {
				t.Fatal("resolver changed input")
			}
			node.Text = "changed"
			if !reflect.DeepEqual(input, before) {
				t.Fatal("expanded payload aliases input")
			}
		})
	}
}

func TestSiblingInheritanceTracksTransferAndIndependentChildren(t *testing.T) {
	input := parseCompositionDocument(t, "source-1", "first: {value: parent}\nsecond: {extends: first}\nthird: {extends: first}\n")
	result, diagnostics := expandSiblingDefinitions(input, Keys("catalog"))
	if len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	if len(result.transfers) != 2 || result.transfers[0].from.String() != "/catalog/first" ||
		result.transfers[0].to.String() != "/catalog/second" ||
		result.transfers[0].reference.String() != "/catalog/second/extends" ||
		len(result.transfers[0].locations) != 1 || result.transfers[0].locations[0].SourceID != "source-1" {
		t.Fatalf("transfers = %#v", result.transfers)
	}
	second, _ := documentAtPath(result.root, Keys("second", "value"))
	third, _ := documentAtPath(result.root, Keys("third", "value"))
	second.Text = "changed"
	if third.Text != "parent" {
		t.Fatal("siblings share mutable expanded values")
	}
}

func TestSiblingInheritanceRejectsInvalidRelationships(t *testing.T) {
	tests := []struct {
		name, input, path string
		code              Code
		related           bool
	}{
		{"missing", "child: {extends: private-reference-canary}\n", "/child/extends", CodeInheritanceMissing, false},
		{"nonmapping parent", "child: {extends: parent}\nparent: null\n", "/child/extends", CodeInheritanceInvalid, true},
		{"boolean reference", "child: {extends: true}\n", "/child/extends", CodeInheritanceInvalid, false},
		{"sequence reference", "child: {extends: [parent]}\n", "/child/extends", CodeInheritanceInvalid, false},
		{"self reference", "child: {extends: child}\n", "/child/extends", CodeInheritanceCycle, true},
		{"longer cycle", "a: {extends: b}\nb: {extends: c}\nc: {extends: a}\n", "/c/extends", CodeInheritanceCycle, true},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			input := parseCompositionDocument(t, "source-1", test.input)
			result, diagnostics := expandSiblingDefinitions(input, Path{})
			if result != nil || len(diagnostics) != 1 {
				t.Fatalf("result and diagnostics = %#v, %#v", result, diagnostics)
			}
			problem := diagnostics[0]
			if problem.Code != test.code || problem.Path.String() != test.path || problem.Primary == nil ||
				problem.Primary.SourceID != "source-1" || problem.Primary.Line < 1 ||
				(len(problem.Related) != 0) != test.related || strings.Contains(problem.Message, "private-reference-canary") {
				t.Fatalf("diagnostic = %#v", problem)
			}
		})
	}
}

func TestLoadDetectsInvalidInheritanceInsideSequence(t *testing.T) {
	input := []byte(`items:
  - child: {extends: true}
`)
	result, err := testLoad[map[string]any](Bytes("nested-inheritance.yml", input), Options[map[string]any]{})
	if result != nil || err == nil {
		t.Fatalf("result, err = %#v, %v; want invalid nested inheritance", result, err)
	}
	loadError, ok := err.(*LoadError)
	if !ok {
		t.Fatalf("error type = %T, want *LoadError", err)
	}
	diagnostics := loadError.Diagnostics()
	if len(diagnostics) != 1 || diagnostics[0].Code != CodeInheritanceInvalid || diagnostics[0].Path.String() != "/items/0/child/extends" {
		t.Fatalf("diagnostics = %#v", diagnostics)
	}
}

func TestSiblingInheritanceDetectsDeepCycleWithoutRecursiveDependencyWalk(t *testing.T) {
	const count = 2048
	entries := make([]document.Entry, count)
	for index := range entries {
		location := document.Location{SourceID: "source-1", Line: index + 1, Column: 1}
		parent := strconv.Itoa((index + 1) % count)
		entries[index] = document.Entry{
			Key: strconv.Itoa(index), Value: &document.Node{Kind: document.Mapping, Location: location,
				Mapping: []document.Entry{{Key: inheritanceKey, Value: &document.Node{
					Kind: document.String, Text: parent, Location: location,
				}}}},
		}
	}
	result, diagnostics := expandSiblingDefinitions(&document.Node{Kind: document.Mapping, Mapping: entries}, Path{})
	if result != nil || len(diagnostics) != 1 || diagnostics[0].Code != CodeInheritanceCycle {
		t.Fatalf("deep cycle result = %#v, diagnostics = %#v", result, diagnostics)
	}
}