package configkit

import (
	"bytes"
	"reflect"
	"testing"

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

func FuzzCompositionAndOverlay(f *testing.F) {
	for _, seed := range [][2]string{
		{"{}\n", "{}\n"},
		{"left: {value: one}\n", "right: [two]\n"},
		{"shared: {left: one}\n", "shared: {right: two}\n"},
		{"value: one\n", "value: two\n"},
	} {
		f.Add([]byte(seed[0]), []byte(seed[1]))
	}

	limits := yamladapter.Limits{Depth: 12, Nodes: 256, ParserDepth: 24}
	f.Fuzz(func(t *testing.T, leftInput, rightInput []byte) {
		if len(leftInput) > 4<<10 || len(rightInput) > 4<<10 {
			return
		}
		left, leftIssues := yamladapter.Parse(bytes.NewReader(leftInput), "left", limits)
		right, rightIssues := yamladapter.Parse(bytes.NewReader(rightInput), "right", limits)
		if len(leftIssues) != 0 || len(rightIssues) != 0 {
			return
		}
		leftBefore, rightBefore := document.Clone(left), document.Clone(right)

		composed, diagnostics := composeDocuments(left, right)
		if !reflect.DeepEqual(left, leftBefore) || !reflect.DeepEqual(right, rightBefore) {
			t.Fatal("composition mutated an input document")
		}
		if len(diagnostics) == 0 {
			reversed, reversedDiagnostics := composeDocuments(right, left)
			if len(reversedDiagnostics) != 0 {
				t.Fatalf("reversed composition failed: %#v", reversedDiagnostics)
			}
			if differences := compareDocumentTrees(composed.root, reversed.root); len(differences) != 0 {
				t.Fatalf("composition order changed effective values: %#v", differences)
			}
			composed.root.Mapping = append(composed.root.Mapping, document.Entry{Key: "fuzz-detachment"})
			if !reflect.DeepEqual(left, leftBefore) || !reflect.DeepEqual(right, rightBefore) {
				t.Fatal("composition result aliases an input document")
			}
		}

		base, baseDiagnostics := composeDocuments(left)
		if len(baseDiagnostics) != 0 {
			t.Fatalf("single accepted mapping did not compose: %#v", baseDiagnostics)
		}
		overlaid, overlayDiagnostics := overlayDocuments(base, right)
		if len(overlayDiagnostics) != 0 {
			t.Fatalf("accepted mappings did not overlay: %#v", overlayDiagnostics)
		}
		if !reflect.DeepEqual(left, leftBefore) || !reflect.DeepEqual(right, rightBefore) {
			t.Fatal("overlay mutated an input document")
		}
		overlaid.root.Mapping = append(overlaid.root.Mapping, document.Entry{Key: "fuzz-detachment"})
		if !reflect.DeepEqual(left, leftBefore) || !reflect.DeepEqual(right, rightBefore) {
			t.Fatal("overlay result aliases an input document")
		}
	})
}