package engine

import (
	"testing"

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

func TestPreparePairedDiffSnapshotRedactsAlignedMappingFromEitherSide(t *testing.T) {
	left := parseCompositionDocument(t, "left", "credential: alpha\npublic: before\n")
	right := parseCompositionDocument(t, "right", "credential: bravo\npublic: after\n")
	sensitivity := newDiffSensitivity(map[string]bool{"/credential": true}, nil)

	paired, supported := preparePairedDiffSnapshot(left, right, Path{}, sensitivity)
	if !supported {
		t.Fatal("compatible mappings were not supported")
	}
	if !paired.leftRedacted || !paired.rightRedacted {
		t.Fatalf("redacted flags = %v, %v; want true on both sides", paired.leftRedacted, paired.rightRedacted)
	}
	assertDiffStringNode(t, mappingValue(t, paired.left, "credential"), "[REDACTED]")
	assertDiffStringNode(t, mappingValue(t, paired.right, "credential"), "[REDACTED]")
	assertDiffStringNode(t, mappingValue(t, paired.left, "public"), "before")
	assertDiffStringNode(t, mappingValue(t, paired.right, "public"), "after")
	assertDiffStringNode(t, mappingValue(t, left, "credential"), "alpha")
	assertDiffStringNode(t, mappingValue(t, right, "credential"), "bravo")
	if paired.left == left || paired.right == right || &paired.left.Mapping[0] == &left.Mapping[0] {
		t.Fatal("safe mapping containers or entries share mutable storage with retained trees")
	}
}

func TestPreparePairedDiffSnapshotPreservesSequencePositionsAndLengths(t *testing.T) {
	left := parseCompositionDocument(t, "left", "items: [left-public, hidden, old-tail]\n")
	right := parseCompositionDocument(t, "right", "items: [right-public, hidden, old-tail, extra]\n")
	sensitivity := newDiffSensitivity(nil, map[string]bool{"/items/1": true})

	paired, supported := preparePairedDiffSnapshot(
		mappingValue(t, left, "items"), mappingValue(t, right, "items"), Keys("items"), sensitivity,
	)
	if !supported {
		t.Fatal("compatible sequences were not supported")
	}
	if !paired.leftRedacted || !paired.rightRedacted {
		t.Fatalf("redacted flags = %v, %v; want true on both sides", paired.leftRedacted, paired.rightRedacted)
	}
	if len(paired.left.Sequence) != 3 || len(paired.right.Sequence) != 4 {
		t.Fatalf("sequence lengths = %d, %d; want 3, 4", len(paired.left.Sequence), len(paired.right.Sequence))
	}
	assertDiffStringNode(t, paired.left.Sequence[0], "left-public")
	assertDiffStringNode(t, paired.right.Sequence[0], "right-public")
	assertDiffStringNode(t, paired.left.Sequence[1], "[REDACTED]")
	assertDiffStringNode(t, paired.right.Sequence[1], "[REDACTED]")
	assertDiffStringNode(t, paired.right.Sequence[3], "extra")
	assertDiffStringNode(t, mappingValue(t, left, "items").Sequence[1], "hidden")
	if &paired.left.Sequence[0] == &mappingValue(t, left, "items").Sequence[0] {
		t.Fatal("safe sequence shares mutable storage with retained tree")
	}
}

func TestPreparePairedDiffSnapshotMasksSensitiveDescendantsOfAbsentSubtrees(t *testing.T) {
	tests := []struct {
		name        string
		left, right string
		absentSide  string
	}{
		{
			name:       "removed subtree",
			left:       "removed: {token: old-secret, public: retained}\n",
			right:      "other: value\n",
			absentSide: "right",
		},
		{
			name:       "added subtree",
			left:       "other: value\n",
			right:      "added: {token: new-secret, public: retained}\n",
			absentSide: "left",
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			left := parseCompositionDocument(t, "left", test.left)
			right := parseCompositionDocument(t, "right", test.right)
			paired, supported := preparePairedDiffSnapshot(
				mappingValueIfPresent(left, "removed", "added"),
				mappingValueIfPresent(right, "removed", "added"),
				Keys("subtree"),
				newDiffSensitivity(map[string]bool{"/subtree/token": true}, nil),
			)
			if !supported {
				t.Fatal("compatible subtree and absence were not supported")
			}
			if test.absentSide == "left" {
				if paired.left != nil || paired.leftRedacted || !paired.rightRedacted {
					t.Fatalf("paired absence/redaction = %#v", paired)
				}
				assertDiffStringNode(t, mappingValue(t, paired.right, "token"), "[REDACTED]")
				assertDiffStringNode(t, mappingValue(t, paired.right, "public"), "retained")
			} else {
				if paired.right != nil || paired.rightRedacted || !paired.leftRedacted {
					t.Fatalf("paired absence/redaction = %#v", paired)
				}
				assertDiffStringNode(t, mappingValue(t, paired.left, "token"), "[REDACTED]")
				assertDiffStringNode(t, mappingValue(t, paired.left, "public"), "retained")
			}
		})
	}
}

func TestPreparePairedDiffSnapshotMasksSelectedRootAndContainer(t *testing.T) {
	tests := []struct {
		name        string
		left, right *document.Node
		path        Path
		selector    string
	}{
		{
			name:     "root",
			left:     parseCompositionDocument(t, "left", "token: old\n"),
			right:    parseCompositionDocument(t, "right", "token: new\n"),
			path:     Path{},
			selector: "",
		},
		{
			name:     "container",
			left:     parseCompositionDocument(t, "left", "group: {public: old}\n"),
			right:    parseCompositionDocument(t, "right", "group: {public: new}\n"),
			path:     Keys("group"),
			selector: "/group",
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			paired, supported := preparePairedDiffSnapshot(
				test.left, test.right, test.path,
				newDiffSensitivity(map[string]bool{test.selector: true}, nil),
			)
			if !supported {
				t.Fatal("selected nodes were not supported")
			}
			if !paired.leftRedacted || !paired.rightRedacted {
				t.Fatalf("redacted flags = %v, %v; want true on both sides", paired.leftRedacted, paired.rightRedacted)
			}
			assertDiffStringNode(t, paired.left, "[REDACTED]")
			assertDiffStringNode(t, paired.right, "[REDACTED]")
		})
	}
}

func TestPreparePairedDiffSnapshotDoesNotInterpretMarkerLookingInput(t *testing.T) {
	left := parseCompositionDocument(t, "left", "label: '[REDACTED]'\n")
	right := parseCompositionDocument(t, "right", "label: '[REDACTED]'\n")
	paired, supported := preparePairedDiffSnapshot(
		mappingValue(t, left, "label"), mappingValue(t, right, "label"), Keys("label"),
		newDiffSensitivity(nil, nil),
	)
	if !supported {
		t.Fatal("ordinary scalar values were not supported")
	}
	if paired.leftRedacted || paired.rightRedacted {
		t.Fatalf("redacted flags = %v, %v; want false", paired.leftRedacted, paired.rightRedacted)
	}
	if paired.left != mappingValue(t, left, "label") || paired.right != mappingValue(t, right, "label") {
		t.Fatal("unselected scalar nodes should remain borrowed immutable nodes")
	}
	assertDiffStringNode(t, paired.left, "[REDACTED]")
	assertDiffStringNode(t, paired.right, "[REDACTED]")
}

func TestPreparePairedDiffSnapshotWithholdsUnsupportedIntermediateShape(t *testing.T) {
	left := parseCompositionDocument(t, "left", "token: undisclosed-canary\npublic: safe\n")
	right := &document.Node{Kind: document.String, Text: "replacement"}
	paired, supported := preparePairedDiffSnapshot(
		left, right, Path{}, newDiffSensitivity(nil, map[string]bool{"/token": true}),
	)
	if supported || paired.left != nil || paired.right != nil {
		t.Fatalf("unsupported shape returned potentially unsafe nodes: %#v, supported=%v", paired, supported)
	}
}

func mappingValueIfPresent(node *document.Node, keys ...string) *document.Node {
	if node == nil {
		return nil
	}
	for _, key := range keys {
		for _, entry := range node.Mapping {
			if entry.Key == key {
				return entry.Value
			}
		}
	}
	return nil
}

func assertDiffStringNode(t *testing.T, node *document.Node, want string) {
	t.Helper()
	if node == nil || node.Kind != document.String || node.Text != want {
		t.Fatalf("node = %#v, want string %q", node, want)
	}
}