package engine

import (
	"fmt"
	"reflect"
	"strings"
	"testing"

	"go.maximumdirect.net/configkit/internal/document"
)

func TestMetadataLocationsAcrossBroadAuthoredAndDefaultMappings(t *testing.T) {
	type config map[string]map[string]string
	defaults := config{}
	var body strings.Builder
	for index := range 96 {
		name := fmt.Sprintf("authored-%03d", index)
		fmt.Fprintf(&body, "%s: {present: source}\n", name)
		defaults[name] = map[string]string{"absent": "default"}
		defaults[fmt.Sprintf("default-%03d", index)] = map[string]string{"absent": "default"}
	}
	input := parseDocumentForDecode(t, body.String())
	decoded, issues := decodeConfiguration(mustSchemaFor[config](t), reflect.ValueOf(defaults), input)
	if len(issues) != 0 {
		t.Fatal(issues)
	}
	located := documentWithMetadataLocations(decoded.final, metadataFromDecoded(decoded), input)
	inputIndex := buildDocumentLookup(input)
	locatedIndex := buildDocumentLookup(located)
	for index := range 96 {
		authored := Keys(fmt.Sprintf("authored-%03d", index))
		mapping, _ := documentAtPathWithLookup(input, authored, inputIndex)
		present, _ := documentAtPathWithLookup(input, authored.Key("present"), inputIndex)
		for _, test := range []struct {
			path Path
			want document.Location
		}{
			{authored.Key("present"), present.Location},
			{authored.Key("absent"), mapping.Location},
			{Keys(fmt.Sprintf("default-%03d", index), "absent"), input.Location},
		} {
			node, found := documentAtPathWithLookup(located, test.path, locatedIndex)
			if !found || node.Location != test.want {
				t.Fatalf("location at %s = %#v, want %#v", test.path, node, test.want)
			}
		}
	}
	walkDocument(located, Path{}, func(_ Path, node *document.Node) {
		for _, entry := range node.Mapping {
			if entry.KeyLocation != entry.Value.Location || entry.ValueLocation != entry.Value.Location {
				t.Fatal("entry and value locations disagree")
			}
		}
	})
	before := decoded.final.Mapping[0].Value.Mapping[0].Value.Text
	located.Mapping[0].Value.Mapping[0].Value.Text = "changed snapshot"
	if decoded.final.Mapping[0].Value.Mapping[0].Value.Text != before || input.Mapping[0].Value.Mapping[0].Value.Text != "source" {
		t.Fatal("location projection changed a borrowed input")
	}
}

func TestIndexedNearestLocationsPreserveMissingAndSyntheticCoordinates(t *testing.T) {
	root := parseDocumentForDecode(t, "mapping: {'0': value}\nitems: [{value: source}]\nscalar: stop\n")
	lookup := buildDocumentLookup(root)
	for _, path := range []Path{Path{}, Keys("missing"), Keys("mapping", "missing"), Keys("mapping", "0"), Keys("mapping").Index(0), Keys("items").Index(4), Keys("items").Index(0).Key("missing"), Keys("scalar", "child"), Path{}.Index(-1)} {
		want, wantOK := nearestDocumentLocation(root, path)
		got, gotOK := nearestDocumentLocationWithLookup(root, path, lookup)
		if got != want || gotOK != wantOK {
			t.Fatalf("nearest location changed for %s: %#v/%t, want %#v/%t", path, got, gotOK, want, wantOK)
		}
	}
	final := parseDocumentForDecode(t, "value: cli\n")
	synthetic := Location{SourceID: "cli-1"}
	metadata := Metadata{
		effectivePaths: effectivePathIndex(final),
		fields:         map[string]FieldInfo{"/value": {Origin: Origin{Layer: LayerCLI, Locations: []Location{synthetic}}}},
	}
	located := documentWithMetadataLocations(final, metadata, root)
	if location := located.Mapping[0].Value.Location; location.SourceID != "cli-1" || location.Line != 0 || location.Column != 0 {
		t.Fatalf("synthetic CLI location was replaced by fallback: %#v", location)
	}
}

func TestMetadataLocationFallbackDoesNotCrossKeyIndexShapes(t *testing.T) {
	fallback := parseDocumentForDecode(t, "settings:\n  - value:\n      child: input\n")
	final := parseDocumentForDecode(t, "settings:\n  '0':\n    value: final\n")
	metadata := Metadata{
		effectivePaths: effectivePathIndex(final),
		fields:         map[string]FieldInfo{"/settings/0/value": {Origin: Origin{Layer: LayerDefault}}},
	}
	located := documentWithMetadataLocations(final, metadata, fallback)
	settings, _ := documentAtPath(located, Keys("settings"))
	value, _ := documentAtPath(located, Keys("settings", "0", "value"))
	if settings == nil || value == nil || value.Location != settings.Location {
		t.Fatalf("fallback crossed from a mapping key to an input sequence item: settings %#v, value %#v", settings, value)
	}
	inputChild, _ := documentAtPath(fallback, Keys("settings").Index(0).Key("value").Key("child"))
	if inputChild == nil || value.Location == inputChild.Location {
		t.Fatalf("fallback fabricated a key location from an index: input child %#v, value %#v", inputChild, value)
	}
}

func TestHistoricalLocationSelectionSeparatesNumericKeyAndIndex(t *testing.T) {
	mappingRoot := &document.Node{Kind: document.Mapping, Mapping: []document.Entry{{
		Key: "shape", Value: &document.Node{Kind: document.Mapping, Mapping: []document.Entry{{
			Key: "0", Value: &document.Node{Kind: document.Mapping, Mapping: []document.Entry{{
				Key: "value", Value: &document.Node{Kind: document.String, Text: "mapping", Location: document.Location{SourceID: "mapping", Line: 3, Column: 5}},
			}}},
		}}},
	}}}
	sequenceRoot := &document.Node{Kind: document.Mapping, Mapping: []document.Entry{{
		Key: "shape", Value: &document.Node{Kind: document.Sequence, Sequence: []*document.Node{{
			Kind: document.Mapping, Mapping: []document.Entry{{
				Key: "value", Value: &document.Node{Kind: document.String, Text: "sequence", Location: document.Location{SourceID: "sequence", Line: 3, Column: 5}},
			}},
		}}},
	}}}
	builder := newHistoryBuilder()
	builder.observeSourceEvidence(sequenceRoot, nil, []historyApplication{
		{layer: LayerMain, value: mappingRoot},
		{layer: LayerOverlay, value: sequenceRoot},
	}, nil)
	model := builder.freeze()
	metadata := Metadata{historyModel: model}
	resolutionOrigin := Origin{Layer: LayerResolution, Operation: ChangeNormalization}
	for _, test := range []struct {
		path Path
		want string
	}{
		{Keys("shape", "0", "value"), "mapping"},
		{Keys("shape").Index(0).Key("value"), "sequence"},
	} {
		location, ok := metadataFieldLocation(metadata, test.path, resolutionOrigin)
		if !ok || location.SourceID != test.want {
			t.Fatalf("historical location for %s = %#v, %v; want %q", test.path, location, ok, test.want)
		}
	}
}