package engine

import (
	"reflect"
	"testing"

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

func TestOverlayDocumentsRecursesMappingsAndReplacesAtomicSubtrees(t *testing.T) {
	baseRoot := parseCompositionDocument(t, "source-1", `shared:
  kept: base
  changed: old
sequence: [one, two]
nullable: value
to_map: scalar
to_scalar: {child: old}
`)
	base, diagnostics := composeDocuments(baseRoot)
	if len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	overlay := parseCompositionDocument(t, "source-2", `shared:
  changed: new
  added: overlay
sequence: []
nullable: null
to_map: {child: new}
to_scalar: scalar
`)
	baseBefore := document.Clone(base.root)
	overlayBefore := document.Clone(overlay)

	result, diagnostics := overlayDocuments(base, overlay)
	if len(diagnostics) != 0 {
		t.Fatalf("overlayDocuments() diagnostics = %#v", diagnostics)
	}
	checks := []struct {
		path Path
		kind document.Kind
		text string
	}{
		{path: Keys("shared", "kept"), kind: document.String, text: "base"},
		{path: Keys("shared", "changed"), kind: document.String, text: "new"},
		{path: Keys("shared", "added"), kind: document.String, text: "overlay"},
		{path: Keys("sequence"), kind: document.Sequence},
		{path: Keys("nullable"), kind: document.Null},
		{path: Keys("to_map"), kind: document.Mapping},
		{path: Keys("to_map", "child"), kind: document.String, text: "new"},
		{path: Keys("to_scalar"), kind: document.String, text: "scalar"},
	}
	for _, check := range checks {
		node, ok := documentAtPath(result.root, check.path)
		if !ok || node.Kind != check.kind || node.Text != check.text {
			t.Errorf("node %s = %#v, %v", check.path.String(), node, ok)
		}
	}
	if _, exists := result.origins["/sequence/0"]; exists {
		t.Fatal("replaced empty sequence retained a stale index origin")
	}
	if _, exists := result.origins["/to_scalar/child"]; exists {
		t.Fatal("parent replacement retained a stale child origin")
	}
	shared := result.origins["/shared"]
	if shared.Layer != LayerOverlay || len(shared.Locations) != 2 {
		t.Fatalf("shared mapping origin = %#v", shared)
	}
	if len(result.overlays) != 5 {
		t.Fatalf("overlay records = %#v, want five replacements", result.overlays)
	}
	if !reflect.DeepEqual(base.root, baseBefore) || !reflect.DeepEqual(overlay, overlayBefore) {
		t.Fatal("overlay mutated an input document")
	}
	result.root.Mapping[0].Value.Mapping[0].Value.Text = "changed"
	if !reflect.DeepEqual(base.root, baseBefore) || !reflect.DeepEqual(overlay, overlayBefore) {
		t.Fatal("overlay result aliases an input document")
	}
}

func TestOwnedOverlayKeepsCompositeContributorsAndAcquiredInputs(t *testing.T) {
	baseInput := parseCompositionDocument(t, "source-1", "catalog:\n  base: true\n")
	base, diagnostics := composeDocuments(baseInput)
	if len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	first := parseCompositionDocument(t, "source-2", "catalog:\n  first: true\n")
	second := parseCompositionDocument(t, "source-3", "catalog:\n  second: true\n")
	firstBefore, secondBefore := document.Clone(first), document.Clone(second)
	incoming, diagnostics := composeDocuments(first, second)
	if len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	assembly := newAssemblyAccumulator(base)
	if diagnostics := assembly.applyOverlay(incoming.root, incoming.origins, incoming.applications, LayerOverlay); len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	for _, key := range []string{"base", "first", "second"} {
		if _, ok := documentAtPath(assembly.current.root, Keys("catalog", key)); !ok {
			t.Fatalf("catalog is missing %q", key)
		}
	}
	origin := assembly.current.origins[Keys("catalog").String()]
	if got, want := origin.Locations, []Location{{SourceID: "source-1", Line: 2, Column: 3}, {SourceID: "source-2", Line: 2, Column: 3}, {SourceID: "source-3", Line: 2, Column: 3}}; !reflect.DeepEqual(got, want) {
		t.Fatalf("catalog origin locations = %#v, want %#v", got, want)
	}
	if len(assembly.current.applications) != 3 {
		t.Fatalf("history applications = %d, want three source contributions", len(assembly.current.applications))
	}
	for _, application := range assembly.current.applications[1:] {
		if application.layer != LayerOverlay {
			t.Fatalf("incoming application layer = %q", application.layer)
		}
	}
	assembly.current.root.Mapping[0].Value.Mapping[1].Value.Text = "false"
	if !reflect.DeepEqual(first, firstBefore) || !reflect.DeepEqual(second, secondBefore) ||
		!reflect.DeepEqual(first, assembly.current.applications[1].value) || !reflect.DeepEqual(second, assembly.current.applications[2].value) {
		t.Fatal("working tree mutation changed an acquired input")
	}
}