package engine

import (
	"testing"
	"testing/fstest"

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

func TestDestinationPlacementCountsAgainstSharedNodeBudget(t *testing.T) {
	t.Parallel()

	limits := defaultImportLimits()
	destination := Keys("collections", "entry")
	empty := Mapping("empty", map[string]any{})
	parsed, diagnostics := parseSource(empty, "fixture", defaultParseLimits())
	if len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	perInput := countInputNodes(parsed.document) + destinationWrapperNodeCount(destination)

	for _, test := range []struct {
		name       string
		delta      int
		wantError  bool
		wantCharge int
	}{
		{name: "below aggregate bound", delta: -1, wantCharge: perInput},
		{name: "at aggregate bound", delta: 0, wantCharge: perInput},
		{name: "above aggregate bound", delta: 1, wantError: true},
	} {
		t.Run(test.name, func(t *testing.T) {
			t.Parallel()
			accounting := &importAccounting{nodes: limits.nodes - perInput + test.delta}
			composition, _, _, diagnostics := acquireUnderlayGroup(loadGroup{inputs: []loadInput{{
				source: empty, destination: destination,
			}}}, 1, nil, accounting)
			if test.wantError {
				if composition != nil || len(diagnostics) != 1 || diagnostics[0].Code != CodeSourceLimitExceeded {
					t.Fatalf("over-budget placement = %#v, %#v", composition, diagnostics)
				}
				return
			}
			if composition == nil || len(diagnostics) != 0 || composition.inputNodes != test.wantCharge {
				t.Fatalf("bounded placement = %#v, %#v", composition, diagnostics)
			}
		})
	}
}

func TestMultipleMountedInputsSharePlacementCharges(t *testing.T) {
	t.Parallel()

	limits := defaultImportLimits()
	inputs := []loadInput{
		{source: Mapping("one", map[string]any{}), destination: Keys("collection", "one")},
		{source: Mapping("two", map[string]any{}), destination: Keys("collection", "two")},
		{source: Mapping("three", map[string]any{}), destination: Keys("collection", "three")},
	}
	perInput := countInputNodes(&document.Node{Kind: document.Mapping}) + destinationWrapperNodeCount(Keys("collection", "one"))
	charge := len(inputs) * perInput
	accounting := &importAccounting{nodes: limits.nodes - charge}
	composition, _, _, diagnostics := acquireUnderlayGroup(loadGroup{inputs: inputs}, 1, nil, accounting)
	if len(diagnostics) != 0 || composition == nil || accounting.nodes != limits.nodes || composition.inputNodes != charge {
		t.Fatalf("shared placement accounting = %#v, %#v, accounting %#v; want charge %d", composition, diagnostics, accounting, charge)
	}
}

func TestImportedEmptyBodiesChargeEachDestinationWrapper(t *testing.T) {
	t.Parallel()

	filesystem := NewFilesystem("bundle", fstest.MapFS{
		"main.yml":     &fstest.MapFile{Data: []byte("configkit: {imports: [{path: fragment.yml}]}\n")},
		"fragment.yml": &fstest.MapFile{Data: []byte("{}\n")},
	})
	mainSource := filesystem.File("main.yml")
	mainParsed, diagnostics := parseSource(mainSource, "fixture", defaultParseLimits())
	if len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	fragmentParsed, diagnostics := parseSource(Bytes("fragment", []byte("{}\n")), "fixture", defaultParseLimits())
	if len(diagnostics) != 0 {
		t.Fatal(diagnostics)
	}
	rawNodes := countInputNodes(mainParsed.document) + countInputNodes(fragmentParsed.document)
	destination := Keys("collection", "empty")
	placementNodes := 2 * destinationWrapperNodeCount(destination)
	limits := defaultImportLimits()
	for _, test := range []struct {
		name      string
		delta     int
		wantError bool
	}{
		{name: "below aggregate bound", delta: -1},
		{name: "at aggregate bound", delta: 0},
		{name: "above aggregate bound", delta: 1, wantError: true},
	} {
		t.Run(test.name, func(t *testing.T) {
			t.Parallel()
			accounting := &importAccounting{nodes: limits.nodes - rawNodes - placementNodes + test.delta}
			composition, sources, _, diagnostics := acquireUnderlayGroup(loadGroup{inputs: []loadInput{{
				source: mainSource, imports: true, destination: destination,
			}}}, 1, nil, accounting)
			if test.wantError {
				if composition != nil || len(diagnostics) == 0 || diagnostics[0].Code != CodeImportLimitExceeded {
					t.Fatalf("over-budget imports = %#v, %#v", composition, diagnostics)
				}
				return
			}
			if len(diagnostics) != 0 || composition == nil || len(sources) != 2 {
				t.Fatalf("bounded imports = %#v, sources %#v, diagnostics %#v", composition, sources, diagnostics)
			}
			if composition.inputNodes != rawNodes+placementNodes || accounting.nodes != limits.nodes+test.delta {
				t.Fatalf("import node charge = %d, accounting %d; want %d and %d", composition.inputNodes, accounting.nodes, rawNodes+placementNodes, limits.nodes+test.delta)
			}
			if node, present := documentAtPath(composition.root, Keys("collection", "empty")); !present || node.Kind != document.Mapping || len(node.Mapping) != 0 {
				t.Fatalf("placed empty import body = %#v, present %v", node, present)
			}
		})
	}
}

func TestNoSourceAndRootPlacementAddNoWrapperCharges(t *testing.T) {
	t.Parallel()

	accounting := &importAccounting{}
	composition, sources, _, diagnostics := acquireUnderlayGroup(loadGroup{inputs: []loadInput{
		{source: NoSource(), destination: Keys("absent")},
		{source: Mapping("root", map[string]any{})},
	}}, 1, nil, accounting)
	if len(diagnostics) != 0 || composition == nil || len(sources) != 1 || accounting.nodes != 1 || composition.inputNodes != 1 {
		t.Fatalf("root and absent placement = %#v, sources %#v, diagnostics %#v, accounting %#v", composition, sources, diagnostics, accounting)
	}
}

func TestSelectedOverlayAndCLIUsePlacementNodeCharges(t *testing.T) {
	t.Parallel()

	limits := defaultImportLimits()
	baseNodes := countInputNodes(&document.Node{Kind: document.Mapping}) + destinationWrapperNodeCount(Keys("mounted"))

	t.Run("selected overlay", func(t *testing.T) {
		t.Parallel()
		filesystem := NewFilesystem("bundle", fstest.MapFS{
			"overlays/test.yml": &fstest.MapFile{Data: []byte("{}\n")},
		})
		request := loadRequest[map[string]any]{
			underlays: []loadGroup{{inputs: []loadInput{{source: Mapping("empty", map[string]any{}), destination: Keys("mounted")}}}},
			overlay:   "test", overlayFilesystem: &FilesystemContext{Root: ".", BaseDir: ".", FS: &filesystem},
		}
		accounting := &importAccounting{nodes: limits.nodes - baseNodes}
		_, diagnostics := assembleLayeredInput(request, assembledInput{}, accounting)
		if len(diagnostics) != 1 || diagnostics[0].Code != CodeOverlayLimitExceeded {
			t.Fatalf("overlay diagnostics = %#v", diagnostics)
		}
	})

	t.Run("CLI override", func(t *testing.T) {
		t.Parallel()
		override := Override{Path: Keys("mounted", "value"), Value: "x", Flag: "--value"}
		builder := valueBuilder{sourceID: "fixture", active: make(map[valueVisit]bool)}
		if _, issue := builder.build(override.Value, override.Path, len(override.Path.segments)); issue != nil {
			t.Fatal(issue)
		}
		overrideNodes := builder.nodes + destinationWrapperNodeCount(override.Path)
		request := loadRequest[map[string]any]{
			underlays: []loadGroup{{inputs: []loadInput{{source: Mapping("empty", map[string]any{}), destination: Keys("mounted")}}}},
			overrides: []Override{override},
		}
		accounting := &importAccounting{nodes: limits.nodes - baseNodes - overrideNodes + 1}
		_, diagnostics := assembleLayeredInput(request, assembledInput{}, accounting)
		if len(diagnostics) != 1 || diagnostics[0].Code != CodeOverrideLimitExceeded {
			t.Fatalf("override diagnostics = %#v", diagnostics)
		}
	})
}