package engine

import (
	"context"
	"errors"
	"os"
	"os/exec"
	"reflect"
	"testing"
	"time"
)

type pointerOnlyLoop *pointerOnlyLoop

type pointerOnlyConfig struct {
	Loop pointerOnlyLoop `yaml:"loop"`
}

func TestPointerOnlyDescriptorsTerminate(t *testing.T) {
	if mode := os.Getenv("CONFIGKIT_POINTER_DESCRIPTOR_TEST_MODE"); mode != "" {
		switch mode {
		case "decode":
			_, err := testLoad[pointerOnlyConfig](Bytes("config.yml", []byte("loop: {}\n")))
			var loadErr *LoadError
			if !errors.As(err, &loadErr) {
				t.Fatalf("load error = %v, want a safe decode failure", err)
			}
			for _, diagnostic := range loadErr.Diagnostics() {
				if diagnostic.Code == CodeDecodeType && diagnostic.Path.String() == "/loop" {
					return
				}
			}
			t.Fatalf("diagnostics = %#v, want decode type at /loop", loadErr.Diagnostics())
		case "paths":
			schema, issue := testBuildSchema(reflect.TypeFor[pointerOnlyConfig]())
			if issue != nil {
				t.Fatalf("schema issue = %#v", issue)
			}
			if _, ok := resolveSchemaPath(schema, Keys("loop", "child")); ok {
				t.Fatal("descendant below a pointer-only loop was accepted")
			}
			if _, ok := schemaSecretRoot(schema, Keys("loop", "child")); ok {
				t.Fatal("secret path below a pointer-only loop was accepted")
			}
			if acceptsMapping(schema.root.fields[schema.root.fieldByName["loop"]].descriptor) {
				t.Fatal("pointer-only loop was accepted as a mapping")
			}
		default:
			t.Fatalf("unknown test mode %q", mode)
		}
		return
	}

	for _, mode := range []string{"decode", "paths"} {
		t.Run(mode, func(t *testing.T) {
			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
			defer cancel()
			command := exec.CommandContext(ctx, os.Args[0], "-test.run=^TestPointerOnlyDescriptorsTerminate$")
			command.Env = append(os.Environ(), "CONFIGKIT_POINTER_DESCRIPTOR_TEST_MODE="+mode)
			output, err := command.CombinedOutput()
			if ctx.Err() != nil {
				t.Fatalf("pointer descriptor %s did not terminate: %s", mode, output)
			}
			if err != nil {
				t.Fatalf("pointer descriptor %s failed: %v, %s", mode, err, output)
			}
		})
	}
}

func TestPointerOnlyNullableFieldAndRecursiveValues(t *testing.T) {
	for name, source := range map[string]Source{
		"omitted": NoSource(),
		"null":    Bytes("config.yml", []byte("loop: null\n")),
	} {
		t.Run(name, func(t *testing.T) {
			result, err := testLoad[pointerOnlyConfig](source)
			if err != nil || result.Config.Loop != nil {
				t.Fatalf("result = %#v, error = %v", result, err)
			}
		})
	}

	result, err := testLoad[recursiveConfig](Bytes("config.yml", []byte("name: root\nnext:\n  name: child\n  next:\n    name: leaf\n")))
	if err != nil {
		t.Fatal(err)
	}
	if result.Config.Name != "root" || result.Config.Next == nil || result.Config.Next.Name != "child" || result.Config.Next.Next == nil || result.Config.Next.Next.Name != "leaf" {
		t.Fatalf("recursive value = %#v", result.Config)
	}

	schema, issue := testBuildSchema(reflect.TypeFor[pointerOnlyConfig]())
	if issue != nil {
		t.Fatal(issue.message)
	}
	resolved, ok := resolveSchemaPath(schema, Keys("loop"))
	if !ok || resolved.descriptor.kind != descriptorPointer {
		t.Fatalf("nullable pointer field resolution = %#v, %v", resolved, ok)
	}

	called := false
	nullableResult, err := testLoad[pointerOnlyConfig](NoSource(), Options[pointerOnlyConfig]{Definition: Definition[pointerOnlyConfig]{
		Resolve: func(config *pointerOnlyConfig, resolution *Resolution) error {
			called = true
			Normalize(resolution, Keys("loop"), &config.Loop, nil, "clear nullable field")
			return nil
		},
	}})
	if err != nil || !called || nullableResult.Config.Loop != nil {
		t.Fatalf("nullable field operation = %#v, called=%v, error=%v", nullableResult, called, err)
	}
}