// Copyright (c) 2026 Charles KWON OhJun (charleskwonohjun@gmail.com)
// All rights reserved.

package hbrt

import "testing"

func TestClassCreateAndInstantiate(t *testing.T) {
	cls := NewClassDef("Person").
		AddData("CNAME", MakeString("")).
		AddData("NAGE", MakeInt(0)).
		Register()

	obj := NewObject(cls)
	if !obj.IsObject() {
		t.Fatal("should be object")
	}

	arr := obj.AsArray()
	if arr.Class != cls {
		t.Errorf("class = %d, want %d", arr.Class, cls)
	}
	if len(arr.Items) != 2 {
		t.Fatalf("fields = %d, want 2", len(arr.Items))
	}

	// Default values
	if arr.Items[0].AsString() != "" {
		t.Errorf("cName default = %q, want empty", arr.Items[0].AsString())
	}
	if arr.Items[1].AsInt() != 0 {
		t.Errorf("nAge default = %d, want 0", arr.Items[1].AsInt())
	}
}

func TestClassMethodDispatch(t *testing.T) {
	cls := NewClassDef("Person")
	cls.AddData("CNAME", MakeString(""))
	cls.AddData("NAGE", MakeInt(0))

	// METHOD New(cName, nAge)
	cls.AddMethod("NEW", func(th *Thread) {
		th.Frame(2, 0)
		defer th.EndProc()
		// ::cName := param1
		th.PushValue(th.Local(1))
		th.SetSelfField("CNAME")
		// ::nAge := param2
		th.PushValue(th.Local(2))
		th.SetSelfField("NAGE")
		// RETURN Self
		th.PushSelf()
		th.RetValue()
	})

	// METHOD Greet() → "Hello, I'm " + ::cName
	cls.AddMethod("GREET", func(th *Thread) {
		th.Frame(0, 0)
		defer th.EndProc()
		th.PushString("Hello, I'm ")
		th.PushSelfField("CNAME")
		th.Plus()
		th.RetValue()
	})

	cls.Register()

	// Create instance
	vm := NewVM()
	th := vm.NewThread()
	th.Frame(0, 0)

	// obj := Person():New("Kim", 30)
	clsID := FindClass("Person").ID
	obj := NewObject(clsID)
	th.push(obj)
	th.PushString("Kim")
	th.PushInt(30)
	th.Send("NEW", 2)
	resultObj := th.pop()

	// Verify fields were set
	arr := resultObj.AsArray()
	if arr.Items[0].AsString() != "Kim" {
		t.Errorf("cName = %q, want Kim", arr.Items[0].AsString())
	}
	if arr.Items[1].AsInt() != 30 {
		t.Errorf("nAge = %d, want 30", arr.Items[1].AsInt())
	}

	// Call Greet
	th.push(resultObj)
	th.Send("GREET", 0)
	greeting := th.pop()
	if greeting.AsString() != "Hello, I'm Kim" {
		t.Errorf("greet = %q, want %q", greeting.AsString(), "Hello, I'm Kim")
	}

	th.EndProc()
}

func TestClassFieldGetterSetter(t *testing.T) {
	cls := NewClassDef("Point")
	cls.AddData("X", MakeInt(0))
	cls.AddData("Y", MakeInt(0))
	cls.Register()

	vm := NewVM()
	th := vm.NewThread()
	th.Frame(0, 0)

	obj := NewObject(FindClass("Point").ID)

	// Getter: obj:X
	th.push(obj)
	th.Send("X", 0)
	if th.pop().AsInt() != 0 {
		t.Error("X default should be 0")
	}

	// Setter: obj:_X := 10 (convention: _FIELDNAME for setter)
	th.push(obj)
	th.PushInt(10)
	th.Send("_X", 1)
	th.pop() // discard setter result

	// Verify
	th.push(obj)
	th.Send("X", 0)
	if th.pop().AsInt() != 10 {
		t.Error("X should be 10 after setter")
	}

	th.EndProc()
}

func TestClassInheritance(t *testing.T) {
	// Parent: Animal
	animal := NewClassDef("Animal")
	animal.AddData("CNAME", MakeString(""))
	animal.AddMethod("SPEAK", func(th *Thread) {
		th.Frame(0, 0)
		defer th.EndProc()
		th.PushString("...")
		th.RetValue()
	})
	animal.Register()

	// Child: Dog INHERIT FROM Animal
	dog := NewClassDef("Dog")
	dog.InheritFrom("Animal")
	// Override SPEAK
	dog.AddMethod("SPEAK", func(th *Thread) {
		th.Frame(0, 0)
		defer th.EndProc()
		th.PushString("Woof!")
		th.RetValue()
	})
	// Add new method
	dog.AddMethod("FETCH", func(th *Thread) {
		th.Frame(0, 0)
		defer th.EndProc()
		th.PushSelfField("CNAME")
		th.PushString(" fetches the ball!")
		th.Plus()
		th.RetValue()
	})
	dog.Register()

	vm := NewVM()
	th := vm.NewThread()
	th.Frame(0, 0)

	// Create Dog
	obj := NewObject(FindClass("Dog").ID)
	arr := obj.AsArray()
	arr.Items[0] = MakeString("Rex") // set cName

	// Dog:Speak → "Woof!" (overridden)
	th.push(obj)
	th.Send("SPEAK", 0)
	if th.pop().AsString() != "Woof!" {
		t.Error("Dog:Speak should be 'Woof!'")
	}

	// Dog:Fetch → "Rex fetches the ball!" (new method using inherited field)
	th.push(obj)
	th.Send("FETCH", 0)
	result := th.pop().AsString()
	if result != "Rex fetches the ball!" {
		t.Errorf("Dog:Fetch = %q", result)
	}

	// Dog has inherited cName from Animal
	th.push(obj)
	th.Send("CNAME", 0)
	if th.pop().AsString() != "Rex" {
		t.Error("inherited CNAME should be Rex")
	}

	th.EndProc()
}

func TestClassFindAndRegistry(t *testing.T) {
	// These classes were registered in previous tests
	if FindClass("Person") == nil {
		t.Error("Person class should be registered")
	}
	if FindClass("PERSON") == nil {
		t.Error("case-insensitive lookup should work")
	}
	if FindClass("NonExistent") != nil {
		t.Error("non-existent class should return nil")
	}
}