package luajit_test

import (
	"bytes"
	"errors"
	"testing"

	luajit "git.sharkk.net/Sky/LuaJIT-to-Go"
)

// TestCompileBytecode tests basic bytecode compilation
func TestCompileBytecode(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	code := "return 42"
	bytecode, err := state.CompileBytecode(code, "test")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	if len(bytecode) == 0 {
		t.Fatal("Expected non-empty bytecode")
	}
}

// TestLoadBytecode tests loading precompiled bytecode
func TestLoadBytecode(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// First compile some bytecode
	code := "answer = 42"
	bytecode, err := state.CompileBytecode(code, "test")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	// Then load it
	err = state.LoadBytecode(bytecode, "test")
	if err != nil {
		t.Fatalf("LoadBytecode failed: %v", err)
	}

	// Verify a function is on the stack
	if !state.IsFunction(-1) {
		t.Fatal("Expected function at top of stack after LoadBytecode")
	}

	// Pop the function
	state.Pop(1)
}

// TestRunBytecode tests running previously loaded bytecode
func TestRunBytecode(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// First compile and load bytecode
	code := "answer = 42"
	bytecode, err := state.CompileBytecode(code, "test")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	err = state.LoadBytecode(bytecode, "test")
	if err != nil {
		t.Fatalf("LoadBytecode failed: %v", err)
	}

	// Run the bytecode
	err = state.RunBytecode()
	if err != nil {
		t.Fatalf("RunBytecode failed: %v", err)
	}

	// Verify the code has executed correctly
	state.GetGlobal("answer")
	if !state.IsNumber(-1) || state.ToNumber(-1) != 42 {
		t.Fatalf("Expected answer to be 42, got %v", state.ToNumber(-1))
	}
	state.Pop(1)
}

// TestLoadAndRunBytecode tests the combined load and run functionality
func TestLoadAndRunBytecode(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// Compile bytecode
	code := "answer = 42"
	bytecode, err := state.CompileBytecode(code, "test")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	// Load and run in one step
	err = state.LoadAndRunBytecode(bytecode, "test")
	if err != nil {
		t.Fatalf("LoadAndRunBytecode failed: %v", err)
	}

	// Verify execution
	state.GetGlobal("answer")
	if !state.IsNumber(-1) || state.ToNumber(-1) != 42 {
		t.Fatalf("Expected answer to be 42, got %v", state.ToNumber(-1))
	}
	state.Pop(1)
}

// TestCompileAndRun tests compile and run functionality
func TestCompileAndRun(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// Compile and run in one step
	code := "answer = 42"
	err := state.CompileAndRun(code, "test")
	if err != nil {
		t.Fatalf("CompileAndRun failed: %v", err)
	}

	// Verify execution
	state.GetGlobal("answer")
	if !state.IsNumber(-1) || state.ToNumber(-1) != 42 {
		t.Fatalf("Expected answer to be 42, got %v", state.ToNumber(-1))
	}
	state.Pop(1)
}

// TestEmptyBytecode tests error handling for empty bytecode
func TestEmptyBytecode(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// Try to load empty bytecode
	err := state.LoadBytecode([]byte{}, "empty")
	if err == nil {
		t.Fatal("Expected error for empty bytecode, got nil")
	}
}

// TestInvalidBytecode tests error handling for invalid bytecode
func TestInvalidBytecode(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// Create some invalid bytecode
	invalidBytecode := []byte("not valid bytecode")

	// Try to load invalid bytecode
	err := state.LoadBytecode(invalidBytecode, "invalid")
	if err == nil {
		t.Fatal("Expected error for invalid bytecode, got nil")
	}
}

// TestBytecodeSerialization tests serializing and deserializing bytecode
func TestBytecodeSerialization(t *testing.T) {
	// First state to compile
	state1 := luajit.New()
	if state1 == nil {
		t.Fatal("Failed to create first Lua state")
	}
	defer state1.Close()

	// Compile bytecode
	code := `
		function add(a, b)
			return a + b
		end
		result = add(10, 20)
	`
	bytecode, err := state1.CompileBytecode(code, "test")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	// Second state to execute
	state2 := luajit.New()
	if state2 == nil {
		t.Fatal("Failed to create second Lua state")
	}
	defer state2.Close()

	// Load and run the bytecode in the second state
	err = state2.LoadAndRunBytecode(bytecode, "test")
	if err != nil {
		t.Fatalf("LoadAndRunBytecode failed: %v", err)
	}

	// Verify execution
	state2.GetGlobal("result")
	if !state2.IsNumber(-1) || state2.ToNumber(-1) != 30 {
		t.Fatalf("Expected result to be 30, got %v", state2.ToNumber(-1))
	}
	state2.Pop(1)

	// Call the function to verify it was properly transferred
	state2.GetGlobal("add")
	if !state2.IsFunction(-1) {
		t.Fatal("Expected add to be a function")
	}
	state2.PushNumber(5)
	state2.PushNumber(7)
	if err := state2.Call(2, 1); err != nil {
		t.Fatalf("Failed to call function: %v", err)
	}
	if state2.ToNumber(-1) != 12 {
		t.Fatalf("Expected add(5, 7) to return 12, got %v", state2.ToNumber(-1))
	}
	state2.Pop(1)
}

// TestCompilationError tests error handling for compilation errors
func TestCompilationError(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// Invalid Lua code that should fail to compile
	code := "function without end"

	// Try to compile
	_, err := state.CompileBytecode(code, "invalid")
	if err == nil {
		t.Fatal("Expected compilation error, got nil")
	}

	// Check error type
	var luaErr *luajit.LuaError
	if !errors.As(err, &luaErr) {
		t.Fatalf("Expected error to wrap *luajit.LuaError, got %T", err)
	}
}

// TestExecutionError tests error handling for runtime errors
func TestExecutionError(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// Code that compiles but fails at runtime
	code := "error('deliberate error')"

	// Compile bytecode
	bytecode, err := state.CompileBytecode(code, "error")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	// Try to execute
	err = state.LoadAndRunBytecode(bytecode, "error")
	if err == nil {
		t.Fatal("Expected execution error, got nil")
	}

	// Check error type
	if _, ok := err.(*luajit.LuaError); !ok {
		t.Fatalf("Expected *luajit.LuaError, got %T", err)
	}
}

// TestBytecodeEquivalence tests that bytecode execution produces the same results as direct execution
func TestBytecodeEquivalence(t *testing.T) {
	code := `
		local result = 0
		for i = 1, 10 do
			result = result + i
		end
		return result
	`

	// First, execute directly
	state1 := luajit.New()
	if state1 == nil {
		t.Fatal("Failed to create first Lua state")
	}
	defer state1.Close()

	directResult, err := state1.ExecuteWithResult(code)
	if err != nil {
		t.Fatalf("ExecuteWithResult failed: %v", err)
	}

	// Then, compile and execute bytecode
	state2 := luajit.New()
	if state2 == nil {
		t.Fatal("Failed to create second Lua state")
	}
	defer state2.Close()

	bytecode, err := state2.CompileBytecode(code, "test")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	err = state2.LoadBytecode(bytecode, "test")
	if err != nil {
		t.Fatalf("LoadBytecode failed: %v", err)
	}

	err = state2.Call(0, 1)
	if err != nil {
		t.Fatalf("Call failed: %v", err)
	}

	bytecodeResult, err := state2.ToValue(-1)
	if err != nil {
		t.Fatalf("ToValue failed: %v", err)
	}
	state2.Pop(1)

	// Compare results
	if directResult != bytecodeResult {
		t.Fatalf("Results differ: direct=%v, bytecode=%v", directResult, bytecodeResult)
	}
}

// TestBytecodeReuse tests reusing the same bytecode multiple times
func TestBytecodeReuse(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// Create a function in bytecode
	code := `
		return function(x)
			return x * 2
		end
	`
	bytecode, err := state.CompileBytecode(code, "func")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	// Execute it several times
	for i := 1; i <= 3; i++ {
		// Load and run to get the function
		err = state.LoadAndRunBytecodeWithResults(bytes.Clone(bytecode), "func", 1)
		if err != nil {
			t.Fatalf("LoadAndRunBytecodeWithResults failed: %v", err)
		}

		// Stack now has the function at the top
		if !state.IsFunction(-1) {
			t.Fatal("Expected function at top of stack")
		}

		// Call with parameter i
		state.PushNumber(float64(i))
		if err := state.Call(1, 1); err != nil {
			t.Fatalf("Call failed: %v", err)
		}

		// Check result
		expected := float64(i * 2)
		if state.ToNumber(-1) != expected {
			t.Fatalf("Expected %v, got %v", expected, state.ToNumber(-1))
		}

		// Pop the result
		state.Pop(1)
	}
}

// TestBytecodeClosure tests that bytecode properly handles closures and upvalues
func TestBytecodeClosure(t *testing.T) {
	state := luajit.New()
	if state == nil {
		t.Fatal("Failed to create Lua state")
	}
	defer state.Close()

	// Create a closure
	code := `
		local counter = 0
		return function()
			counter = counter + 1
			return counter
		end
	`

	// Compile to bytecode
	bytecode, err := state.CompileBytecode(code, "closure")
	if err != nil {
		t.Fatalf("CompileBytecode failed: %v", err)
	}

	// Load and run to get the counter function
	err = state.LoadAndRunBytecodeWithResults(bytecode, "closure", 1)
	if err != nil {
		t.Fatalf("LoadAndRunBytecode failed: %v", err)
	}

	// Stack now has the function at the top
	if !state.IsFunction(-1) {
		t.Fatal("Expected function at top of stack")
	}

	// Store in a global
	state.SetGlobal("counter_func")

	// Call it multiple times and check the results
	for i := 1; i <= 3; i++ {
		state.GetGlobal("counter_func")
		if err := state.Call(0, 1); err != nil {
			t.Fatalf("Call failed: %v", err)
		}

		if state.ToNumber(-1) != float64(i) {
			t.Fatalf("Expected counter to be %d, got %v", i, state.ToNumber(-1))
		}
		state.Pop(1)
	}
}