package sandbox

import (
	"fmt"
	"sync"

	"github.com/goccy/go-json"
	"github.com/valyala/bytebufferpool"
	"github.com/valyala/fasthttp"

	"Moonshark/core/utils/logger"

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

// Global bytecode cache to improve performance
var (
	sandboxBytecode []byte
	bytecodeOnce    sync.Once
)

// precompileSandbox compiles the sandbox.lua code to bytecode once
func precompileSandbox() {
	tempState := luajit.New()
	if tempState == nil {
		logger.Error("Failed to create temporary Lua state for bytecode compilation")
		return
	}
	defer tempState.Close()
	defer tempState.Cleanup()

	var err error
	sandboxBytecode, err = tempState.CompileBytecode(sandboxLua, "sandbox.lua")
	if err != nil {
		logger.Error("Failed to precompile sandbox.lua: %v", err)
	} else {
		logger.Debug("Successfully precompiled sandbox.lua to bytecode (%d bytes)", len(sandboxBytecode))
	}
}

// Sandbox provides a secure execution environment for Lua scripts
type Sandbox struct {
	modules      map[string]any      // Custom modules for environment
	debug        bool                // Enable debug output
	mu           sync.RWMutex        // Protects modules
	initializers *ModuleInitializers // Module initializers
}

// NewSandbox creates a new sandbox environment
func NewSandbox() *Sandbox {
	return &Sandbox{
		modules:      make(map[string]any, 8), // Pre-allocate with reasonable capacity
		debug:        false,
		initializers: DefaultInitializers(),
	}
}

// EnableDebug turns on debug logging
func (s *Sandbox) EnableDebug() {
	s.debug = true
}

// debugLog logs a message if debug mode is enabled
func (s *Sandbox) debugLog(format string, args ...interface{}) {
	if s.debug {
		logger.Debug("Sandbox "+format, args...)
	}
}

// debugLogCont logs a continuation message if debug mode is enabled
func (s *Sandbox) debugLogCont(format string, args ...interface{}) {
	if s.debug {
		logger.DebugCont(format, args...)
	}
}

// AddModule adds a module to the sandbox environment
func (s *Sandbox) AddModule(name string, module any) {
	s.mu.Lock()
	defer s.mu.Unlock()

	s.modules[name] = module
	s.debugLog("Added module: %s", name)
}

// Setup initializes the sandbox in a Lua state
func (s *Sandbox) Setup(state *luajit.State, stateIndex int) error {
	verbose := stateIndex == 0

	if verbose {
		s.debugLog("Setting up sandbox...")
	}

	// Initialize modules with the embedded sandbox code
	if err := InitializeAll(state, s.initializers); err != nil {
		if verbose {
			s.debugLog("Failed to initialize sandbox: %v", err)
		}
		return err
	}

	// Register custom modules in the global environment
	s.mu.RLock()
	for name, module := range s.modules {
		if verbose {
			s.debugLog("Registering module: %s", name)
		}
		if err := state.PushValue(module); err != nil {
			s.mu.RUnlock()
			if verbose {
				s.debugLog("Failed to register module %s: %v", name, err)
			}
			return err
		}
		state.SetGlobal(name)
	}
	s.mu.RUnlock()

	if verbose {
		s.debugLogCont("Sandbox setup complete")
	}
	return nil
}

// Execute runs bytecode in the sandbox
func (s *Sandbox) Execute(state *luajit.State, bytecode []byte, ctx map[string]any) (any, error) {
	// Create a temporary context if we only have a map
	if ctx != nil {
		tempCtx := &Context{
			Values: ctx,
		}
		return s.OptimizedExecute(state, bytecode, tempCtx)
	}

	// Just pass nil through if we have no context
	return s.OptimizedExecute(state, bytecode, nil)
}

// Context represents execution context for a Lua script
type Context struct {
	// Values stores any context values (route params, HTTP request info, etc.)
	Values map[string]any
	// RequestCtx for HTTP requests
	RequestCtx *fasthttp.RequestCtx
}

// OptimizedExecute runs bytecode with a fasthttp context if available
func (s *Sandbox) OptimizedExecute(state *luajit.State, bytecode []byte, ctx *Context) (any, error) {
	// Use a buffer from the pool for any string operations
	buf := bytebufferpool.Get()
	defer bytebufferpool.Put(buf)

	// Load bytecode
	if err := state.LoadBytecode(bytecode, "script"); err != nil {
		s.debugLog("Failed to load bytecode: %v", err)
		return nil, fmt.Errorf("failed to load script: %w", err)
	}

	// Prepare context values
	var ctxValues map[string]any
	if ctx != nil {
		ctxValues = ctx.Values
	} else {
		ctxValues = nil
	}

	// Prepare context table
	if ctxValues != nil {
		state.CreateTable(0, len(ctxValues))
		for k, v := range ctxValues {
			state.PushString(k)
			if err := state.PushValue(v); err != nil {
				state.Pop(2) // Pop key and table
				s.debugLog("Failed to push context value %s: %v", k, err)
				return nil, fmt.Errorf("failed to prepare context: %w", err)
			}
			state.SetTable(-3)
		}
	} else {
		state.PushNil() // No context
	}

	// Get execution function
	state.GetGlobal("__execute_script")
	if !state.IsFunction(-1) {
		state.Pop(2) // Pop context and non-function
		s.debugLog("__execute_script is not a function")
		return nil, fmt.Errorf("sandbox execution function not found")
	}

	// Stack setup for call: __execute_script, bytecode function, context
	state.PushCopy(-3) // bytecode function (copy from -3)
	state.PushCopy(-3) // context (copy from -3)

	// Clean up duplicate references
	state.Remove(-5) // Remove original bytecode function
	state.Remove(-4) // Remove original context

	// Call with 2 args (function, context), 1 result
	if err := state.Call(2, 1); err != nil {
		s.debugLog("Execution failed: %v", err)
		return nil, fmt.Errorf("script execution failed: %w", err)
	}

	// Get result
	result, err := state.ToValue(-1)
	state.Pop(1) // Pop result

	// Check for HTTP response
	httpResponse, hasResponse := GetHTTPResponse(state)
	if hasResponse {
		// Add the script result as the response body
		httpResponse.Body = result

		// If we have a fasthttp context, apply the response directly
		if ctx != nil && ctx.RequestCtx != nil {
			ApplyHTTPResponse(httpResponse, ctx.RequestCtx)
			ReleaseResponse(httpResponse)
			return nil, nil // No need to return response object
		}

		return httpResponse, nil
	}

	// If we have a fasthttp context and the result needs to be written directly
	if ctx != nil && ctx.RequestCtx != nil && (result != nil) {
		// For direct HTTP responses
		switch r := result.(type) {
		case string:
			ctx.RequestCtx.SetBodyString(r)
		case []byte:
			ctx.RequestCtx.SetBody(r)
		case map[string]any, []any:
			// JSON response
			ctx.RequestCtx.Response.Header.SetContentType("application/json")
			if err := json.NewEncoder(buf).Encode(r); err == nil {
				ctx.RequestCtx.SetBody(buf.Bytes())
			} else {
				ctx.RequestCtx.SetBodyString(fmt.Sprintf("%v", r))
			}
		default:
			// Default string conversion
			ctx.RequestCtx.SetBodyString(fmt.Sprintf("%v", r))
		}
		return nil, nil
	}

	return result, err
}