package runner

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"Moonshark/router"
	"Moonshark/runner/lualibs"
	"Moonshark/runner/sqlite"
	"Moonshark/sessions"
	"Moonshark/utils/logger"

	luajit "git.sharkk.net/Sky/LuaJIT-to-Go"
	"github.com/goccy/go-json"
	"github.com/valyala/bytebufferpool"
	"github.com/valyala/fasthttp"
)

var emptyMap = make(map[string]any)

var (
	ErrRunnerClosed  = errors.New("lua runner is closed")
	ErrTimeout       = errors.New("operation timed out")
	ErrStateNotReady = errors.New("lua state not ready")
)

type State struct {
	L       *luajit.State
	sandbox *Sandbox
	index   int
	inUse   atomic.Bool
}

type Runner struct {
	states       []*State
	statePool    chan int
	poolSize     int
	moduleLoader *ModuleLoader
	isRunning    atomic.Bool
	mu           sync.RWMutex
	scriptDir    string

	// Pre-allocated pools for HTTP processing
	ctxPool    sync.Pool
	paramsPool sync.Pool
}

func NewRunner(poolSize int, dataDir, fsDir string, libDirs []string) (*Runner, error) {
	if poolSize <= 0 {
		poolSize = runtime.GOMAXPROCS(0)
	}

	// Configure module loader with lib directories
	moduleConfig := &ModuleConfig{
		LibDirs: libDirs,
	}

	r := &Runner{
		poolSize:     poolSize,
		moduleLoader: NewModuleLoader(moduleConfig),
		ctxPool: sync.Pool{
			New: func() any { return make(map[string]any, 8) },
		},
		paramsPool: sync.Pool{
			New: func() any { return make(map[string]any, 4) },
		},
	}

	sqlite.InitSQLite(dataDir)
	lualibs.InitFS(fsDir)
	sqlite.SetSQLitePoolSize(poolSize)

	r.states = make([]*State, poolSize)
	r.statePool = make(chan int, poolSize)

	if err := r.initStates(); err != nil {
		sqlite.CleanupSQLite()
		return nil, err
	}

	r.isRunning.Store(true)
	return r, nil
}

// Single entry point for HTTP execution
func (r *Runner) ExecuteHTTP(bytecode []byte, httpCtx *fasthttp.RequestCtx,
	params *router.Params, session *sessions.Session) (*Response, error) {

	if !r.isRunning.Load() {
		return nil, ErrRunnerClosed
	}

	// Get state with timeout
	var stateIndex int
	select {
	case stateIndex = <-r.statePool:
	case <-time.After(time.Second):
		return nil, ErrTimeout
	}

	state := r.states[stateIndex]
	state.inUse.Store(true)

	defer func() {
		state.inUse.Store(false)
		if r.isRunning.Load() {
			select {
			case r.statePool <- stateIndex:
			default:
			}
		}
	}()

	// Build Lua context directly from HTTP request
	luaCtx := r.buildHTTPContext(httpCtx, params, session)
	defer r.releaseHTTPContext(luaCtx)

	return state.sandbox.Execute(state.L, bytecode, luaCtx)
}

// Build Lua context from HTTP request
func (r *Runner) buildHTTPContext(ctx *fasthttp.RequestCtx, params *router.Params, session *sessions.Session) *Context {
	luaCtx := NewContext()

	// Basic request info
	luaCtx.Set("method", string(ctx.Method()))
	luaCtx.Set("path", string(ctx.Path()))
	luaCtx.Set("host", string(ctx.Host()))

	// Headers
	headers := r.ctxPool.Get().(map[string]any)
	ctx.Request.Header.VisitAll(func(key, value []byte) {
		headers[string(key)] = string(value)
	})
	luaCtx.Set("headers", headers)

	// Cookies
	cookies := r.ctxPool.Get().(map[string]any)
	ctx.Request.Header.VisitAllCookie(func(key, value []byte) {
		cookies[string(key)] = string(value)
	})
	luaCtx.Set("cookies", cookies)

	// Route parameters
	if params != nil && len(params.Keys) > 0 {
		paramMap := r.paramsPool.Get().(map[string]any)
		for i, key := range params.Keys {
			if i < len(params.Values) {
				paramMap[key] = params.Values[i]
			}
		}
		luaCtx.Set("params", paramMap)
	} else {
		luaCtx.Set("params", emptyMap)
	}

	// Form data for POST/PUT/PATCH
	method := ctx.Method()
	if string(method) == "POST" || string(method) == "PUT" || string(method) == "PATCH" {
		if formData := parseForm(ctx); formData != nil {
			luaCtx.Set("form", formData)
		} else {
			luaCtx.Set("form", emptyMap)
		}
	} else {
		luaCtx.Set("form", emptyMap)
	}

	// Session data
	sessionMap := r.ctxPool.Get().(map[string]any)
	session.AdvanceFlash()
	sessionMap["id"] = session.ID

	if !session.IsEmpty() {
		sessionMap["data"] = session.GetAll()
		sessionMap["flash"] = session.GetAllFlash()
	} else {
		sessionMap["data"] = emptyMap
		sessionMap["flash"] = emptyMap
	}
	luaCtx.Set("session", sessionMap)

	// Environment variables
	if envMgr := lualibs.GetGlobalEnvManager(); envMgr != nil {
		luaCtx.Set("env", envMgr.GetAll())
	}

	return luaCtx
}

// Releases the HTTP context's maps back to their pool
func (r *Runner) releaseHTTPContext(luaCtx *Context) {
	if headers, ok := luaCtx.Get("headers").(map[string]any); ok {
		for k := range headers {
			delete(headers, k)
		}
		r.ctxPool.Put(headers)
	}

	if cookies, ok := luaCtx.Get("cookies").(map[string]any); ok {
		for k := range cookies {
			delete(cookies, k)
		}
		r.ctxPool.Put(cookies)
	}

	if params, ok := luaCtx.Get("params").(map[string]any); ok && len(params) > 0 {
		for k := range params {
			delete(params, k)
		}
		r.paramsPool.Put(params)
	}

	if sessionMap, ok := luaCtx.Get("session").(map[string]any); ok {
		for k := range sessionMap {
			delete(sessionMap, k)
		}
		r.ctxPool.Put(sessionMap)
	}

	luaCtx.Release()
}

func (r *Runner) initStates() error {
	logger.Infof("[LuaRunner] Creating %d states...", r.poolSize)

	for i := range r.poolSize {
		state, err := r.createState(i)
		if err != nil {
			return err
		}
		r.states[i] = state
		r.statePool <- i
	}
	return nil
}

func (r *Runner) createState(index int) (*State, error) {
	L := luajit.New(true)
	if L == nil {
		return nil, errors.New("failed to create Lua state")
	}

	sb := NewSandbox()
	if err := sb.Setup(L, index, index == 0); err != nil {
		L.Cleanup()
		L.Close()
		return nil, err
	}

	if err := r.moduleLoader.SetupRequire(L); err != nil {
		L.Cleanup()
		L.Close()
		return nil, err
	}

	if err := r.moduleLoader.PreloadModules(L); err != nil {
		L.Cleanup()
		L.Close()
		return nil, err
	}

	return &State{L: L, sandbox: sb, index: index}, nil
}

func (r *Runner) Close() error {
	r.mu.Lock()
	defer r.mu.Unlock()

	if !r.isRunning.Load() {
		return ErrRunnerClosed
	}
	r.isRunning.Store(false)

	// Drain pool
	for {
		select {
		case <-r.statePool:
		default:
			goto cleanup
		}
	}

cleanup:
	// Wait for states to finish
	timeout := time.Now().Add(10 * time.Second)
	for time.Now().Before(timeout) {
		allIdle := true
		for _, state := range r.states {
			if state != nil && state.inUse.Load() {
				allIdle = false
				break
			}
		}
		if allIdle {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}

	// Close states
	for i, state := range r.states {
		if state != nil {
			state.L.Cleanup()
			state.L.Close()
			r.states[i] = nil
		}
	}

	lualibs.CleanupFS()
	sqlite.CleanupSQLite()
	return nil
}

// parseForm extracts form data from HTTP request
func parseForm(ctx *fasthttp.RequestCtx) map[string]any {
	form := make(map[string]any)

	// Parse POST form data
	ctx.PostArgs().VisitAll(func(key, value []byte) {
		form[string(key)] = string(value)
	})

	// Parse multipart form if present
	if multipartForm, err := ctx.MultipartForm(); err == nil {
		for key, values := range multipartForm.Value {
			if len(values) == 1 {
				form[key] = values[0]
			} else {
				form[key] = values
			}
		}
	}

	if len(form) == 0 {
		return nil
	}
	return form
}

// NotifyFileChanged alerts the runner about file changes
func (r *Runner) NotifyFileChanged(filePath string) bool {
	logger.Debugf("Runner notified of file change: %s", filePath)

	module, isModule := r.moduleLoader.GetModuleByPath(filePath)
	if isModule {
		logger.Debugf("Refreshing module: %s", module)
		return r.RefreshModule(module)
	}

	logger.Debugf("File change noted but no refresh needed: %s", filePath)
	return true
}

// RefreshModule refreshes a specific module across all states
func (r *Runner) RefreshModule(moduleName string) bool {
	r.mu.RLock()
	defer r.mu.RUnlock()

	if !r.isRunning.Load() {
		return false
	}

	logger.Debugf("Refreshing module: %s", moduleName)

	success := true
	for _, state := range r.states {
		if state == nil || state.inUse.Load() {
			continue
		}

		if err := r.moduleLoader.RefreshModule(state.L, moduleName); err != nil {
			success = false
			logger.Debugf("Failed to refresh module %s in state %d: %v", moduleName, state.index, err)
		}
	}

	if success {
		logger.Debugf("Successfully refreshed module: %s", moduleName)
	}

	return success
}

// RunScriptFile loads, compiles and executes a Lua script file
func (r *Runner) RunScriptFile(filePath string) (*Response, error) {
	if !r.isRunning.Load() {
		return nil, ErrRunnerClosed
	}

	if _, err := os.Stat(filePath); os.IsNotExist(err) {
		return nil, fmt.Errorf("script file not found: %s", filePath)
	}

	content, err := os.ReadFile(filePath)
	if err != nil {
		return nil, fmt.Errorf("failed to read file: %w", err)
	}

	absPath, err := filepath.Abs(filePath)
	if err != nil {
		return nil, fmt.Errorf("failed to get absolute path: %w", err)
	}
	scriptDir := filepath.Dir(absPath)

	r.mu.Lock()
	prevScriptDir := r.scriptDir
	r.scriptDir = scriptDir
	r.moduleLoader.SetScriptDir(scriptDir)
	r.mu.Unlock()

	defer func() {
		r.mu.Lock()
		r.scriptDir = prevScriptDir
		r.moduleLoader.SetScriptDir(prevScriptDir)
		r.mu.Unlock()
	}()

	// Get state from pool
	var stateIndex int
	select {
	case stateIndex = <-r.statePool:
	case <-time.After(5 * time.Second):
		return nil, ErrTimeout
	}

	state := r.states[stateIndex]
	if state == nil {
		r.statePool <- stateIndex
		return nil, ErrStateNotReady
	}

	state.inUse.Store(true)

	defer func() {
		state.inUse.Store(false)
		if r.isRunning.Load() {
			select {
			case r.statePool <- stateIndex:
			default:
			}
		}
	}()

	// Compile script
	bytecode, err := state.L.CompileBytecode(string(content), filepath.Base(absPath))
	if err != nil {
		return nil, fmt.Errorf("compilation error: %w", err)
	}

	// Create simple context for script execution
	ctx := NewContext()
	defer ctx.Release()

	ctx.Set("_script_path", absPath)
	ctx.Set("_script_dir", scriptDir)

	// Execute script
	response, err := state.sandbox.Execute(state.L, bytecode, ctx)
	if err != nil {
		return nil, fmt.Errorf("execution error: %w", err)
	}

	return response, nil
}

// ApplyResponse applies a Response to a fasthttp.RequestCtx
func ApplyResponse(resp *Response, ctx *fasthttp.RequestCtx) {
	// Set status code
	ctx.SetStatusCode(resp.Status)

	// Set headers
	for name, value := range resp.Headers {
		ctx.Response.Header.Set(name, value)
	}

	// Set cookies
	for _, cookie := range resp.Cookies {
		ctx.Response.Header.SetCookie(cookie)
	}

	// Process the body based on its type
	if resp.Body == nil {
		return
	}

	// Check if Content-Type was manually set
	contentTypeSet := false
	for name := range resp.Headers {
		if strings.ToLower(name) == "content-type" {
			contentTypeSet = true
			break
		}
	}

	// Get a buffer from the pool
	buf := bytebufferpool.Get()
	defer bytebufferpool.Put(buf)

	// Set body based on type
	switch body := resp.Body.(type) {
	case string:
		if !contentTypeSet {
			ctx.Response.Header.SetContentType("text/plain; charset=utf-8")
		}
		ctx.SetBodyString(body)
	case []byte:
		if !contentTypeSet {
			ctx.Response.Header.SetContentType("text/plain; charset=utf-8")
		}
		ctx.SetBody(body)
	case map[string]any, map[any]any, []any, []float64, []string, []int, []map[string]any:
		// Marshal JSON
		if err := json.NewEncoder(buf).Encode(body); err == nil {
			if !contentTypeSet {
				ctx.Response.Header.SetContentType("application/json")
			}
			ctx.SetBody(buf.Bytes())
		} else {
			// Fallback to string representation
			if !contentTypeSet {
				ctx.Response.Header.SetContentType("text/plain; charset=utf-8")
			}
			ctx.SetBodyString(fmt.Sprintf("%v", body))
		}
	default:
		// Check if it's any other map or slice type
		typeStr := fmt.Sprintf("%T", body)
		if typeStr[0] == '[' || (len(typeStr) > 3 && typeStr[:3] == "map") {
			if err := json.NewEncoder(buf).Encode(body); err == nil {
				if !contentTypeSet {
					ctx.Response.Header.SetContentType("application/json")
				}
				ctx.SetBody(buf.Bytes())
			} else {
				if !contentTypeSet {
					ctx.Response.Header.SetContentType("text/plain; charset=utf-8")
				}
				ctx.SetBodyString(fmt.Sprintf("%v", body))
			}
		} else {
			// Default to string representation
			if !contentTypeSet {
				ctx.Response.Header.SetContentType("text/plain; charset=utf-8")
			}
			ctx.SetBodyString(fmt.Sprintf("%v", body))
		}
	}
}