package lualibs

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"Moonshark/utils/color"
	"Moonshark/utils/logger"

	lru "git.sharkk.net/Go/LRU"
	luajit "git.sharkk.net/Sky/LuaJIT-to-Go"
	"github.com/golang/snappy"
)

// Global filesystem path (set during initialization)
var fsBasePath string

// Global file cache with compressed data
var fileCache *lru.LRUCache

// Cache entry info for statistics/debugging
type cacheStats struct {
	hits   int64
	misses int64
}

var stats cacheStats

// InitFS initializes the filesystem with the given base path
func InitFS(basePath string) error {
	if basePath == "" {
		return errors.New("filesystem base path cannot be empty")
	}

	// Create the directory if it doesn't exist
	if err := os.MkdirAll(basePath, 0755); err != nil {
		return fmt.Errorf("failed to create filesystem directory: %w", err)
	}

	// Store the absolute path
	absPath, err := filepath.Abs(basePath)
	if err != nil {
		return fmt.Errorf("failed to get absolute path: %w", err)
	}

	fsBasePath = absPath

	// Initialize file cache with 2000 entries (reasonable for most use cases)
	fileCache = lru.NewLRUCache(2000)

	logger.Infof("Filesystem is g2g! %s", color.Yellow(fsBasePath))
	return nil
}

// CleanupFS performs any necessary cleanup
func CleanupFS() {
	if fileCache != nil {
		fileCache.Clear()
		logger.Infof(
			"File cache cleared - %s hits, %s misses",
			color.Yellow(fmt.Sprintf("%d", stats.hits)),
			color.Red(fmt.Sprintf("%d", stats.misses)),
		)
	}
}

// ResolvePath resolves a given path relative to the filesystem base
// Returns the actual path and an error if the path tries to escape the sandbox
func ResolvePath(path string) (string, error) {
	if fsBasePath == "" {
		return "", errors.New("filesystem not initialized")
	}

	// Clean the path to remove any .. or . components
	cleanPath := filepath.Clean(path)

	// Replace backslashes with forward slashes for consistent handling
	cleanPath = strings.ReplaceAll(cleanPath, "\\", "/")

	// Remove any leading / or drive letter to make it relative
	cleanPath = strings.TrimPrefix(cleanPath, "/")

	// Remove drive letter on Windows (e.g. C:)
	if len(cleanPath) >= 2 && cleanPath[1] == ':' {
		cleanPath = cleanPath[2:]
	}

	// Ensure the path doesn't contain .. to prevent escaping
	if strings.Contains(cleanPath, "..") {
		return "", errors.New("path cannot contain .. components")
	}

	// Join with the base path
	fullPath := filepath.Join(fsBasePath, cleanPath)

	// Verify the path is still within the base directory
	if !strings.HasPrefix(fullPath, fsBasePath) {
		return "", errors.New("path escapes the filesystem sandbox")
	}

	return fullPath, nil
}

// getCacheKey creates a cache key from path and modification time
func getCacheKey(fullPath string, modTime time.Time) string {
	return fmt.Sprintf("%s:%d", fullPath, modTime.Unix())
}

// fsReadFile reads a file and returns its contents
func fsReadFile(state *luajit.State) int {
	if err := state.CheckExactArgs(1); err != nil {
		return state.PushError("fs.read_file: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.read_file: path must be string")
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.read_file: %v", err)
	}

	// Get file info for cache key and validation
	info, err := os.Stat(fullPath)
	if err != nil {
		return state.PushError("fs.read_file: %v", err)
	}

	// Create cache key with path and modification time
	cacheKey := getCacheKey(fullPath, info.ModTime())

	// Try to get from cache first
	if fileCache != nil {
		if cachedData, exists := fileCache.Get(cacheKey); exists {
			if compressedData, ok := cachedData.([]byte); ok {
				// Decompress cached data
				data, err := snappy.Decode(nil, compressedData)
				if err == nil {
					stats.hits++
					state.PushString(string(data))
					return 1
				}
				// Cache corruption - continue to disk read
			}
		}
	}

	// Cache miss or error - read from disk
	stats.misses++
	data, err := os.ReadFile(fullPath)
	if err != nil {
		return state.PushError("fs.read_file: %v", err)
	}

	// Compress and cache the data
	if fileCache != nil {
		compressedData := snappy.Encode(nil, data)
		fileCache.Put(cacheKey, compressedData)
	}

	state.PushString(string(data))
	return 1
}

// fsWriteFile writes data to a file
func fsWriteFile(state *luajit.State) int {
	if err := state.CheckExactArgs(2); err != nil {
		return state.PushError("fs.write_file: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.write_file: path must be string")
	}

	content, err := state.SafeToString(2)
	if err != nil {
		return state.PushError("fs.write_file: content must be string")
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.write_file: %v", err)
	}

	// Ensure the directory exists
	dir := filepath.Dir(fullPath)
	if err := os.MkdirAll(dir, 0755); err != nil {
		return state.PushError("fs.write_file: failed to create directory: %v", err)
	}

	if err := os.WriteFile(fullPath, []byte(content), 0644); err != nil {
		return state.PushError("fs.write_file: %v", err)
	}

	state.PushBoolean(true)
	return 1
}

// fsAppendFile appends data to a file
func fsAppendFile(state *luajit.State) int {
	if err := state.CheckExactArgs(2); err != nil {
		return state.PushError("fs.append_file: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.append_file: path must be string")
	}

	content, err := state.SafeToString(2)
	if err != nil {
		return state.PushError("fs.append_file: content must be string")
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.append_file: %v", err)
	}

	// Ensure the directory exists
	dir := filepath.Dir(fullPath)
	if err := os.MkdirAll(dir, 0755); err != nil {
		return state.PushError("fs.append_file: failed to create directory: %v", err)
	}

	file, err := os.OpenFile(fullPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return state.PushError("fs.append_file: %v", err)
	}
	defer file.Close()

	if _, err = file.Write([]byte(content)); err != nil {
		return state.PushError("fs.append_file: %v", err)
	}

	state.PushBoolean(true)
	return 1
}

// fsExists checks if a file or directory exists
func fsExists(state *luajit.State) int {
	if err := state.CheckExactArgs(1); err != nil {
		return state.PushError("fs.exists: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.exists: path must be string")
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.exists: %v", err)
	}

	_, err = os.Stat(fullPath)
	state.PushBoolean(err == nil)
	return 1
}

// fsRemoveFile removes a file
func fsRemoveFile(state *luajit.State) int {
	if err := state.CheckExactArgs(1); err != nil {
		return state.PushError("fs.remove_file: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.remove_file: path must be string")
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.remove_file: %v", err)
	}

	// Check if it's a directory
	info, err := os.Stat(fullPath)
	if err != nil {
		return state.PushError("fs.remove_file: %v", err)
	}

	if info.IsDir() {
		return state.PushError("fs.remove_file: cannot remove directory, use remove_dir instead")
	}

	if err := os.Remove(fullPath); err != nil {
		return state.PushError("fs.remove_file: %v", err)
	}

	state.PushBoolean(true)
	return 1
}

// fsGetInfo gets information about a file
func fsGetInfo(state *luajit.State) int {
	if err := state.CheckExactArgs(1); err != nil {
		return state.PushError("fs.get_info: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.get_info: path must be string")
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.get_info: %v", err)
	}

	info, err := os.Stat(fullPath)
	if err != nil {
		return state.PushError("fs.get_info: %v", err)
	}

	fileInfo := map[string]any{
		"name":     info.Name(),
		"size":     info.Size(),
		"mode":     int(info.Mode()),
		"mod_time": info.ModTime().Unix(),
		"is_dir":   info.IsDir(),
	}

	if err := state.PushValue(fileInfo); err != nil {
		return state.PushError("fs.get_info: %v", err)
	}

	return 1
}

// fsMakeDir creates a directory
func fsMakeDir(state *luajit.State) int {
	if err := state.CheckMinArgs(1); err != nil {
		return state.PushError("fs.make_dir: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.make_dir: path must be string")
	}

	perm := os.FileMode(0755)
	if state.GetTop() >= 2 {
		if permVal, err := state.SafeToNumber(2); err == nil {
			perm = os.FileMode(permVal)
		}
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.make_dir: %v", err)
	}

	if err := os.MkdirAll(fullPath, perm); err != nil {
		return state.PushError("fs.make_dir: %v", err)
	}

	state.PushBoolean(true)
	return 1
}

// fsListDir lists the contents of a directory
func fsListDir(state *luajit.State) int {
	if err := state.CheckExactArgs(1); err != nil {
		return state.PushError("fs.list_dir: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.list_dir: path must be string")
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.list_dir: %v", err)
	}

	info, err := os.Stat(fullPath)
	if err != nil {
		return state.PushError("fs.list_dir: %v", err)
	}

	if !info.IsDir() {
		return state.PushError("fs.list_dir: not a directory")
	}

	files, err := os.ReadDir(fullPath)
	if err != nil {
		return state.PushError("fs.list_dir: %v", err)
	}

	// Create array of filenames
	filenames := make([]string, len(files))
	for i, file := range files {
		filenames[i] = file.Name()
	}

	if err := state.PushValue(filenames); err != nil {
		return state.PushError("fs.list_dir: %v", err)
	}

	return 1
}

// fsRemoveDir removes a directory
func fsRemoveDir(state *luajit.State) int {
	if err := state.CheckMinArgs(1); err != nil {
		return state.PushError("fs.remove_dir: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.remove_dir: path must be string")
	}

	recursive := false
	if state.GetTop() >= 2 {
		recursive = state.ToBoolean(2)
	}

	fullPath, err := ResolvePath(path)
	if err != nil {
		return state.PushError("fs.remove_dir: %v", err)
	}

	info, err := os.Stat(fullPath)
	if err != nil {
		return state.PushError("fs.remove_dir: %v", err)
	}

	if !info.IsDir() {
		return state.PushError("fs.remove_dir: not a directory")
	}

	if recursive {
		err = os.RemoveAll(fullPath)
	} else {
		err = os.Remove(fullPath)
	}

	if err != nil {
		return state.PushError("fs.remove_dir: %v", err)
	}

	state.PushBoolean(true)
	return 1
}

// fsJoinPaths joins path components
func fsJoinPaths(state *luajit.State) int {
	if err := state.CheckMinArgs(1); err != nil {
		return state.PushError("fs.join_paths: %v", err)
	}

	components := make([]string, state.GetTop())
	for i := 1; i <= state.GetTop(); i++ {
		comp, err := state.SafeToString(i)
		if err != nil {
			return state.PushError("fs.join_paths: all arguments must be strings")
		}
		components[i-1] = comp
	}

	result := filepath.Join(components...)
	result = strings.ReplaceAll(result, "\\", "/")

	state.PushString(result)
	return 1
}

// fsDirName returns the directory portion of a path
func fsDirName(state *luajit.State) int {
	if err := state.CheckExactArgs(1); err != nil {
		return state.PushError("fs.dir_name: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.dir_name: path must be string")
	}

	dir := filepath.Dir(path)
	dir = strings.ReplaceAll(dir, "\\", "/")

	state.PushString(dir)
	return 1
}

// fsBaseName returns the file name portion of a path
func fsBaseName(state *luajit.State) int {
	if err := state.CheckExactArgs(1); err != nil {
		return state.PushError("fs.base_name: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.base_name: path must be string")
	}

	base := filepath.Base(path)
	state.PushString(base)
	return 1
}

// fsExtension returns the file extension
func fsExtension(state *luajit.State) int {
	if err := state.CheckExactArgs(1); err != nil {
		return state.PushError("fs.extension: %v", err)
	}

	path, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("fs.extension: path must be string")
	}

	ext := filepath.Ext(path)
	state.PushString(ext)
	return 1
}

// RegisterFSFunctions registers filesystem functions with the Lua state
func RegisterFSFunctions(state *luajit.State) error {
	if err := state.RegisterGoFunction("__fs_read_file", fsReadFile); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_write_file", fsWriteFile); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_append_file", fsAppendFile); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_exists", fsExists); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_remove_file", fsRemoveFile); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_get_info", fsGetInfo); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_make_dir", fsMakeDir); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_list_dir", fsListDir); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_remove_dir", fsRemoveDir); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_join_paths", fsJoinPaths); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_dir_name", fsDirName); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_base_name", fsBaseName); err != nil {
		return err
	}
	if err := state.RegisterGoFunction("__fs_extension", fsExtension); err != nil {
		return err
	}

	return nil
}