package samba

import (
	"bufio"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"time"

	"imuslab.com/arozos/mod/user"
	"imuslab.com/arozos/mod/utils"
)

/*

	Samba Share Warpper

	Note that this module only provide exposing of local disk / storage.
	This module do not handle providing the virtualized interface for samba

*/

type ShareManager struct {
	SambaConfigPath string //Config file for samba, aka smb.conf
	BackupDir       string //Backup directory for restoring previous config
	UserHandler     *user.UserHandler
}

type ShareConfig struct {
	Name       string
	Path       string
	ValidUsers []string
	ReadOnly   bool
	Browseable bool
	GuestOk    bool
}

func NewSambaShareManager() (*ShareManager, error) {
	if runtime.GOOS == "linux" {
		//Check if samba installed
		if !utils.FileExists("/bin/smbcontrol") {
			return nil, errors.New("samba not installed")
		}
	} else {
		return nil, errors.New("platform not supported")
	}
	return &ShareManager{
		SambaConfigPath: "/etc/samba/smb.conf",
		BackupDir:       "./backup",
	}, nil
}

// ReadSambaShares reads the smb.conf file and extracts all existing shares
func (s *ShareManager) ReadSambaShares() ([]ShareConfig, error) {
	file, err := os.Open(s.SambaConfigPath)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	var shares []ShareConfig
	var currentShare *ShareConfig

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())

		// Check for section headers
		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
			if currentShare != nil {
				shares = append(shares, *currentShare)
			}
			currentShare = &ShareConfig{
				Name: strings.Trim(line, "[]"),
			}
			continue
		}

		// Check if we are currently processing a share section
		if currentShare != nil {
			tokens := strings.SplitN(line, "=", 2)
			if len(tokens) != 2 {
				continue
			}
			key := strings.TrimSpace(tokens[0])
			value := strings.TrimSpace(tokens[1])

			switch key {
			case "path":
				currentShare.Path = value
			case "valid users":
				currentShare.ValidUsers = strings.Fields(value)
			case "read only":
				currentShare.ReadOnly = (value == "yes")
			case "browseable":
				currentShare.Browseable = (value == "yes")
			case "guest ok":
				currentShare.GuestOk = (value == "yes")
			}
		}
	}

	// Add the last share if there is one
	if currentShare != nil {
		shares = append(shares, *currentShare)
	}

	// Check for scanner errors
	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return shares, nil
}

// Check if a share name is already used
func (s *ShareManager) ShareNameExists(sharename string) (bool, error) {
	allShares, err := s.ReadSambaShares()
	if err != nil {
		return false, err
	}

	for _, share := range allShares {
		if strings.EqualFold(share.Name, sharename) {
			return true, nil
		}
	}

	return false, nil
}

// A basic filter to remove system created smb shares entry in the list
func (s *ShareManager) FilterSystemCreatedShares(shares []ShareConfig) []ShareConfig {
	namesToRemove := []string{"global", "homes", "printers", "print$"}
	filteredShares := []ShareConfig{}
	for _, share := range shares {
		if !utils.StringInArray(namesToRemove, share.Name) {
			filteredShares = append(filteredShares, share)
		}
	}
	return filteredShares
}

// CreateNewSambaShare converts the shareConfig to string and appends it to smb.conf if the share name does not already exist
func (s *ShareManager) CreateNewSambaShare(shareToCreate *ShareConfig) error {
	// Path to smb.conf
	smbConfPath := s.SambaConfigPath

	// Open the smb.conf file for reading
	file, err := os.Open(smbConfPath)
	if err != nil {
		return fmt.Errorf("failed to open smb.conf: %v", err)
	}
	defer file.Close()

	// Check if the share already exists
	scanner := bufio.NewScanner(file)
	shareExists := false
	shareNameSection := fmt.Sprintf("[%s]", shareToCreate.Name)
	for scanner.Scan() {
		if strings.TrimSpace(scanner.Text()) == shareNameSection {
			shareExists = true
			break
		}
	}

	if err := scanner.Err(); err != nil {
		return fmt.Errorf("failed to read smb.conf: %v", err)
	}

	if shareExists {
		return fmt.Errorf("share %s already exists", shareToCreate.Name)
	}

	// Convert ShareConfig to string
	shareConfigString := convertShareConfigToString(shareToCreate)

	// Open the smb.conf file for appending
	file, err = os.OpenFile(smbConfPath, os.O_APPEND|os.O_WRONLY, 0644)
	if err != nil {
		return fmt.Errorf("failed to open smb.conf for writing: %v", err)
	}
	defer file.Close()

	// Append the new share configuration
	if _, err := file.WriteString(shareConfigString); err != nil {
		return fmt.Errorf("failed to write to smb.conf: %v", err)
	}

	return nil
}

// RemoveSambaShareConfig removes the Samba share configuration from smb.conf
func (s *ShareManager) RemoveSambaShareConfig(shareName string) error {
	// Open the smb.conf file for reading
	file, err := os.Open(s.SambaConfigPath)
	if err != nil {
		return err
	}
	defer file.Close()

	// Create a temporary file to store modified smb.conf
	tmpFile, err := os.CreateTemp("", "smb.conf.*.tmp")
	if err != nil {
		return err
	}
	defer tmpFile.Close()

	// Create a scanner to read the smb.conf file line by line
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()

		// Check if the line contains the share name
		if strings.HasPrefix(line, "["+shareName+"]") {
			// Skip the lines until the next section
			for scanner.Scan() {
				if strings.HasPrefix(scanner.Text(), "[") {
					break
				}
			}
			continue // Skip writing the share configuration to the temporary file
		}

		// Write the line to the temporary file
		_, err := fmt.Fprintln(tmpFile, line)
		if err != nil {
			return err
		}
	}

	// Check for scanner errors
	if err := scanner.Err(); err != nil {
		return err
	}

	// Close the original smb.conf file
	if err := file.Close(); err != nil {
		return err
	}

	// Close the temporary file
	if err := tmpFile.Close(); err != nil {
		return err
	}

	// Replace the original smb.conf file with the temporary file
	if err := os.Rename(tmpFile.Name(), "/etc/samba/smb.conf"); err != nil {
		return err
	}

	return nil
}

// ShareExists checks if a given share name exists in smb.conf
func (s *ShareManager) ShareExists(shareName string) (bool, error) {
	// Path to smb.conf
	smbConfPath := s.SambaConfigPath

	// Open the smb.conf file for reading
	file, err := os.Open(smbConfPath)
	if err != nil {
		return false, fmt.Errorf("failed to open smb.conf: %v", err)
	}
	defer file.Close()

	// Check if the share already exists
	scanner := bufio.NewScanner(file)
	shareNameSection := fmt.Sprintf("[%s]", shareName)
	for scanner.Scan() {
		if strings.TrimSpace(scanner.Text()) == shareNameSection {
			return true, nil
		}
	}

	if err := scanner.Err(); err != nil {
		return false, fmt.Errorf("failed to read smb.conf: %v", err)
	}

	return false, nil
}

// Backup the current smb.conf to the backup folder
func (s *ShareManager) BackupSmbConf() error {
	// Define source and backup directory
	sourceFile := s.SambaConfigPath
	backupDir := s.BackupDir

	// Ensure the backup directory exists
	err := os.MkdirAll(backupDir, 0755)
	if err != nil {
		return fmt.Errorf("failed to create backup directory: %v", err)
	}

	// Create a timestamped backup filename
	timestamp := time.Now().Format("20060102_150405")
	backupFile := filepath.Join(backupDir, fmt.Sprintf("%s.smb.conf", timestamp))

	// Open the source file
	src, err := os.Open(sourceFile)
	if err != nil {
		return fmt.Errorf("failed to open source file: %v", err)
	}
	defer src.Close()

	// Create the destination file
	dst, err := os.Create(backupFile)
	if err != nil {
		return fmt.Errorf("failed to create backup file: %v", err)
	}
	defer dst.Close()

	// Copy the contents of the source file to the backup file
	_, err = io.Copy(dst, src)
	if err != nil {
		return fmt.Errorf("failed to copy file contents: %v", err)
	}

	return nil
}

// Add a new user to smb.conf share by name
func (s *ShareManager) AddUserToSambaShare(shareName, username string) error {
	// Open the smb.conf file for reading
	file, err := os.Open(s.SambaConfigPath)
	if err != nil {
		return fmt.Errorf("failed to open smb.conf: %v", err)
	}
	defer file.Close()

	var lines []string
	var insideShare bool
	var shareExists bool
	var userAdded bool

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()
		lines = append(lines, line)

		// Check if we are inside the specified share section
		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
			if insideShare && shareExists && !userAdded {
				// Add the username to the valid users list
				lines = append(lines, "   valid users = @"+username)
				userAdded = true
			}
			insideShare = false
		}

		if strings.TrimSpace(line) == fmt.Sprintf("[%s]", shareName) {
			insideShare = true
			shareExists = true
		}

		if insideShare && strings.HasPrefix(strings.TrimSpace(line), "valid users =") {
			// Check if the username already exists in the valid users list
			validUsersLine := strings.TrimSpace(line)
			if !strings.Contains(validUsersLine, username) {
				lines[len(lines)-1] = validUsersLine + ", @" + username
				userAdded = true
			}
		}
	}

	if err := scanner.Err(); err != nil {
		return fmt.Errorf("error reading smb.conf: %v", err)
	}

	if !shareExists {
		return fmt.Errorf("share [%s] not found in smb.conf", shareName)
	}

	if !userAdded {
		// If no valid users line was found, add the username to the share
		lines = append(lines, fmt.Sprintf("[%s]", shareName))
		lines = append(lines, "   valid users = @"+username)
	}

	// Write the updated configuration back to the smb.conf file
	outputFile, err := os.Create(s.SambaConfigPath)
	if err != nil {
		return fmt.Errorf("failed to open smb.conf for writing: %v", err)
	}
	defer outputFile.Close()

	writer := bufio.NewWriter(outputFile)
	for _, line := range lines {
		_, err := writer.WriteString(line + "\n")
		if err != nil {
			return fmt.Errorf("error writing to smb.conf: %v", err)
		}
	}
	writer.Flush()

	return nil
}