package server

import (
	"bytes"
	"io"
	"io/ioutil"
	"log"
	"math/rand"
	"os"
	"strconv"
	"strings"

	"github.com/spf13/viper"
	"github.com/zyxar/image2ascii/ascii"
)

func randSeq(n int) string {
	var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
	b := make([]rune, n)
	for i := range b {
		b[i] = letters[rand.Intn(len(letters))]
	}
	return string(b)
}

// UploadFile uploads a file to the server
func UploadFile(c Client, filename string) error {
	f, err := os.Create(MakePathFromStringStack(c.Stack()) + filename)
	if err != nil {
		return err
	}
	defer f.Close()

	io.Copy(f, c.Connection())

	return nil
}

// SendASCIIPic sends an image as ascii text to the client.
func SendASCIIPic(c Client, path string) error {
	f, err := os.Open(MakePathFromStringStack(c.Stack()) + path)
	if err != nil {
		log.Println(err)
		return err
	}
	defer f.Close()
	opt := ascii.Options{
		Width:  viper.GetInt("pic.x"),
		Height: viper.GetInt("pic.y"),
		Color:  viper.GetBool("pic.color"),
		Invert: false,
		Flipx:  false,
		Flipy:  false}

	a, err := ascii.Decode(f, opt)
	if err != nil {
		log.Println(err)
		return err
	}
	_, err = a.WriteTo(c.Connection())
	return err
}

// GetFile sends the file to the client and returns true if it succeeds and false otherwise.
// it also returns the total number of send bytes.
func GetFile(c Client, path string) (int64, error) {
	fileName, sanitized := sanitizeFilePath(path)
	if sanitized {
		return 0, ErrSlashNotAllowed
	}

	file, err := os.Open(MakePathFromStringStack(c.Stack()) + fileName)
	if err != nil {
		log.Println(err.Error())
		return 0, err
	}
	defer file.Close()

	totalSend, err := io.Copy(c.Connection(), file)

	return totalSend, err
}

func sanitizeFilePath(path string) (string, bool) {
	var fileName string
	var sanitized bool
	// Make sure the user can't request any files on the system.
	lastForwardSlash := strings.LastIndex(path, "/")
	if lastForwardSlash != -1 {
		// Eliminate the last forward slash i.e ../../asdas will become asdas
		fileName = path[lastForwardSlash+1:]
		sanitized = true
	} else {
		fileName = path
		sanitized = false
	}
	return fileName, sanitized
}

// ListFiles list the files from path and sends them to the connection
func ListFiles(c Client) error {

	files, err := ioutil.ReadDir(MakePathFromStringStack(c.Stack()))
	if err != nil {
		return err
	}

	buffer := bytes.NewBufferString("Directory Mode Size LastModified Name\n")
	for _, f := range files {
		buffer.WriteString(strconv.FormatBool(f.IsDir()) + " " + string(f.Mode().String()) + " " +
			strconv.FormatInt(f.Size(), 10) + " " + f.ModTime().String() + " " + string(f.Name()) + " " + "\n")
	}

	_, err = c.Connection().Write(buffer.Bytes())
	return err
}

// ClearScreen cleans the client's screen by sending clear to the terminal.
func ClearScreen(c Client) error {
	// Ansi clear: 1b 5b 48 1b 5b 4a
	// clear | hexdump -C
	var b = []byte{0x1b, 0x5b, 0x48, 0x1b, 0x5b, 0x4a}
	_, err := c.Connection().Write(b)

	return err
}

// ChangeDirectoryCommand changes the directory to the given directory
func ChangeDirectoryCommand(c Client, directory string) error {
	var err error
	path, sanitized := sanitizeFilePath(directory)
	if sanitized {
		return ErrSlashNotAllowed
	}

	if path == "." {
		err = nil
	} else if path == ".." {
		err = ChangeDirectoryToPrevious(c.Stack())
	} else {
		err = ChangeDirectory(c.Stack(), path)
	}

	return err
}

// ShowHelp writes the help text to the client.
func ShowHelp(c Client) error {
	var helpText = `
The available commands are:
get <filename> - Download the requested filename.
ls             - List the files in the current directory.
cd             - Changes the directory.
clear          - Clear the screen.
exit           - Close the connection with the server.c
pic            - Returns the ascii art of an image. :-)
`
	_, err := c.Connection().Write([]byte(helpText))

	return err
}