package at

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"strings"

	"github.com/mattn/go-isatty"
	"github.com/spf13/cobra"
	"golang.org/x/sys/unix"
	"golang.org/x/term"

	"kitty"
	"kitty/tools/base85"
	"kitty/tools/cli"
	"kitty/tools/crypto"
	"kitty/tools/utils"
)

func add_bool_set(cmd *cobra.Command, name string, short string, usage string) *bool {
	if short == "" {
		return cmd.Flags().Bool(name, false, usage)
	}
	return cmd.Flags().BoolP(name, short, false, usage)
}

type GlobalOptions struct {
	to_address, password       string
	to_address_is_from_env_var bool
}

var global_options GlobalOptions

func cut(a string, sep string) (string, string, bool) {
	idx := strings.Index(a, sep)
	if idx < 0 {
		return "", "", false
	}
	return a[:idx], a[idx+len(sep):], true
}

func get_pubkey(encoded_key string) (encryption_version string, pubkey []byte, err error) {
	if encoded_key == "" {
		encoded_key = os.Getenv("KITTY_PUBLIC_KEY")
		if encoded_key == "" {
			err = fmt.Errorf("Password usage requested but KITTY_PUBLIC_KEY environment variable is not available")
			return
		}
	}
	encryption_version, encoded_key, found := cut(encoded_key, ":")
	if !found {
		err = fmt.Errorf("KITTY_PUBLIC_KEY environment variable does not have a : in it")
		return
	}
	if encryption_version != kitty.RC_ENCRYPTION_PROTOCOL_VERSION {
		err = fmt.Errorf("KITTY_PUBLIC_KEY has unknown version, if you are running on a remote system, update kitty on this system")
		return
	}
	pubkey = make([]byte, base85.DecodedLen(len(encoded_key)))
	n, err := base85.Decode(pubkey, []byte(encoded_key))
	if err == nil {
		pubkey = pubkey[:n]
	}
	return
}

func simple_serializer(rc *utils.RemoteControlCmd) (ans []byte, err error) {
	ans, err = json.Marshal(rc)
	return
}

type serializer_func func(rc *utils.RemoteControlCmd) ([]byte, error)

var serializer serializer_func = simple_serializer

func create_serializer(password string, encoded_pubkey string) (ans serializer_func, err error) {
	if password != "" {
		encryption_version, pubkey, err := get_pubkey(encoded_pubkey)
		if err != nil {
			return nil, err
		}
		ans = func(rc *utils.RemoteControlCmd) (ans []byte, err error) {
			ec, err := crypto.Encrypt_cmd(rc, global_options.password, pubkey, encryption_version)
			ans, err = json.Marshal(ec)
			return
		}
	}
	return simple_serializer, nil
}

func send_rc_command(rc *utils.RemoteControlCmd, timeout float64) (err error) {
	serializer, err = create_serializer(global_options.password, "")
	if err != nil {
		return
	}
	d, err := serializer(rc)
	if err != nil {
		return
	}
	println(string(d))
	return
}

func get_password(password string, password_file string, password_env string, use_password string) (ans string, err error) {
	if use_password == "never" {
		return
	}
	if password != "" {
		ans = password
	}
	if ans == "" && password_file != "" {
		if password_file == "-" {
			if isatty.IsTerminal(os.Stdin.Fd()) {
				q, err := term.ReadPassword(int(os.Stdin.Fd()))
				if err != nil {
					ans = string(q)
				}
			} else {
				q, err := ioutil.ReadAll(os.Stdin)
				if err != nil {
					ans = strings.TrimRight(string(q), " \n\t")
				}
				ttyf, err := os.Open("/dev/tty")
				if err != nil {
					err = unix.Dup2(int(ttyf.Fd()), int(os.Stdin.Fd()))
					ttyf.Close()
				}
			}
		} else {
			q, err := ioutil.ReadFile(password_file)
			if err != nil {
				ans = strings.TrimRight(string(q), " \n\t")
			}
		}
	}
	if ans == "" && password_env != "" {
		ans = os.Getenv(password_env)
	}
	if ans == "" && use_password == "always" {
		return ans, fmt.Errorf("No password was found")
	}
	if len(ans) > 1024 {
		return ans, fmt.Errorf("Specified password is too long")
	}
	return ans, nil
}

var all_commands map[string]func(*cobra.Command) *cobra.Command = make(map[string]func(*cobra.Command) *cobra.Command)
var command_objects map[string]*cobra.Command = make(map[string]*cobra.Command)

func EntryPoint(tool_root *cobra.Command) *cobra.Command {
	var at_root_command *cobra.Command
	var to, password, password_file, password_env *string
	var use_password *cli.ChoicesVal
	at_root_command = cli.CreateCommand(&cobra.Command{
		Use:   "@ [global options] command [command options] [command args]",
		Short: "Control kitty remotely",
		Long:  "Control kitty by sending it commands. Set the allow_remote_control option in :file:`kitty.conf` or use a password, for this to work.",
		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
			if *to == "" {
				*to = os.Getenv("KITTY_LISTEN_ON")
				global_options.to_address_is_from_env_var = true
			}
			global_options.to_address = *to
			q, err := get_password(*password, *password_file, *password_env, use_password.Choice)
			global_options.password = q
			return err
		},
	})
	at_root_command.Annotations["options_title"] = "Global options"
	fs := at_root_command.PersistentFlags()

	to = fs.String("to", "",
		"An address for the kitty instance to control. Corresponds to the address given"+
			" to the kitty instance via the :option:`kitty --listen-on` option or the :opt:`listen_on` setting in :file:`kitty.conf`. If not"+
			" specified, the environment variable :envvar:`KITTY_LISTEN_ON` is checked. If that"+
			" is also not found, messages are sent to the controlling terminal for this"+
			" process, i.e. they will only work if this process is run within a kitty window.")

	password = fs.String("password", "",
		"A password to use when contacting kitty. This will cause kitty to ask the user"+
			" for permission to perform the specified action, unless the password has been"+
			" accepted before or is pre-configured in :file:`kitty.conf`.")

	password_file = fs.String("password-file", "rc-pass",
		"A file from which to read the password. Trailing whitespace is ignored. Relative"+
			" paths are resolved from the kitty configuration directory. Use - to read from STDIN."+
			" Used if no :option:`--password` is supplied. Defaults to checking for the"+
			" :file:`rc-pass` file in the kitty configuration directory.")

	password_env = fs.String("password-env", "KITTY_RC_PASSWORD",
		"The name of an environment variable to read the password from."+
			" Used if no :option:`--password-file` or :option:`--password` is supplied.")

	use_password = cli.Choices(fs, "use-password", "If no password is available, kitty will usually just send the remote control command without a password. This option can be used to force it to always or never use the supplied password.", "if-available", "always", "never")

	for cmd_name, reg_func := range all_commands {
		c := reg_func(at_root_command)
		at_root_command.AddCommand(c)
		command_objects[cmd_name] = c
		alias := *c
		alias.Use = "@" + alias.Use
		alias.Hidden = true
		tool_root.AddCommand(&alias)
	}
	return at_root_command
}