// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>

package at

import (
	"errors"
	"io"
	"os"
	"strings"

	"github.com/emmansun/base64"

	"github.com/kovidgoyal/kitty/tools/tty"
	"github.com/kovidgoyal/kitty/tools/tui/loop"
	"github.com/kovidgoyal/kitty/tools/utils"
	"github.com/kovidgoyal/kitty/tools/utils/shlex"
)

var end_reading_from_stdin = errors.New("end reading from STDIN")
var waiting_on_stdin = errors.New("wait for key events from STDIN")

func make_file_gen(f *os.File) func(*rc_io_data) (bool, error) {
	chunk := make([]byte, 2048)
	file_gen := func(io_data *rc_io_data) (bool, error) {
		n, err := f.Read(chunk)
		if err != nil && !errors.Is(err, io.EOF) {
			return false, err
		}
		set_payload_data(io_data, "base64:"+base64.StdEncoding.EncodeToString(chunk[:n]))
		return n == 0 || errors.Is(err, io.EOF), nil
	}
	return file_gen

}
func parse_send_text(io_data *rc_io_data, args []string) error {
	generators := make([]func(io_data *rc_io_data) (bool, error), 0, 1)

	if len(args) > 0 {
		for i, arg := range args {
			args[i] = shlex.ExpandANSICEscapes(arg)
		}
		text := strings.Join(args, " ")
		text_gen := func(io_data *rc_io_data) (bool, error) {
			limit := min(len(text), 2048)
			set_payload_data(io_data, "base64:"+base64.StdEncoding.EncodeToString(utils.UnsafeStringToBytes(text[:limit])))
			text = text[limit:]
			return len(text) == 0, nil
		}
		generators = append(generators, text_gen)
	}

	if options_send_text.FromFile != "" {
		f, err := os.Open(options_send_text.FromFile)
		if err != nil {
			return err
		}
		generators = append(generators, make_file_gen(f))
	}

	if options_send_text.Stdin {
		if tty.IsTerminal(os.Stdin.Fd()) {
			pending_key_events := make([]string, 0, 1)

			io_data.on_key_event = func(lp *loop.Loop, ke *loop.KeyEvent) error {
				ke.Handled = true
				if ke.MatchesPressOrRepeat("ctrl+d") {
					return end_reading_from_stdin
				}
				bs := "kitty-key:" + base64.StdEncoding.EncodeToString([]byte(ke.AsCSI()))
				pending_key_events = append(pending_key_events, bs)
				if ke.Text != "" {
					lp.QueueWriteString(ke.Text)
				} else if ke.MatchesPressOrRepeat("backspace") {
					lp.QueueWriteString("\x08\x1b[P")
				}
				return nil
			}

			key_gen := func(io_data *rc_io_data) (bool, error) {
				if len(pending_key_events) > 0 {
					payload := io_data.rc.Payload.(send_text_json_type)
					payload.Exclude_active = true
					io_data.rc.Payload = payload
					set_payload_data(io_data, pending_key_events[0])
					pending_key_events = pending_key_events[1:]
					return false, nil
				}
				return false, waiting_on_stdin
			}
			generators = append(generators, key_gen)
		} else {
			generators = append(generators, make_file_gen(os.Stdin))
		}
	}

	io_data.multiple_payload_generator = func(io_data *rc_io_data) (bool, error) {
		if len(generators) == 0 {
			set_payload_data(io_data, "text:")
			return true, nil
		}
		finished, err := generators[0](io_data)
		if finished {
			generators = generators[1:]
			finished = len(generators) == 0
		}
		return finished, err
	}

	return nil
}
