package shell

import (
	"context"
	"fmt"
	"io"

	"git.t-juice.club/torjus/oubliette/internal/storage"
)

// Shell is the interface that all honeypot shell implementations must satisfy.
type Shell interface {
	Name() string
	Description() string
	Handle(ctx context.Context, sess *SessionContext, rw io.ReadWriteCloser) error
}

// SessionContext carries metadata about the current SSH session.
type SessionContext struct {
	SessionID     string
	Username      string
	RemoteAddr    string
	ClientVersion string
	Store         storage.Store
	ShellConfig   map[string]any
	CommonConfig  ShellCommonConfig
}

// ShellCommonConfig holds settings shared across all shell types.
type ShellCommonConfig struct {
	Hostname string
	Banner   string
	FakeUser string // override username in prompt; empty = use authenticated user
}

// ReadLine reads a line of input byte-by-byte, handling backspace, Ctrl+C, and Ctrl+D.
func ReadLine(ctx context.Context, rw io.ReadWriter) (string, error) {
	var buf []byte
	b := make([]byte, 1)

	for {
		select {
		case <-ctx.Done():
			return "", ctx.Err()
		default:
		}

		n, err := rw.Read(b)
		if err != nil {
			return "", err
		}
		if n == 0 {
			continue
		}

		ch := b[0]
		switch {
		case ch == '\r' || ch == '\n':
			fmt.Fprint(rw, "\r\n")
			return string(buf), nil

		case ch == 4: // Ctrl+D
			if len(buf) == 0 {
				return "", io.EOF
			}

		case ch == 3: // Ctrl+C
			fmt.Fprint(rw, "^C\r\n")
			return "", nil

		case ch == 127 || ch == 8: // DEL or Backspace
			if len(buf) > 0 {
				buf = buf[:len(buf)-1]
				fmt.Fprint(rw, "\b \b")
			}

		case ch == 27: // ESC - start of escape sequence
			// Read and discard the rest of the escape sequence.
			// Most are 3 bytes: ESC [ X (arrow keys, etc.)
			next := make([]byte, 1)
			if n, _ := rw.Read(next); n > 0 && next[0] == '[' {
				rw.Read(next) // read the final byte
			}

		case ch >= 32 && ch < 127: // printable ASCII
			buf = append(buf, ch)
			rw.Write([]byte{ch})
		}
	}
}