"""
Terminal UI con scrollback usando Pyte
Versione semplificata e robusta
"""
import os
import sys
import signal
import shutil
from typing import Optional, Callable

try:
    import pyte
    PYTE_AVAILABLE = True
except ImportError:
    PYTE_AVAILABLE = False


class TerminalUI:
    """
    Terminal emulator con scrollback usando pyte.
    
    Features:
    - Scrollback buffer completo (10000 righe)
    - Output colorato con ANSI
    - Resize del terminale
    """
    
    def __init__(
        self,
        scrollback: int = 10000,
        prompt: str = "❯ "
    ):
        """
        Inizializza il terminale emulator.
        
        Args:
            scrollback: Numero di righe nello scrollback buffer
            prompt: Prompt da mostrare
        """
        if not PYTE_AVAILABLE:
            raise ImportError("pyte non è installato. Esegui: pip install pyte")
        
        self.scrollback = scrollback
        self.prompt = prompt
        
        # Dimensioni terminale
        self.term_rows, self.term_cols = shutil.get_terminal_size()
        self.term_rows = max(24, min(self.term_rows, 50))
        self.term_cols = max(80, min(self.term_cols, 120))
        
        # Crea lo screen pyte
        self.screen = pyte.Screen(self.term_cols, self.term_rows)
        self.screen.scroll_history = scrollback
        self.stream = pyte.Stream(self.screen)
        
        # Buffer per l'output completo (per scrollback)
        self.output_buffer: list = []
        
        # Flag per uscire
        self.running = False
        
        # Callback per l'agent
        self.agent_callback: Optional[Callable[[str], str]] = None
    
    def _redraw(self):
        """Ridisegna lo schermo"""
        # Clear schermo
        sys.stdout.write("\033[2J\033[H")
        
        # Header
        header = f"╔{'═' * (self.term_cols - 4)}╗"
        title = f" LangCode Agent - Terminal con Scrollback ({self.scrollback} righe) "
        header2 = f"║{title:^{self.term_cols - 4}}║"
        header3 = f"╚{'═' * (self.term_cols - 4)}╝"
        
        sys.stdout.write(f"\033[1;36m{header}\033[0m\n")
        sys.stdout.write(f"\033[1;36m{header2}\033[0m\n")
        sys.stdout.write(f"\033[1;36m{header3}\033[0m\n\n")
        
        # Mostra output buffer (solo le ultime righe che ci stanno)
        visible_lines = self.term_rows - 10  # Lascia spazio per prompt e status
        start_idx = max(0, len(self.output_buffer) - visible_lines)
        
        for line in self.output_buffer[start_idx:]:
            sys.stdout.write(line)
        
        # Status bar
        sys.stdout.write("\n")
        status_bar = f"\033[1;34m─" * (self.term_cols - 30) + f" Scrollback: {len(self.output_buffer)} righe\033[0m"
        sys.stdout.write(status_bar)
        
        # Prompt
        sys.stdout.write(f"\n\033[1;35m{self.prompt}\033[0m ")
        sys.stdout.flush()
    
    def _add_output(self, text: str, color: str = "32"):
        """Aggiunge output al buffer"""
        lines = text.split('\n')
        for line in lines:
            self.output_buffer.append(f"\033[1;{color}m{line}\033[0m\n")
    
    def start(self, agent_callback: Callable[[str], str]):
        """
        Avvia il terminale interattivo.
        
        Args:
            agent_callback: Funzione che riceve l'input e ritorna la risposta
        """
        self.agent_callback = agent_callback
        self.running = True
        
        # Registra signal handler per Ctrl+C
        def handle_sigint(signum, frame):
            sys.stdout.write("\n\033[1;33m👋 Arrivederci!\033[0m\n")
            sys.stdout.flush()
            self.running = False
            sys.exit(0)
        
        old_handler = signal.signal(signal.SIGINT, handle_sigint)
        
        try:
            # Mostra schermo iniziale
            self._redraw()
            
            while self.running:
                try:
                    # Leggi input
                    user_input = input()
                except EOFError:
                    break
                except KeyboardInterrupt:
                    continue
                
                if not user_input.strip():
                    continue
                
                if user_input.strip().lower() in ['/exit', '/quit']:
                    sys.stdout.write("\033[1;33m👋 Arrivederci!\033[0m\n")
                    break
                
                if user_input.strip() == '/clear':
                    self.output_buffer.clear()
                    self._redraw()
                    continue
                
                if user_input.strip() == '/help':
                    help_text = """
\033[1;36m╔══════════════════════════════════════════════════════╗\033[0m
\033[1;36m║                    COMANDI DISPONIBILI                ║\033[0m
\033[1;36m╠══════════════════════════════════════════════════════╣\033[0m
\033[1;36m║  /help   - Mostra questo messaggio                  ║\033[0m
\033[1;36m║  /clear  - Pulisci lo schermo                       ║\033[0m
\033[1;36m║  /exit   - Esci                                      ║\033[0m
\033[1;36m╚══════════════════════════════════════════════════════╝\033[0m
"""
                    self._add_output(help_text, "36")
                    self._redraw()
                    continue
                
                # Mostra comando utente
                self._add_output(f"👤 {user_input}", "36")
                self._redraw()
                
                # Mostra "thinking"
                self._add_output("🤔 Pensando...", "33")
                self._redraw()
                
                # Chiamata all'agent
                try:
                    response = agent_callback(user_input)
                    
                    # Rimuovi "thinking" e mostra risposta
                    if self.output_buffer and "🤔 Pensando..." in self.output_buffer[-1]:
                        self.output_buffer.pop()
                    
                    self._add_output(response, "32")
                except Exception as e:
                    self._add_output(f"❌ Errore: {str(e)}", "31")
                
                self._redraw()
                
        finally:
            signal.signal(signal.SIGINT, old_handler)
    
    def close(self):
        """Chiude il terminale"""
        self.running = False


def create_terminal_ui(
    scrollback: int = 10000,
    prompt: str = "❯ "
) -> TerminalUI:
    """Factory function per creare TerminalUI"""
    return TerminalUI(
        scrollback=scrollback,
        prompt=prompt
    )


# Test standalone
if __name__ == "__main__":
    def test_callback(text):
        return f"Ricevuto: {text}\n\nRisposta multi-linea:\n1. Prima\n2. Seconda\n3. Terza"
    
    print("Avvio TerminalUI di test...")
    term = create_terminal_ui()
    try:
        term.start(test_callback)
    except KeyboardInterrupt:
        print("\nUscito")