"""
Terminal UI con scrollback semplice
Usa input() standard + visualizzazione scrollback
"""
import os
import sys
import signal
from typing import Optional, Callable


class TerminalUI:
    """
    Terminal UI con scrollback.
    Uso semplice: input() per input, history buffer per scrollback.
    """
    
    def __init__(self, scrollback: int = 10000, prompt: str = "❯ "):
        self.scrollback = scrollback
        self.prompt = prompt
        
        # History buffer
        self.history: list = []
        
        # Callback
        self.agent_callback: Optional[Callable[[str], str]] = None
    
    def _print(self, text: str):
        """Stampa con colori base"""
        # Semplice - solo reset e bold
        if text.startswith("👤"):
            print(f"\033[1;36m{text}\033[0m")
        elif text.startswith("🤖"):
            print(f"\033[1;32m{text}\033[0m")
        elif text.startswith("🤔"):
            print(f"\033[1;33m{text}\033[0m")
        elif text.startswith("❌"):
            print(f"\033[1;31m{text}\033[0m")
        else:
            print(text)
    
    def _wrap_line(self, text: str, width: int = 80) -> list:
        """Wrap linea a width"""
        lines = []
        while len(text) > width:
            lines.append(text[:width])
            text = text[width:]
        if text:
            lines.append(text)
        return lines
    
    def _add_history(self, text: str):
        """Aggiunge a history"""
        self.history.append(text)
        while len(self.history) > self.scrollback:
            self.history.pop(0)
    
    def _show_history(self, lines: int = None):
        """Mostra ultime N linee di history"""
        if lines is None:
            # Determina righe visibili
            try:
                size = os.get_terminal_size()
                lines = size.lines - 5  # spazio per header, status, prompt
            except:
                lines = 20
        
        # Mostra ultime righe
        start = max(0, len(self.history) - lines)
        for line in self.history[start:]:
            self._print(line)
    
    def _process(self, cmd: str):
        """Processa comando"""
        if not cmd.strip():
            return
        
        self._add_history(f"👤 {cmd}")
        
        # Thinking
        print("\033[1;33m🤔 Pensando...\033[0m")
        
        try:
            resp = self.agent_callback(cmd)
            
            # Rimuovi thinking (print sopra con risposta)
            print("\033[2A\033[K", end="")  # move up 2, clear line
            
            # Stampa risposta
            for line in resp.split('\n'):
                if line.strip():
                    self._add_history(f"🤖 {line}")
                    self._print(f"🤖 {line}")
            
        except Exception as e:
            print("\033[2A\033[K", end="")
            err_msg = f"❌ {str(e)}"
            self._add_history(err_msg)
            self._print(err_msg)
    
    def _scroll_help(self):
        """Mostra aiuto scroll"""
        print("\n" + "=" * 60)
        print("SCROLLBACK - Premi q per uscire, frecce per navigare")
        print("=" * 60)
        print()
        
        # Paginator semplice
        page_size = 30
        start = 0
        total = len(self.history)
        
        while start < total:
            # Mostra pagina
            for i in range(start, min(start + page_size, total)):
                self._print(self.history[i])
            
            start += page_size
            
            if start < total:
                print()
                print(f"[{start}/{total} righe] - Premi ENTER per continuare, q per uscire")
                try:
                    choice = input().strip()
                    if choice.lower() == 'q':
                        break
                except:
                    break
        
        print()
        print("=" * 60)
        print("FINE SCROLLBACK")
        print("=" * 60)
    
    def start(self, agent_callback: Callable[[str], str]):
        """Avvia UI"""
        self.agent_callback = agent_callback
        
        # Signal handler
        def sigint_handler(signum, frame):
            print("\n\033[1;33m👋 Arrivederci!\033[0m\n")
            sys.exit(0)
        
        signal.signal(signal.SIGINT, sigint_handler)
        
        # Header
        print()
        print("\033[1;36m" + "=" * 50 + "\033[0m")
        print("\033[1;36m=\033[0m" + " " * 15 + "\033[1;33mLangCode Agent\033[0m" + " " * 15 + "\033[1;36m=\033[0m")
        print("\033[1;36m" + "=" * 50 + "\033[0m")
        print()
        print("digita /help per aiuto, /exit per uscire")
        print()
        
        while True:
            try:
                # Input
                user_input = input(f"\033[1;35m{self.prompt}\033[0m ").strip()
            except EOFError:
                break
            except KeyboardInterrupt:
                print("\n\033[1;33m👋 Arrivederci!\033[0m")
                break
            
            if not user_input:
                continue
            
            # Comandi speciali
            if user_input.lower() == '/exit':
                print("\033[1;33m👋 Arrivederci!\033[0m")
                break
            
            elif user_input.lower() == '/quit':
                print("\033[1;33m👋 Arrivederci!\033[0m")
                break
            
            elif user_input.lower() == '/help':
                print()
                print("\033[1;36m" + "=" * 40 + "\033[0m")
                print("COMANDI:")
                print("  /help           - Questo messaggio")
                print("  /clear          - Pulisci schermo")
                print("  /history        - Mostra cronologia")
                print("  /scroll         - Entra in scrollback")
                print("  /exit, /quit    - Esci")
                print()
                print("SCROLLBACK:")
                print("  /scroll         - Mostra tutto lo scrollback")
                print("  Frecce su/giù   - Naviga cronologia (in some terminals)")
                print()
                print("\033[1;36m" + "=" * 40 + "\033[0m")
                print()
                continue
            
            elif user_input.lower() == '/clear':
                os.system('clear' if os.name != 'nt' else 'cls')
                continue
            
            elif user_input.lower() == '/history':
                print()
                self._show_history(50)
                print()
                continue
            
            elif user_input.lower() == '/scroll':
                self._scroll_help()
                continue
            
            # Processa comando normale
            self._process(user_input)
            print()


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


if __name__ == "__main__":
    def test(text):
        lines = [f"Ricevuto: {text}"]
        lines += [f"Linea {i}: contenuto di esempio" for i in range(1, 31)]
        return "\n".join(lines)
    
    ui = create_terminal_ui()
    ui.start(test)