<?php

namespace NoccyLabs\React\Shell;

use Evenement\EventEmitterInterface;
use Evenement\EventEmitterTrait;
use PgSql\Lob;
use React\EventLoop\Loop;
use React\Stream\ReadableResourceStream;
use React\Stream\ReadableStreamInterface;
use React\Stream\WritableResourceStream;
use React\Stream\WritableStreamInterface;

class Shell implements WritableStreamInterface, EventEmitterInterface
{
    use EventEmitterTrait;

    private ReadableStreamInterface $istream;

    private WritableStreamInterface $ostream;

    private string $oldStty;

    private bool $isPrompting = false;

    private string $buffer = '';

    private int $cursorPos = 0;

    private int $termWidth = 0;

    private int $scrollOffset = 0;

    private string $prompt = '';

    private int $promptWidth = 0;

    private ?string $promptStyle = "2";

    private ?string $inputStyle = "1";

    private array $history = [];

    private ?int $historyIndex = null;

    private ?string $historyCache = null;

    private int $maxHistory = 100;

    public function __construct(?ReadableStreamInterface $input=null, ?WritableStreamInterface $output=null)
    {
        $this->istream = $input ?? new ReadableResourceStream(STDIN);
        $this->ostream = $output ?? new WritableResourceStream(STDOUT);

        $this->istream->on('data', $this->handleInput(...));
        
        Loop::futureTick($this->redrawPrompt(...));

        Loop::addSignal(SIGINT, function () {
            Loop::futureTick(function () {
                if (count($this->listeners("abort")) == 0)
                    $this->end("Received ^C\n");
                else
                    $this->emit("abort", [ $this ]);
            });
        });
        // Loop::addSignal(SIGWINCH, function () {
        //     Loop::futureTick($this->redrawPrompt(...));
        // });

        // Save terminal settings and disable inupt buffering
        $this->oldStty = exec("stty -g");
        exec("stty -icanon min 1 time 0 -echo");
    }

    public function  __destruct()
    {
        // Restore the terminal to regular buffered mode
        exec("stty {$this->oldStty}");
    }

    public function setPrompt(string $prompt): void
    {
        $this->prompt = $prompt;
        $this->promptWidth = mb_strlen(preg_replace('<(\e\[[0-9;]+?m)>m', '', $this->prompt));
    }

    private function handleInput($v) {

        switch ($v) {

            case "\x03":
                if (count($this->listeners("abort")) == 0)
                    $this->end("Received ^C\n");
                else
                    $this->emit("abort", [ $this ]);

            case "\n":
                // Update the history
                array_unshift($this->history, $this->buffer);
                while (count($this->history) > $this->maxHistory) array_pop($this->history);
                $this->historyIndex = 0;
                // Parse and empty the buffer
                $buffer = str_getcsv(trim($this->buffer), " ");
                $this->buffer = '';
                $this->cursorPos = 0;
                $this->scrollOffset = 0;
                $this->ostream->write("\n");
                if ($buffer[0] !== NULL) {
                    $this->emit('input', [ $buffer, $this ]);
                } else {
                    $this->redrawPrompt();
                }
                break;

            case "\x7F": // backspace
                if ($this->cursorPos < 1) return;
                $this->buffer = mb_substr($this->buffer, 0, $this->cursorPos - 1) .
                                mb_substr($this->buffer, $this->cursorPos);
                $this->cursorPos--;
                break;

            case "\e[3~": // delete
                $this->buffer = mb_substr($this->buffer, 0, $this->cursorPos) .
                                mb_substr($this->buffer, $this->cursorPos + 1);
                break;
    
            case "\e[A": // up
                if ($this->historyIndex === null && count($this->history) > 0) {
                    $this->historyCache = $this->buffer;
                    $this->historyIndex = 0;
                    $this->buffer = $this->history[$this->historyIndex]??'';
                } elseif ($this->historyIndex < count($this->history) - 1) {
                    $this->historyIndex++;
                    $this->buffer = $this->history[$this->historyIndex]??'';
                }
                $this->cursorPos = mb_strlen($this->buffer);
                break;
            case "\e[B": // down
                if ($this->historyIndex === null) {
                    break;
                } elseif ($this->historyIndex === 0) {
                    $this->historyIndex = null;
                    $this->buffer = $this->historyCache;
                    $this->historyCache = null;
                } else {
                    $this->historyIndex--;
                    $this->buffer = $this->history[$this->historyIndex]??'';
                }
                $this->cursorPos = mb_strlen($this->buffer);
                break;

            case "\e[H": // home
                $this->cursorPos = 0;
                break;
            case "\e[F": // end
                $this->cursorPos = mb_strlen($this->buffer);
                break;
        
            case "\e[D": // left
                if ($this->cursorPos < 1) return;
                $this->cursorPos--;                
                break;

            case "\e[C": // right
                if ($this->cursorPos >= mb_strlen($this->buffer)) return;
                $this->cursorPos++;
                break;

            default:
                if (mb_strlen($v) == 1 && mb_ord($v) >= 32) {
                    $this->buffer = mb_substr($this->buffer, 0, $this->cursorPos) .
                                    $v . 
                                    mb_substr($this->buffer, $this->cursorPos);
                    $this->cursorPos++;
                } else {
                    $this->ostream->write("\e[7m".substr($v,2)."\e[27m");
                    return;
                }
        }
        if ($this->cursorPos < $this->scrollOffset) {
            $this->scrollOffset = $this->cursorPos;
        }
        $availWidth = $this->termWidth - $this->promptWidth;
        if ($this->cursorPos - $this->scrollOffset >= $availWidth) {
            $this->scrollOffset = abs($availWidth - $this->cursorPos) + 2;
        }
        $this->updatePrompt();
    }


    public function write($data)
    {
        $this->hidePrompt();
        $this->ostream->write($data);
        Loop::futureTick($this->redrawPrompt(...));
        return true;
    }

    public function isWritable()
    {
        return true;
    }

    public function end($data = null)
    {
        $this->hidePrompt();
        $this->ostream->write($data);
        $this->emit('end', [ $this ]);
        Loop::futureTick(fn() => exit(1));
    }

    public function close()
    {
        $this->hidePrompt();
        $this->emit('end', [ $this ]);
        Loop::futureTick(fn() => exit(0));
    }


    public function hidePrompt(): void
    {
        if (!$this->isPrompting) return;

        $this->isPrompting = false;

        $this->ostream->write("\r\e[K");
    }

    public function redrawPrompt(): void
    {
        $this->emit("prompt", [ $this ]);

        $this->termWidth = intval(exec("tput cols"));
        $this->isPrompting = true;

        $this->updatePrompt();
    }

    private function updatePrompt(): void
    {
        if (!$this->isPrompting) return;

        $pos = $this->promptWidth + $this->cursorPos - $this->scrollOffset + 1;

        $obuf = "\r" . "\e[{$this->promptStyle}m" . $this->prompt . "\e[0m";
        $ostr = mb_substr($this->buffer, $this->scrollOffset) . " ";
        $ostr = mb_substr($ostr, 0, $this->termWidth - $this->promptWidth);
        $obuf .= "\e[{$this->inputStyle}m" . $ostr . "\e[K\e[0m\e[" . $pos . "G";

        $this->ostream->write($obuf);
    }
}