<?php

namespace NoccyLabs\Shell;

class LineRead
{

    const STATE_IDLE = 0;
    const STATE_READ = 1;

    protected $state = self::STATE_IDLE;
    
    protected $prompt = "cmd:>";
    
    protected $buffer = null;

    protected $history = [];
    
    protected $posHistory = 0;
    
    protected $posCursor = 0;
    
    protected $posScroll = 0;
    
    protected $termWidth = 0;
    
    protected $sttyOld;

    public function __construct()
    {
        stream_set_blocking(STDIN, false);
        $this->sttyOld = exec('stty -g');
        exec('stty raw -echo isig');
    }
    
    public function __destruct()
    {
        exec('stty {$this->sttyOld}');
    }

    public function update()
    {
        if ($this->state == self::STATE_IDLE) {
            $this->state = self::STATE_READ;
            $this->redraw();
        }
        $buffer = $this->handleInput();
        return $buffer;
    }

    public function erase()
    {
        fprintf(STDOUT, "\r\e[0m\e[2K");
    }

    public function redraw()
    {
        $prompt = $this->prompt;
        $buffer = $this->buffer;
        $cursor = strlen($this->prompt) + 2 + $this->posCursor - $this->posScroll;
        fprintf(STDOUT, "\r\e[2K\e[36;1;4m%s\e[37;24m %s\e[%dG\e[0m", $prompt, $buffer, $cursor);
    }
    
    protected function handleInput()
    {
        static $keyBuffer;
        $readBuf = fread(STDIN, 32);
        $keyBuffer .= $readBuf;
        $update = false;
        $returnBuffer = null;
        while (strlen($keyBuffer)>0) {
            if ($keyBuffer[0] == "\e") {
                if ($keyBuffer[1] == "[") {
                    $ctrlChar = substr($keyBuffer, 0,3);
                    $keyBuffer = substr($keyBuffer, 3);
                    $this->parseControlCode($ctrlChar);
                }
            } else {
                $keyChar = $keyBuffer[0];
                $keyCode = ord($keyChar);
                $keyBuffer = substr($keyBuffer, 1);
                if (($keyCode >= 32) && ($keyCode < 127)) {
                    $edBuffer = substr($this->buffer, 0, $this->posCursor) . $keyChar . substr($this->buffer, $this->posCursor);
                    $this->posCursor++;
                    $this->buffer = $edBuffer;
                    $update = true;
                } elseif ($keyCode == 127) {
                    if ($this->posCursor > 0) {
                        $this->posCursor--;
                        $edBuffer = substr($this->buffer, 0, $this->posCursor) . substr($this->buffer, $this->posCursor+1);
                        $this->buffer = $edBuffer;
                        $update = true;
                    }
                } elseif ($keyCode == 13) {
                    $returnBuffer = $this->buffer;
                    $this->buffer = null;
                    $this->posCursor = 0;
                    printf("\n");
                    $this->state = self::STATE_IDLE;
                }
            }
        }
        if ($update) {
            $this->redraw();
        }
        return $returnBuffer;
    }
    
    protected function parseControlCode($code)
    {
        switch ($code) {
            case "\e[D":
                $this->posCursor = max($this->posCursor-1,0);
                $this->redraw();
                break;
            case "\e[C":
                $this->posCursor = min($this->posCursor+1,strlen($this->buffer));
                $this->redraw();
                break;
            case "\e[H":
                $this->posCursor = 0;
                $this->redraw();
                break;
            case "\e[F":
                $this->posCursor = strlen($this->buffer);
                $this->redraw();
                break;
            case "\e[A": // up
            case "\e[B": // down
                break;
            default:
                fprintf(STDERR, "\n%s\n", substr($code,1));
        }
    }

}