TODO.TXT to VTODO ICS (iCalendar) file

todotxt2vtodo.php

<?php

// CB's Todo.txt to ics script
// from https://chrisbeckstrom.com/2018/06/07/how-to-generate-a-calendar-from-your-todo-txt-file/
// shunf4 modified
// goes through todo.txt and generates a calendar
// 2018-06-06
//
// HOW TO USE THIS
// this script parses a file in the todo.txt format and generates an ics file
// the ics file will have a series of VTODO
// you can load this calendar into email or calendar application that supports
// to-do lists (tasks)  (like Fastmail's calendar) or other systems
//
// WHY?
// I love todo.txt but sometimes it's tough to get a picture of what I really
// need to do. Sticking my dated tasks on a calendar really helps me!

// inspiration from here:
// https://gist.github.com/jakebellacera/635416

// hide all errors, we don't want them mucking up our ics output
error_reporting(0);
ini_set('display_errors', 0);

if ($_SERVER['REQUEST_METHOD'] !== "GET") {
	http_response_code(405);
	die("Not Allowed");
}

// where does the todo.txt file live?
$todopath = "/path/to/TODO.TXT";

// timezone of date strings in $todopath
$todoTimezone = new DateTimeZone('+0800');

// load the todo file, give us an error if we can't open it
$todofile = fopen($todopath, "r") or die("Unable to open todo file!");

// calendar file top stuff
$ical = "BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN";

// iterate through each line of the file
while(!feof($todofile)) {	  
	$line = fgets($todofile);
	$trimmedLine = trim($line);
	if ($trimmedLine === "") {
		continue;
	}

	//print "line contains DUE! doing stuff <br>";
	// explode the string into an array
	$array = explode(" ", $line);
	// iterate through each word and figure out what it is
	// i.e. a due date, a context, a project, threshold, hidden, etc.
	$done = false;
	$indexOfFirstDate = 0;
	$indexOfSecondDate = -10;
	$dateDone = "";
	$dateDoneOrig = "";
	$dateAdded = "";
	$dateAddedOrig = "";
	$dateDue = "";
	$categories = "";
	$priority = "";
	$priorityOrig = "";
	$url = "";
	$project = "";
	$processingAdvancedWords = true;
	foreach ($array as $i=>&$word){
		$word = trim($word, "\r\n");
		$word = str_replace("\r", "", $word);
		$word = str_replace("\n", " ", $word);
		$tryDate = DateTime::createFromFormat('!Y-m-d', $word, $todoTimezone);
		$isCurrentWordAdvancedWord = false;
		if ($tryDate !== FALSE) {
			$tryDate->setTimezone(new DateTimeZone("UTC"));
			//echo "---this word is a date! <br>";
			if ($i === $indexOfFirstDate) {
				$dateAdded = $tryDate->format("Ymd\THis\Z");
				$dateAddedOrig = $word;
				$indexOfSecondDate = $indexOfFirstDate + 1;
				$isCurrentWordAdvancedWord = true;
			} elseif ($i === $indexOfSecondDate) {
				$dateDone = $dateAdded;
				$dateDoneOrig = $dateAddedOrig;
				$dateAdded = $tryDate->format("Ymd\THis\Z");
				$dateAddedOrig = $word;
				$isCurrentWordAdvancedWord = true;
			}
		}
		$trimmedWord = trim($word);
		if ($trimmedWord === "x" && $i === 0) {
			$done = true;
			$indexOfFirstDate += 1;
			$indexOfSecondDate += 1;
			$isCurrentWordAdvancedWord = true;
		}
		if ($processingAdvancedWords && strlen($trimmedWord) === 3 && substr($trimmedWord, 0, 1) === "(" && substr($trimmedWord, 2, 1) === ")" && substr($trimmedWord, 1, 1) >= "A" && substr($trimmedWord, 1, 1) <= "Z") {
			$priorityOrig = $trimmedWord;
			$priority = strval(ord(substr($trimmedWord, 1, 1)) - ord("A") + 1);
			$indexOfFirstDate += 1;
			$indexOfSecondDate += 1;
			$isCurrentWordAdvancedWord = true;
		}
		//print "value: $value <br>";
		// IF WORD CONTAINS "due:"
		if (strpos($word, "due:") === 0) {
			$due = substr($word, 4);
			$due = trim($due);
			$dateDue = DateTime::createFromFormat('!Y-m-d', $due, $todoTimezone)->setTimezone(new DateTimeZone("UTC"))->format("Ymd\THis\Z");
		}
		// IF WORD CONTAINS "@"
		if (strpos($word, "@") === 0) {
			//echo "--- this word has a context! <br>";
			$context = str_replace("\n","",$word);
		}

		// IF WORD CONTAINS "+"
		if (strpos($word, "+") === 0) {
			//echo "--- this word has a project! <br>";
			$project = $word;
			$projectName = substr($project, 1);
			$categories .= "CATEGORIES:$projectName\n";
		}

		// IF WORD CONTAINS "t:"
		if (strpos($word, "t:") === 0) {
			//echo "--- this word contains t: <br>";
			$threshold = $word;
		}

		// IF WORD CONTAINS "h:"
		if (strpos($word, "h:") === 0) {
			//echo "--- this word contains h: <br>";
			$hide = $word;
		}
		// IS THIS A URL?
		if (strpos($word, "http://") === 0 || strpos($word, "https://") === 0) {
			//echo "--- this word is a URL!<br>";
			$url = $word;
		}
		
		if ($isCurrentWordAdvancedWord === false) {
			$processingAdvancedWords = false;
		}
	}

	// put together a summary
	// summary: the name of the calendar event
	// description: more info when you click on the calendar event
	
	// BUILD THE SUMMARY
	// +projectname something something
	$summary = $line;
	if (strpos($summary, "x ") === 0) {
		$summary = substr($summary, 2);
	}
	// get rid of due date
	$summary = (str_replace("due:".$due,"",$summary));
	// get rid of the added&done date
	$summary = (str_replace($dateAddedOrig,"",$summary));
	$summary = (str_replace($dateDoneOrig,"",$summary));
	$summary = (str_replace($priorityOrig,"",$summary));
	// get rid of the context
	// $summary = (str_replace($context,"",$summary));
	// get rid of the threshold
	$summary = (str_replace($threshold,"",$summary));
	// get rid of the URL
	$summary = (str_replace($url,"",$summary));
	// remove project....
	$summary = (str_replace($project,"",$summary));
	//... so we can make it first
	if ($project !== "") {
		$summary = $project . " " . $summary;
	}
	// remove newlines
	$summary = (str_replace("\n","",$summary));
	// remove double spaces
	$summary = (str_replace("  "," ",$summary));

	$summary = implode(" ", array_filter(explode(" ", $summary), function($x) { return $x !== ""; }));

	$summaryBase64 = base64_encode($summary);

	//print "summary: $summary <br>";

	// create the ICS entry
	$ical = $ical . "
BEGIN:VTODO
SUMMARY:$summary
DESCRIPTION:$trimmedLine
UID:$summaryBase64
";
	$ical .= $categories;

	if ($url !== "") {
		$ical = $ical . "URL:$url\n";
	}

	if ($dateDone !== "") {
		$ical = $ical . "COMPLETED:$dateDone\n";
		$ical = $ical . "DTSTAMP:$dateDone\n";
		$ical = $ical . "LAST-MODIFIED:$dateDone\n";
	}

	if ($dateAdded !== "") {
		$ical = $ical . "CREATED:$dateAdded\n";
		$ical = $ical . "DTSTART:$dateAdded\n";
		if ($dateDone === "") {
			$ical = $ical . "DTSTAMP:$dateAdded\n";
			$ical = $ical . "LAST-MODIFIED:$dateAdded\n";
		}
	}

	if ($dateDue !== "") {
		$ical = $ical . "DUE:$dateDue\n";
	}

	if ($done) {
		$ical = $ical . "STATUS:COMPLETED\n";
	}

	if ($priority !== "") {
		$ical = $ical . "PRIORITY:$priority\n";
	}

	$ical .= "END:VTODO\n";
		
}

fclose($todofile); // close the todofile

$ical = $ical . "
END:VCALENDAR";

// comment these headers out to load the text in a web browser
// uncomment to generate an ics file when loading this script
header('Content-Type: text/calendar; charset=utf-8');
header('Content-Disposition: attachment; filename=invite.ics');

echo $ical;
exit;
?>