<?php
	
	require_once __DIR__.'/../../include/php/const';


	/* [1] Function that generates a random secret
	=========================================================*/
	function generate_secret(){

		/* (1) Generate random set */
		$charlist = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_';

		/* (2) Set useful variables */
		$clen = strlen($charlist);
		$secret = '';

		/* (3) Generate random characters one by one */
		for( $i = 0 ; $i < SECRET_SIZE ; $i++ )
			$secret .= $charlist[rand(0, $clen - 1)];

		/* (4) Return the secret */
		return $secret;
	}


	function cyclichash_decr(){

		/* [2] Fetch necessary data
		=========================================================*/

		/* (1) Fetch secret file */
		$secret = @file_get_contents(SECRET_CONF);
		
		/* (2) Check secret file format */
		if( !is_string($secret) || !preg_match("/^(.{".SECRET_SIZE."}):(\d+):(.{".SECRET_SIZE."})$/", $secret, $match) ){

			// Generate full secret
			$secret = generate_secret().':999:'.generate_secret();

			// Try to override the secret file
			if( @file_put_contents(SECRET_CONF, $secret) ){
				slog("Random secret generated successfully", 'cyclic-hash:decr', 'update');
				return 0;
			}else{
				slog("Error while generating new random secret", 'cyclic-hash:decr', 'update');
				return 127;
			}
		}

		/* (3) Extract data */
		$key   = (string) $match[1];
		$depth = (int)    $match[2];
		$next  = (string) $match[3];


		/* [3] If can decrement, decrement
		=========================================================*/
		if( $depth > 1 ){

			/* (1) Decrement the depth */
			$depth--;

			/* (2) Try to override the secret file */
			if( @file_put_contents(SECRET_CONF, "$key:$depth:$next") ){
				slog("Secret depth decremented to $depth", 'cyclic-hash:decr', 'update');
				return 0;
			}else{
				slog("Error while decrementing secret depth", 'cyclic-hash:decr', 'update');
				return 127;
			}


		/* [4] If cannot decrement, use new secret and generate next
		=========================================================*/
		}else{
			
			// Generate new secret
			$secret = $next.':999:'.generate_secret();

			// Try to override the secret file
			if( @file_put_contents(SECRET_CONF, $secret) ){
				slog("Random secret generated successfully", 'cyclic-hash:decr', 'update');
				return 0;
			}else{
				slog("Error while generating new random secret", 'cyclic-hash:decr', 'update');
				return 127;
			}

		}

		return 0;


	}

	echo cyclichash_decr();


?>