feat: first version of exporter

LICENSE

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+MIT License
+
+Copyright (c) 2020 Terin Stock <[email protected]>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+

README.md

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+# OpenRCT2 Prometheus Exporter
+
+An OpenRCT2 plugin that exports Prometheus metrics for a (limited but growing) set of park metrics.
+
+## Installation
+
+This plugin requires the in-development [networking API](https://github.com/OpenRCT2/OpenRCT2/pull/12712). It has been tested against
+commit 66fb9f556e1ff6b7e52776083303d17b98721ebf.
+
+Download [index.js](./index.js) from GitHub and save the file into your OpenRCT2 plugin folder. This location can be found
+according to the [OpenRCT2 scripting](https://github.com/OpenRCT2/OpenRCT2/blob/e9803fc4b51d80fdeabf5fdb57469ff6fc753db3/distribution/scripting.md#scripts-for-openrct2) documentation.
+
+## Usage
+
+The plugin runs in the background, listening for scripts at the address "localhost:9751", which is currently hardcoded into the file, but may be configurable soon.

index.js

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+(function () {
+  'use strict';
+
+  var port = 9751;
+
+  function Gauge(name, labels) {
+    this.name = name;
+    this.val = 0;
+    this.labels = labels;
+  }
+
+  Gauge.prototype.set = function(val) {
+    this.val = val;
+  };
+
+  Gauge.prototype.inc = function(val) {
+    this.val += val;
+  };
+
+  Gauge.prototype.toString = function() {
+    if (this.labels.length%2 != 0) {
+      console.log('error: invalid label length');
+    }
+    var labels = ""
+    var i = 0;
+    while (i < this.labels.length) {
+      labels += this.labels[i] + '="' + this.labels[i+1] + '"';
+
+      if (i+2 < this.labels.length) {
+        labels += ',';
+      }
+
+      i += 2;
+    }
+
+    return this.name + '{' + labels + '} '+ this.val;
+  };
+
+  function httpServer() {
+    var server = network.createListener();
+    server.on('connection', function(conn) {
+      conn.on('data', function() {
+        var park_cash = new Gauge("park_cash", ["park", park.name]);
+        park_cash.set(park.cash/10);
+        var park_rating = new Gauge("park_rating", ["park", park.name]);
+        park_rating.set(park.rating);
+        var park_bankLoan = new Gauge("park_bankLoan", ["park", park.name]);
+        park_bankLoan.set(park.bankLoan);
+
+        conn.write('HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\n');
+        conn.write('# TYPE park_cash gauge\n' + park_cash + '\n');
+        conn.write('# TYPE park_rating gauge\n' + park_rating + '\n');
+        conn.write('# TYPE park_bank_loan gauge\n' + park_bankLoan + '\n');
+        conn.write('# TYPE park_max_bank_loan counter\npark_max_bank_loan{park="' + park.name + '"} ' + park.maxBankLoan/10 + '\n');
+
+        var guest_count = new Gauge("guest_count", ["park", park.name]);
+        var staff_count = new Gauge("staff_count", ["park", park.name]);
+        var peep_count = new Gauge("peep_count", ["park", park.name]);
+        var duck_count = new Gauge("duck_count", ["park", park.name]);
+
+        var peeps = map.getAllEntities("peep");
+        peep_count.set(peeps.length);
+
+        var ducks = map.getAllEntities("duck");
+        duck_count.set(ducks.length);
+
+        peeps.forEach(function(peep) {
+          if (peep.peepType === 'guest' && peep.getFlag("hasPaidForParkEntry")) {
+            guest_count.inc(1);
+          } else if (peep.peepType === 'staff') {
+            staff_count.inc(1);
+          }
+        });
+
+        conn.write('# TYPE peep_count gauge\n' + peep_count + '\n');
+        conn.write('# TYPE guest_count gauge\n' + guest_count + '\n');
+        conn.write('# TYPE staff_count gauge\n' + staff_count + '\n');
+        conn.write('# TYPE duck_count gauge\n' + duck_count + '\n');
+        conn.end();
+      });
+    });
+    server.listen(port);
+    console.log('listening on port ' + port + '...');
+  }
+
+  function main() {
+    httpServer();
+  }
+
+  registerPlugin({
+    name: 'openrct2-prometheus-exporter',
+    version: '0.0.0',
+    licence: 'MIT',
+    authors: ['Terin Stock'],
+    type: 'local',
+    main: main
+  });
+
+}());