feat: allow using a transform file

Fixes #1

Author: fcoury

package.json

@@ -15,6 +15,7 @@
   "dependencies": {
     "blessed": "0.1.81",
     "blessed-contrib": "4.8.5",
+    "ini": "1.3.5",
     "lodash": "4.17.4",
     "minimist": "1.2.0"
   },

src/log.js

@@ -1,9 +1,50 @@
 const fs = require('fs');
+const os = require('os');
+const path = require('path');
+const ini = require('ini');
 const _ = require('lodash');
 
+let _transform = 'unloaded';
+
+function loadTransform(_fs=fs) {
+  if (_transform === 'unloaded') {
+    const transformFile = path.join(os.homedir(), '.json-log-viewer');
+    if (!_fs.existsSync(transformFile)) {
+      return;
+    }
+
+    const contents = _fs.readFileSync(transformFile, 'utf8');
+    const { transform } = ini.parse(contents);
+    if (!transform) {
+      return;
+    }
+
+    _transform = transform;
+  }
+
+  return _transform;
+}
+
+function transform(entry, _fs=fs) {
+  const transform = loadTransform(_fs);
+  if (!transform) {
+    return entry;
+  }
+
+  return Object.keys(transform).reduce((hash, key) => {
+    const value = transform[key];
+    if (value === '$') {
+      hash[key] = _.cloneDeep(entry);
+    } else {
+      hash[key] = _.get(entry, value);
+    }
+    return hash;
+  }, {});
+}
+
 function parse(line) {
   try {
-    return JSON.parse(line);
+    return transform(JSON.parse(line));
   } catch (e) {
     return null;
   }
@@ -20,4 +61,4 @@ function readLog(file, reader=fs) {
   });
 };
 
-module.exports = { readLog };
+module.exports = { readLog, transform };

test/fixtures/monolog.log.json

@@ -0,0 +1,14 @@
+{
+  "message":
+    "Matched route \"**_heartbeat_check\" (parameters: \"_controller\": \"**\\Controller\\**Controller::heartbeatCheckAction\", \"_route\": \"**_heartbeat_check\")",
+  "context": [],
+  "level": 200,
+  "level_name": "INFO",
+  "channel": "request",
+  "datetime": {
+    "date": "2017-12-06 09:23:42.253060",
+    "timezone_type": 3,
+    "timezone": "Europe/Berlin"
+  },
+  "extra": []
+}

test/fixtures/transform1.ini

@@ -0,0 +1,5 @@
+[transform]
+level=level_name
+timestamp=datetime.date
+message=message
+extra=$

test/log.test.js

@@ -1,5 +1,5 @@
 const { loadFixture } = require('./support/fixtures');
-const { readLog } = require('../src/log');
+const { readLog, transform } = require('../src/log');
 
 describe('readLog', () => {
   let entries;
@@ -40,3 +40,30 @@ describe('readLog', () => {
     });
   });
 });
+
+describe.only('transform', () => {
+  let exists = false;
+  let contents = null;
+
+  const fs = {
+    existsSync: () => exists,
+    readFileSync: () => contents,
+  };
+
+  describe('when config doesn\'t exist', () => {
+    it('returns the unmodified line', () => {
+      expect(transform('something', fs)).to.eql('something');
+    });
+  });
+
+  describe('when config exists', () => {
+    it('transforms the line', () => {
+      exists = true;
+      contents = loadFixture('transform1.ini');
+      const logEntry = JSON.parse(loadFixture('monolog.log.json'));
+      const entry = transform(logEntry, fs);
+      expect(entry.timestamp).to.eql('2017-12-06 09:23:42.253060');
+      expect(entry.level).to.eql('INFO');
+    });
+  });
+});

yarn.lock

@@ -1516,6 +1516,10 @@ inherits@2, [email protected], inherits@^2.0.1, inherits@^2.0.3, inherits@~2.0.0, i
   version "2.0.3"
   resolved "https://registry.yarnpkg.com/inherits/-/inherits-2.0.3.tgz#633c2c83e3da42a502f52466022480f4208261de"
 
+[email protected]:
+  version "1.3.5"
+  resolved "https://registry.yarnpkg.com/ini/-/ini-1.3.5.tgz#eee25f56db1c9ec6085e0c22778083f596abf927"
+
 ini@~1.3.0:
   version "1.3.4"
   resolved "https://registry.yarnpkg.com/ini/-/ini-1.3.4.tgz#0537cb79daf59b59a1a517dff706c86ec039162e"