Replace gdalinfo-json.js with node-gdal

This patch derived from a bug where non-metric projections didn't
generate the correct `gsd` resolution. `gdalinfo-json` parses gdal's CLI
output rather than interface with the underlying gdal ABI. So using
`node-gdal` gives a more powerful and better maintained interface.

This patch also removes support for batch processing of s3 files as that
is no longer used with the OAM ecosystem.

Tests, Travis and HoundCI (linting) integration are now also included.

Fixes hotosm/oam-uploader-api#42

.eslintrc

@@ -0,0 +1,7 @@
+{
+  "env": {
+    "node": true,
+    "es6": true
+  },
+  "extends": "semistandard"
+}

.hound.yml

@@ -0,0 +1,2 @@
+eslint:
+  enabled: true

.nvmrc

@@ -0,0 +1 @@
+6.10.2

.travis.yml

@@ -0,0 +1,2 @@
+language: node_js
+

README.md

@@ -1,28 +1,18 @@
 ### Metadata Generator for OIN
 
-This node app reads objects from a S3 bucket and generates metadata json files based on OIN metadata standard.
+The Open Imagery Network standardizes on a single format for imagery. This small CLI tool generates
+a JSON string of the standard metadata for a given OIN geo image.
 
 ### Dependencies
 
 You must have GDAL installed.
 
-### Setup
+### Installation
 
 - `$ npm install`
-- Copy the `.env-sample` file to `.env` and edit with your own values or set via a source like `$HOME/.aws/credentials`.
-- Copy the `config-sample.json` file to `config.json` and edit with your own values.
-
 
 ### Usage
 
-    $ npm start
-
-The default setting runs 20 tasks in parallel. You can change the number by playing around with `var limitParallel = 20;` on line 13 of `index.js`
-
-#### Command Line
-
-Metadata may also be generated for individual files by running the command line tool. If installed via `npm install`, it will be available as `node_modules/.bin/oin-meta-generator`, otherwise `bin/index.js`.
-
 ```
 Usage: oin-meta-generator [args] <file>
 
@@ -83,38 +73,5 @@ $ oin-meta-generator \
 }
 ```
 
-
-### Expected Output
-
-If you've provided a `config.json` and have provided AWS credentials, you should see a successful connection message. At this point, the app will be querying all the data files in the bucket and generating metadata for each matching file. When it finds a matching file and creates the metadata, you will see something like below in the terminal
-
-`1 - The file saved!: 339.tiff_meta.json`
-
-Output data is saved to the `meta` directory by default (changeable) and will look similar to
-
-```json
-{
-  "uuid": "http://bucket.s3.amazonaws.com/4326/srtm_01_02.tiff",
-  "title": "srtm_01_02.tiff",
-  "projection": "GEOGCS[\"WGS84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433],AUTHORITY[\"EPSG\",\"4326\"]]",
-  "bbox": [
-    -180.00041666666667,
-    49.999583333333334,
-    -174.99958333333333,
-    55.000416666666666
-  ],
-  "footprint": "POLYGON((-180.00041666666667 55.000416666666666,-174.99958333333333 55.000416666666666,-174.99958333333333 49.999583333333334,-180.00041666666667 49.999583333333334,-180.00041666666667 55.000416666666666))",
-  "gsd": 0.000833333333333,
-  "file_size": 953117,
-  "acquisition_start":"2015-03-02T00:00:00.000",
-  "acquisition_end":"2015-03-03T00:00:00.000",
-  "platform": "satellite",
-  "provider": "some satellite company",
-  "contact": "[email protected]",
-  "properties": {
-    "thumbnail": "link to thumbnail if available",
-    "tms": "link to TMS if available",
-    "sensor": "name of satellite"
-  }
-}
-```
+### Testing
+Run `npm test`

bin/index.js

@@ -1,14 +1,13 @@
 #!/usr/bin/env node
 
-var fs = require('fs');
+const fs = require('fs');
 
-var gdalinfo = require('gdalinfo-json');
 require('epipebomb')();
-var yargs = require('yargs');
+const yargs = require('yargs');
 
-var applyGdalinfo = require('../lib/apply-gdalinfo');
+const GdalInfo = require('../lib/GdalInfo');
 
-var argv = yargs.usage('Usage: $0 [args] <file>')
+const argv = yargs.usage('Usage: $0 [args] <file>')
   .option('u', {
     alias: 'uuid',
     describe: 'Source UUID',
@@ -64,16 +63,16 @@ var argv = yargs.usage('Usage: $0 [args] <file>')
   .version()
   .argv;
 
-var filename = argv._[0];
+const filename = argv._[0];
 
-var metadata = {
+let metadata = {
   uuid: argv.uuid,
   title: argv.title,
   platform: argv.platform,
   provider: argv.provider,
   contact: argv.contact,
   properties: (argv.additionalMetadata || []).reduce(function (obj, pair) {
-    var parts = pair.split('=', 2);
+    const parts = pair.split('=', 2);
 
     obj[parts[0]] = parts[1];
 
@@ -93,7 +92,7 @@ if (argv.uploadedAt) {
   metadata.uploaded_at = new Date(argv.uploadedAt);
 }
 
-// filter out null values
+// Filter out null values
 metadata = Object.keys(metadata)
   .filter(function (k) {
     return metadata[k] != null;
@@ -104,15 +103,13 @@ metadata = Object.keys(metadata)
     return obj;
   }, {});
 
-var stats = fs.statSync(filename);
+const stats = fs.statSync(filename);
 metadata.file_size = stats.size;
 
-gdalinfo.local(filename, function (err, oin) {
-  if (err) {
-    throw err;
-  }
+const imagery = new GdalInfo(filename);
+metadata.projection = imagery.projectionAsWKT();
+metadata.gsd = imagery.calculatePixelSize();
+metadata.bbox = imagery.bboxAsArray();
+metadata.footprint = imagery.bboxAsWKT();
 
-  applyGdalinfo(metadata, oin);
-
-  process.stdout.write(JSON.stringify(metadata));
-});
+process.stdout.write(JSON.stringify(metadata));