Add usage section

README.md

@@ -7,12 +7,112 @@ This is a basic library/wrapper for digital vehicle state safety/emissions inspe
 |Maryland|[Emissions/Smog](http://mva.mdveip.com/), [Safety](https://egov.maryland.gov/msp/vsi/api/Lookup/Inspections?vehicleVin=)|Pending further tests, but it appears that MD only keeps the e-inspection record until it expires (6 months)|
 
 # Usage
-TDB
+### Files
+Import the three core files
+```PHP
+require("classes/Inspections.class.php");
+require("classes/StateInspection.class.php");
+require("interfaces/StateInspection.interface.php");
+```
+
+Then import the state (or states) file
+```PHP
+require("classes/states/MD.class.php");
+```
+
+### Functions
+##### Inspections::all
+Retrieve all inspection types (smog/safety inspections)
+```PHP
+$all = amattu\Inspections::all("VIN", "STATE_ABBR");
+```
+
+`VIN` is the 17 digit VIN number of the vehicle of interest. `STATE_ABBR` is the *2 digit* [ISO-3166-2](https://en.wikipedia.org/wiki/ISO_3166-2:US) state abbreviation.
+
+Returns an array containing `Emissions`, `Safety` multi-dimensional arrays.
+
+##### Inspections::safety
+Retrieve all state safety (mechanical) inspection reports.
+
+PHPDoc
+```PHP
+/**
+ * A endpoint wrapper to return a structured state safety inspection search result
+ * All return attributes are nullable, given that each state returns different information.
+ *
+ * @param string VIN number
+ * @return array Array<Array<?bool result, ?string date, ?string url>, ...>
+ * @return array Structured return result
+ * @throws TypeError
+ * @throws UnsupportedStateOperationException
+ * @author Alec M. <https://amattu.com>
+ * @date 2021-04-07T11:05:27-040
+ */
+```
+
+Usage
+```PHP
+amattu\Inspections::safety("VIN", "STATE_ABBR");
+```
+
+`VIN` is the 17 digit VIN number of the vehicle of interest. `STATE_ABBR` is the *2 digit* [ISO-3166-2](https://en.wikipedia.org/wiki/ISO_3166-2:US) state abbreviation.
+
+Returns the following array:
+```PHP
+Array
+(
+  [0] => Array
+  (
+    [date] => ?string (Format: YYYY-MM-DD)
+    [result] => ?bool
+    [url] => ?string
+  )
+)
+```
+
+##### Inspections::emissions
+Pull all emissions records for a vehicle.
+
+PHPDoc
+```PHP
+/**
+ * A endpoint wrapper to return a structured state emissions test result
+ * All return attributes are nullable, given that each state returns different information.
+ *
+ * @param string VIN number
+ * @return array Array<Array<?string type, ?string date, ?bool result, ?string url>, ...>
+ * @throws TypeError
+ * @throws UnsupportedStateOperationException
+ * @author Alec M. <https://amattu.com>
+ * @date 2021-04-07T14:51:13-040
+ */
+```
+
+Usage
+```PHP
+amattu\Inspections::emissions("VIN", "STATE_ABBR")
+```
+
+`VIN` is the 17 digit VIN number of the vehicle of interest. `STATE_ABBR` is the *2 digit* [ISO-3166-2](https://en.wikipedia.org/wiki/ISO_3166-2:US) state abbreviation.
+
+Returns the following array:
+```PHP
+Array
+(
+  [0] => Array
+  (
+    [date] => ?string (Format: YYYY-MM-DD)
+    [result] => ?bool
+    [type] => ?string
+    [url] => ?string
+  )
+)
+```
 
 # To-Do Integrations
-### Safety Inspections
 A list of potential integrations with state systems. These require advanced parsing or endpoint manipulation to grab the information.
 
+### Safety Inspections
 |State|Portal|
 |:-|:-:|
 |Delaware|[Link](https://dealers.dmv.de.gov/Dealer/VehicleInspection/citizeninspection)|