Add rest-api (#147)

Author: glennj

bin/generate-spec

@@ -132,7 +132,7 @@ canonical_data = json.decode read_file(canonical_data_path), 1, json.null
 tests_toml_path = exercise_directory .. '/.meta/tests.toml'
 included_tests = included_tests_from_toml tests_toml_path
 
-package.moonpath = "#{exercise_directory}/.meta/?.moon;#{package.moonpath}"
+package.moonpath = "#{exercise_directory}/.meta/?.moon;./lib/?.moon;#{package.moonpath}"
 spec_generator = require 'spec_generator'
 
 local spec

config.json

@@ -842,6 +842,14 @@
         "prerequisites": [],
         "difficulty": 7
       },
+      {
+        "slug": "rest-api",
+        "name": "REST API",
+        "uuid": "a999597a-d5db-4a72-83f7-133a2b7f3add",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 7
+      },
       {
         "slug": "satellite",
         "name": "Satellite",

exercises/practice/rest-api/.busted

@@ -0,0 +1,5 @@
+return {
+  default = {
+    ROOT = { '.' }
+  }
+}

exercises/practice/rest-api/.docs/instructions.md

@@ -0,0 +1,48 @@
+# Instructions
+
+Implement a RESTful API for tracking IOUs.
+
+Four roommates have a habit of borrowing money from each other frequently, and have trouble remembering who owes whom, and how much.
+
+Your task is to implement a simple [RESTful API][restful-wikipedia] that receives [IOU][iou]s as POST requests, and can deliver specified summary information via GET requests.
+
+## API Specification
+
+### User object
+
+```json
+{
+  "name": "Adam",
+  "owes": {
+    "Bob": 12.0,
+    "Chuck": 4.0,
+    "Dan": 9.5
+  },
+  "owed_by": {
+    "Bob": 6.5,
+    "Dan": 2.75
+  },
+  "balance": "<(total owed by other users) - (total owed to other users)>"
+}
+```
+
+### Methods
+
+| Description              | HTTP Method | URL    | Payload Format                                                            | Response w/o Payload                   | Response w/ Payload                                                             |
+| ------------------------ | ----------- | ------ | ------------------------------------------------------------------------- | -------------------------------------- | ------------------------------------------------------------------------------- |
+| List of user information | GET         | /users | `{"users":["Adam","Bob"]}`                                                | `{"users":<List of all User objects>}` | `{"users":<List of User objects for <users> (sorted by name)}`                  |
+| Create user              | POST        | /add   | `{"user":<name of new user (unique)>}`                                    | N/A                                    | `<User object for new user>`                                                    |
+| Create IOU               | POST        | /iou   | `{"lender":<name of lender>,"borrower":<name of borrower>,"amount":5.25}` | N/A                                    | `{"users":<updated User objects for <lender> and <borrower> (sorted by name)>}` |
+
+## Other Resources
+
+- [REST API Tutorial][restfulapi]
+- Example RESTful APIs
+  - [GitHub][github-rest]
+  - [Reddit][reddit-rest]
+
+[restful-wikipedia]: https://en.wikipedia.org/wiki/Representational_state_transfer
+[iou]: https://en.wikipedia.org/wiki/IOU
+[github-rest]: https://docs.github.com/en/rest
+[reddit-rest]: https://web.archive.org/web/20231202231149/https://www.reddit.com/dev/api/
+[restfulapi]: https://restfulapi.net/

exercises/practice/rest-api/.meta/config.json

@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "glennj"
+  ],
+  "files": {
+    "solution": [
+      "rest_api.moon"
+    ],
+    "test": [
+      "rest_api_spec.moon"
+    ],
+    "example": [
+      ".meta/example.moon"
+    ]
+  },
+  "blurb": "Implement a RESTful API for tracking IOUs."
+}

exercises/practice/rest-api/.meta/example.moon

@@ -0,0 +1,63 @@
+contains = (list, elem) ->
+  for item in *list
+    return true if item == elem
+  false
+
+sort_users = (list) ->
+  table.sort list, (a, b) -> a.name < b.name
+  list
+
+-- The tests do not require the payload to be validated.
+-- Also, I'm not concerned about accepting references to user's tables,
+-- or returning references to internal tables.
+
+class RestApi
+  new: (@db) =>
+
+  GET:  (url, payload) => @route 'GET', url, payload
+  POST: (url, payload) => @route 'POST', url, payload
+
+  route: (method, url, payload) =>
+    subject = url\match '^/(%w+)'
+    func = "#{subject}_#{method}"
+    return {error: "Unknown endpoint: #{method} #{url}"} if not @[func]
+    @[func] @, payload
+
+  users_GET: (payload) =>
+    filter = if payload
+      (user) -> contains payload.users, user.name
+    else
+      (user) -> true
+    {users: sort_users [u for u in *@db.users when filter u]}
+
+  add_POST: (payload) =>
+    user = {
+      name: payload.user
+      balance: 0
+      owes: {}
+      owed_by: {}
+    }
+    table.insert @db.users, user
+    user
+
+  iou_POST: (payload) =>
+    {users: {lender}} = @users_GET {users: {payload.lender}}
+    {users: {borrower}} = @users_GET {users: {payload.borrower}}
+    borrower.balance -= payload.amount
+    lender.balance += payload.amount
+
+    debt = (lender.owes[borrower.name] or 0) - (lender.owed_by[borrower.name] or 0) - payload.amount
+
+    lender.owes[borrower.name] = nil
+    lender.owed_by[borrower.name] = nil
+    borrower.owes[lender.name] = nil
+    borrower.owed_by[lender.name] = nil
+
+    if debt > 0
+      lender.owes[borrower.name] = debt
+      borrower.owed_by[lender.name] = debt
+    elseif debt < 0
+      lender.owed_by[borrower.name] = -debt
+      borrower.owes[lender.name] = -debt
+
+    {users: sort_users {lender, borrower}}

exercises/practice/rest-api/.meta/spec_generator.moon

@@ -0,0 +1,25 @@
+test_helpers = require 'test_helpers'
+import table_dump from test_helpers
+
+{
+  module_name: 'RestApi',
+
+  generate_test: (case, level) ->
+    lines = {
+      "database = #{table_dump case.input.database, level}",
+      "api = RestApi database"
+    }
+    call = "result = api\\#{case.property\upper!} #{quote case.input.url}"
+    if case.input.payload
+      table.insert lines, "payload = #{table_dump case.input.payload, level}"
+      call ..= ", payload"
+    table.insert lines, call
+    table.insert lines, "expected = #{table_dump case.expected, level}"
+    table.insert lines, "assert.are.same expected, result"
+    table.concat [indent line, level for line in *lines], '\n'
+
+  -- we have deep tables to compare, display it all when not the same
+  test_helpers: [[
+  assert\set_parameter "TableFormatLevel", 4
+]]
+}

exercises/practice/rest-api/.meta/tests.toml

@@ -0,0 +1,37 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[5be01ffb-a814-47a8-a19f-490a5622ba07]
+description = "user management -> no users"
+
+[382b70cc-9f6c-486d-9bee-fda2df81c803]
+description = "user management -> add user"
+
+[d624e5e5-1abb-4f18-95b3-45d55c818dc3]
+description = "user management -> get single user"
+
+[7a81b82c-7276-433e-8fce-29ce983a7c56]
+description = "iou -> both users have 0 balance"
+
+[1c61f957-cf8c-48ba-9e77-b221ab068803]
+description = "iou -> borrower has negative balance"
+
+[8a8567b3-c097-468a-9541-6bb17d5afc85]
+description = "iou -> lender has negative balance"
+
+[29fb7c12-7099-4a85-a7c4-9c290d2dc01a]
+description = "iou -> lender owes borrower"
+
+[ce969e70-163c-4135-a4a6-2c3a5da286f5]
+description = "iou -> lender owes borrower less than new loan"
+
+[7f4aafd9-ae9b-4e15-a406-87a87bdf47a4]
+description = "iou -> lender owes borrower same as new loan"

exercises/practice/rest-api/rest_api.moon

@@ -0,0 +1 @@
+error 'Implement me'