Add todo

Reviewed-on: https://git.fsmi.org/paul/jon/pulls/4

README.md

@@ -4,6 +4,11 @@
 
 ## Setup
 
+`jon` is a Python WSGI application written using Flask.
+This means you'll have to install a bunch of Python packages to get up and running.
+
+### Dependencies
+
 ```
 pip install -r requirements.txt
 ```
@@ -11,6 +16,14 @@ pip install -r requirements.txt
 You should probably use a virtualenv for that.
 I develop `jon` using Python 3.10 but it should work with older versions as well.
 
+#### Arch Linux
+
+If you're on Arch, these packages are required for running the server:
+
+```
+python python-flask python-flask-login python-psycopg2
+```
+
 ### Building Frontend JS
 
 Most of jon works without JS but there are some features that require it.
@@ -46,9 +59,13 @@ ssh -nNTvL 5432:fsmi-db.fsmi.org:5432 fsmi-login.fsmi.uni-karlsruhe.de
   - [ ] etc.
   - [ ] Make it print nicely
 - [ ] Make it possible to edit entries
+- [ ] Fix unsafe client-side sessions, either:
+  - [ ] Use `flask-session` for file-backed sessions
+  - [ ] Use `flask-login` with a single user stored in memory
 - [ ] Improve project structure
 - [ ] Use `flask.flash` for error messages
 - [x] Implement item and snack entry as Elm application
   - [x] Figure out/Add documentation about building `entry.js`
   - [ ] Clean up the code a little and add some comments
   - [ ] Needs good documentation for maintainability
+- [ ] Use cool new function for deactivating items

frontend/Calculator.elm

@@ -9,7 +9,15 @@ import Select
 
 type Tax = Net | Gross
 
-ctShow ct = case ct of
+-- Duplicated from Entry.elm but too lazy to sandwich this out
+type alias TaxGroup =
+  { id : Int
+  , description : String
+  , percentage : Float
+  }
+
+showTax : Tax -> String
+showTax tax = case tax of
   Gross -> "Brutto"
   Net -> "Netto"
 
@@ -19,11 +27,13 @@ type alias Model =
   , bundleSize : NumberInput.Model Int
   }
 
+init : Float -> Model
 init bundlePrice = Model
-  (Select.init ctShow ctShow Net [Net, Gross])
+  (Select.init showTax showTax Net [Net, Gross])
   (NumberInput.fromFloat bundlePrice)
   (NumberInput.fromInt 1)
 
+getResult : Model -> TaxGroup -> Maybe Float
 getResult model taxGroup =
   case (NumberInput.get model.bundlePrice, NumberInput.get model.bundleSize) of
     (Just bundlePrice, Just bundleSize) ->
@@ -41,6 +51,7 @@ type Msg
   | SetBundlePrice String
   | SetBundleSize String
 
+update : Msg -> Model -> Model
 update msg model = case msg of
   SetTax key ->
     { model | tax = Select.update key model.tax }
@@ -49,6 +60,7 @@ update msg model = case msg of
   SetBundleSize str ->
     { model | bundleSize = NumberInput.update str model.bundleSize }
 
+view : Model -> TaxGroup -> Html Msg
 view model taxGroup =
   let
     mainPart =
@@ -112,4 +124,5 @@ view model taxGroup =
         ]
       ]
 
-roundTo places x = toFloat (round <| x * 10 ^ places) / 10 ^ places
+roundTo : Int -> Float -> Float
+roundTo places x = toFloat (round <| x * 10 ^ toFloat places) / 10 ^ toFloat places

frontend/Entry.elm

@@ -14,6 +14,50 @@ import Calculator
 import NumberInput
 import Select
 
+{-
+Elm forces us to use the Elm architecture:
+
+              ┌──────┐
+ ┌─────Model──► view ├──Html───────┐
+ │            └──────┘             │
+ │                                 │
+┌┴─────────────────────────────────▼┐
+│            Elm runtime            │
+└▲─────────────────────────────────┬┘
+ │                                 │
+ │            ┌──────┐             │
+ └─Model+Cmd──┤update◄──Msg+Model──┘
+              └──────┘
+
+This architecture is similar to what React does but its implementation
+in Elm is a bit special since it's purely functional and side effects
+are isolated into the runtime system.
+
+An Elm component is usually centered around two types, Model and Msg.
+Model contains all data the application is concerned with, including the state
+of UI elements. Msg encodes all updates to Model that the application supports.
+
+In addition to Msg and Model, we have to provide two functions, view and update.
+
+view : Model -> Html Msg
+update : Msg -> Model -> (Model, Cmd Msg)
+
+view maps a Model to a DOM tree. Events in this DOM tree create Msg values.
+update maps a Msg and a Model to a new Model. In addition, update can create
+a command. Commands are used to make the runtime do side effects, which in
+turn create new Msg values.
+
+For example, we have a SetSearchTerm message which simply updates the searchTerm
+property in the model. This message is triggered every time the search box input
+is changed. Submitting the search box form triggers a SubmitSearch event.
+This event leaves the model unchanged but issues a command that sends the search
+term to a JSON endpoint. When the request successfully resolves, the runtime
+triggers a ReceiveSearchResults messages which updates the list of search results
+in the model.
+
+See Calculator.elm for a simpler example of this architecture.
+-}
+
 main = Browser.element
   { init = \globals ->
     ( Context globals <| ItemSearch { searchTerm = "", searchResults = [] }

jon/db/add_views.sql

@@ -58,3 +58,56 @@ FROM garfield.inventory_items
   ) m USING (item_id)
 ORDER BY inventory_items.name;
 
+-- How many *other* active inventory lines exist with the same barcode in the same location that are newer?
+CREATE TEMPORARY VIEW more_recent_inventory_lines_with_same_barcode AS
+SELECT
+  a.item_id,
+  -- It's important not to count(*) here because item_id is NULL
+  -- when no other inventory lines exist.
+  count(b.item_id) AS other_lines_count
+FROM garfield.inventory_items AS a
+LEFT JOIN garfield.inventory_items AS b
+       ON a.item_barcode = b.item_barcode
+      AND a.item_id != b.item_id
+      AND a.location = b.location
+      AND b.available
+      AND b.bought > a.bought
+GROUP BY a.item_id;
+
+-- We need to create this table so that we can put an index on it
+-- Otherwise the join in the consumption graph query becomes much slower
+-- Perhaps it would be nicer to use a materialized view instead
+DROP TABLE IF EXISTS last_n_days;
+CREATE TEMPORARY TABLE last_n_days AS (
+  SELECT
+    generate_series(now() - interval '14 days', now(), interval '1 day')::date AS sale_date
+);
+CREATE UNIQUE INDEX last_n_days_sale_date ON last_n_days (sale_date);
+
+-- Get an array of how often items were sold over the last 14 days
+CREATE TEMPORARY VIEW inventory_last_n_days_sales AS
+WITH
+sales_by_date AS (
+  SELECT
+    inventory_line AS item_id,
+    date_trunc('day', snack_sales_log_timestamp AT TIME ZONE 'UTC+1') AS sale_date,
+    count(*)::int AS sales
+  FROM garfield.snack_sales_log
+  GROUP BY item_id, sale_date
+),
+beeg AS (
+  SELECT item_id, sale_date, count(snack_sales_log_timestamp)::int AS sales
+  FROM garfield.inventory_items
+  CROSS JOIN last_n_days
+  LEFT JOIN garfield.snack_sales_log
+         ON inventory_line = item_id
+-- snack_sales_log has an index on snack_sales_log_timestamp to speed up this query
+-- If that index doesn't exist the query takes much longer.
+        AND sale_date = date_trunc('day', snack_sales_log_timestamp AT TIME ZONE 'UTC+1')
+  WHERE available
+  GROUP BY item_id, sale_date
+  ORDER BY item_id, sale_date
+)
+SELECT item_id, array_agg(sales) AS last_n_days_sales
+FROM beeg
+GROUP BY item_id

jon/db/get_inventory_overview.sql

@@ -1,6 +1,8 @@
 SELECT
   *
 FROM all_inventory_item_overview
+LEFT JOIN more_recent_inventory_lines_with_same_barcode USING (item_id)
+LEFT JOIN inventory_last_n_days_sales USING (item_id)
 WHERE (%(location_id)s IS NULL OR location = %(location_id)s)
   AND available
 ORDER BY

jon/static/jon.css

@@ -74,3 +74,7 @@ th {
 details {
   font-size: 0.8em;
 }
+.consumption-graph {
+  display: block;
+  height: 1em;
+}

jon/templates/inventory/index.html

@@ -1,9 +1,34 @@
+{% macro consumption_graph_svg(values) -%}
+{% set stroke_width = 8 %}
+{% set width = 300 %}
+{% set height = 100 %}
+{% set padding = 4 %}
+{% set dx = (width - 2 * padding) / ((values | length) + 1) %}
+{% set dy = (height - 2 * padding) / ((values + [1]) | max) %}
+<svg viewBox="0 0 {{ width }} {{ height }}" role="img" class="consumption-graph">
+  <polyline
+    points="
+    {% for value in values %}
+      {{ padding + loop.index * dx }}, {{ height - padding - value * dy }}
+    {% endfor %}
+    "
+    stroke="green"
+    stroke-width="{{ stroke_width }}"
+    stroke-linecap="round"
+    stroke-linejoin="round"
+    fill="none"
+  >
+</svg>
+{% endmacro -%}
+
 {% extends "base.html" %}
 
 {% block content %}
 <table>
   <tr>
+    <th>Stat</th>
     <th>ID</th>
+    <th>Graph</th>
     <th>Barcode</th>
     <th>Name</th>
     <th>Preis (Netto)</th>
@@ -17,7 +42,12 @@
   </tr>
 {% for item in items %}
   <tr>
+    <td>
+      {% if item.units_left == 0 %}<span title="Leerer aktiver Inventareintrag">🅾️</span>{% endif %}
+      {% if item.other_lines_count != 0 %}<span title="{% if item.other_lines_count == 1 %}Neuerer Eintrag mit demselben Barcode ist aktiv{% else %}{{ item.other_lines_count }} Einträge mit demselben Barcode sind aktiv{% endif %}">🔄</span>{% endif %}
+    </td>
     <td><a href="/inventory/item/{{ item.item_id }}">{{ item.item_id }}</a></td>
+    <td>{{ consumption_graph_svg(item.last_n_days_sales) }}</td>
     <td><code>{{ item.item_barcode }}</code></td>
     <td>{{ item.name }}</td>
     <td class="--align-right">{{ format_currency(item.unit_price) }}</td>