(62) Show air quality alerts and 3-day forecast for selected zone

.env.example

@@ -18,3 +18,6 @@ CANONICAL_HOSTNAME=example.com
 # app to respond to and redirect to the canonical hostname, or delete
 # this line completely
 ADDITIONAL_HOSTNAMES=
+
+CERC_API_HOST_URL=https://cerc.example.com
+CERC_API_KEY=SECRET-API-KEY

Gemfile

@@ -21,6 +21,7 @@ gem "turbolinks", "~> 5"
 gem "tzinfo-data", platforms: %i[mingw mswin x64_mingw jruby]
 gem "terser"
 gem "govuk-components"
+gem "httparty"
 
 group :development do
   gem "better_errors"
@@ -52,4 +53,5 @@ group :test do
   gem "selenium-webdriver"
   gem "simplecov"
   gem "climate_control"
+  gem "webmock"
 end

Gemfile.lock

@@ -112,7 +112,11 @@ GEM
     coderay (1.1.3)
     concurrent-ruby (1.3.4)
     connection_pool (2.4.1)
+    crack (1.0.0)
+      bigdecimal
+      rexml
     crass (1.0.6)
+    csv (3.3.0)
     database_cleaner (2.0.2)
       database_cleaner-active_record (>= 2, < 3)
     database_cleaner-active_record (2.2.0)
@@ -144,10 +148,15 @@ GEM
       html-attributes-utils (~> 1.0.0, >= 1.0.0)
       pagy (>= 6, < 10)
       view_component (>= 3.9, < 3.15)
+    hashdiff (1.1.1)
     high_voltage (4.0.0)
     html-attributes-utils (1.0.2)
       activesupport (>= 6.1.4.4)
     htmlbeautifier (1.4.3)
+    httparty (0.22.0)
+      csv
+      mini_mime (>= 1.0.0)
+      multi_xml (>= 0.5.2)
     i18n (1.14.6)
       concurrent-ruby (~> 1.0)
     io-console (0.7.2)
@@ -195,6 +204,8 @@ GEM
     mini_mime (1.1.5)
     minitest (5.25.1)
     msgpack (1.7.2)
+    multi_xml (0.7.1)
+      bigdecimal (~> 3.1)
     net-imap (0.4.16)
       date
       net-protocol
@@ -411,6 +422,10 @@ GEM
       activemodel (>= 6.0.0)
       bindex (>= 0.4.0)
       railties (>= 6.0.0)
+    webmock (3.24.0)
+      addressable (>= 2.8.0)
+      crack (>= 0.3.2)
+      hashdiff (>= 0.4.0, < 2.0.0)
     webrick (1.8.2)
     websocket (1.2.11)
     websocket-driver (0.7.6)
@@ -444,6 +459,7 @@ DEPENDENCIES
   govuk-components
   high_voltage
   htmlbeautifier
+  httparty
   jbuilder (~> 2.11)
   jquery-rails
   launchy
@@ -469,6 +485,7 @@ DEPENDENCIES
   turbolinks (~> 5)
   tzinfo-data
   web-console (>= 3.3.0)
+  webmock
 
 RUBY VERSION
    ruby 3.3.5p100

README.md

@@ -54,6 +54,11 @@ To manage sensitive environment variables:
    which should never be checked into Git. This file will look something like
    `ROLLBAR_TOKEN=123456789`
 
+### Required environment variables
+
+- `CERC_API_HOST_URL`: find the URL of the CERC API host in the 1Password vault
+- `CERC_API_KEY`: find the API key in the 1Password vault
+
 ## Access
 
 TODO: Where can people find the service and the different environments?

app/assets/stylesheets/application.css.scss

@@ -21,3 +21,38 @@ $govuk-fonts-path: "govuk-frontend/dist/govuk/assets/fonts/";
 $govuk-page-width: 1100px;
 
 @import "govuk-frontend/dist/govuk/all";
+
+.air-quality-alerts {
+  list-style-type: none;
+  margin-bottom: 2rem;
+}
+
+.air-quality-alert {
+  padding-bottom: 1rem;
+}
+
+.air-quality-alert .heading {
+  background-color: white;
+  padding: 1rem;
+}
+
+.air-quality-alert .body {
+  padding: 1rem;
+}
+
+.air-quality-alert .guidance {
+  padding-left: 1rem;
+  padding-right: 1rem;
+}
+
+.air-quality-alert.alert-level-high {
+  background-color: #febfca;
+}
+
+.air-quality-alert.alert-level-moderate {
+  background-color: #f4e9b6;
+}
+
+.air-quality-alert.alert-level-very-high {
+  background-color: #dfb4ed;
+}

app/controllers/forecasts_controller.rb

@@ -1,6 +1,8 @@
 class ForecastsController < ApplicationController
-  def index
-    @forecast = JSON.parse(File.read("#{Rails.root}/public/sample-forecast.json"))["zones"][0]
-    @dates = @forecast["forecasts"].map { |forecast| forecast["forecast_date"] }
+  def show
+    @forecasts = CercApiClient
+      .forecasts_for(params.has_key?("zone") ? params["zone"] : "Southwark")
+    @zones = JSON.parse(File.read("#{Rails.root}/config/list-of-zones.json"))
+    @air_quality_alerts = @forecasts.map(&:alerts).flatten
   end
 end

app/lib/forecast_factory.rb

@@ -0,0 +1,40 @@
+class ForecastFactory
+  def self.build(forecast_representation)
+    obtained_at = Time.zone.parse(forecast_representation.fetch("forecastdate"))
+
+    zone = forecast_representation
+      .fetch("zones")
+      .first
+
+    zone.fetch("forecasts")
+      .map do |forecast|
+      Forecast.new({
+        obtained_at: obtained_at,
+        forecast_for: Date.parse(forecast.fetch("forecast_date")),
+
+        zone: ForecastZone.new(
+          id: zone.fetch("zone_id"),
+          name: zone.fetch("zone_name"),
+          type: zone.fetch("zone_type")
+        ),
+
+        air_pollution: AirPollutionPrediction.new(
+          forecasted_at: Time.zone.parse(forecast.fetch("pollution_version").to_s),
+          nitrogen_dioxide: forecast.fetch("NO2"),
+          particulate_matter_10: forecast.fetch("PM10"),
+          particulate_matter_2_5: forecast.fetch("PM2.5"),
+          ozone: forecast.fetch("O3"),
+          overall_score: forecast.fetch("total"),
+          overall_label: forecast.fetch("total_status")
+        ),
+
+        uv: UvPrediction.new(forecast.fetch("uv")),
+        pollen: forecast.fetch("pollen"),
+        temperature: TemperaturePrediction.new(
+          min: forecast.fetch("temp_min"),
+          max: forecast.fetch("temp_max")
+        )
+      })
+    end
+  end
+end

app/models/air_pollution_prediction.rb

@@ -0,0 +1,46 @@
+class AirPollutionPrediction
+  attr_reader :forecasted_at,
+    :nitrogen_dioxide,
+    :particulate_matter_10,
+    :particulate_matter_2_5,
+    :ozone,
+    :overall_score
+
+  def initialize(
+    forecasted_at:,
+    nitrogen_dioxide:,
+    particulate_matter_10:,
+    particulate_matter_2_5:,
+    ozone:,
+    overall_score:,
+    overall_label:
+  )
+    @forecasted_at = forecasted_at
+    @nitrogen_dioxide = nitrogen_dioxide
+    @particulate_matter_10 = particulate_matter_10
+    @particulate_matter_2_5 = particulate_matter_2_5
+    @ozone = ozone
+    @overall_score = overall_score
+    @overall_label = overall_label
+  end
+
+  def overall_label
+    ActiveSupport::Inflector.upcase_first(@overall_label.downcase)
+  end
+
+  # :nocov:
+  def inspect
+    attr_values = [
+      "@forecasted_at=#{forecasted_at}",
+      "@nitrogen_dioxide=#{nitrogen_dioxide}>",
+      "@particulate_matter_10=#{particulate_matter_10}",
+      "@particulate_matter_2_5=#{particulate_matter_2_5}",
+      "@ozone=#{ozone}",
+      "@overall_score=#{overall_score}",
+      "@overall_label=#{@overall_label}"
+    ]
+
+    "#<#{self.class.name} #{attr_values.join(" ")}>"
+  end
+  # :nocov:
+end

app/models/air_quality_alert.rb

@@ -0,0 +1,29 @@
+class AirQualityAlert
+  def initialize(forecast)
+    @forecast = forecast
+  end
+
+  TAG_COLOURS = {
+    moderate: :yellow,
+    high: :red,
+    very_high: :purple
+  }
+
+  def date
+    @forecast.forecast_for
+  end
+
+  def level
+    @forecast.air_pollution.overall_label
+  end
+
+  def score
+    @forecast.air_pollution.overall_score
+  end
+
+  def tag_colour
+    TAG_COLOURS.fetch(
+      ActiveSupport::Inflector.parameterize(level, separator: "_").to_sym
+    )
+  end
+end

app/models/cerc_api_client.rb

@@ -0,0 +1,22 @@
+require "httparty"
+
+class CercApiClient
+  include HTTParty
+
+  def self.fetch_data(zone)
+    base_url = ENV.fetch("CERC_API_HOST_URL")
+
+    query = {
+      "from" => Date.today,
+      "numdays" => 3,
+      "zone" => zone,
+      "key" => ENV.fetch("CERC_API_KEY")
+    }
+
+    HTTParty.get("#{base_url}/getforecast/all", query: query)
+  end
+
+  def self.forecasts_for(zone)
+    ForecastFactory.build(fetch_data(zone))
+  end
+end

app/models/forecast.rb

@@ -0,0 +1,39 @@
+class Forecast
+  attr_reader :obtained_at, :forecast_for, :zone, :air_pollution, :uv, :pollen, :temperature
+
+  def initialize(attrs)
+    @obtained_at = attrs.fetch(:obtained_at)
+    @forecast_for = attrs.fetch(:forecast_for)
+    @zone = attrs.fetch(:zone)
+    @air_pollution = attrs.fetch(:air_pollution)
+    @uv = attrs.fetch(:uv)
+    @pollen = attrs.fetch(:pollen)
+    @temperature = attrs.fetch(:temperature)
+  end
+
+  def alerts
+    [air_quality_alert].compact
+  end
+
+  def air_quality_alert
+    return if air_pollution.overall_label.downcase == "low"
+
+    AirQualityAlert.new(self)
+  end
+
+  # :nocov:
+  def inspect
+    attr_values = [
+      "@obtained_at=#{obtained_at}",
+      "@forecast_for=#{forecast_for}",
+      "@zone=#{zone.inspect}",
+      "@air_pollution=#{air_pollution.inspect}",
+      "@uv=#{uv.inspect}",
+      "@pollen=#{pollen}",
+      "@temperature=#{temperature.inspect}"
+    ]
+
+    "#<#{self.class.name} #{attr_values.join(" ")}>"
+  end
+  # :nocov:
+end

app/models/forecast_zone.rb

@@ -0,0 +1,21 @@
+class ForecastZone
+  attr_reader :id, :name
+
+  def initialize(id:, name:, type:)
+    @id = id
+    @name = name
+    @type = type
+  end
+
+  def type
+    return "London Borough" if @type == 1
+
+    "Area"
+  end
+
+  # :nocov:
+  def inspect
+    "#<#{self.class.name} @id=#{id} @name=#{name} @type=#{@type}>"
+  end
+  # :nocov:
+end

app/models/temperature_prediction.rb

@@ -0,0 +1,14 @@
+class TemperaturePrediction
+  attr_reader :min, :max
+
+  def initialize(min:, max:)
+    @min = min
+    @max = max
+  end
+
+  # :nocov:
+  def inspect
+    "#<#{self.class.name} @min=#{min} @max=#{max}>"
+  end
+  # :nocov:
+end

app/models/uv_prediction.rb

@@ -0,0 +1,27 @@
+class UvPrediction
+  attr_reader :level, :label, :guidance
+
+  def initialize(level)
+    @level = level
+    case level
+    when 1..3
+      @label = "Low"
+      @guidance = "No action required. You can safely stay outside."
+    when 4..6
+      @label = "Moderate"
+      @guidance = "Protection required. Seek shade during midday hours, cover up and wear suncream."
+    when 7..9
+      @label = "High"
+      @guidance = "some high UV guidance"
+    else
+      @label = "Very high"
+      @guidance = "some very high UV guidance"
+    end
+  end
+
+  # :nocov:
+  def inspect
+    "#<#{self.class.name} @level=#{level} @label=#{label} @guidance=#{guidance}>"
+  end
+  # :nocov:
+end