Currency_converter

Currency_converter is a graphical interface designed with PyQt5 allows to convert currencies and view the rates history graph. Rates can be retrieved from two free APIs: free.currconv and finnhub.io.

The application is in the form of 3 tabs:

Options
Currency converter
Historical graph

What does the program do ?

Main window

A rectangle placed at the top left constantly displays the day of the week, the current date and time according to the format chosen by the user
A status message area at the bottom of the window

Option tab

The user can choose their API from a drop-down menu
For each API a key is proposed by default but it can be modified and saved
The API key displayed changes depending on the API selected in the drop-down menu
A 'TEST' button is used to check the validity of the inserted API key, if the API key is wrong, the program proposes to restore the previous one
The graph theme can be modified ('Light' or 'Dark')
User can choose to show grid on graph or not
The date and hour format can be modified
The 'Save all' button allows to save all the preferences in a JSON file, these preferences will be loaded directly the next time the application is started.

Currency Converter

The input field is checked to ensure that an integer or float number is inserted
Two drop-down menus allow to select the currencies
A 'swipe' button allows to reverse the currency pair
The 'convert' button converts the amount inserted using the API chosen by the user
An output area displays the converted value, this value can be directly selected by the cursor
Additional information area displayed at the bottom gives the conversion of one unit of the currency (ex : 1 EURO = 1.2 US Dollar), the area also displays the local name of the currency, its symbol as well as the date and time of the last update
A 'copy' button allows to directly copy the result obtained to the clipboard
A 'clear' button is used to clear the input field, the output area and the additional information area

Historical graph

Two drop-down menus allow to select the currencies
A 'swipe' button allows to reverse the currency pair
A 'VIEW' button allows to retrieve historical data from the API and represent it graphically
A graph frame showing the historical rate curve
The graph displays the rates on the y axis, the date on the x axis (according to the format chosen by the user) and a title displaying the selected currency pair and the start and end date of the measurement
A column on the right displays graph statistics (start / end date of the measurement, duration of the measurement, last rate, last variation, total variation, min / max / mean
A drop-down menu allow to select the range time of the measurement
The 'Save the graph' button allows to save the image of the graph in the current folder in .png format
The 'Copy rate value' copies the code of the chosen currency pairs, the dates (timestamps) and their corresponding rate to the clipboard in the form of a dictionary

Additional info

The data used to draw the graph of historical rates is only taken from free.currconv
A thread periodically analyzes the state of the Internet connection by connecting to the Google DNS, if a cut is noticed certain buttons launching processes requiring Internet will be disabled during the cut
Each time current tab change, the title at the top of the window changes to the name of the selected tab
The program retrieves the information regarding the name of currencies, their code, their local name, etc. from the currencies.json file (retrieved from https://gist.github.com/Fluidbyte/2973986)
Each time the application is started, the save.json file is loaded in order to apply the user's preferences (API chosen, the scope of the historical data in days 'range', the choosen graph theme, the choice to display graph grid or not, the time format and the date format).
The name of the APIs as well as their key are entered in the save.json file, these are browsed each time the application is started in order to fill in the API comboBoxes in the option tab and to pre-fill the field dedicated to API keys.