Backend/API Developer Code Challenge

Overview

In this task, you will develop a commandline interface for working with a standard todo.txt file. (todo.txt is a plaintext format for organizing tasks inspired by David Allen's Getting Things Done (GTD) methodology). Since the purpose of this project is primarily to demonstrate your ability to quickly learn and modify an existing codebase, we ask that you use 1set's todotxt library, which you will need to extend to complete the list of requirements.

Format

Your program should run on a standard *nix (MacOS Terminal, Linux Shell, etc.) - or Windows PowerShell - commandline. It should accept input from a user and make appropriate modifications to a file called todo.txt which should be stored somewhere "nearby" (i.e. in the same folder as or possibly a subfolder of the folder in which the person evaluating your code would run the program). You do not need to rely on environment variables or config files to specify the location of this file, as it's really not important to the test. It's OK to hardcode the path to the todo.txt file.

In a *nix environment, the tester would expect to run your program in the following way:

prompt> ./todo add {task}

Command List

Your CLI should support the following commands:

ls - lists all tasks. It should accept the following optional filter parameters:
1. @context - any string that starts with '@' should be interpreted as a "context tag," and the output should only include tasks with that context. If more than one "context tag" param is included, the filter should accept any todo that has one or more of the given context tagss and reject any todo lacking all of the specified context tags
2. +project - any string that starts with '+' should be interpreted as a "project tag," and the output should only include tasks associated with that project. If more than one "project tag" param is included, the filter should accept any todo that has one or more of the given project tags and reject any todo lacking all of the specified project tags
3. (A) - any string that is surrounded with () should be interpreted as a "priority" tag, and the output should include only tasks that have the associated priority. If more than one priority tag is included in the params, the output should include all and only tasks that have any of the specified priority tags.
4. tag: - any string that ends in a : should filter out any tasks that do not contain the associated tag. If more than one such string is included, the application should filter out any tasks that do not include any of the specified tags
5. >datestring, <datestring - any string that starts with a > and is in YYYY-MM-DD format (e.g. "2021-01-01") should filter out any tasks that have due dates before the specified time. Any string that starts with a < and is in YYYY-MM-DD format (e.g. "2021-01-01") should filter out any tasks that have due dates after the specified time. If multiple such strings are included, it should respect the instructions of all of them (this may result in an empty list returned).
6. |order Any param that starts with | should be interpreted as an ordering parameters. You can define your own list of strings for the "order" param, but you should support all the orders defined by the TaskSortByType type in the codebase (defined here)
7. completed If this string is included, output completed tasks at the end of the list, subject to all the same filters, separated from the other tasks by an empty line
completed - lists all completed tasks. It should accept the same filters as ls, with the difference that the <datestring and >datestring filters should apply to the "completed" date rather than the due date.
add {task_string} - adds a task to the file
rm {task_id} - removes a task from the file
do {task_id} - mark the task specified by the id as completed
tags - list all unique tags in the file. It is not enough to simply list the tags, you have to ensure that there are no duplicates in the output.
projects - list all unique projects in the file. It is not enough to simply list the projects, you must ensure that there are no duplicates in the output.
due - output a list of unique due dates followed by the number of tasks due on that date. At the end of the list, include the number of tasks that are missing a due date. Example output:
```
2021-03-01 16
2021-03-02 5
2021-03-15 1
26
```
extend {task_id} {quantity} {unit} - Should extend the due date of the task identified by {task_id} by {quantity} number of {unit} time. For example, extend 5 1 day would add one day to the due date on task 5. extend 6 -2 week would shorten the due date of task 6 by two weeks. So, if task 5 was due on 2021-03-03, it would be due on 2021-03-04 as a result of the command. If task 6 were due on 2021-03-03, it would be due on 2021-02-17 as a result of the command. If a task has no duedate when this call is made on it, it should behave as though the task were due today. You should support the following units:
1. day
2. week
3. month
4. year

Other Requirements

By default - i.e. in the absence of any other filters - output should be sorted primarily by priority, secondarily by due date, and tertiarily by created date. Completed tasks should always be listed separately (when they are listed at all)

Bonus Requirements

Add support for >= and <= as due date filters
Add a "help" or "man" page instruction that prints out instructions on how to use the app.
For the due command, include the number of tasks due on the date that are not completed in parentheses. E.g.:
```
2021-03-01 16 (8)
2021-03-02 5 (1) 
2021-03-15 1 (0)
26 (22)
```
Include a "TOTAL: {number}" tag at the end of the output of the ls command that shows the number of tasks in the output
Add terminal colors to the output. So, for example, all tasks of priority (A) might be yellow, the tasks of priority (B) might be red, etc.

Fullstack API Developer Code Challenge

As an alternative, you can implement a web interface (instead of a commandline interface). This should be a REST interface to the todotxt library.

Setup - Running apichallenge.go

The basic framework has been done for you. The file apichallenge.go implements a basic server that can handle the web connection for you (you don't need to implement authentication or user management for this task). To run this setup you will need to:

Install todotxt: go get github.com/1set/todotxt
Install httprouter: go get github.com/julienschmidt/httprouter
Compile: go build
Run it! : ./apichallenge

Now if you navigate to http://localhost:8080/mainpage.html you should see the main page.

Integration

You will see that the basic REST routes have been implemented for you. All you need to do is modify the relevant functions to satisfy the tasks below.

Static Assets

apichallenge.go will serve up any file that is stored in the static/ folder as a direct path. For example, navigating to http://localhost:8080/mainpage.html serves the mainpage.html file. Navigating to http://localhost:8080/stylesheets/main.css serves the main stylesheet. ETC. You can put any html or css or javascript libraries you need for the interface in the static folder.

todo.txt

The application will load tasks from and save tasks into the provided todo.txt file. You do not need to integrate with any kind of database. Just using this file for storage is OK.

Tasks

Be sure that you are familiar with the todo.txt file format before starting this task. Don't worry, it's easy to learn!

Your web application should support the following actions:

List all the tasks. This part of the project should accept query parameters to filter the list of todos. The filtering must be done on the backend. The point of this part of the task is to demonstrate that you can use an existing Go codebase. So, you must implement the list filters on the backend in Go (and not on the frontend in Javascript)!!! The following query parameters should be accepted:
1. projects - Any projects included here should filter the output to include only those tasks that are associated with one or more of the given projects.
2. priority - Any priorities included here should filter the output to include only those tasks that have one of the priorities in question
3. context - Any contexts included here should filter the output to include only those tasks that have one of the contexts in question
4. order - If the order param is set, the tasks should come back in the order specified. You should support all the orders given in the TaskSortByType) struct.
5. duebefore - this should accept a string representing a datetime and only return tasks that (a) have a duedate (b) which is before the date specified
6. dueafter - this should accept a string representing a datetime and only return tasks that (a) have a dueate (b) which is after the date specified
Accept input from a user and add a new todo to the list
Update any aspect of a task. This includes:
1. Adding (or removing) a project
2. Adding (or removing) a context
3. Setting (or changing) the priority
4. Setting (or changing) the duedate
Mark a task as complete
(Optional) Delete a task

periodicapp / apichallenge