Calendly implementation

README.md

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-# Harbor Take Home Project
-
-Welcome to the Harbor take home project. We hope this is a good opportunity for you to showcase your skills.
-
-## The Challenge
-
-Build us a REST API for calendly. Remember to support
-
-- Setting own availability
-- Showing own availability
-- Finding overlap in schedule between 2 users
-
-It is up to you what else to support.
-
-## Expectations
-
-We care about
-
-- Have you thought through what a good MVP looks like? Does your API support that?
-- What trade-offs are you making in your design?
-- Working code - we should be able to pull and hit the code locally. Bonus points if deployed somewhere.
-- Any good engineer will make hacks when necessary - what are your hacks and why?
-
-We don't care about
-
-- Authentication
-- UI
-- Perfection - good and working quickly is better
-
-It is up to you how much time you want to spend on this project. There are likely diminishing returns as the time spent goes up.
-
-## Submission
-
-Please fork this repository and reach out to Prakash when finished.
-
-## Next Steps
-
-After submission, we will conduct a 30 to 60 minute code review in person. We will ask you about your thinking and design choices.
+## This is my implementation of calendly with below-mentioned components, features, use cases, assumptions, future scopes, etc.
+
+## Components
+1. This is a spring boot application which is divided into controller(API layer), service(service layer), model(contains object/DTOs), datastore(in-memeroy DB). 
+2. We have 2 entities i.e. User & Meeting, these entities in turn have 2 dedicated singleton datastores, 2 services and 2 controllers.
+3. UserController has user CRUD APIs.
+4. MeetingController has scheduleMeeting() API which is used to schedule a meeting between a requestor and a requestee.
+
+## Features
+1. Users can be created, deleted, read and modified(new available slots can be added).
+2. Meetings can be scheduled between 2 people.
+3. Exception handling is added at all the required places.
+
+## APIs
+1. Create User 
+2. Delete User
+3. Display all users
+4. Display a specific user
+5. Add available slots to an user
+6. Schedule meeting between the requestor and the requestee.
+
+## Assumptions:
+1. A user will always call an API with only his userId as a requestor to schedule a meeting.
+2. An in-memory singleton database is used.
+3. Requestor will schedule a meet in his own available slot, if not then our pre-validation check throws an exception.
+4. By default, all slots are unavailable for a new user.
+5. Time format used is [yyyy-MM-dd HH:mm].
+
+## Use Case
+1. Create user1
+2. Add available slots to user1 e.g. [2024-09-20 10:00 to 2024-09-20 10:30], [2024-09-20 12:00 to 2024-09-20 13:00], [2024-09-20 16:00 to 2024-09-20 16:45]  
+3. Create user2
+4. Add available slots to user1 e.g. [2024-09-20 10:00 to 2024-09-20 10:30], [2024-09-20 13:00 to 2024-09-20 14:00], [2024-09-20 16:00 to 2024-09-20 16:30]
+5. user1 requests to schedule a meeting with user2 at [2024-09-20 10:00 to 2024-09-20 10:30]

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.example</groupId>
+    <artifactId>basic-spring-boot</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.2.5.RELEASE</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.12</version>
+            <scope>provided</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.modelmapper</groupId>
+            <artifactId>modelmapper</artifactId>
+            <version>2.3.0</version>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

src/main/java/com/kaps/Application.java

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+package com.kaps;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+    public static void main(String[] args){
+        SpringApplication.run(Application.class,args);
+    }
+}

src/main/java/com/kaps/Utility.java

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+package com.kaps;
+
+import java.util.UUID;
+
+public class Utility {
+
+    public static final String generateUUID() {
+        return UUID.randomUUID().toString().replace("-", "");
+    }
+}

src/main/java/com/kaps/controller/MeetingController.java

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+package com.kaps.controller;
+
+import com.kaps.model.Meeting;
+import com.kaps.service.MeetingService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.format.annotation.DateTimeFormat;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.*;
+
+import java.time.LocalDateTime;
+
+@Controller
+@RequestMapping("/meeting")
+public class MeetingController {
+    @Autowired MeetingService meetingService;
+
+    @ResponseBody
+    @PostMapping("schedule")
+    public Meeting scheduleMeeting(@RequestParam("requestor") String requestor,
+                                   @RequestParam("requestee") String requestee,
+                                   @RequestParam("startTime") @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm") LocalDateTime startTime,
+                                   @RequestParam("endTime") @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm") LocalDateTime endTime) throws Exception {
+        return meetingService.scheduleMeeting(requestor, requestee, startTime, endTime);
+    }
+}

src/main/java/com/kaps/controller/UserController.java

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+package com.kaps.controller;
+
+import com.kaps.model.User;
+import com.kaps.service.UserService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.format.annotation.DateTimeFormat;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.*;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+@Controller
+@RequestMapping("/user")
+public class UserController {
+    @Autowired UserService userService;
+
+    @ResponseBody
+    @PostMapping
+    public User createUser(@RequestBody User user) throws Exception {
+        return userService.createUser(user);
+    }
+
+    @ResponseBody
+    @GetMapping("/allusers")
+    public List<User> getUsers() throws Exception {
+        return userService.getUsers();
+    }
+
+    @ResponseBody
+    @GetMapping
+    public User getUser(@RequestParam("userName") String userName) throws Exception {
+        return userService.getUserByName(userName);
+    }
+
+    @ResponseBody
+    @DeleteMapping
+    public void deleteUser(@RequestParam("userName") String userName) throws Exception {
+        userService.deleteUser(userName);
+    }
+
+    @ResponseBody
+    @PutMapping
+    public User addAvailableSlot(@RequestParam("userName") String userName,
+                                  @RequestParam("startTime") @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm") LocalDateTime startTime,
+                                  @RequestParam("endTime") @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm") LocalDateTime endTime) throws Exception {
+        return userService.addAvailableSlot(userName, startTime, endTime);
+    }
+}

src/main/java/com/kaps/datastore/MeetingDataStore.java

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+package com.kaps.datastore;
+
+import com.kaps.Utility;
+import com.kaps.model.Meeting;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class MeetingDataStore {
+    Map<String, Meeting> meetingDataMap;
+
+    public static MeetingDataStore getInstance() {
+        return new MeetingDataStore();
+    }
+
+    private MeetingDataStore() {
+        meetingDataMap = new HashMap<>();
+    }
+
+    public Meeting scheduleMeeting(Meeting meeting) {
+        meeting.setId(Utility.generateUUID());
+        meetingDataMap.put(meeting.getId(), meeting);
+
+        return meetingDataMap.get(meeting.getId());
+    }
+}

src/main/java/com/kaps/datastore/UserDataStore.java

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+package com.kaps.datastore;
+
+import com.kaps.Utility;
+import com.kaps.model.Slot;
+import com.kaps.model.User;
+
+import java.time.LocalDateTime;
+import java.util.*;
+
+public class UserDataStore {
+    Map<String, User> userNameToUserMap;
+
+    public static UserDataStore getInstance() {
+        return new UserDataStore();
+    }
+
+    private UserDataStore() {
+        userNameToUserMap = new HashMap<>();
+    }
+
+    public User createUser(User user) throws Exception {
+        checkIfUserAlreadyExists(user.getName());
+        user.setId(Utility.generateUUID());
+        userNameToUserMap.put(user.getName(), user);
+
+        return userNameToUserMap.get(user.getName());
+    }
+
+    public void deleteUser(String userName) throws Exception {
+        checkIfUserExists(userName);
+        userNameToUserMap.remove(userName);
+    }
+
+    public User addAvailableSlot(String userName, LocalDateTime startTime, LocalDateTime endTime) throws Exception {
+        checkIfUserExists(userName);
+        performSanity(startTime, endTime);
+
+        User user = userNameToUserMap.get(userName);
+        user.getAvailableSlots().add(
+                new Slot(UUID.randomUUID().toString().replace("-", ""), startTime, endTime));
+
+        return userNameToUserMap.get(userName);
+    }
+
+    public List<User> getUsers() {
+        List<User> users = new ArrayList<>();
+
+        for (String userName: userNameToUserMap.keySet()) {
+            users.add(userNameToUserMap.get(userName));
+        }
+
+        return users;
+    }
+
+    public User getUserByName(String userName) throws Exception {
+        checkIfUserExists(userName);
+
+        return userNameToUserMap.get(userName);
+    }
+
+    public List<Slot> getAvailableSlots(String userName) throws Exception {
+        checkIfUserExists(userName);
+
+        return new ArrayList<>(userNameToUserMap.get(userName).getAvailableSlots());
+    }
+
+    public void removeSlot(String userName, String slotId) throws Exception {
+        Set<Slot> slots = userNameToUserMap.get(userName).getAvailableSlots();
+        Set<Slot> newSlots = new HashSet<>();
+
+        for (Slot slot: slots) {
+            if (!slot.getId().equals(slotId))
+                newSlots.add(slot);
+        }
+
+        userNameToUserMap.get(userName).setAvailableSlots(newSlots);
+    }
+
+    private void checkIfUserExists(String userName) throws Exception {
+        if (!userNameToUserMap.containsKey(userName)) {
+            throw new Exception("No user exists with userName: " + userName);
+        }
+    }
+
+    private void checkIfUserAlreadyExists(String userName) throws Exception {
+        if (userNameToUserMap.containsKey(userName)) {
+            throw new Exception("User already exists with userName: " + userName);
+        }
+    }
+
+    public void performSanity(LocalDateTime startTime, LocalDateTime endTime) throws Exception {
+        if (startTime.isAfter(endTime)) {
+            throw new Exception("Meeting start time cannot be after meeting end time!");
+        }
+        if (startTime.isBefore(LocalDateTime.now())) {
+            throw new Exception("Cannot schedule an expired meeting!");
+        }
+    }
+}

src/main/java/com/kaps/model/Meeting.java

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+package com.kaps.model;
+
+import javafx.util.Pair;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+import org.springframework.data.annotation.Id;
+
+import java.time.LocalDateTime;
+import java.util.Set;
+
+@NoArgsConstructor
+@AllArgsConstructor
+@Getter
+@Setter
+public class Meeting {
+    @Id private String id;
+    private String requestor;
+    private String requestee;
+    private LocalDateTime startTime;
+    private LocalDateTime endTime;
+}