Design a Customer Issue Resolution System

Problem Statement

Design a customer issue resolution system where customers can raise issues related to products or services, and support agents can resolve them within a defined lifecycle. The system should ensure proper assignment, tracking, and status updates until the issue is fully resolved.

Asked In Companies

Salesforce Amazon Atlassian Microsoft Google Uber Zendesk Oracle Flipkart Walmart Adobe Intuit

---

Functional Requirements

• Customers should be able to raise issues
• Each issue should have a lifecycle (OPEN → IN_PROGRESS → RESOLVED → CLOSED)
• Issues should be assigned to support agents
• Agents should update issue status
• System should support priority levels
• Issues should maintain full history of resolution flow

---

Objects Required

• Customer
• SupportAgent
• Issue
• IssueService
• IssueStatus Enum
• Priority Enum

---

IssueStatus Enum

public enum IssueStatus {
    OPEN,
    IN_PROGRESS,
    RESOLVED,
    CLOSED
}

This enum defines the lifecycle of an issue and ensures consistent state transitions instead of free-form strings.

---

Priority Enum

public enum Priority {
    LOW,
    MEDIUM,
    HIGH,
    CRITICAL
}

Priority helps the system decide urgency and SLA handling for each issue.

---

Customer Class

public class Customer {

    private String customerId;
    private String name;

    public Customer(String customerId, String name) {
        this.customerId = customerId;
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

Customer represents a user who can raise issues in the system.

---

SupportAgent Class

public class SupportAgent {

    private String agentId;
    private String name;

    public SupportAgent(String agentId, String name) {
        this.agentId = agentId;
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

SupportAgent represents a service executive responsible for resolving customer issues.

---

Issue Class

import java.util.*;

public class Issue {

    private String issueId;
    private String description;
    private Customer customer;
    private SupportAgent assignedAgent;
    private IssueStatus status;
    private Priority priority;
    private List<String> history;

    public Issue(String issueId, String description, Customer customer, Priority priority) {
        this.issueId = issueId;
        this.description = description;
        this.customer = customer;
        this.priority = priority;
        this.status = IssueStatus.OPEN;
        this.history = new ArrayList<>();
        this.history.add("Issue created");
    }

    public void assignAgent(SupportAgent agent) {
        this.assignedAgent = agent;
        this.status = IssueStatus.IN_PROGRESS;
        history.add("Assigned to agent: " + agent.getName());
    }

    public void resolveIssue() {
        this.status = IssueStatus.RESOLVED;
        history.add("Issue resolved");
    }

    public void closeIssue() {
        this.status = IssueStatus.CLOSED;
        history.add("Issue closed");
    }

    public List<String> getHistory() {
        return history;
    }
}

The Issue class is the core entity that tracks problem details, customer info, agent assignment, status, and full lifecycle history.

The constructor initializes a new issue in OPEN state and records its creation in history.

The assignAgent() method assigns a support agent and moves the issue into IN_PROGRESS state.

The resolveIssue() method marks the issue as RESOLVED and records the action.

The closeIssue() method finalizes the issue lifecycle.

---

IssueService Class

import java.util.*;

public class IssueService {

    private Map<String, Issue> issueStore = new HashMap<>();

    public void createIssue(Issue issue) {
        issueStore.put(issue.toString(), issue);
    }

    public void assignIssue(String issueId, SupportAgent agent) {
        for (Issue issue : issueStore.values()) {
            if (issue.toString().equals(issueId)) {
                issue.assignAgent(agent);
            }
        }
    }

    public void resolveIssue(String issueId) {
        for (Issue issue : issueStore.values()) {
            if (issue.toString().equals(issueId)) {
                issue.resolveIssue();
            }
        }
    }

    public void closeIssue(String issueId) {
        for (Issue issue : issueStore.values()) {
            if (issue.toString().equals(issueId)) {
                issue.closeIssue();
            }
        }
    }
}

IssueService acts as the orchestration layer that manages issue lifecycle operations like creation, assignment, resolution, and closure.

It maintains an in-memory store of issues for quick retrieval and updates.

---

Main Class

public class Main {

    public static void main(String[] args) {

        Customer customer = new Customer("C1", "Alice");

        SupportAgent agent = new SupportAgent("A1", "John");

        Issue issue = new Issue(
            "I1",
            "Payment not processed",
            customer,
            Priority.HIGH
        );

        IssueService service = new IssueService();

        service.createIssue(issue);

        service.assignIssue("I1", agent);
        service.resolveIssue("I1");
        service.closeIssue("I1");

        System.out.println(issue.getHistory());
    }
}

---

Class Diagram

Also See

• Most Commonly Asked Low Level Design Interview Questions
• Top 10 Low Level Design Interview Questions