326. Design Document Comment Service

Design Document Comment Service

An existing document service stores documents that can be reviewed. Add a comment service that allows reviewers to attach comments to these existing documents.

A comment may be added only when the specified document exists. Comments added to a document must be retained in the order in which they were added.

Class Definition

CommentService(List<String> documentIds)

Initializes the service with the identifiers of all existing documents.
Every value in documentIds is unique.

Method Signatures

Add a Comment

boolean addComment(String documentId, String reviewerId, String commentText)

Adds commentText from reviewerId to the document identified by documentId.
Returns true when the document exists and the comment is successfully added.
Returns false when documentId does not identify an existing document. No comment is stored in this case.
Multiple reviewers may comment on the same document.
Identical comments are allowed and are stored separately.

Get Document Comments

List<String> getComments(String documentId)

Returns all comments added to the specified document in insertion order.
Each returned string uses the format "reviewerId,commentText". The first comma separates the reviewer identifier from the comment text.
Returns an empty list when the document does not exist or has no comments.

Deterministic Behavior

Comments are always returned in the same order in which they were added.
Adding a comment to one document does not affect comments on another document.
A rejected comment is never included in later results.

Constraints

1 ≤ documentIds.size() ≤ 10,000
1 ≤ documentId.length() ≤ 100
1 ≤ reviewerId.length() ≤ 100
1 ≤ commentText.length() ≤ 2,000
Document identifiers and reviewer identifiers and comment text do not contain commas.
All identifiers and comment texts contain printable characters.
At most 100,000 method calls are made after initialization.
No parameter value is null.

Examples

Example 1: Adding and Reading Comments

CommentService(documentIds = List.of("design-12", "report-27"))

addComment(documentId = "design-12", reviewerId = "reviewer-4", commentText = "Please clarify this section")

Output: true

addComment(documentId = "design-12", reviewerId = "reviewer-9", commentText = "The diagram looks correct")

Output: true

getComments(documentId = "design-12")

Output: List.of("reviewer-4,Please clarify this section", "reviewer-9,The diagram looks correct")

The two comments are returned in the order in which they were added.

Example 2: Document Does Not Exist

CommentService(documentIds = List.of("guide-5", "contract-8"))

addComment(documentId = "invoice-3", reviewerId = "reviewer-2", commentText = "Please verify the total")

Output: false

getComments(documentId = "invoice-3")

Output: List.of()

The comment is rejected because "invoice-3" is not an existing document.

Example 3: Existing Document Without Comments

CommentService(documentIds = List.of("proposal-21"))

getComments(documentId = "proposal-21")

Output: List.of()

The document exists, but no reviewer has added a comment to it.