Plan resumable upload chunks

Build a gap-free chunk plan for a Dropbox-inspired resumable upload flow.

EasyResumable Uploads

25 min0% acceptance

Description

Implement planUploadChunks for an original Dropbox-inspired upload planner. Given a file size and a maximum chunk size, return the exact ordered byte ranges needed to upload the file without gaps or overlaps. This exercise is based on public chunked-upload guidance and is not presented as a Dropbox interview question or company affiliation.

Requirements

The solution exports a callable function named planUploadChunks.
Chunk offsets start at zero and cover every byte exactly once without gaps or overlaps.
Every returned chunk has a positive integer size no greater than config.chunkSize.
Only the last chunk is marked final, including when the file size is an exact chunk-size multiple.
A fileSize of zero returns an empty array.
Invalid, fractional, unsafe, or out-of-range configuration values throw a RangeError.
The function returns a new result array containing newly created chunk records.
The config object and its property descriptors are not mutated.

Upload with a partial final chunk

Input

{ fileSize: 11, chunkSize: 4 }

Expected output

[{ offset: 0, size: 4, final: false }, { offset: 4, size: 4, final: false }, { offset: 8, size: 3, final: true }]

Explanation

The first two chunks use the maximum size. The final chunk covers the remaining three bytes and is the only record marked final.

Empty file

Input

{ fileSize: 0, chunkSize: 4 }

Expected output

[]

Explanation

There are no byte ranges to upload.

Constraints

config is an object with fileSize and chunkSize properties
fileSize must be a safe integer from 0 through Number.MAX_SAFE_INTEGER
chunkSize must be a safe integer from 1 through Number.MAX_SAFE_INTEGER
The number of generated chunks will not exceed 2500
Do not mutate, freeze, seal, or redefine the caller-owned config object

Hints

Hint 1

Advance a byte offset by one bounded chunk at a time until it reaches the file size.

Hint 2

Derive each end offset from the smaller of the next chunk boundary and the file boundary.

Hint 3

Decide whether a chunk is final by comparing its end offset with the total size.

arraysboundary arithmeticuploadsimmutability