Aggregate Time Series for Dashboard

Problem

Given a list of event records, where each record is a tuple (timestamp, metric, value), aggregate the data into fixed-size time buckets and return a structure suitable for plotting. Each bucket should contain the sum of values for every metric seen in the input. Missing metric values in a bucket should be reported as 0. Return the buckets sorted by start time.

Constraints

• 1 <= len(events) <= 10^5
• 0 <= timestamp <= 10^9
• 1 <= bucket_size <= 10^6
• metric is a non-empty string
• 0 <= value <= 10^6