// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
library fuchsia.legacymetrics;

using zx;

/// A single metric event to be recorded and sent to the UMA backend.
type Event = strict union {
    1: user_action_event UserActionEvent;
    2: histogram Histogram;
    3: impl_defined_event ImplementationDefinedEvent;
};

/// Event that occurs in response to a user action. See
/// https://chromium.googlesource.com/chromium/src.git/+/HEAD/tools/metrics/actions/README.md
type UserActionEvent = table {
    1: name string:MAX;

    /// Required timestamp of the event occurrence. See TimeTicks in
    /// https://cs.chromium.org/chromium/src/base/time/time.h
    2: time zx.Time;
};

type Histogram = table {
    /// Required histogram identifier. See these guidelines for more info:
    /// https://chromium.googlesource.com/chromium/src.git/+/HEAD/tools/metrics/histograms/README.md#naming-your-histogram
    1: name string:MAX;

    2: buckets vector<HistogramBucket>:MAX;

    // The sum of all the sample values.
    // Together with the total count of the sample values, this allows us to
    // compute the average value.  The count of all sample values is just the sum
    // of the counts of all the buckets.
    3: sum int64;
};

type HistogramBucket = struct {
    // Each bucket's range is bounded by min <= x < max.
    min int64;
    max int64;

    // The number of entries in this bucket.
    count int64;
};

/// A custom event defined by the MetricsRecorder service. Refer to your
/// MetricsRecorder implementation for more details on the payload structure.
type ImplementationDefinedEvent = table {
    /// Custom binary payload whose structure is defined by the MetricsRecorder
    /// implementation. For example, it can represent a custom event protocol
    /// buffer serialized to its wire format.
    1: data vector<uint8>:MAX;

    /// Event identifier required if it's not already included in binary `data`.
    /// This field takes precedence over any equivalent name included in binary
    /// `data`, if both are provided.
    2: name string:MAX;
};