// Copyright 2022 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.metricslogger.test;

// Type aliase for client Id for convenience
alias ClientId = string:8;

/// Errors associated with MetricsLogger methods.
/// If the request contains any of the following errors, it will fail without
/// affecting the existing logging tasks.
type MetricsLoggerError = strict enum : uint32 {
    /// Indicates that no driver is found for requested metric logging.
    NO_DRIVERS = 1;
    /// Indicates that an invalid sampling interval was provided.
    INVALID_SAMPLING_INTERVAL = 2;
    /// Requests to start logging will fail if logging is already active for a
    /// given client.
    ALREADY_LOGGING = 3;
    /// Indicates that the logging request contains duplicated metric type.
    DUPLICATED_METRIC = 4;
    /// Indicates that the total number of active clients has reached the
    /// allowed maxium (defined by `MAX_CONCURRENT_CLIENTS = 20` in
    /// the MetricsLogger to keep memory use bounded).
    TOO_MANY_ACTIVE_CLIENTS = 5;
    /// Indicates that statistics is enabled and an invalid statistics interval
    /// is provided.
    INVALID_STATISTICS_INTERVAL = 6;
};

/// Metric type requested in MetricsLogger methods.
type Metric = strict union {
    1: temperature Temperature;
    2: cpu_load CpuLoad;
    3: power Power;
};

type StatisticsArgs = struct {
    /// Length of the interval in milliseconds for summarizing statistics (e.g.,
    /// min, max, avg).
    /// Must be equal to or larger than `sampling_interval_ms` in the metrics.
    /// Must be smaller than `duration_ms` of the logging request.
    /// Must not be smaller than 500ms if `output_stats_to_syslog` is enabled in
    /// the logging request.
    statistics_interval_ms uint32;
};

/// Temperature metric details.
type Temperature = struct {
    /// Length of the sampling interval in milliseconds.
    /// Must not be smaller than 500ms if `output_samples_to_syslog` is enabled
    /// in the logging request.
    /// Must be smaller than `duration_ms` of the logging request.
    sampling_interval_ms uint32;

    /// Boxed(optional) statistics arguments. If none, statistics is disabled.
    statistics_args box<StatisticsArgs>;
};

/// CPU Load metric details.
type CpuLoad = struct {
    /// Length of the polling interval in milliseconds.
    /// Must be smaller than `duration_ms` of the logging request.
    /// Must not be smaller than 500ms if `output_samples_to_syslog` is enabled
    /// in the logging request.
    interval_ms uint32;
};

/// Power metric details.
type Power = struct {
    /// Length of the sampling interval in milliseconds.
    /// Must not be smaller than 500ms if `output_samples_to_syslog` is enabled
    /// in the logging request.
    /// Must be smaller than `duration_ms` of the logging request.
    sampling_interval_ms uint32;

    /// Boxed(optional) statistics arguments. If none, statistics is disabled.
    statistics_args box<StatisticsArgs>;
};

/// A protocol for managing on-demand metrics logging.
@discoverable
protocol MetricsLogger {
    /// Initiates logging of specified metrics for the provided duration.
    /// Supports concurrent logging of different metrics. Logging may be
    /// terminated early with a call to `StopLogging`.
    ///
    /// This call will fail if logging of the specified metric is already
    /// active. For this reason, a client may wish to precede a `StartLogging`
    /// call with a `StopLogging` call, after which the only reason for The
    /// logger to be active would be a conflict with another client.
    ///
    /// + request `client_id` String format Id of the client. Client may choose
    ///     any Id with a maximum byte size of 8 (e.g., "ffxTest").
    /// + request `metrics` Type of the metrics to be polled and logged.
    /// + request `duration_ms` Duration of logging in milliseconds. After this
    ///     duration, polling and logging will cease.
    /// + request `output_samples_to_syslog` Toggle for outputting raw data to
    ///     syslog.
    /// + request `output_stats_to_syslog` Toggle for outputting any available
    ///     statistics to syslog.
    /// + error a [fuchsia.metrics.test/MeticsLoggerError] value indicating why
    ///     the request failed.
    StartLogging(struct {
        client_id ClientId;
        metrics vector<Metric>:MAX;
        duration_ms uint32;
        output_samples_to_syslog bool;
        output_stats_to_syslog bool;
    }) -> (struct {}) error MetricsLoggerError;

    /// Initiates logging of specified metrics. Supports concurrent logging of
    /// different metrics. Logging will only end upon a `StopLogging` call.
    ///
    /// `StartLogging` should be preferred for usage in automated tests to
    /// ensure that logging terminates even if the test crashes.
    ///
    /// + request `client_id` String format Id of the client. Client may choose
    ///     any Id with a maximum byte size of 8 (e.g., "ffxTest").
    /// + request `metrics` Type of the metrics to be polled and logged.
    /// + request `output_samples_to_syslog` Toggle for outputting raw data to
    ///     syslog.
    /// + request `output_stats_to_syslog` Toggle for outputting any available
    ///     statistics to syslog.
    /// + error a [fuchsia.metrics.test/MetricsLoggerError] value indicating why
    ///     the request failed.
    StartLoggingForever(struct {
        client_id ClientId;
        metrics vector<Metric>:MAX;
        output_samples_to_syslog bool;
        output_stats_to_syslog bool;
    }) -> (struct {}) error MetricsLoggerError;

    /// Terminates all active logging tasks with the given client_id. It is
    /// valid to call this method when logging is inactive.
    ///
    /// + request `client_id` String format Id of the client.
    /// - response `status` A bool value indicating if existing logging was
    ///     stopped (true) or there'sno existing logging for the client.
    StopLogging(struct {
        client_id ClientId;
    }) -> (struct {
        stopped bool;
    });
};