using System;
using System.Diagnostics;

namespace StellaOps.Provcache;

public static partial class ProvcacheTelemetry
{
    /// <summary>
    /// Start a cache lookup activity.
    /// </summary>
    /// <param name="veriKey">The VeriKey being looked up.</param>
    /// <returns>The activity or null if tracing is not enabled.</returns>
    public static Activity? StartGetActivity(string veriKey)
    {
        var activity = ActivitySource.StartActivity("provcache.get", ActivityKind.Internal);
        if (activity is null) return null;

        activity.SetTag("provcache.verikey", TruncateVeriKey(veriKey));
        return activity;
    }

    /// <summary>
    /// Start a cache store activity.
    /// </summary>
    /// <param name="veriKey">The VeriKey being stored.</param>
    /// <param name="trustScore">The trust score of the entry.</param>
    /// <returns>The activity or null if tracing is not enabled.</returns>
    public static Activity? StartSetActivity(string veriKey, int trustScore)
    {
        var activity = ActivitySource.StartActivity("provcache.set", ActivityKind.Internal);
        if (activity is null) return null;

        activity.SetTag("provcache.verikey", TruncateVeriKey(veriKey));
        activity.SetTag("provcache.trust_score", trustScore);
        return activity;
    }

    /// <summary>
    /// Start an invalidation activity.
    /// </summary>
    /// <param name="invalidationType">The type of invalidation (verikey, policy_hash, signer_set_hash, feed_epoch).</param>
    /// <param name="targetValue">The target value for invalidation.</param>
    /// <returns>The activity or null if tracing is not enabled.</returns>
    public static Activity? StartInvalidateActivity(string invalidationType, string? targetValue)
    {
        var activity = ActivitySource.StartActivity("provcache.invalidate", ActivityKind.Internal);
        if (activity is null) return null;

        activity.SetTag("provcache.invalidation_type", invalidationType);
        if (!string.IsNullOrWhiteSpace(targetValue))
        {
            activity.SetTag("provcache.target", TruncateVeriKey(targetValue));
        }

        return activity;
    }

    /// <summary>
    /// Start a write-behind flush activity.
    /// </summary>
    /// <param name="batchSize">Number of entries in the batch.</param>
    /// <returns>The activity or null if tracing is not enabled.</returns>
    public static Activity? StartWriteBehindFlushActivity(int batchSize)
    {
        var activity = ActivitySource.StartActivity("provcache.writebehind.flush", ActivityKind.Internal);
        if (activity is null) return null;

        activity.SetTag("provcache.batch_size", batchSize);
        return activity;
    }

    /// <summary>
    /// Start a VeriKey construction activity.
    /// </summary>
    /// <returns>The activity or null if tracing is not enabled.</returns>
    public static Activity? StartVeriKeyBuildActivity()
    {
        return ActivitySource.StartActivity("provcache.verikey.build", ActivityKind.Internal);
    }

    /// <summary>
    /// Start a DecisionDigest construction activity.
    /// </summary>
    /// <returns>The activity or null if tracing is not enabled.</returns>
    public static Activity? StartDecisionDigestBuildActivity()
    {
        return ActivitySource.StartActivity("provcache.digest.build", ActivityKind.Internal);
    }
}