using System;
using Jellyfin.Plugin.JRay.Configuration;

namespace Jellyfin.Plugin.JRay.Services;

/// <summary>
/// The outcome of comparing a local audio signature against a remote one.
/// </summary>
/// <remarks>
/// Produced only when the two signatures actually align; a comparison that
/// reaches no tier yields no result at all rather than a zero-scored one, so a
/// caller cannot mistake "did not match" for "matched at the bottom".
/// </remarks>
public readonly struct AudioSignatureMatch : IEquatable<AudioSignatureMatch>
{
    /// <summary>
    /// Gets the fraction of overlapping frames whose peak band agreed, in [0, 1].
    /// </summary>
    public double Score { get; init; }

    /// <summary>
    /// Gets the best-scoring alignment, in frames, between the two analysis
    /// windows.
    /// </summary>
    /// <remarks>
    /// Positive means the local window lags the remote one. This is a
    /// window-relative quantity and is <b>not</b> the offset to apply to
    /// timings — see <see cref="OffsetSec"/>, which additionally accounts for
    /// the two windows being anchored at different points in their files.
    /// </remarks>
    public int OffsetFrames { get; init; }

    /// <summary>
    /// Gets the seconds to add to every remote window to bring it into the local
    /// file's timebase.
    /// </summary>
    /// <remarks>
    /// This is the quantity JR-030 applies at store time, and the one
    /// <see cref="ManifestConverter.ToTruthFile"/> takes.
    /// </remarks>
    public double OffsetSec { get; init; }

    /// <summary>Gets the tier this score earns.</summary>
    public MatchTier Tier { get; init; }

    /// <summary>Compares two matches for equality.</summary>
    /// <param name="left">Left operand.</param>
    /// <param name="right">Right operand.</param>
    /// <returns><c>true</c> when the two are equal.</returns>
    public static bool operator ==(AudioSignatureMatch left, AudioSignatureMatch right) => left.Equals(right);

    /// <summary>Compares two matches for inequality.</summary>
    /// <param name="left">Left operand.</param>
    /// <param name="right">Right operand.</param>
    /// <returns><c>true</c> when the two differ.</returns>
    public static bool operator !=(AudioSignatureMatch left, AudioSignatureMatch right) => !left.Equals(right);

    /// <inheritdoc/>
    public bool Equals(AudioSignatureMatch other)
        => Score.Equals(other.Score)
           && OffsetFrames == other.OffsetFrames
           && OffsetSec.Equals(other.OffsetSec)
           && Tier == other.Tier;

    /// <inheritdoc/>
    public override bool Equals(object? obj) => obj is AudioSignatureMatch other && Equals(other);

    /// <inheritdoc/>
    public override int GetHashCode() => HashCode.Combine(Score, OffsetFrames, OffsetSec, Tier);
}