using MeterVault.App.Localization;
using MeterVault.Core.Analysis;
using MeterVault.Infrastructure.Dashboard;

namespace MeterVault.App.Analysis;

/// <summary>
/// How every page states a cost change (D-07, brief §10 Phase 4 exit): one rule — <see cref="OverviewComparison.Between"/>,
/// the totals when both periods are complete, else the paired buckets both sides have complete, else not comparable —
/// and one wording, so the Overview, an energy type, the Analysis page and a meter never disagree about the same scope and
/// period.
/// </summary>
public static class CostChanges
{
    /// <summary>The change for a card: null without a comparison; unavailable ("No comparison") when not comparable.</summary>
    public static Change? ForCard(CostChange change)
    {
        ArgumentNullException.ThrowIfNull(change);

        return change.Basis == CostChangeBasis.NoComparison ? null : change.Change;
    }

    /// <summary>The change for a table's total row; null unless one is stated.</summary>
    public static Change? ForTotalRow(CostChange change)
    {
        ArgumentNullException.ThrowIfNull(change);

        return change.Change.IsAvailable ? change.Change : null;
    }

    /// <summary>Whether a rise is good news: neutral when either amount is a credit.</summary>
    public static ChangePolarity Polarity(CostChange change)
    {
        ArgumentNullException.ThrowIfNull(change);

        return ChangePolarities.ForCost(change.Current, change.Previous);
    }

    /// <summary>
    /// The caption of a change: what it is compared with, and — when only part of the period could be matched — that it
    /// is ("Same period last year · over the part both periods cover").
    /// </summary>
    public static string? Caption(AnalysisQuery query, CostChange change)
    {
        ArgumentNullException.ThrowIfNull(query);
        ArgumentNullException.ThrowIfNull(change);

        if (change.Basis == CostChangeBasis.NoComparison)
        {
            return null;
        }

        var compared = query.Comparison.Display();
        return change.IsPartial ? compared + " · " + Strings.Overview_MatchedOnly : compared;
    }
}