using MeterVault.Core.Analysis;
using MeterVault.Core.Analysis.Totals;

namespace MeterVault.App.Analysis;

/// <summary>
/// What an analysis view charts (D-47 <c>metric=consumption|generation|export|runtime|net|cost|balance</c>): a
/// quantity kind, the cost, or a tank's balance. The URL token is the stable identifier; the visible label comes from
/// <see cref="Localization.DisplayNames"/>.
/// </summary>
public enum AnalysisMetric
{
    Consumption,
    Generation,
    Export,
    Runtime,

    /// <summary>A signed virtual result (a difference of kinds, D-26).</summary>
    Net,

    /// <summary>The cost of the scope (D-34 – D-43).</summary>
    Cost,

    /// <summary>A tank's level over time (consumables).</summary>
    Balance,
}

/// <summary>URL tokens and meaning of <see cref="AnalysisMetric"/>.</summary>
public static class AnalysisMetrics
{
    private static readonly (AnalysisMetric Value, string Token)[] Tokens =
    [
        (AnalysisMetric.Consumption, "consumption"),
        (AnalysisMetric.Generation, "generation"),
        (AnalysisMetric.Export, "export"),
        (AnalysisMetric.Runtime, "runtime"),
        (AnalysisMetric.Net, "net"),
        (AnalysisMetric.Cost, "cost"),
        (AnalysisMetric.Balance, "balance"),
    ];

    /// <summary>The URL token of a metric (<c>consumption</c>, <c>cost</c>, …).</summary>
    public static string Format(AnalysisMetric metric)
    {
        foreach (var (value, token) in Tokens)
        {
            if (value == metric)
            {
                return token;
            }
        }

        throw new ArgumentOutOfRangeException(nameof(metric), metric, "No URL token for this metric.");
    }

    /// <summary>Parses a metric token, ignoring case and surrounding blanks; false for anything else.</summary>
    public static bool TryParse(string? token, out AnalysisMetric metric)
    {
        metric = default;
        if (string.IsNullOrWhiteSpace(token))
        {
            return false;
        }

        var text = token.Trim();
        foreach (var (value, name) in Tokens)
        {
            if (string.Equals(name, text, StringComparison.OrdinalIgnoreCase))
            {
                metric = value;
                return true;
            }
        }

        return false;
    }

    /// <summary>True for the quantity metrics (everything but cost and balance), which the analysis reader answers.</summary>
    public static bool IsQuantity(this AnalysisMetric metric) => metric is not (AnalysisMetric.Cost or AnalysisMetric.Balance);

    /// <summary>The quantity kind a quantity metric charts; null for cost and balance.</summary>
    public static QuantityKind? QuantityKindOf(AnalysisMetric metric) => metric switch
    {
        AnalysisMetric.Consumption => QuantityKind.Consumption,
        AnalysisMetric.Generation => QuantityKind.Generation,
        AnalysisMetric.Export => QuantityKind.Export,
        AnalysisMetric.Runtime => QuantityKind.Runtime,
        AnalysisMetric.Net => QuantityKind.Net,
        _ => null,
    };

    /// <summary>
    /// The per-type measures (D-22) a quantity metric shows for an energy type or the portfolio: consumption is the
    /// household use and, separately, the billed grid import (never added to each other); net has no measure, being a
    /// virtual meter's own result.
    /// </summary>
    public static IReadOnlyList<TotalsMeasure> MeasuresOf(AnalysisMetric metric) => metric switch
    {
        AnalysisMetric.Consumption => [TotalsMeasure.Use, TotalsMeasure.GridImport],
        AnalysisMetric.Generation => [TotalsMeasure.Generation],
        AnalysisMetric.Export => [TotalsMeasure.Export],
        AnalysisMetric.Runtime => [TotalsMeasure.Runtime],
        _ => [],
    };

    /// <summary>The metric a quantity kind is charted under; <see cref="QuantityKind.Indicator"/> has none.</summary>
    public static AnalysisMetric? MetricOf(QuantityKind kind) => kind switch
    {
        QuantityKind.Consumption => AnalysisMetric.Consumption,
        QuantityKind.Generation => AnalysisMetric.Generation,
        QuantityKind.Export => AnalysisMetric.Export,
        QuantityKind.Runtime => AnalysisMetric.Runtime,
        QuantityKind.Net => AnalysisMetric.Net,
        QuantityKind.Cost => AnalysisMetric.Cost,
        _ => null,
    };
}