using System;
using System.Globalization;

namespace ytLive.Models;

/// <summary>
/// TASK 39·2: the three metrics that count towards YouTube Partner Program eligibility, as progress
/// towards the ad-revenue thresholds.
/// <para><b>YouTube decides.</b> This only reports what the published numbers say; it never claims
/// eligibility, and it cannot see strikes, AdSense state, 2FA or the review decision.</para>
/// <para><b>The view criteria are either/or</b> — 4,000 public watch hours <i>or</i> 10M Shorts views —
/// so "2 of 3" is reported with that qualifier rather than implying all three must pass.</para>
/// </summary>
public sealed record YppProgress(
    long Subscribers,
    long SubscriberTarget,
    long WatchHours,
    long WatchHoursTarget,
    long ShortsViews,
    long ShortsViewsTarget)
{
    public bool SubscribersMet => Subscribers >= SubscriberTarget;
    public bool WatchHoursMet => WatchHours >= WatchHoursTarget;
    public bool ShortsViewsMet => ShortsViews >= ShortsViewsTarget;

    /// <summary>Criteria currently met (0–3). Two of three can mean eligible: subs plus EITHER view route.</summary>
    public int CriteriaMet => (SubscribersMet ? 1 : 0) + (WatchHoursMet ? 1 : 0) + (ShortsViewsMet ? 1 : 0);

    /// <summary>True when the subscriber bar AND at least one view route are satisfied — the shape of the
    /// published rule. Still not a qualification claim: YouTube reviews it.</summary>
    public bool MeetsPublishedRule => SubscribersMet && (WatchHoursMet || ShortsViewsMet);

    public double SubscribersFraction => Fraction(Subscribers, SubscriberTarget);
    public double WatchHoursFraction => Fraction(WatchHours, WatchHoursTarget);
    public double ShortsViewsFraction => Fraction(ShortsViews, ShortsViewsTarget);

    public string SubscribersText => $"{Compact(Subscribers)} / {Compact(SubscriberTarget)}";
    public string WatchHoursText => $"{Compact(WatchHours)} / {Compact(WatchHoursTarget)} h";
    public string ShortsViewsText => $"{Compact(ShortsViews)} / {Compact(ShortsViewsTarget)}";

    public string CriteriaMetText => CriteriaMet == 1
        ? "1 of 3 criteria met — YouTube reviews eligibility."
        : $"{CriteriaMet} of 3 criteria met — YouTube reviews eligibility.";

    private static double Fraction(long value, long target)
        => target <= 0 ? 0 : Math.Clamp((double)value / target, 0, 1);

    /// <summary>1,234 → "1,234"; 12,345 → "12.3k"; 1,234,567 → "1.23M". Mono-face friendly and stable
    /// in width, so the three bars do not jitter as values move.</summary>
    internal static string Compact(long value) => value switch
    {
        >= 1_000_000 => (value / 1_000_000d).ToString("0.##", CultureInfo.InvariantCulture) + "M",
        >= 10_000 => (value / 1_000d).ToString("0.#", CultureInfo.InvariantCulture) + "k",
        _ => value.ToString("N0", CultureInfo.InvariantCulture),
    };
}