namespace Aeshnidae.Expedition;

/// <summary>
/// The island's zones (Settings.Zones) as a landblock lookup: every landblock id of every
/// box, first zone to claim it wins. Built when the settings are read.
/// </summary>
public static class Zones
{
    private static Dictionary<ushort, ZoneSetting> _byLandblock = new();

    public static IReadOnlyList<ZoneSetting> All => Mod.Settings.Zones ?? new List<ZoneSetting>();

    public static void Build()
    {
        var map = new Dictionary<ushort, ZoneSetting>();

        foreach (var zone in All)
        {
            foreach (var box in zone.Boxes ?? new List<string>())
            {
                if (!TryParseBox(box, out var x0, out var x1, out var y0, out var y1))
                {
                    ModManager.Log($"[{Mod.Name}] zone '{zone.Name}': cannot read box '{box}' (want \"B3-B5,E8-EE\")", ModManager.LogLevel.Warn);
                    continue;
                }

                for (var x = x0; x <= x1; x++)
                    for (var y = y0; y <= y1; y++)
                        map.TryAdd((ushort)(x << 8 | y), zone);
            }
        }

        _byLandblock = map;
    }

    public static ZoneSetting? Of(ushort landblock) =>
        _byLandblock.TryGetValue(landblock, out var zone) ? zone : null;

    public static ZoneSetting? Named(string name) =>
        All.FirstOrDefault(z => string.Equals(z.Name, name, StringComparison.OrdinalIgnoreCase))
        ?? All.FirstOrDefault(z => z.Name.StartsWith(name, StringComparison.OrdinalIgnoreCase));

    /// <summary>The zones whose meters are this act's goal.</summary>
    public static IEnumerable<ZoneSetting> OfAct(int act) =>
        All.Where(z => z.Act == act && z.MeterTarget > 0);

    public static IEnumerable<ushort> LandblocksOf(ZoneSetting zone) =>
        _byLandblock.Where(kv => ReferenceEquals(kv.Value, zone)).Select(kv => kv.Key);

    private static bool TryParseBox(string box, out int x0, out int x1, out int y0, out int y1)
    {
        x0 = x1 = y0 = y1 = 0;
        var parts = (box ?? "").Split(',', StringSplitOptions.TrimEntries);

        return parts.Length == 2 && TryRange(parts[0], out x0, out x1) && TryRange(parts[1], out y0, out y1);
    }

    private static bool TryRange(string text, out int from, out int to)
    {
        from = to = 0;
        var ends = text.Split('-', StringSplitOptions.TrimEntries);

        if (ends.Length is < 1 or > 2)
            return false;

        if (!int.TryParse(ends[0], System.Globalization.NumberStyles.HexNumber, null, out from))
            return false;

        to = from;
        return ends.Length == 1 || int.TryParse(ends[1], System.Globalization.NumberStyles.HexNumber, null, out to);
    }
}