using System.Xml;
using System.Xml.Linq;
using Launcher.Next.Core;

namespace Launcher.Next.Application;

public sealed record LegacyPluginDefinition(string Id, string Renewal, string Catalog, string Install, int DefinitionOrder);
public sealed record LegacyProductPattern(string Name, string Filter, string Roster, IReadOnlyList<LegacyPluginDefinition> Plugins);
public sealed record LegacyLauncherSettings(string Help, string CareMarker, IReadOnlyList<LegacyProductPattern> Patterns);
public sealed record LegacyDownloadSelection(IReadOnlyList<string> PluginIds);
public sealed record LegacyCompatibilityMapping(string LegacyId, string PackageId, string Version, string Channel);
public sealed record LegacyCompatibilityOverlay(string MappingId, string Product, int ProductYear, string Architecture, bool AllowOfflineFallback, IReadOnlyList<LegacyCompatibilityMapping> Plugins);

public sealed class LegacyConfigurationAdapter
{
    private static readonly XmlReaderSettings XmlSettings = new() { DtdProcessing = DtdProcessing.Prohibit, XmlResolver = null, MaxCharactersInDocument = 1_000_000 };

    public LegacyLauncherSettings ParseSettings(string xml)
    {
        using var reader = XmlReader.Create(new StringReader(xml), XmlSettings); var root = XDocument.Load(reader).Root ?? throw new InvalidOperationException("LEGACY_SETTINGS_INVALID");
        var path = root.Element("path") ?? throw new InvalidOperationException("LEGACY_SETTINGS_PATH_MISSING");
        var patterns = root.Elements("data").Select(data =>
        {
            var pattern = data.Element("pattern") ?? throw new InvalidOperationException("LEGACY_PATTERN_MISSING");
            string Value(string name) => pattern.Element(name)?.Value ?? throw new InvalidOperationException("LEGACY_PATTERN_FIELD_MISSING:" + name);
            var plugins = data.Elements("plugin").Select((plugin, index) => new LegacyPluginDefinition(
                plugin.Element("id")?.Value ?? throw new InvalidOperationException("LEGACY_PLUGIN_ID_MISSING"),
                plugin.Element("renewal")?.Value ?? throw new InvalidOperationException("LEGACY_RENEWAL_MISSING"),
                plugin.Element("catalog")?.Value ?? throw new InvalidOperationException("LEGACY_CATALOG_MISSING"),
                plugin.Element("install")?.Value ?? throw new InvalidOperationException("LEGACY_INSTALL_MISSING"), index)).ToArray();
            return new LegacyProductPattern(Value("name"), Value("filter"), Value("roster"), plugins);
        }).ToArray();
        return new(path.Element("help")?.Value ?? throw new InvalidOperationException("LEGACY_HELP_MISSING"), path.Element("care")?.Value ?? throw new InvalidOperationException("LEGACY_CARE_MISSING"), patterns);
    }

    public LegacyDownloadSelection ParseDownloadList(string xml)
    {
        using var reader = XmlReader.Create(new StringReader(xml), XmlSettings); var root = XDocument.Load(reader).Root;
        if (root?.Name != "root") throw new InvalidOperationException("LEGACY_DOWNLOAD_LIST_INVALID");
        var ids = root.Elements("id").Select(x => x.Value.Trim()).ToArray();
        if (ids.Length == 0 || ids.Any(string.IsNullOrWhiteSpace) || ids.GroupBy(x => x, StringComparer.OrdinalIgnoreCase).Any(x => x.Count() > 1))
            throw new InvalidOperationException("LEGACY_DOWNLOAD_SELECTION_INVALID");
        return new(ids);
    }

    public IReadOnlyList<PackageRequirement> Join(LegacyProductPattern pattern, LegacyDownloadSelection selection, LegacyCompatibilityOverlay overlay)
    {
        var result = new List<PackageRequirement>();
        foreach (var id in selection.PluginIds)
        {
            var definition = pattern.Plugins.Where(x => string.Equals(x.Id, id, StringComparison.OrdinalIgnoreCase)).ToArray();
            if (definition.Length == 0) throw new InvalidOperationException("LEGACY_PLUGIN_ID_NOT_DEFINED");
            if (definition.Length > 1) throw new InvalidOperationException("AMBIGUOUS_LEGACY_PLUGIN_DEFINITION");
            var mapping = overlay.Plugins.Where(x => string.Equals(x.LegacyId, id, StringComparison.OrdinalIgnoreCase)).ToArray();
            if (mapping.Length == 0) throw new InvalidOperationException("LEGACY_MAPPING_NOT_FOUND");
            if (mapping.Length > 1) throw new InvalidOperationException("LEGACY_MAPPING_DUPLICATE");
            result.Add(new(mapping[0].PackageId, overlay.Product, overlay.ProductYear, overlay.Architecture, mapping[0].Channel, mapping[0].Version, overlay.MappingId, overlay.AllowOfflineFallback));
        }
        return result;
    }
}