using System.Text.Json;

namespace BSO.Launcher;

/// <summary>
/// Releases direkt vom Git-Server (git.mbm.wtf, Gitea): Mod aus BSO-Mod, Launcher aus BSO-Launcher (beide oeffentlich).
/// Jedes Release hat die Datei und bso-release.json (Version, SHA-256, Signatur aus release.ps1) - installiert wird weiter
/// nur, was mit dem BSO-Release-Schluessel signiert ist, egal woher die Datei kommt.
/// </summary>
public static class GiteaReleases
{
    public const string ApiBase = "https://git.mbm.wtf/api/v1/repos/MrMaho/";
    public const string ManifestName = "bso-release.json";

    static string Repo(string product) => product == "launcher" ? "BSO-Launcher" : "BSO-Mod";

    sealed record Manifest(string product, string version, string sha256, long size, string file, string signature);

    /// <summary>Version aus dem Tag ("v0.5.0" -> "0.5.0") oder null.</summary>
    static string? TagVersion(JsonElement release)
    {
        string tag = release.GetProperty("tag_name").GetString() ?? "";
        string v = tag.TrimStart('v', 'V');
        return Version.TryParse(v, out _) ? v : null;
    }

    static bool Published(JsonElement release) =>
        !release.GetProperty("draft").GetBoolean() && !release.GetProperty("prerelease").GetBoolean();

    static async Task<JsonElement[]> Fetch(string product)
    {
        using var doc = JsonDocument.Parse(await Api.Http.GetStringAsync(ApiBase + Repo(product) + "/releases?limit=20"));
        return doc.RootElement.EnumerateArray().Where(Published).Select(r => r.Clone()).ToArray();
    }

    /// <summary>Neueste Version von mod/launcher - null, wenn es keine gibt oder Gitea nicht erreichbar ist.</summary>
    public static async Task<Api.Release?> Latest(string product)
    {
        try
        {
            var newest = (await Fetch(product))
                .Select(r => (release: r, version: TagVersion(r)))
                .Where(x => x.version != null)
                .OrderByDescending(x => Version.Parse(x.version!))
                .FirstOrDefault();
            if (newest.version == null) return null;

            var assets = newest.release.GetProperty("assets").EnumerateArray()
                .ToDictionary(a => a.GetProperty("name").GetString() ?? "", a => a.GetProperty("browser_download_url").GetString() ?? "");
            if (!assets.TryGetValue(ManifestName, out string? manifestUrl)) return null;
            var m = JsonSerializer.Deserialize<Manifest>(await Api.Http.GetStringAsync(manifestUrl));
            if (m == null || m.product != product || !assets.TryGetValue(m.file, out string? fileUrl)) return null;
            return new Api.Release(product, m.version, m.sha256, m.size, newest.release.GetProperty("body").GetString() ?? "",
                newest.release.GetProperty("published_at").GetString() ?? "", m.file, fileUrl, m.signature);
        }
        catch (Exception e)
        {
            LauncherLog.Error($"Gitea-Release {product}: {e.Message}");
            return null;
        }
    }

    /// <summary>Neuigkeiten: Releases von Mod und Launcher, neueste zuerst. null = Gitea nicht erreichbar.</summary>
    public static async Task<List<object>?> List()
    {
        var items = new List<(DateTimeOffset date, object item)>();
        int reached = 0;
        foreach (string product in new[] { "mod", "launcher" })
        {
            try
            {
                foreach (var r in await Fetch(product))
                {
                    if (TagVersion(r) is not { } version) continue;
                    string date = r.GetProperty("published_at").GetString() ?? "";
                    items.Add((DateTimeOffset.TryParse(date, out var d) ? d : default,
                        new { product, version, changelog = r.GetProperty("body").GetString() ?? "", date }));
                }
                reached++;
            }
            catch (Exception e) { LauncherLog.Error($"Gitea-Releases {product}: {e.Message}"); }
        }
        return reached == 0 ? null : items.OrderByDescending(x => x.date).Select(x => x.item).ToList();
    }
}