using System.Net.Http.Headers;
using System.Text.Json;
using MediaBrowser.Common.Net;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Plugin.Vanguard.Services;

public sealed record DiscordMember(string UserId, string Username, string DisplayName, string? AvatarUrl);
public sealed record DiscordEvent(string Id, string Name, string? Description, DateTimeOffset Start, DateTimeOffset? End, string? Status, DateTimeOffset SeenAt);

/// <summary>Thin REST client for the Discord bot API (no gateway). Uses the same application Authentik uses; add a bot user to it.</summary>
public sealed class DiscordClient
{
    private const string Api = "https://discord.com/api/v10";
    private readonly IHttpClientFactory _http;
    private readonly ILogger<DiscordClient> _log;

    public DiscordClient(IHttpClientFactory http, ILogger<DiscordClient> log) { _http = http; _log = log; }

    private HttpClient Client(string token)
    {
        var c = _http.CreateClient(NamedClient.Default);
        c.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bot", token);
        return c;
    }

    public async Task<DiscordMember?> GetGuildMemberAsync(string token, string guildId, string userId, CancellationToken ct)
    {
        using var resp = await Client(token).GetAsync($"{Api}/guilds/{guildId}/members/{userId}", ct).ConfigureAwait(false);
        if (!resp.IsSuccessStatusCode)
        {
            _log.LogWarning("Discord member lookup {User} failed: {Status}", userId, resp.StatusCode);
            return null;
        }
        using var doc = JsonDocument.Parse(await resp.Content.ReadAsStringAsync(ct).ConfigureAwait(false));
        var root = doc.RootElement;
        var user = root.GetProperty("user");
        var username = user.GetProperty("username").GetString() ?? userId;
        var global = user.TryGetProperty("global_name", out var g) && g.ValueKind == JsonValueKind.String ? g.GetString() : null;
        var nick = root.TryGetProperty("nick", out var n) && n.ValueKind == JsonValueKind.String ? n.GetString() : null;
        var guildAvatar = root.TryGetProperty("avatar", out var ga) && ga.ValueKind == JsonValueKind.String ? ga.GetString() : null;
        var userAvatar = user.TryGetProperty("avatar", out var ua) && ua.ValueKind == JsonValueKind.String ? ua.GetString() : null;
        string? avatarUrl = guildAvatar is not null
            ? $"https://cdn.discordapp.com/guilds/{guildId}/users/{userId}/avatars/{guildAvatar}.png?size=512"
            : userAvatar is not null ? $"https://cdn.discordapp.com/avatars/{userId}/{userAvatar}.png?size=512"
            : $"https://cdn.discordapp.com/embed/avatars/{(ulong.TryParse(userId, out var id) ? (id >> 22) % 6 : 0)}.png";
        return new DiscordMember(userId, username, nick ?? global ?? username, avatarUrl);
    }

    /// <summary>Post an embed to a channel. <paramref name="fields"/> are (name, value) pairs.</summary>
    public async Task<bool> PostEmbedAsync(string token, string channelId, string title, string? description, string? url, string? thumbnailUrl, IEnumerable<(string Name, string Value)> fields, int color, CancellationToken ct, byte[]? imageBytes = null, string imageName = "thumb.jpg")
    {
        var embed = new Dictionary<string, object?>
        {
            ["title"] = title.Length > 256 ? title[..256] : title,
            ["description"] = description is { Length: > 0 } ? (description.Length > 2000 ? description[..2000] : description) : null,
            ["url"] = url,
            ["color"] = color,
            ["timestamp"] = DateTimeOffset.UtcNow.ToString("o"),
            ["fields"] = fields.Select(f => new { name = f.Name, value = f.Value, inline = true }).ToArray(),
        };
        if (thumbnailUrl is not null) embed["thumbnail"] = new { url = thumbnailUrl };
        if (imageBytes is { Length: > 0 }) embed["image"] = new { url = $"attachment://{imageName}" };   // big picture = the frame grab
        var payload = JsonSerializer.Serialize(new { embeds = new[] { embed } }, new JsonSerializerOptions { DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull });

        HttpContent content;
        if (imageBytes is { Length: > 0 })
        {
            var mp = new MultipartFormDataContent();
            mp.Add(new StringContent(payload, System.Text.Encoding.UTF8, "application/json"), "payload_json");
            var file = new ByteArrayContent(imageBytes);
            file.Headers.ContentType = new MediaTypeHeaderValue(imageName.EndsWith(".png", StringComparison.OrdinalIgnoreCase) ? "image/png" : "image/jpeg");
            mp.Add(file, "files[0]", imageName);
            content = mp;
        }
        else
        {
            content = new StringContent(payload, System.Text.Encoding.UTF8, "application/json");
        }
        using var _ = content;
        using var resp = await Client(token).PostAsync($"{Api}/channels/{channelId}/messages", content, ct).ConfigureAwait(false);
        if (!resp.IsSuccessStatusCode) _log.LogWarning("Discord post to {Channel} failed: {Status} {Body}", channelId, resp.StatusCode, await resp.Content.ReadAsStringAsync(ct).ConfigureAwait(false));
        return resp.IsSuccessStatusCode;
    }

    public async Task<IReadOnlyList<DiscordEvent>> GetScheduledEventsAsync(string token, string guildId, CancellationToken ct)
    {
        using var resp = await Client(token).GetAsync($"{Api}/guilds/{guildId}/scheduled-events", ct).ConfigureAwait(false);
        if (!resp.IsSuccessStatusCode)
        {
            _log.LogWarning("Discord scheduled-events failed: {Status}", resp.StatusCode);
            return [];
        }
        using var doc = JsonDocument.Parse(await resp.Content.ReadAsStringAsync(ct).ConfigureAwait(false));
        var list = new List<DiscordEvent>();
        var now = DateTimeOffset.UtcNow;
        foreach (var e in doc.RootElement.EnumerateArray())
        {
            var start = e.GetProperty("scheduled_start_time").GetDateTimeOffset();
            DateTimeOffset? end = e.TryGetProperty("scheduled_end_time", out var et) && et.ValueKind == JsonValueKind.String ? et.GetDateTimeOffset() : null;
            list.Add(new DiscordEvent(
                e.GetProperty("id").GetString()!,
                e.GetProperty("name").GetString() ?? "(event)",
                e.TryGetProperty("description", out var d) && d.ValueKind == JsonValueKind.String ? d.GetString() : null,
                start, end,
                e.TryGetProperty("status", out var st) ? st.ToString() : null,
                now));
        }
        return list;
    }
}