using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;

using PrivaPub.Api.Mastodon.Infrastructure;
using PrivaPub.Domain.Statistics;

namespace PrivaPub.Api.Mastodon.Controllers
{
	// The CDNs in front of the servers this server knows, each named by its own domain (owner decision 2026-10-04): how many
	// servers are behind it, how it is recognised, and week by week who joined and who left.
	public class CdnsController : MastodonController
	{
		const int MaxWeeks = 260;

		readonly IServerPlaces _places;

		public CdnsController(IServerPlaces places) => _places = places;

		[HttpGet("/api/privapub/v1/cdns"), Scope("read", requiresUser: false), AllowAnonymous]
		public async Task<IActionResult> List(CancellationToken token) => Json((await _places.Cdns(token)).Select(Summary).ToList());

		[HttpGet("/api/privapub/v1/cdns/{key}"), Scope("read", requiresUser: false), AllowAnonymous]
		public async Task<IActionResult> Detail(string key, CancellationToken token)
		{
			var history = await _places.Cdn(key, Math.Clamp(Params.Int("weeks") ?? 52, 1, MaxWeeks), token);
			if (history == default)
				return NotFoundError();
			var detail = new CdnDetail
			{
				Hosts = history.Hosts,
				HostsTruncated = history.Group.Servers > history.Hosts.Count,
				Weeks = history.Weeks.Select(w => new CdnWeekEntry { Week = w.Week, Servers = w.Servers, Joined = w.Joined, Left = w.Left }).ToList()
			};
			Fill(detail, history.Group);
			return Json(detail);
		}

		static CdnSummary Summary(CdnGroup group)
		{
			var summary = new CdnSummary();
			Fill(summary, group);
			return summary;
		}

		static void Fill(CdnSummary summary, CdnGroup group)
		{
			summary.Key = group.Key;
			summary.Name = group.Name;
			summary.Domain = group.Domain;
			summary.Servers = group.Servers;
			summary.Ranges = group.Ranges;
			summary.RangesUpdatedAt = group.RangesUpdatedAt is { } at ? MastodonJson.Time(at) : default;
			summary.DetectedBy = group.DetectedBy;
		}

		public class CdnSummary
		{
			public string Key { get; set; }
			public string Name { get; set; }
			public string Domain { get; set; }
			public int Servers { get; set; }
			public int Ranges { get; set; }
			public string RangesUpdatedAt { get; set; }
			public List<string> DetectedBy { get; set; } = new();
		}

		public class CdnDetail : CdnSummary
		{
			public List<string> Hosts { get; set; } = new();
			public bool HostsTruncated { get; set; }
			public List<CdnWeekEntry> Weeks { get; set; } = new();
		}

		public class CdnWeekEntry
		{
			public string Week { get; set; }
			public int Servers { get; set; }
			public List<string> Joined { get; set; } = new();
			public List<string> Left { get; set; } = new();
		}
	}
}