using System.Net;
using System.Net.Http.Headers;

using decePubClient.Extensions;
using decePubClient.Models;

using Microsoft.AspNetCore.Components.Forms;

using PrivaPub.ClientModels;
using PrivaPub.ClientModels.Admin;

namespace decePubClient.Services
{
	/// <summary>
	/// The server's own settings from the administrator's page (PrivaPub's InstanceAdminController, /clientapi/admin): what
	/// it says of itself, its rules, its thumbnail, its media limits, whether its weekly activity is published, its
	/// announcements and the relays it subscribes to. PrivaPub checks the administrator against its database on every call.
	/// A save replaces everything the form carries (a rule left out is removed), so SaveSettings always starts from the
	/// settings as PrivaPub has them now and changes only what the caller changes. Lists come back empty and values null on
	/// failure; nothing throws.
	/// </summary>
	public class InstanceAdminService(IHttpService httpService, AboutService aboutService, ILoggingService logger, CoalescingStringLocalizer localizer)
	{
		/// <summary>The settings as the page shows them, deleted rules too; null on failure.</summary>
		public async Task<ViewServerSettings> Settings(CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.ClientApi.GET_AdminSettings, cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.DefaultReadFromJsonAsync<ViewServerSettings>(cancellationToken);

			await LogFailure(response, nameof(Settings), cancellationToken);
			return null;
		}

		/// <summary>The form that saves the settings exactly as they are: the rules not deleted in their order, the media
		/// overrides, every text.</summary>
		public static ServerSettingsForm FormOf(ViewServerSettings settings) => new()
		{
			Title = settings.Title,
			ShortDescription = settings.ShortDescription,
			Description = settings.Description,
			ContactEmail = settings.ContactEmail,
			ContactAccountId = settings.ContactAccountId,
			PrivacyPolicy = settings.PrivacyPolicy,
			TermsOfService = settings.TermsOfService,
			TermsEffectiveAt = settings.TermsEffectiveAt,
			Rules = [.. settings.Rules.Where(r => !r.IsDeleted).OrderBy(r => r.Position).Select(r => new ServerRuleForm { Id = r.Id, Text = r.Text, Hint = r.Hint })],
			Media = new()
			{
				QuotaBytesPerRoot = settings.Media.QuotaBytesPerRoot,
				MaxImageBytes = settings.Media.MaxImageBytes,
				MaxVideoBytes = settings.Media.MaxVideoBytes,
				MaxSeconds = settings.Media.MaxSeconds
			},
			PublishActivity = settings.PublishActivity
		};

		/// <summary>
		/// Reads the settings as PrivaPub has them now, lets `change` edit the form made of them, and saves the whole form;
		/// Data is the ViewServerSettings saved. What another panel or another administrator saved meanwhile stays.
		/// </summary>
		public async Task<WebResult> SaveSettings(Action<ServerSettingsForm> change, CancellationToken cancellationToken = default)
		{
			using var current = await httpService.Get(APIs.ClientApi.GET_AdminSettings, cancellationToken: cancellationToken);
			if (!current.IsSuccessStatusCode)
				return await current.Content.ReadWebResult(current.StatusCode, localizer, cancellationToken);
			if (await current.DefaultReadFromJsonAsync<ViewServerSettings>(cancellationToken) is not { } latest)
				return new WebResult().Invalidate(localizer["The server sent an invalid response."], (int)HttpStatusCode.BadGateway);

			var form = FormOf(latest);
			change(form);
			using var response = await httpService.Post(APIs.ClientApi.POST_AdminSettings, form, cancellationToken: cancellationToken);
			return await Saved(response, cancellationToken);
		}

		/// <summary>A new thumbnail, streamed from the browser's file; PrivaPub checks it, strips it and fits it within
		/// 1200×630. Data is the ViewServerSettings.</summary>
		public async Task<WebResult> SaveThumbnail(IBrowserFile file, long maximumSize, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Post(APIs.ClientApi.POST_AdminThumbnail, (Func<HttpContent>)(() =>
			{
				var picture = new StreamContent(file.OpenReadStream(maximumSize, cancellationToken));
				picture.Headers.ContentType = new MediaTypeHeaderValue(file.ContentType);
				return new MultipartFormDataContent { { picture, "file", file.Name } };
			}), cancellationToken: cancellationToken);
			return await Saved(response, cancellationToken);
		}

		/// <summary>Back to the default picture; the uploaded one is trashed. Data is the ViewServerSettings.</summary>
		public async Task<WebResult> RemoveThumbnail(CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Delete(APIs.ClientApi.DELETE_AdminThumbnail, cancellationToken: cancellationToken);
			return await Saved(response, cancellationToken);
		}

		/// <summary>Every announcement, published or not, with its reads and reactions.</summary>
		public async Task<List<ViewAnnouncement>> Announcements(CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.ClientApi.GET_AdminAnnouncements, cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.DefaultReadFromJsonAsync<List<ViewAnnouncement>>(cancellationToken) ?? [];

			await LogFailure(response, nameof(Announcements), cancellationToken);
			return [];
		}

		/// <summary>Writes a new announcement (no Id) or changes one; Data is the ViewAnnouncement.</summary>
		public async Task<WebResult> SaveAnnouncement(AnnouncementForm form, CancellationToken cancellationToken = default)
		{
			var route = form.Id is { Length: > 0 } ? APIs.ClientApi.POST_AdminAnnouncementUpdate : APIs.ClientApi.POST_AdminAnnouncementInsert;
			using var response = await httpService.Post(route, form, cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			return new WebResult { Data = await response.DefaultReadFromJsonAsync<ViewAnnouncement>(cancellationToken) };
		}

		/// <summary>Deletes an announcement, its reads and reactions with it; every persona's stream hears it go.</summary>
		public async Task<WebResult> DeleteAnnouncement(string id, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Post(APIs.ClientApi.POST_M_AdminAnnouncementDelete(id), cancellationToken: cancellationToken);
			return response.IsSuccessStatusCode ? new WebResult() : await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);
		}

		/// <summary>The relays the server subscribes to: the configuration's, then the settings'.</summary>
		public async Task<List<ViewRelay>> Relays(CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.ClientApi.GET_AdminRelays, cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.DefaultReadFromJsonAsync<List<ViewRelay>>(cancellationToken) ?? [];

			await LogFailure(response, nameof(Relays), cancellationToken);
			return [];
		}

		/// <summary>Subscribes to a relay by its actor's or inbox's https address. PrivaPub answers 202 and subscribes in the
		/// background, so the list it answers with (Data) shows the relay before its state does; read it again shortly.</summary>
		public async Task<WebResult> AddRelay(string address, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Post(APIs.ClientApi.POST_AdminRelayInsert, new RelayForm { Address = address?.Trim() },
				cancellationToken: cancellationToken);
			return await RelayList(response, cancellationToken);
		}

		/// <summary>Unsubscribes from a relay the settings named (a configured one is refused with 409); answered 202 like
		/// AddRelay.</summary>
		public async Task<WebResult> RemoveRelay(string address, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Post(APIs.ClientApi.POST_M_AdminRelayDelete(address), cancellationToken: cancellationToken);
			return await RelayList(response, cancellationToken);
		}

		async Task<WebResult> Saved(HttpResponseMessage response, CancellationToken cancellationToken)
		{
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			// the title and the rules everyone reads have changed
			aboutService.Forget();
			return new WebResult { Data = await response.DefaultReadFromJsonAsync<ViewServerSettings>(cancellationToken) };
		}

		async Task<WebResult> RelayList(HttpResponseMessage response, CancellationToken cancellationToken)
		{
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			return new WebResult { Data = await response.DefaultReadFromJsonAsync<List<ViewRelay>>(cancellationToken) ?? [] };
		}

		async Task LogFailure(HttpResponseMessage response, string caller, CancellationToken cancellationToken)
		{
			var result = await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);
			if (result.StatusCode is not ((int)HttpStatusCode.Gone or (int)HttpStatusCode.Forbidden))
				await logger.ProcessWarning(result.ToString(localizer), $"{nameof(InstanceAdminService)}.{caller}", cancellationToken);
		}
	}
}