using System.Net;

using collAnon.Client.Services;

using decePubClient.Extensions;
using decePubClient.Models;
using decePubClient.Models.Mastodon;

using PrivaPub.ClientModels;

namespace decePubClient.Services
{
	/// <summary>What the current persona does to and learns of other accounts.</summary>
	public enum AccountAction
	{
		Follow,
		Unfollow,
		Block,
		Unblock,
		Mute,
		Unmute
	}

	/// <summary>Which of an account's posts its profile lists.</summary>
	public enum ProfileTab
	{
		Posts,
		PostsAndReplies,
		Media
	}

	/// <summary>
	/// Accounts as the current persona sees them: a profile, its relationship to the persona, its posts, following,
	/// blocking and muting it, the persona's follow requests, and search across the fediverse (a remote handle or URL is
	/// resolved by PrivaPub, never by the browser). Lists come back empty and values null on failure; nothing throws.
	/// </summary>
	public class AccountService(IHttpService httpService, ILoggingService logger, CoalescingStringLocalizer localizer)
	{
		const int PageSize = 20;

		public async Task<Account> Get(string accountId, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.Mastodon.GET_M_Account(accountId), cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.MastodonReadFromJsonAsync<Account>(cancellationToken);

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

		/// <summary>An account by its handle (name or name@host), resolved by PrivaPub if it has not met it yet.</summary>
		public async Task<Account> Lookup(string acct, CancellationToken cancellationToken = default)
		{
			acct = acct?.Trim().TrimStart('@');
			if (string.IsNullOrEmpty(acct))
				return null;
			using var response = await httpService.Get(APIs.Mastodon.GET_AccountLookup, [$"acct={Uri.EscapeDataString(acct)}"],
				cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.MastodonReadFromJsonAsync<Account>(cancellationToken);

			var found = await Search(acct, resolve: true, cancellationToken);
			return found.Accounts.FirstOrDefault(a => string.Equals(a.Acct, acct, StringComparison.OrdinalIgnoreCase))
				?? found.Accounts.FirstOrDefault();
		}

		public async Task<Relationship> Relationship(string accountId, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.Mastodon.GET_Relationships, [$"id[]={Uri.EscapeDataString(accountId)}"],
				cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return (await response.MastodonReadFromJsonAsync<List<Relationship>>(cancellationToken) ?? []).FirstOrDefault();

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

		/// <summary>The relationships of many accounts at once, 40 a request.</summary>
		public async Task<List<Relationship>> Relationships(IReadOnlyList<string> accountIds, CancellationToken cancellationToken = default)
		{
			var relationships = new List<Relationship>();
			foreach (var batch in accountIds.Chunk(40))
			{
				using var response = await httpService.Get(APIs.Mastodon.GET_Relationships, [.. batch.Select(id => $"id[]={Uri.EscapeDataString(id)}")],
					cancellationToken: cancellationToken);
				if (!response.IsSuccessStatusCode)
				{
					await LogFailure(response, nameof(Relationships), cancellationToken);
					return relationships;
				}
				relationships.AddRange(await response.MastodonReadFromJsonAsync<List<Relationship>>(cancellationToken) ?? []);
			}
			return relationships;
		}

		/// <summary>Follows the account, its boosts shown in the home feed or not; Data is the new Relationship.</summary>
		public async Task<WebResult> Follow(string accountId, bool showReblogs, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Post(APIs.Mastodon.POST_M_AccountAction(accountId, "follow"),
				new[] { new KeyValuePair<string, string>("reblogs", showReblogs ? "true" : "false") }, cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

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

		/// <summary>Follows, unfollows, blocks, unblocks, mutes or unmutes; Data is the new Relationship.</summary>
		public async Task<WebResult> Act(string accountId, AccountAction action, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Post(APIs.Mastodon.POST_M_AccountAction(accountId, action.ToString().ToLowerInvariant()),
				cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

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

		/// <summary>A page of the account's posts, newest first; Data is a FeedPage.</summary>
		public async Task<WebResult> Statuses(string accountId, ProfileTab tab, string maxId, CancellationToken cancellationToken = default)
		{
			var parameters = new List<string> { $"limit={PageSize}" };
			parameters.AddRange(tab switch
			{
				ProfileTab.Posts => ["exclude_replies=true"],
				ProfileTab.Media => ["only_media=true"],
				_ => Array.Empty<string>()
			});
			if (maxId is not null)
				parameters.Add($"max_id={Uri.EscapeDataString(maxId)}");
			using var response = await httpService.Get(APIs.Mastodon.GET_M_AccountStatuses(accountId), [.. parameters],
				cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			var statuses = await response.MastodonReadFromJsonAsync<List<Status>>(cancellationToken) ?? [];
			var (nextMaxId, _) = response.PageCursors();
			return new WebResult
			{
				Data = new FeedPage
				{
					Posts = [.. statuses.Select(FeedPost.Of)],
					MaxId = statuses.Count < PageSize ? null : nextMaxId ?? statuses.LastOrDefault()?.Id
				}
			};
		}

		/// <summary>The accounts waiting for the persona to accept their follow.</summary>
		public async Task<List<Account>> FollowRequests(CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.Mastodon.GET_FollowRequests, ["limit=80"], cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.MastodonReadFromJsonAsync<List<Account>>(cancellationToken) ?? [];

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

		/// <summary>Accepts (authorize) or refuses (reject) a follow request.</summary>
		public async Task<WebResult> Answer(string accountId, bool accept, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Post(APIs.Mastodon.POST_M_FollowRequest(accountId, accept ? "authorize" : "reject"),
				cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

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

		/// <summary>Accounts, posts and hashtags matching the query; a handle or a URL is resolved when `resolve`.</summary>
		public async Task<SearchResults> Search(string query, bool resolve, CancellationToken cancellationToken = default)
		{
			if (string.IsNullOrWhiteSpace(query))
				return new SearchResults();
			using var response = await httpService.Get(APIs.Mastodon.GET_Search,
				[$"q={Uri.EscapeDataString(query.Trim())}", $"resolve={(resolve ? "true" : "false")}", "limit=20"],
				cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.MastodonReadFromJsonAsync<SearchResults>(cancellationToken) ?? new SearchResults();

			await LogFailure(response, nameof(Search), cancellationToken);
			return new SearchResults();
		}

		/// <summary>Saves the persona's profile; Data is its account as PrivaPub now describes it (with its Source).</summary>
		public async Task<WebResult> UpdateProfile(ProfileForm form, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Patch(APIs.Mastodon.PATCH_UpdateCredentials, (Func<HttpContent>)form.Content,
				cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			var account = await response.MastodonReadFromJsonAsync<Account>(cancellationToken);
			return account?.Id is null
				? new WebResult().Invalidate(localizer["The server sent an invalid response."], (int)HttpStatusCode.BadGateway)
				: new WebResult { Data = account };
		}

		/// <summary>A page of the accounts the persona follows (only the persona itself may read it); Data is an AccountPage.</summary>
		public Task<WebResult> Following(string accountId, string maxId, CancellationToken cancellationToken = default) =>
			Accounts(APIs.Mastodon.GET_M_AccountFollowing(accountId), maxId, cancellationToken);

		/// <summary>A page of the accounts the persona muted; Data is an AccountPage.</summary>
		public Task<WebResult> Mutes(string maxId, CancellationToken cancellationToken = default) =>
			Accounts(APIs.Mastodon.GET_Mutes, maxId, cancellationToken);

		/// <summary>A page of the accounts the persona blocked; Data is an AccountPage.</summary>
		public Task<WebResult> Blocks(string maxId, CancellationToken cancellationToken = default) =>
			Accounts(APIs.Mastodon.GET_Blocks, maxId, cancellationToken);

		async Task<WebResult> Accounts(string route, string maxId, CancellationToken cancellationToken)
		{
			var parameters = new List<string> { "limit=40" };
			if (maxId is not null)
				parameters.Add($"max_id={Uri.EscapeDataString(maxId)}");
			using var response = await httpService.Get(route, [.. parameters], cancellationToken: cancellationToken);
			if (!response.IsSuccessStatusCode)
				return await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);

			var accounts = await response.MastodonReadFromJsonAsync<List<Account>>(cancellationToken) ?? [];
			var (nextMaxId, _) = response.PageCursors();
			return new WebResult { Data = new AccountPage { Accounts = accounts, MaxId = accounts.Count == 0 ? null : nextMaxId } };
		}

		/// <summary>The servers the persona blocked: nothing from them reaches it, and its followers there are removed.</summary>
		public async Task<List<string>> DomainBlocks(CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Get(APIs.Mastodon.GET_DomainBlocks, ["limit=200"], cancellationToken: cancellationToken);
			if (response.IsSuccessStatusCode)
				return await response.MastodonReadFromJsonAsync<List<string>>(cancellationToken) ?? [];

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

		public async Task<WebResult> BlockDomain(string domain, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Post(APIs.Mastodon.POST_DomainBlocks, new[] { new KeyValuePair<string, string>("domain", domain.Trim()) },
				cancellationToken: cancellationToken);
			return response.IsSuccessStatusCode ? new WebResult() : await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);
		}

		public async Task<WebResult> UnblockDomain(string domain, CancellationToken cancellationToken = default)
		{
			using var response = await httpService.Delete(APIs.Mastodon.DELETE_DomainBlocks, [$"domain={Uri.EscapeDataString(domain)}"],
				cancellationToken: cancellationToken);
			return response.IsSuccessStatusCode ? new WebResult() : await response.Content.ReadWebResult(response.StatusCode, localizer, 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.NotFound))
				await logger.ProcessWarning(result.ToString(localizer), $"{nameof(AccountService)}.{caller}", cancellationToken);
		}
	}
}