using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

using Newtonsoft.Json.Linq;

using UnityEngine;

using Crowdin.Plugin.Server_API.Helpers;
using Crowdin.Plugin.Server_API.Models.StringTranslations;

#nullable enable

namespace Crowdin.Plugin.Server_API.Services
{
    public class StringTranslationsApiService : BaseApiService
    {
        private static string BaseUri => SettingsHelper.GetUri("languages", SettingsHelper.GetProjectId());

        private readonly CrowdinHttpClient _httpClient = CrowdinHttpClient.Default;

        private const int SingleRequestThreshold = 500;
        private const string PluralContentType = "application/vnd.crowdin.text+plural";

        public async Task<List<LanguageTranslation>> ListLanguageTranslations(
            string languageId,
            IEnumerable<int>? stringIds = null,
            int limit = 500,
            int? branchId = null,
            CancellationToken ct = default)
        {
            if (stringIds is null || stringIds.Count() <= SingleRequestThreshold)
            {
                return await ListLanguageTranslations_Request(languageId, stringIds, limit, branchId, ct);
            }

            IEnumerable<int[]> chunks = stringIds
                .Select((value, index) => new { value, index })
                .GroupBy(x => x.index / SingleRequestThreshold)
                .Select(grouping => grouping.Select(x => x.value).ToArray());

            var responseList = new List<LanguageTranslation>();

            foreach (int[] chunk in chunks)
            {
                List<LanguageTranslation> partialResponse =
                    await ListLanguageTranslations_Request(languageId, chunk, limit, branchId, ct);

                responseList.AddRange(partialResponse);
            }

            return responseList;
        }

        private async Task<List<LanguageTranslation>> ListLanguageTranslations_Request(
            string languageId,
            IEnumerable<int>? stringIds,
            int limit,
            int? branchId,
            CancellationToken ct)
        {
            var url = $"{BaseUri}/{languageId}/translations";

            if (stringIds is not null)
            {
                string stringIdsQuery = string.Join(",", stringIds);

                if (!string.IsNullOrWhiteSpace(stringIdsQuery))
                {
                    url += url.Contains('?') ? $"&stringIds={stringIdsQuery}" : $"?stringIds={stringIdsQuery}";
                }
            }

            if (branchId.HasValue)
            {
                url += url.Contains('?') ? $"&branchId={branchId.Value}" : $"?branchId={branchId.Value}";
            }

            try
            {
                List<JObject> rawItems = await _httpClient.ListAllRawAsync(url, limit, ct);

                var responseList = new List<LanguageTranslation>();

                foreach (JObject obj in rawItems)
                {
                    var contentType = obj["contentType"]?.Value<string>();
                    if (string.IsNullOrWhiteSpace(contentType) || contentType is PluralContentType)
                    {
                        continue;
                    }

                    LanguageTranslation? languageTranslation = CrowdinHttpClient.Deserialize<LanguageTranslation>(obj);

                    if (languageTranslation is null)
                    {
                        continue;
                    }

                    responseList.Add(languageTranslation);
                }

                return responseList;
            }
            catch (CrowdinApiException ex)
            {
                // Matches main's behaviour: a failure fetching one language/chunk must not abort
                // the whole pull - the caller (PullStrings) continues with the remaining
                // languages and tables instead of failing the entire operation.
                Debug.LogException(ex);
                return new List<LanguageTranslation>();
            }
        }
    }
}