using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using RudderSdk.Core.Models.Storage;

namespace RudderSdk.Core;

/// <summary>Player key-value storage.</summary>
public sealed class StorageService
{
    private readonly RudderClient _client;

    internal StorageService(RudderClient client) => _client = client;

    /// <summary>Fetches one page of storage items, optionally filtered by type.</summary>
    public Task<GetStorageResponse> GetAsync(string? type = null, int limit = 100, string? cursor = null, CancellationToken cancellationToken = default)
    {
        var query = Url.Query(
            ("types", type),
            ("limit", limit > 0 ? limit.ToString() : null),
            ("cursor", cursor));

        return _client.SendAsync<GetStorageResponse>("GET", "/sdk/v1/storage" + query, cancellationToken);
    }

    /// <summary>Iterates over all storage items, following the cursor pagination.</summary>
    public async IAsyncEnumerable<StorageItem> ListAllAsync(
        string? type = null,
        int limit = 100,
        [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
        string? cursor = null;
        do
        {
            var page = await GetAsync(type, limit, cursor, cancellationToken).ConfigureAwait(false);
            if (page?.Items != null)
            {
                foreach (var item in page.Items)
                    yield return item;
            }

            cursor = page?.NextCursor;
        }
        while (!string.IsNullOrEmpty(cursor));
    }

    /// <summary>Saves (upserts) storage items.</summary>
    public Task SaveAsync(IEnumerable<StorageItem> items, CancellationToken cancellationToken = default)
        => _client.SendAsync(
            "PUT",
            "/sdk/v1/storage",
            new UpdateStorageRequest { Items = items?.ToList() ?? new List<StorageItem>() },
            cancellationToken);

    /// <summary>Deletes all items of the given type.</summary>
    public Task DeleteAsync(string type, CancellationToken cancellationToken = default)
        => _client.SendAsync("DELETE", "/sdk/v1/storage" + Url.Query(("type", type)), cancellationToken);
}