using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using Newtonsoft.Json.Linq;
using RudderSdk.Core.Models.Ugc;

namespace RudderSdk.Core;

/// <summary>User-generated content: upload, list, download URLs, deletion.</summary>
public sealed class UgcService
{
    private readonly RudderClient _client;

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

    /// <summary>
    /// Uploads a file in one call: pre-signed URL, PUT of the bytes, submission.
    /// Requires an upload transport in <see cref="RudderClientOptions.UploadTransport"/>.
    /// </summary>
    public async Task<UgcSubmission> UploadAsync(
        string name,
        byte[] data,
        string? description = null,
        JToken? metadata = null,
        CancellationToken cancellationToken = default)
    {
        var uploadTransport = _client.Options.UploadTransport
            ?? throw new InvalidOperationException("UploadTransport is not configured.");

        var upload = await GetUploadUrlAsync(name, cancellationToken).ConfigureAwait(false);
        await uploadTransport.PutAsync(
            upload.UploadUrl,
            data ?? Array.Empty<byte>(),
            GetContentType(name),
            cancellationToken).ConfigureAwait(false);

        return await SubmitAsync(
            name,
            upload.FileKey,
            data?.LongLength ?? 0,
            description,
            metadata,
            cancellationToken).ConfigureAwait(false);
    }

    /// <summary>Fetches one page of the player's submissions.</summary>
    public Task<ListUgcResponse> ListAsync(string? status = null, int limit = 20, string? cursor = null, CancellationToken cancellationToken = default)
        => _client.SendAsync<ListUgcResponse>(
            "GET",
            "/sdk/v1/ugc" + Url.Query(
                ("status", status),
                ("limit", limit > 0 ? limit.ToString() : null),
                ("cursor", cursor)),
            cancellationToken);

    /// <summary>Iterates over all of the player's submissions, following the cursor pagination.</summary>
    public async IAsyncEnumerable<UgcSubmission> ListAllAsync(
        string? status = null,
        int limit = 20,
        [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
        string? cursor = null;
        do
        {
            var page = await ListAsync(status, 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>Returns one submission.</summary>
    public Task<UgcSubmission> GetAsync(string id, CancellationToken cancellationToken = default)
        => _client.SendAsync<UgcSubmission>("GET", "/sdk/v1/ugc/" + Url.Encode(id), cancellationToken);

    /// <summary>Deletes a submission; returns false when the server refused.</summary>
    public async Task<bool> DeleteAsync(string id, CancellationToken cancellationToken = default)
    {
        var response = await _client.SendAsync<DeleteUgcResponse>(
            "DELETE",
            "/sdk/v1/ugc/" + Url.Encode(id),
            cancellationToken).ConfigureAwait(false);

        return response == null || response.Success;
    }

    /// <summary>Requests a pre-signed upload URL.</summary>
    public Task<GetUploadUrlResponse> GetUploadUrlAsync(string filename, CancellationToken cancellationToken = default)
        => _client.SendAsync<GetUploadUrlResponse>(
            "GET",
            "/sdk/v1/ugc/upload-url" + Url.Query(("filename", filename)),
            cancellationToken);

    /// <summary>
    /// Resolves the download URL of a submission.
    /// Throws <see cref="InvalidOperationException"/> when the server returned none.
    /// </summary>
    public async Task<string> GetDownloadUrlAsync(string id, CancellationToken cancellationToken = default)
    {
        var response = await _client.SendAsync<GetDownloadUrlResponse>(
            "GET",
            "/sdk/v1/ugc/" + Url.Encode(id) + "/download",
            cancellationToken).ConfigureAwait(false);

        if (response == null || string.IsNullOrEmpty(response.DownloadUrl))
            throw new InvalidOperationException("The server returned no download URL.");

        return response.DownloadUrl;
    }

    /// <summary>Registers an uploaded file as a submission.</summary>
    public Task<UgcSubmission> SubmitAsync(
        string name,
        string fileKey,
        long fileSize,
        string? description = null,
        JToken? metadata = null,
        CancellationToken cancellationToken = default)
    {
        return _client.SendAsync<SubmitUgcRequest, UgcSubmission>(
            "POST",
            "/sdk/v1/ugc",
            new SubmitUgcRequest
            {
                Name = name,
                FileKey = fileKey,
                FileSize = fileSize,
                Description = description!,
                Metadata = metadata!
            },
            cancellationToken);
    }

    private static string GetContentType(string filename)
    {
        var ext = System.IO.Path.GetExtension(filename)?.ToLowerInvariant();
        switch (ext)
        {
            case ".png": return "image/png";
            case ".jpg":
            case ".jpeg": return "image/jpeg";
            case ".gif": return "image/gif";
            case ".webp": return "image/webp";
            case ".txt": return "text/plain";
            default: return "application/octet-stream";
        }
    }
}