Nexus.Reader/src/NexusReader.Web.Client/Services/WasmEpubService.cs

using System.Net.Http.Json;
using FluentResults;
using NexusReader.Application.Abstractions.Services;
using NexusReader.Application.Queries.Reader;

namespace NexusReader.Web.Client.Services;

public class WasmEpubReader : IEpubReader
{
    private readonly HttpClient _httpClient;

    public WasmEpubReader(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    public async Task<Result<ReaderPageViewModel>> GetEpubContentAsync(
        Guid ebookId,
        int chapterIndex,
        string? userId = null,
        CancellationToken cancellationToken = default)
    {
        try
        {
            var response = await _httpClient.GetAsync($"/api/epub/{ebookId}/{chapterIndex}", cancellationToken);
            if (response.IsSuccessStatusCode)
            {
                var viewModel = await response.Content.ReadFromJsonAsync<ReaderPageViewModel>(cancellationToken: cancellationToken);
                return viewModel != null ? Result.Ok(viewModel) : Result.Fail("Failed to deserialize response.");
            }

            var errorBody = await response.Content.ReadAsStringAsync(cancellationToken);
            return Result.Fail($"Server error ({response.StatusCode}): {errorBody}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error($"Network or parsing error: {ex.Message}").CausedBy(ex));
        }
    }
    public async Task<Result<byte[]>> GetEpubResourceAsync(
        Guid ebookId,
        string resourcePath,
        string? userId = null,
        CancellationToken cancellationToken = default)
    {
        try
        {
            var response = await _httpClient.GetAsync($"/api/epub/{ebookId}/resource?path={Uri.EscapeDataString(resourcePath)}", cancellationToken);
            if (response.IsSuccessStatusCode)
            {
                var bytes = await response.Content.ReadAsByteArrayAsync(cancellationToken);
                return Result.Ok(bytes);
            }

            var errorBody = await response.Content.ReadAsStringAsync(cancellationToken);
            return Result.Fail($"Server error fetching EPUB resource ({response.StatusCode}): {errorBody}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error($"Network error fetching EPUB resource: {ex.Message}").CausedBy(ex));
        }
    }
}

public class WasmEpubMetadataExtractor : IEpubMetadataExtractor
{
    public async Task<Result<LocalEpubMetadata>> ExtractMetadataAsync(Stream epubStream)
    {
        try
        {
            using var bookRef = await VersOne.Epub.EpubReader.OpenBookAsync(epubStream);
            var title = bookRef.Title ?? "Unknown Title";
            var author = bookRef.Author ?? "Unknown Author";
            byte[]? cover = await bookRef.ReadCoverAsync();
            return Result.Ok(new LocalEpubMetadata { Title = title, Author = author, CoverImage = cover });
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error($"Failed to extract EPUB metadata locally: {ex.Message}").CausedBy(ex));
        }
    }
}