feat: Add specialized client implementations for PDF operations

DocumentService.Client/Clients/BaseDocumentClient.cs

@@ -0,0 +1,179 @@
+using Microsoft.Extensions.Logging;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+
+namespace DocumentService.Client.Clients;
+
+/// <summary>
+/// Base class for all DocumentService HTTP clients.
+/// Provides common HTTP operations and error handling.
+/// </summary>
+/// <remarks>
+/// 
+/// </remarks>
+/// <param name="HttpClient"></param>
+/// <param name="logger"></param>
+/// <exception cref="ArgumentNullException"></exception>
+public abstract class BaseDocumentClient(HttpClient HttpClient, ILogger logger)
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    protected readonly ILogger Logger = logger ?? throw new ArgumentNullException(nameof(logger));
+
+    /// <summary>
+    /// Sends a multipart/form-data POST with a single file and deserializes the JSON response.
+    /// </summary>
+    protected async Task<TResponse?> SendMultipartAsync<TResponse>(
+        string endpoint,
+        Stream fileStream,
+        string fileName = "file.pdf",
+        CancellationToken cancellationToken = default)
+    {
+        using var content = new MultipartFormDataContent();
+        var streamContent = new StreamContent(fileStream);
+        streamContent.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        content.Add(streamContent, "file", fileName);
+
+        var response = await HttpClient.PostAsync(endpoint, content, cancellationToken);
+        response.EnsureSuccessStatusCode();
+
+        return await response.Content.ReadFromJsonAsync<TResponse>(cancellationToken);
+    }
+
+    /// <summary>
+    /// Sends a multipart/form-data POST with a single file and returns the response as a stream.
+    /// </summary>
+    protected async Task<Stream> SendMultipartForStreamAsync(
+        string endpoint,
+        Stream fileStream,
+        string fileName = "file.pdf",
+        CancellationToken cancellationToken = default)
+    {
+        using var content = new MultipartFormDataContent();
+        var streamContent = new StreamContent(fileStream);
+        streamContent.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        content.Add(streamContent, "file", fileName);
+
+        var response = await HttpClient.PostAsync(endpoint, content, cancellationToken);
+        response.EnsureSuccessStatusCode();
+
+#if NETFRAMEWORK
+        return await response.Content.ReadAsStreamAsync();
+#else
+        return await response.Content.ReadAsStreamAsync(cancellationToken);
+#endif
+    }
+
+    /// <summary>
+    /// Sends a multipart/form-data POST with a single file and returns the raw byte array.
+    /// </summary>
+    protected async Task<byte[]> SendMultipartForBinaryAsync(
+        string endpoint,
+        Stream fileStream,
+        string fileName = "file.pdf",
+        CancellationToken cancellationToken = default)
+    {
+        using var content = new MultipartFormDataContent();
+        var streamContent = new StreamContent(fileStream);
+        streamContent.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        content.Add(streamContent, "file", fileName);
+
+        var response = await HttpClient.PostAsync(endpoint, content, cancellationToken);
+        response.EnsureSuccessStatusCode();
+
+#if NETFRAMEWORK
+        return await response.Content.ReadAsByteArrayAsync();
+#else
+        return await response.Content.ReadAsByteArrayAsync(cancellationToken);
+#endif
+    }
+
+    /// <summary>
+    /// Sends a caller-built <see cref="MultipartFormDataContent"/> and returns the response as a stream.
+    /// Use this overload when the multipart body contains more than one file (e.g., merge).
+    /// </summary>
+    protected async Task<Stream> SendMultipartContentForStreamAsync(
+        string endpoint,
+        MultipartFormDataContent content,
+        CancellationToken cancellationToken = default)
+    {
+        var response = await HttpClient.PostAsync(endpoint, content, cancellationToken);
+        response.EnsureSuccessStatusCode();
+
+#if NETFRAMEWORK
+        return await response.Content.ReadAsStreamAsync();
+#else
+        return await response.Content.ReadAsStreamAsync(cancellationToken);
+#endif
+    }
+
+    /// <summary>
+    /// Serializes <paramref name="request"/> as JSON, POSTs it, and deserializes the response.
+    /// </summary>
+    protected async Task<TResponse?> SendJsonAsync<TRequest, TResponse>(
+        string endpoint,
+        TRequest request,
+        CancellationToken cancellationToken = default)
+    {
+        var response = await HttpClient.PostAsJsonAsync(endpoint, request, cancellationToken);
+        response.EnsureSuccessStatusCode();
+
+        return await response.Content.ReadFromJsonAsync<TResponse>(cancellationToken);
+    }
+
+    /// <summary>
+    /// Serializes <paramref name="request"/> as JSON, POSTs it, and returns the response as a stream.
+    /// </summary>
+    protected async Task<Stream> SendJsonForStreamAsync<TRequest>(
+        string endpoint,
+        TRequest request,
+        CancellationToken cancellationToken = default)
+    {
+        var response = await HttpClient.PostAsJsonAsync(endpoint, request, cancellationToken);
+        response.EnsureSuccessStatusCode();
+
+#if NETFRAMEWORK
+        return await response.Content.ReadAsStreamAsync();
+#else
+        return await response.Content.ReadAsStreamAsync(cancellationToken);
+#endif
+    }
+
+    /// <summary>
+    /// Serializes <paramref name="request"/> as JSON, POSTs it, and returns the raw byte array.
+    /// </summary>
+    protected async Task<byte[]> SendJsonForBinaryAsync<TRequest>(
+        string endpoint,
+        TRequest request,
+        CancellationToken cancellationToken = default)
+    {
+        var response = await HttpClient.PostAsJsonAsync(endpoint, request, cancellationToken);
+        response.EnsureSuccessStatusCode();
+
+#if NETFRAMEWORK
+        return await response.Content.ReadAsByteArrayAsync();
+#else
+        return await response.Content.ReadAsByteArrayAsync(cancellationToken);
+#endif
+    }
+
+    /// <summary>Converts a byte array to a Base64 string.</summary>
+    protected static string ToBase64(byte[] bytes) => Convert.ToBase64String(bytes);
+
+    /// <summary>Reads a stream fully into a byte array.</summary>
+    protected static async Task<byte[]> StreamToBytesAsync(Stream stream, CancellationToken cancellationToken = default)
+    {
+        if (stream is MemoryStream ms)
+            return ms.ToArray();
+
+        using var memoryStream = new MemoryStream();
+#if NET8_0
+        await stream.CopyToAsync(memoryStream, cancellationToken);
+#else
+        await stream.CopyToAsync(memoryStream);
+#endif
+        return memoryStream.ToArray();
+    }
+}