refactor: modularize Beam into new projects and interfaces

- Introduced modularity by splitting Beam into new projects: Beam.Abstractions, Beam.Models, and Beam.Downloaders.
- Refactored existing classes into appropriate namespaces and projects.
- Replaced specific implementations with abstractions (e.g., SourceLinkBuilder to LinkBuilder, State to IState, etc.).
- Updated interfaces: added ITemplate, IArticleData, IDownloadReport, and others for improved extensibility.
- Removed deprecated classes like SourceLinkBuilder and StateChangerFactory.
- Enhanced link handling in downloaders by refactoring to use `string` over `SourceLink`.
- Consolidated shared logic under Beam.Abstractions.

Beam.Abstractions/Beam.Abstractions.csproj

@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net9.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+        <RootNamespace>Beam.Abstract</RootNamespace>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <PackageReference Include="aeqw89.DataKeys" Version="2.1.0" />
+      <PackageReference Include="aeqw89.PersistentData" Version="1.3.3" />
+      <PackageReference Include="HtmlAgilityPack" Version="1.11.72" />
+    </ItemGroup>
+
+</Project>

Beam.Abstractions/IArticleData.cs

@@ -0,0 +1,10 @@
+namespace Beam.Abstractions;
+
+public interface IArticleData : IDocumentMetaData, IEquatable<IArticleData?> {
+    string? Name { get; set; }
+    string[] Authors { get; set; }
+    string? Language { get; set; }
+    string[] Categories { get; set; }
+    string? Version { get; set; }
+    string? Description { get; set; }
+}

Beam.Abstractions/IDataBindings.cs

@@ -0,0 +1,27 @@
+using Beam.Dynamic;
+
+namespace Beam.Abstractions;
+
+public interface IDataBindings {
+    IDataProvider<string>? Title { get; set; }
+    IDataProvider<string[]>? Authors { get; set; }
+    IDataProvider<string>? Description { get; set; }
+    IDataProvider<string>? Content { get; set; }
+    IDataProvider<string[]>? Language { get; set; }
+    IDataProvider<string[]>? Tags { get; set; }
+    IDataProvider<string>? Publisher { get; set; }
+    IDataProvider<DateTimeOffset>? PublicationDate { get; set; }
+    IDataProvider<string>? ISBN { get; set; }
+    IDataProvider<int>? PageCount { get; set; }
+    IDataProvider<string>? CoverImage { get; set; }
+    IDataProvider<string[]>? Series { get; set; }
+    IDataProvider<int>? Edition { get; set; }
+    IDataProvider<string[]>? Contributors { get; set; }
+    IDataProvider<string[]>? Subjects { get; set; }
+    IDataProvider<string>? Rights { get; set; }
+    IDataProvider<string[]>? TableOfContents { get; set; }
+    IDataProvider<string[]>? PagesDropDown { get; set; }
+    IDataProvider<string>? NextPageButton { get; set; }
+    IDataProvider<string>? PreviousPageButton { get; set; }
+    Dictionary<string, IDataProvider?> Providers { get; set; }
+}

Beam.Abstractions/IDataProvider.cs

@@ -0,0 +1,14 @@
+using HtmlAgilityPack;
+using System.Text.Json.Serialization;
+
+namespace Beam.Dynamic;
+
+public interface IDataProvider {
+    public string GetString(HtmlDocument document)
+        => (this as IDataProvider<object>)?.Get(document)?.ToString() ?? "";
+}
+
+public interface IDataProvider<out T> : IDataProvider {
+    public T Get(HtmlDocument document);
+    //public HtmlNode? GetNode(HtmlDocument document);
+}

Beam.Abstractions/IDocument.cs

@@ -0,0 +1,28 @@
+using aeqw89.DataKeys;
+
+namespace Beam.Abstractions;
+
+public interface IDocument {
+    /// <summary>
+    /// The file name of the document. Must be valid in both <c>UNIX</c>, 
+    /// <c>WINDOWS</c>, <c>APPLE</c>, and <c>ANDROID</c> file systems.
+    /// </summary>
+    string Filename { get; }
+
+    /// <summary>
+    /// Additional descriptive data
+    /// </summary>
+    IDictionary<IDataKey<IDocumentMetaData>, IDocumentMetaData> MetaData { get; }
+
+    /// <summary>
+    /// Retrieves the binary representation for the <see cref="IDocument"/>
+    /// </summary>
+    /// <returns>Binary representation of the <see cref="IDocument"/></returns>
+    byte[] ToBytes();
+
+    /// <summary>
+    /// Retrieves the string representation for the <see cref="IDocument"/>
+    /// </summary>
+    /// <returns>String representation of the <see cref="IDocument"/></returns>
+    string ToString();
+}

Beam.Abstractions/IDocumentMetaData.cs

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+using System.Text.Json;
+
+namespace Beam.Abstractions;
+
+public interface IDocumentMetaData {
+    string AsJson(JsonSerializerOptions? options = null);
+}

Beam.Abstractions/IDownloadReport.cs

@@ -0,0 +1,3 @@
+namespace Beam.Abstractions;
+
+public interface IDownloadReport { }

Beam.Abstractions/ILinkBuilder.cs

@@ -0,0 +1,11 @@
+using Beam.Models;
+
+namespace Beam.Abstractions;
+
+public interface ILinkBuilder {
+    /// <summary>
+    /// Produces a concrete <see cref="SourceLink"/> using values from an external <see cref="State"/> object.
+    /// </summary>
+    /// <param name="parameterValues">Object providing positional values.</param>
+    string Build(IReadOnlyState parameterValues);
+}

Beam.Abstractions/IOrdered.cs

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+namespace Beam.Abstractions;
+
+public interface IOrdered<out T> {
+    T Data { get; }
+    int Order { get; }
+}

Beam.Abstractions/IReadOnlyState.cs

@@ -0,0 +1,6 @@
+namespace Beam.Models;
+
+public interface IReadOnlyState {
+    public string[] GetState();
+    IReadOnlyState Copy();
+}

Beam.Abstractions/IResourceDictionary.cs

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+namespace Beam.Abstractions;
+
+public interface IResourceDictionary { }

Beam.Abstractions/IRetryReport.cs

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+namespace Beam.Abstractions;
+
+public interface IRetryReport {
+    int TryNumber { get; }
+    string Link { get; }
+}

Beam.Abstractions/IState.cs

@@ -0,0 +1,8 @@
+using Beam.Models;
+
+namespace Beam.Abstractions;
+
+public interface IState : IReadOnlyState {
+    void SetState(string[] state);
+    new IState Copy();
+}

Beam.Abstractions/IStateChangeBehaviour.cs

@@ -0,0 +1,10 @@
+using Beam.Models;
+
+namespace Beam.Abstractions;
+
+/// <summary>
+/// Defines how a url template should should be updated, in what order, and by how much
+/// </summary>
+public interface IStateChangeBehaviour {
+    public void Apply(IState state, object stimulus);
+}

Beam.Abstractions/IStateChangerFactory.cs

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+namespace Beam.Abstractions;
+
+public interface IStateChangerFactory { }

Beam.Abstractions/ITemplate.cs

@@ -0,0 +1,8 @@
+using aeqw89.DataKeys;
+
+namespace Beam.Abstractions;
+
+public interface ITemplate : IKeyed<ITemplate> {
+    IStateChangerFactory Factory { get; set; }
+    ILinkBuilder Builder { get; set; }
+}

Beam.Abstractions/IUnitDownloader.cs

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+
+namespace Beam.Abstractions;
+
+public interface IUnitDownloader<T> {
+    public int LinksPerDownload { get; }
+    public Task<(bool, T?)> TryDownload(IOrdered<string>[] link, CancellationToken ct, int maximumRetryCount = 7, IProgress<IRetryReport>? tryProgress = null);
+}