BRAKING refactor project structure.

Refactor: the project is now divided into a more clear structure, with **Infrastructure** and **Application** layers added.

Refactor: configurations are split into sections for different layers.

Fix: now EF Core related operations, such as migration, should be invoked in `OptixServe.Infrastructure`, with config file and data dir passed into `dotnet ef` command. See `OptixServe.Infrastructure/Utilites/DesignTimeDbContextFactory.cs` for details.

Fix: EF migrations are ignored in gitignore on purpose in early development.

OptixServe.Infrastructure/Utilites/DatabaseHelper.cs

@@ -0,0 +1,33 @@
+using Microsoft.EntityFrameworkCore;
+using OptixServe.Infrastructure.Configuration;
+
+namespace OptixServe.Infrastructure.Utilites;
+
+public static class DatabaseHelper
+{
+    public static string BuildConnectionString(DatabaseSettings dbSettings)
+    {
+        return dbSettings.Type switch
+        {
+            DatabaseType.Sqlite => $"Data Source={dbSettings.Host ?? "optixserve.db"}",
+            DatabaseType.MySQL => throw new NotSupportedException("MySQL connection is not yet implemented"),
+            _ => throw new NotSupportedException($"Database type {dbSettings.Type} is not supported")
+        };
+    }
+
+    public static void ConfigureDbContext(DbContextOptionsBuilder options, DatabaseSettings dbSettings)
+    {
+        if (dbSettings?.Type == DatabaseType.Sqlite)
+        {
+            var dbPath = dbSettings.Host ?? "optixserve.db";
+            var connectionString = $"Data Source={dbPath}";
+
+            options.UseSqlite(connectionString, b => b.MigrationsAssembly("OptixServe.Infrastructure"));
+
+        }
+        else
+        {
+            throw new NotImplementedException("Only SQLite database is currently supported");
+        }
+    }
+}

OptixServe.Infrastructure/Utilites/DesignTimeDbContextFactory.cs

@@ -0,0 +1,129 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Design;
+using Microsoft.Extensions.Configuration;
+using OptixServe.Infrastructure.Configuration;
+using OptixServe.Infrastructure.Data;
+
+namespace OptixServe.Infrastructure.Utilites;
+
+public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<AppDbContext>
+{
+    private record CommandParseResult
+    {
+        public string? ConfigPath { get; set; } = null;
+        public string? DataDir { get; set; } = null;
+    }
+
+    private static CommandParseResult ParseArgs(string[] args)
+    {
+        var result = new CommandParseResult();
+        bool configSet = false;
+        bool dataDirSet = false;
+
+        for (int i = 0; i < args.Length; i++)
+        {
+            string arg = args[i];
+
+            if (arg == "--config" || arg == "-c")
+            {
+                if (configSet)
+                {
+                    throw new ArgumentException("The --config/-c option can only be specified once.");
+                }
+                if (i + 1 >= args.Length)
+                {
+                    throw new ArgumentException("Missing value for --config/-c option.");
+                }
+
+                result.ConfigPath = args[i + 1];
+                configSet = true;
+                i++;
+            }
+            else if (arg == "--data-dir" || arg == "-d")
+            {
+                if (dataDirSet)
+                {
+                    throw new ArgumentException("The --data-dir/-d option can only be specified once.");
+                }
+                if (i + 1 >= args.Length)
+                {
+                    throw new ArgumentException("Missing value for --data-dir/-d option.");
+                }
+
+                result.DataDir = args[i + 1];
+                dataDirSet = true;
+                i++;
+            }
+            else
+            {
+                throw new ArgumentException($"Unknown argument: {arg}");
+            }
+        }
+
+        return result;
+    }
+
+    /// <summary>
+    /// Creates DbContext instance in Design-Time
+    /// 
+    /// <para>Custom arguments should be passed in <i>dotnet</i> command </para>
+    /// 
+    /// <b>Example:</b><br/>
+    /// <example><c>dotnet ef database update -- -c ../data/appsettings.Development.json -d ../data/`</c></example>
+    /// 
+    /// </summary>
+    /// <param name="args">
+    ///     <list type="bullet">
+    ///         <item>
+    ///             --config/-c: App configuration file to load with database connection settings.
+    ///         </item>
+    ///         <item>
+    ///             --data-dir/-d: App data dir to work with.
+    ///             Currently this only affects finding SQLite database when relative path
+    ///             is specified in database settings.
+    ///         </item>
+    ///     </list>
+    /// </param>
+    /// <returns></returns>
+    public AppDbContext CreateDbContext(string[] args)
+    {
+        var parsedArgs = ParseArgs(args);
+
+        IConfigurationRoot configuration;
+
+        if (!string.IsNullOrEmpty(parsedArgs.ConfigPath))
+        {
+            var absConfigPath = Path.GetFullPath(parsedArgs.ConfigPath);
+            var configDirectory = Path.GetDirectoryName(absConfigPath);
+            var configFileName = Path.GetFileName(absConfigPath);
+            // Use the provided config file path
+            configuration = new ConfigurationBuilder()
+                .SetBasePath(configDirectory ?? "")
+                .AddJsonFile(configFileName, optional: false)
+                .Build();
+        }
+        else
+        {
+            // Default search configuration path
+            configuration = ConfigurationHelper.CreateDefaultBuilder().Build();
+        }
+
+        var dbSettings = configuration.GetSection("OptixServe:Infrastructure:Database").Get<DatabaseSettings>()!;
+
+        // Resolve SQLite database if `--data-dir` is specified and `dbSettings.Host` is relative
+        if (parsedArgs.DataDir != null)
+        {
+            if (dbSettings.Type == DatabaseType.Sqlite && !Path.IsPathFullyQualified(dbSettings.Host!))
+            {
+                var dbRelPath = Path.Combine(parsedArgs.DataDir, dbSettings.Host!);
+                var dbAbsPath = Path.GetFullPath(dbRelPath);
+                dbSettings.Host = dbAbsPath;
+            }
+        }
+
+        var optionsBuilder = new DbContextOptionsBuilder<AppDbContext>();
+        DatabaseHelper.ConfigureDbContext(optionsBuilder, dbSettings);
+
+        return new AppDbContext(optionsBuilder.Options);
+    }
+}