Refactor Blazor components to use code-behind files

- Move @code blocks from Exercises.razor, Home.razor, and Routines.razor to separate .cs files
- Add XML documentation comments to all methods in the code-behind files

src/ASTRAIN.Client/Pages/Exercises.razor.cs

@@ -0,0 +1,159 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Components;
+using Microsoft.JSInterop;
+using ASTRAIN.Shared.Dtos;
+using ASTRAIN.Shared.Requests;
+
+namespace ASTRAIN.Client.Pages;
+
+public partial class Exercises
+{
+    /// <summary>
+    /// Optional user id from route.
+    /// </summary>
+    [Parameter]
+    public string? UserId { get; set; }
+
+    /// <summary>
+    /// The list of exercises for the current user.
+    /// </summary>
+    private List<ExerciseDto> ExerciseList { get; set; } = new();
+
+    /// <summary>
+    /// Whether the page is currently loading data.
+    /// </summary>
+    private bool IsLoading { get; set; } = true;
+
+    /// <summary>
+    /// Whether the create exercise UI is visible.
+    /// </summary>
+    private bool ShowCreateExercise { get; set; }
+
+    /// <summary>
+    /// Name for a new exercise being created.
+    /// </summary>
+    private string NewExerciseName { get; set; } = string.Empty;
+
+    /// <summary>
+    /// The currently edited exercise id, if any.
+    /// </summary>
+    private int? EditingId { get; set; }
+
+    /// <summary>
+    /// The current edited exercise name.
+    /// </summary>
+    private string EditingName { get; set; } = string.Empty;
+
+    /// <inheritdoc/>
+    protected override async Task OnInitializedAsync()
+    {
+        var ensured = await Api.EnsureUserAsync(UserId);
+        if (string.IsNullOrWhiteSpace(ensured))
+        {
+            return;
+        }
+
+        UserContext.SetUserId(ensured);
+        if (UserId != ensured)
+        {
+            Navigation.NavigateTo($"/{ensured}/exercises", true);
+            return;
+        }
+
+        await LoadExercisesAsync();
+    }
+
+    /// <summary>
+    /// Loads exercises from the API.
+    /// </summary>
+    private async Task LoadExercisesAsync()
+    {
+        IsLoading = true;
+        ExerciseList = await Api.GetExercisesAsync(UserContext.UserId);
+        IsLoading = false;
+    }
+
+    /// <summary>
+    /// Creates a new exercise with the provided name.
+    /// </summary>
+    private async Task CreateExerciseAsync()
+    {
+        if (string.IsNullOrWhiteSpace(NewExerciseName))
+        {
+            return;
+        }
+
+        var result = await Api.CreateExerciseAsync(UserContext.UserId, new ExerciseUpsertRequest(NewExerciseName));
+        if (result is not null)
+        {
+            ExerciseList.Add(result);
+            ExerciseList = ExerciseList.OrderBy(e => e.Name).ToList();
+            NewExerciseName = string.Empty;
+        }
+    }
+
+    /// <summary>
+    /// Toggles the create form visibility.
+    /// </summary>
+    private void ToggleCreate()
+    {
+        ShowCreateExercise = !ShowCreateExercise;
+    }
+
+    /// <summary>
+    /// Begin editing the supplied exercise.
+    /// </summary>
+    private void StartEdit(ExerciseDto exercise)
+    {
+        EditingId = exercise.Id;
+        EditingName = exercise.Name;
+    }
+
+    /// <summary>
+    /// Cancel the current edit.
+    /// </summary>
+    private void CancelEdit()
+    {
+        EditingId = null;
+        EditingName = string.Empty;
+    }
+
+    /// <summary>
+    /// Save the edited exercise name.
+    /// </summary>
+    private async Task SaveEditAsync(int exerciseId)
+    {
+        if (string.IsNullOrWhiteSpace(EditingName))
+        {
+            return;
+        }
+
+        var result = await Api.UpdateExerciseAsync(UserContext.UserId, exerciseId, new ExerciseUpsertRequest(EditingName));
+        if (result is not null)
+        {
+            var index = ExerciseList.FindIndex(e => e.Id == exerciseId);
+            if (index >= 0)
+            {
+                ExerciseList[index] = result;
+                ExerciseList = ExerciseList.OrderBy(e => e.Name).ToList();
+            }
+        }
+
+        CancelEdit();
+    }
+
+    /// <summary>
+    /// Deletes the exercise with the given id after confirmation.
+    /// </summary>
+    private async Task DeleteExerciseAsync(int exerciseId)
+    {
+        var confirmed = await JS.InvokeAsync<bool>("confirm", "Are you sure you want to delete this exercise?");
+        if (!confirmed) return;
+
+        await Api.DeleteExerciseAsync(UserContext.UserId, exerciseId);
+        ExerciseList.RemoveAll(e => e.Id == exerciseId);
+    }
+}