Support Ticket System — Refactor Monolithic Controller

public TicketsController(AppDbContext db)
{
    _db = db;
}

[HttpGet]
public async Task<IActionResult> GetAll([FromQuery] string? status, [FromQuery] int page = 1)
{
    var query = _db.Tickets.Include(t => t.AssignedAgent).AsQueryable();
    if (!string.IsNullOrEmpty(status))
        query = query.Where(t => t.Status.ToString() == status);

    var tickets = await query
        .OrderByDescending(t => t.Priority)
        .ThenByDescending(t => t.CreatedAt)
        .Skip((page - 1) * 20)
        .Take(20)
        .Select(t => new {
            t.Id, t.Title, t.Status, t.Priority,
            Agent = t.AssignedAgent != null ? t.AssignedAgent.Name : null,
            t.CreatedAt
        })
        .ToListAsync();

    return Ok(tickets);
}

[HttpGet("{id}")]
public async Task<IActionResult> GetById(int id)
{
    var ticket = await _db.Tickets
        .Include(t => t.Comments)
        .Include(t => t.AssignedAgent)
        .FirstOrDefaultAsync(t => t.Id == id);

    if (ticket == null)
        return NotFound(new { error = "Ticket not found" });

    return Ok(new {
        ticket.Id, ticket.Title, ticket.Description,
        ticket.Status, ticket.Priority,
        Agent = ticket.AssignedAgent != null ? ticket.AssignedAgent.Name : null,
        Comments = ticket.Comments.Select(c => new {
            c.Id, c.Text, c.AuthorName, c.CreatedAt
        }),
        ticket.CreatedAt
    });
}

[HttpPost]
public async Task<IActionResult> Create([FromBody] CreateTicketInput input)
{
    if (string.IsNullOrWhiteSpace(input.Title))
        return BadRequest(new { error = "Title is required" });
    if (string.IsNullOrWhiteSpace(input.Description))
        return BadRequest(new { error = "Description is required" });

    var ticket = new Ticket
    {
        Title = input.Title,
        Description = input.Description,
        Priority = input.Priority,
        Status = TicketStatus.Open,
        CreatedAt = DateTime.UtcNow
    };
    _db.Tickets.Add(ticket);
    await _db.SaveChangesAsync();

    return CreatedAtAction(nameof(GetById), new { id = ticket.Id }, new {
        ticket.Id, ticket.Title, ticket.Status
    });
}

[HttpPost("{id}/comments")]
public async Task<IActionResult> AddComment(int id, [FromBody] AddCommentInput input)
{
    var ticket = await _db.Tickets.FindAsync(id);
    if (ticket == null)
        return NotFound(new { error = "Ticket not found" });

    if (ticket.Status == TicketStatus.Closed)
        return BadRequest(new { error = "Cannot add comments to closed tickets" });

    var comment = new Comment
    {
        TicketId = id,
        Text = input.Text,
        AuthorName = input.AuthorName,
        CreatedAt = DateTime.UtcNow
    };
    _db.Comments.Add(comment);
    await _db.SaveChangesAsync();

    return Ok(new { comment.Id, comment.Text, comment.AuthorName, comment.CreatedAt });
}

[HttpPatch("{id}/assign")]
public async Task<IActionResult> AssignAgent(int id, [FromBody] AssignAgentInput input)
{
    var ticket = await _db.Tickets.FindAsync(id);
    if (ticket == null)
        return NotFound(new { error = "Ticket not found" });

    var agent = await _db.Agents.FindAsync(input.AgentId);
    if (agent == null)
        return NotFound(new { error = "Agent not found" });

    ticket.AssignedAgentId = agent.Id;
    await _db.SaveChangesAsync();

    return Ok(new { ticket.Id, Agent = agent.Name });
}