Notes

[HttpPost("join")]
public ActionResult JoinEvent([FromBody] JoinRequest joinRequest)
{
string eventName = joinRequest.Eventname;
string username = joinRequest.Username;

// Check if the event exists
Event eventDetails = Events.FirstOrDefault(e => e.Name == eventName);

if (eventDetails == null)
{
return NotFound($"Event '{eventName}' does not exist.");
}

if (UserEventss.ContainsKey(username))
{
// Ensure the user's event list is initialized
UserEventss[username] ??= new List<string>();

// Check if the user has already joined the event
if (UserEventss[username].Any(e => e.Contains($"Participant: {username}, Event: {eventName}")))
{
return Conflict($"User '{username}' has already joined the event '{eventName}'.");
}

// Check if the user has already booked an event on the same date
if (UserEventss[username].Any(e => Events.Any(ev => ev.Date.Date == eventDetails.Date.Date)))
{
return Conflict($"User '{username}' has already booked an event on the same date.");
}

// Add the user to the event
UserEventss[username].Add($"Participant: {username}, Event: {eventName}");

// Keep track of the dates the user has joined
var joinedDates = UserEventss[username]
.Select(e => Events.FirstOrDefault(ev => e.Contains($"Event: {ev.Name}")))
.Where(ev => ev != null)
.Select(ev => ev.Date.Date);

// Check if the user is trying to join an event on the same date
if (joinedDates.Any(date => date == eventDetails.Date.Date))
{
// Remove the user from the event since they cannot join on the same date
UserEventss[username].Remove($"Participant: {username}, Event: {eventName}");
return Conflict($"User '{username}' cannot join an event on the same date.");
}

// Additional event information can be added here

return Ok($"Successfully joined event: {eventName}");
}
else
{
return NotFound($"User '{username}' not found.");
}
}