use std::collections::HashSet;
use crate::errors::DomainError;
use crate::value_objects::SystemId;

#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
pub struct Group {
    pub group_id: SystemId,
    pub name: String,
    pub owner_user_id: SystemId,
    pub members: HashSet<SystemId>,
}

impl Group {
    pub fn new(name: impl Into<String>, owner_user_id: SystemId) -> Self {
        let mut members = HashSet::new();
        members.insert(owner_user_id);
        Self {
            group_id: SystemId::new(),
            name: name.into(),
            owner_user_id,
            members,
        }
    }

    pub fn add_member(&mut self, user_id: SystemId) -> Result<(), DomainError> {
        if self.members.contains(&user_id) {
            return Err(DomainError::Conflict(format!("User {user_id} is already a member")));
        }
        self.members.insert(user_id);
        Ok(())
    }

    pub fn remove_member(&mut self, user_id: SystemId) -> Result<(), DomainError> {
        if user_id == self.owner_user_id {
            return Err(DomainError::Validation("Cannot remove the group owner".to_string()));
        }
        if !self.members.remove(&user_id) {
            return Err(DomainError::NotFound(format!("User {user_id} is not a member")));
        }
        Ok(())
    }

    pub fn is_member(&self, user_id: &SystemId) -> bool {
        self.members.contains(user_id)
    }
}