use std::collections::BTreeMap;

use crate::gateway::action;

/// 订阅表达式：topic → `tag1 || tag2 ...`，与投递端共用同一份目录。
pub fn plan(prefixes: &[String]) -> BTreeMap<String, String> {
    let mut topics: BTreeMap<String, Vec<&'static str>> = BTreeMap::new();
    for (prefix, area, tag) in action::catalog() {
        if !prefixes.iter().any(|configured| configured == prefix) {
            continue;
        }
        let tags = topics.entry(format!("{prefix}-{area}")).or_default();
        if !tags.contains(&tag) {
            tags.push(tag);
        }
    }
    topics
        .into_iter()
        .map(|(topic, tags)| (topic, tags.join(" || ")))
        .collect()
}