use serde_json::{json, Value};
use yrs::{ReadTxn, Text, Xml, XmlFragment, XmlFragmentRef, XmlOut};

pub fn node_id(node: &XmlOut) -> String {
    serde_json::to_string(&node.id()).expect("branch identity serializes")
}
pub fn children<T: ReadTxn>(root: &XmlFragmentRef, txn: &T) -> Vec<Value> {
    (0..root.len(txn)).filter_map(|i| root.get(txn, i)).map(|node| project(&node, txn)).collect()
}
fn project<T: ReadTxn>(node: &XmlOut, txn: &T) -> Value {
    match node {
        XmlOut::Text(text) => {
            let runs: Vec<_> = text.diff(txn, |_| ()).iter().map(|run| {
                json!({"insert": run.insert.clone().to_string(txn), "marks": run.attributes})
            }).collect();
            json!({"id": node_id(node), "type": "text", "runs": runs})
        },
        XmlOut::Element(element) => {
            let attrs: serde_json::Map<String, Value> = element.attributes(txn)
                .map(|(key,value)| (key.to_string(), Value::String(value))).collect();
            json!({"id": node_id(node), "type": element.tag().as_ref(), "attrs": attrs, "children": children(element.as_ref(), txn)})
        },
        XmlOut::Fragment(fragment) => json!({"id": node_id(node), "type": "fragment", "children": children(fragment, txn)}),
    }
}
pub fn find<T: ReadTxn>(root: &XmlFragmentRef, txn: &T, id: &str) -> Option<XmlOut> {
    for index in 0..root.len(txn) {
        let node = root.get(txn, index)?;
        if node_id(&node) == id { return Some(node); }
        let nested = match &node {
            XmlOut::Element(el) => find(el.as_ref(), txn, id),
            XmlOut::Fragment(f) => find(f, txn, id),
            _ => None,
        };
        if nested.is_some() { return nested; }
    }
    None
}