use std::fmt;
use std::path::{Path, PathBuf};
use serde::de::{MapAccess, Visitor};
use serde::{Deserialize, Deserializer, Serialize, Serializer};
use crate::ledger::location::mint_token;
pub const LOOKUP_FILE: &str = "lookup-by-cloud-session.json";
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct CloudBinding {
#[serde(default, skip_serializing_if = "Option::is_none")]
pub thread_id: Option<String>,
#[serde(default, skip_serializing_if = "Option::is_none")]
pub registered_at: Option<String>,
#[serde(flatten)]
pub extra: serde_json::Map<String, serde_json::Value>,
}
impl CloudBinding {
pub fn new(thread_id: &str, registered_at: &str) -> CloudBinding {
CloudBinding {
thread_id: Some(thread_id.to_string()),
registered_at: Some(registered_at.to_string()),
extra: serde_json::Map::new(),
}
}
}
#[derive(Debug, Default, Clone, PartialEq)]
pub struct Lookup {
entries: Vec<(String, CloudBinding)>,
}
pub fn lookup_path(wt: &Path) -> PathBuf {
wt.join("threads").join(LOOKUP_FILE)
}
impl Lookup {
pub fn parse(text: &str, path: &Path) -> Result<Lookup, String> {
serde_json::from_str(text).map_err(|e| {
format!(
"error: {} is not a cloud session lookup: {}",
path.display(),
e
)
})
}
pub fn read(path: &Path) -> Result<Option<Lookup>, String> {
match std::fs::read_to_string(path) {
Ok(text) => Lookup::parse(&text, path).map(Some),
Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(None),
Err(e) => Err(format!("error: could not read {}: {}", path.display(), e)),
}
}
pub fn entries(&self) -> &[(String, CloudBinding)] {
&self.entries
}
pub fn thread_for(&self, session: &str) -> Option<&str> {
self.entries
.iter()
.find(|(key, _)| key == session)
.and_then(|(_, binding)| binding.thread_id.as_deref())
.filter(|id| !id.is_empty())
}
pub fn set(&mut self, session: &str, binding: CloudBinding) {
match self.entries.iter_mut().find(|(key, _)| key == session) {
Some(entry) => entry.1 = binding,
None => self.entries.push((session.to_string(), binding)),
}
}
pub fn remove(&mut self, session: &str) {
self.entries.retain(|(key, _)| key != session);
}
pub fn remove_thread(&mut self, thread_id: &str) {
self.entries
.retain(|(_, binding)| binding.thread_id.as_deref() != Some(thread_id));
}
pub fn to_json(&self) -> String {
let mut text = serde_json::to_string_pretty(self).unwrap_or_else(|_| "{}".to_string());
text.push('\n');
text
}
pub fn write(&self, path: &Path) -> Result<(), String> {
let dir = path
.parent()
.ok_or_else(|| format!("error: {} has no parent directory", path.display()))?;
std::fs::create_dir_all(dir)
.map_err(|e| format!("error: could not create {}: {}", dir.display(), e))?;
let tmp = dir.join(format!(
".{}.tmp-{}",
LOOKUP_FILE,
mint_token(8, &path.to_string_lossy())
));
std::fs::write(&tmp, self.to_json())
.map_err(|e| format!("error: could not write {}: {}", tmp.display(), e))?;
std::fs::rename(&tmp, path).map_err(|e| {
let _ = std::fs::remove_file(&tmp);
format!("error: could not replace {}: {}", path.display(), e)
})
}
}
impl Serialize for Lookup {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
serializer.collect_map(self.entries.iter().map(|(k, v)| (k, v)))
}
}
struct LookupVisitor;
impl<'de> Visitor<'de> for LookupVisitor {
type Value = Lookup;
fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("a JSON object keyed by cloud session id")
}
fn visit_map<A: MapAccess<'de>>(self, mut map: A) -> Result<Lookup, A::Error> {
let mut lookup = Lookup::default();
while let Some((key, binding)) = map.next_entry::<String, CloudBinding>()? {
lookup.set(&key, binding);
}
Ok(lookup)
}
}
impl<'de> Deserialize<'de> for Lookup {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Lookup, D::Error> {
deserializer.deserialize_map(LookupVisitor)
}
}
#[cfg(test)]
mod tests {
use super::*;
const TEXT: &str = "{\n \"cse_b\": {\n \"thread_id\": \"2222bbbb\",\n \"registered_at\": \"2026-09-17T18:26:21Z\"\n },\n \"cse_a\": {\n \"thread_id\": \"1111aaaa\",\n \"registered_at\": \"2026-09-18T03:30:40Z\"\n }\n}\n";
fn parse(text: &str) -> Lookup {
Lookup::parse(text, Path::new("lookup")).unwrap()
}
#[test]
fn round_trips_in_the_jq_layout_and_keeps_key_order() {
assert_eq!(parse(TEXT).to_json(), TEXT);
}
#[test]
fn empty_lookup_is_an_empty_object() {
assert_eq!(parse("{}").to_json(), "{}\n");
}
#[test]
fn thread_for_finds_the_session() {
let lookup = parse(TEXT);
assert_eq!(lookup.thread_for("cse_a"), Some("1111aaaa"));
assert_eq!(lookup.thread_for("cse_x"), None);
}
#[test]
fn set_replaces_in_place_and_appends_new_sessions() {
let mut lookup = parse(TEXT);
lookup.set(
"cse_b",
CloudBinding::new("3333cccc", "2026-10-03T00:00:00Z"),
);
lookup.set(
"cse_c",
CloudBinding::new("4444dddd", "2026-10-03T00:00:01Z"),
);
let json = lookup.to_json();
let b = json.find("cse_b").unwrap();
let a = json.find("cse_a").unwrap();
let c = json.find("cse_c").unwrap();
assert!(b < a && a < c, "{}", json);
assert_eq!(lookup.thread_for("cse_b"), Some("3333cccc"));
}
#[test]
fn remove_deletes_one_session() {
let mut lookup = parse(TEXT);
lookup.remove("cse_b");
assert_eq!(lookup.thread_for("cse_b"), None);
assert_eq!(lookup.thread_for("cse_a"), Some("1111aaaa"));
}
#[test]
fn remove_thread_deletes_every_session_bound_to_it() {
let mut lookup = parse(TEXT);
lookup.set(
"cse_c",
CloudBinding::new("1111aaaa", "2026-10-03T00:00:00Z"),
);
lookup.remove_thread("1111aaaa");
assert_eq!(lookup.thread_for("cse_a"), None);
assert_eq!(lookup.thread_for("cse_c"), None);
assert_eq!(lookup.thread_for("cse_b"), Some("2222bbbb"));
}
#[test]
fn keeps_unknown_fields() {
let lookup = parse("{\"cse_a\":{\"thread_id\":\"1111aaaa\",\"note\":\"x\"}}");
assert!(lookup.to_json().contains("\"note\": \"x\""));
}
#[test]
fn rejects_a_non_object() {
assert!(Lookup::parse("[]", Path::new("lookup")).is_err());
}
#[test]
fn write_replaces_the_file_and_leaves_no_temporary_file() {
let dir = tempfile::tempdir().unwrap();
let path = dir.path().join("threads").join(LOOKUP_FILE);
parse(TEXT).write(&path).unwrap();
assert_eq!(std::fs::read_to_string(&path).unwrap(), TEXT);
let names: Vec<_> = std::fs::read_dir(path.parent().unwrap())
.unwrap()
.map(|e| e.unwrap().file_name())
.collect();
assert_eq!(names, vec![std::ffi::OsString::from(LOOKUP_FILE)]);
}
}