//! Stateful HTTP fixture. It verifies wire methods and bodies, not live credentials.
use serde_json::{Value, json};
use std::{
    collections::BTreeMap,
    sync::{Arc, Mutex},
};
use tokio::{
    io::{AsyncReadExt, AsyncWriteExt},
    net::TcpListener,
};

#[derive(Default)]
pub struct State {
    pub objects: BTreeMap<String, Value>,
    pub writes: usize,
    pub fail_once: Option<String>,
    pub external_override: bool,
    pub users: Vec<Value>,
    pub lookups: usize,
}
pub struct Server {
    pub base: String,
    pub state: Arc<Mutex<State>>,
    task: tokio::task::JoinHandle<()>,
}
impl Drop for Server {
    fn drop(&mut self) {
        self.task.abort();
    }
}
impl Server {
    pub async fn start() -> Self {
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let base = format!("http://{}", listener.local_addr().unwrap());
        let state = Arc::new(Mutex::new(State::default()));
        let copy = state.clone();
        let task = tokio::spawn(async move {
            loop {
                let (mut socket, _) = listener.accept().await.unwrap();
                let shared = copy.clone();
                tokio::spawn(async move {
                    let mut buffer = vec![];
                    let (head_end, length) = loop {
                        let mut chunk = [0; 4096];
                        let n = socket.read(&mut chunk).await.unwrap();
                        if n == 0 {
                            return;
                        }
                        buffer.extend_from_slice(&chunk[..n]);
                        if let Some(end) = buffer.windows(4).position(|w| w == b"\r\n\r\n") {
                            let head = String::from_utf8_lossy(&buffer[..end]);
                            let length = head
                                .lines()
                                .find_map(|l| {
                                    l.to_lowercase()
                                        .strip_prefix("content-length: ")
                                        .and_then(|v| v.parse::<usize>().ok())
                                })
                                .unwrap_or(0);
                            break (end + 4, length);
                        }
                    };
                    while buffer.len() < head_end + length {
                        let mut chunk = [0; 4096];
                        let n = socket.read(&mut chunk).await.unwrap();
                        if n == 0 {
                            return;
                        }
                        buffer.extend_from_slice(&chunk[..n]);
                    }
                    let head = String::from_utf8_lossy(&buffer[..head_end]);
                    assert!(head.to_lowercase().contains("authorization: basic "));
                    let mut first = head.lines().next().unwrap().split_whitespace();
                    let method = first.next().unwrap();
                    let path = first.next().unwrap().split('?').next().unwrap();
                    let body = if length > 0 {
                        serde_json::from_slice(&buffer[head_end..head_end + length]).unwrap()
                    } else {
                        Value::Null
                    };
                    let (code, result) = handle(&mut shared.lock().unwrap(), method, path, body);
                    let body = result.to_string();
                    let response = format!(
                        "HTTP/1.1 {code} Result\r\nContent-Type: application/json\r\nContent-Length: {}\r\nConnection: close\r\n\r\n{body}",
                        body.len()
                    );
                    socket.write_all(response.as_bytes()).await.unwrap();
                });
            }
        });
        Self { base, state, task }
    }
}
fn handle(s: &mut State, method: &str, path: &str, mut body: Value) -> (u16, Value) {
    if method == "POST" && s.fail_once.as_ref().is_some_and(|p| path.ends_with(p)) {
        s.fail_once = None;
        return (429, json!({"error":"Try later"}));
    }
    if method == "GET" {
        if path.ends_with("/user/search") {
            s.lookups += 1;
            return (200, json!(s.users));
        }
        if path.ends_with("/overrides") {
            return (
                200,
                json!({"values":if s.external_override{vec![json!({"alias":"external"})]}else{vec![]}}),
            );
        }
        if let Some(parent) = path.strip_suffix("/rotations") {
            return (
                200,
                json!({"values":s.objects.get(parent).unwrap()["rotations"]}),
            );
        }
        if let Some(value) = s.objects.get(path) {
            return (200, value.clone());
        }
        if path.ends_with("/schedules")
            || path.ends_with("/escalations")
            || path.ends_with("/routing-rules")
        {
            return (
                200,
                json!({"values":s.objects.iter().filter(|(k,_)|k.rsplit_once('/').is_some_and(|(p,_)|p==path)).map(|(_,v)|v.clone()).collect::<Vec<_>>()}),
            );
        }
        return (404, json!({}));
    }
    if method == "DELETE" {
        s.writes += 1;
        if path.ends_with("/overrides/external") {
            s.external_override = false;
        } else {
            s.objects.remove(path);
        }
        return (200, json!({"result":"deleted"}));
    }
    if path.contains("routing-rules") {
        assert!(body["order"].as_u64().unwrap() <= 100);
        assert!(body["notify"].is_object());
    }
    if path.contains("escalations") {
        assert!((1..=20).contains(&body["repeat"]["count"].as_u64().unwrap()));
        assert!(body["rules"].is_array());
    }
    if path.contains("schedules") {
        for rotation in body["rotations"].as_array().unwrap() {
            assert_eq!(rotation["participants"].as_array().unwrap().len(), 1);
            assert!(
                rotation["endDate"].as_str().unwrap() > rotation["startDate"].as_str().unwrap()
            );
        }
    }
    s.writes += 1;
    if method == "POST" {
        let id = uuid::Uuid::new_v4().to_string();
        body["id"] = json!(id);
        s.objects.insert(format!("{path}/{id}"), body.clone());
        return (201, body);
    }
    assert_eq!(method, "PATCH");
    if let Some(previous) = s.objects.get(path) {
        body["id"] = previous["id"].clone();
        s.objects.insert(path.into(), body.clone());
        (200, body)
    } else {
        (404, json!({}))
    }
}