//! `assign <number> <user> [--remove]` — add or remove a user from an
//! issue/PR's assignee list. Forgejo has no dedicated POST endpoint —
//! we read the current list, mutate, and PATCH the issue back (closes
//! #353's "no such endpoint" trap; matches the bash helper's logic).

use anyhow::Result;
use clap::Args as ClapArgs;
use serde_json::{Value, json};

use crate::client::Client;
use crate::verbs::print_json;

#[derive(ClapArgs)]
pub struct Args {
    /// Issue or PR number.
    number: u64,
    /// User login to assign (or unassign with `--remove`).
    user: String,
    /// Remove the user instead of adding.
    #[arg(long)]
    remove: bool,
}

pub fn run(client: &Client, args: Args) -> Result<()> {
    let repo = client.repo();
    let current = client.get_json(&format!("/repos/{repo}/issues/{}", args.number))?;
    let mut assignees: Vec<String> = current
        .get("assignees")
        .and_then(Value::as_array)
        .map(|a| {
            a.iter()
                .filter_map(|u| u.get("login").and_then(Value::as_str).map(str::to_owned))
                .collect()
        })
        .unwrap_or_default();
    if args.remove {
        assignees.retain(|u| u != &args.user);
    } else if !assignees.contains(&args.user) {
        assignees.push(args.user.clone());
    }
    let resp = client.patch_json(
        &format!("/repos/{repo}/issues/{}", args.number),
        &json!({ "assignees": assignees }),
    )?;
    let logins: Vec<&str> = resp
        .get("assignees")
        .and_then(Value::as_array)
        .map(|a| {
            a.iter()
                .filter_map(|u| u.get("login").and_then(Value::as_str))
                .collect()
        })
        .unwrap_or_default();
    print_json(&json!({
        "number": resp.get("number"),
        "assignees": logins,
    }))
}