//! Generic scanner for MCP loose-end summary files.
//!
//! External MCP daemons (hive-bash-mcp, hive-matrix-mcp, etc.) write
//! JSON files to `$HYPERHIVE_HARNESS_DIR/mcp-loose-ends/<name>.json`.
//! Each file contains a JSON array of plain-text summary strings.
//!
//! The harness reads all files in this directory in `get_loose_ends` to
//! surface active background work from any MCP without hardcoding
//! per-MCP knowledge here.

use std::path::PathBuf;

/// NOTE: the base-dir resolution logic here is intentionally mirrored in
/// `hive-bash-mcp/src/paths.rs::mcp_loose_ends_dir()`. They can't share
/// code across crates — keep them in sync if the fallback logic changes.
fn loose_ends_dir() -> PathBuf {
    let base = if let Some(p) = std::env::var_os("HYPERHIVE_HARNESS_DIR") {
        PathBuf::from(p)
    } else {
        let state = std::env::var("HYPERHIVE_STATE_DIR").unwrap_or_default();
        let state_path = PathBuf::from(&state);
        state_path
            .parent()
            .map(|p| p.join("harness"))
            .unwrap_or_else(|| PathBuf::from(state))
    };
    base.join("mcp-loose-ends")
}

/// Collect all loose-end summary strings published by external MCP daemons.
/// Each string is a single line suitable for inclusion in `get_loose_ends`
/// output. Returns an empty vec if the directory doesn't exist or is empty.
#[must_use]
pub fn collect() -> Vec<String> {
    let Ok(rd) = std::fs::read_dir(loose_ends_dir()) else {
        return Vec::new();
    };
    let mut out = Vec::new();
    for entry in rd.flatten() {
        let path = entry.path();
        if path.extension().and_then(|e| e.to_str()) != Some("json") {
            continue;
        }
        let Ok(content) = std::fs::read_to_string(&path) else {
            continue;
        };
        let Ok(items) = serde_json::from_str::<Vec<String>>(&content) else {
            continue;
        };
        out.extend(items);
    }
    out
}