//! The wave-2 factory binding demonstrator (mem-gated — mem is the
//! skip-free reference shape): the concrete `Store` facade vended by
//! [`StoreFactory::open`] in both constructible wave-2 shapes, the
//! factory contract's isolation + idempotent-teardown requirements
//! exercised, the wave-1 mock probe retired by the binding. The real
//! columns carry these factories forward with rows (suite-column-mem,
//! suite-column-local).

#![allow(dead_code)]

use std::path::PathBuf;
use std::sync::atomic::{AtomicU64, Ordering};
use std::sync::Mutex;
use std::time::{SystemTime, UNIX_EPOCH};

use crate::factory::StoreFactory;
use alkblobs::{Error, Store, StoreMode, DEFAULT_DISPATCH_THRESHOLD};

/// The binding demo factory, mem-only mode: a fresh `BTreeMap`-backed
/// store per `open` (isolated by construction — the ephemeral engine
/// shares nothing across instances), teardown a no-op. Mem is the
/// skip-free reference shape, so this column never skips.
struct MemOnlyBinding;

impl StoreFactory for MemOnlyBinding {
    fn name(&self) -> &'static str {
        "mem-only (binding demo)"
    }

    async fn open(&self) -> Result<Store, Error> {
        Ok(Store::mem_only())
    }

    async fn teardown(&self) -> Result<(), Error> {
        Ok(())
    }
}

/// A fresh temp root per factory `open` — the isolated backing for the
/// dual-tier binding demo. No Drop guard: teardown owns removal (the
/// factory contract's ownership; a factory dropped without teardown
/// leaks its temp roots — harmless temp debris, and teardown makes
/// sense over the abandoned instance per the contract).
fn fresh_temp_root() -> PathBuf {
    static SEQ: AtomicU64 = AtomicU64::new(0);
    let seq = SEQ.fetch_add(1, Ordering::Relaxed);
    let nanos = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .map(|d| d.as_nanos())
        .unwrap_or(0);
    let dir = std::env::temp_dir().join(format!(
        "alkblobs-conformance-{}-{:x}-{seq}",
        std::process::id(),
        nanos
    ));
    std::fs::create_dir_all(&dir).expect("temp root created");
    dir
}

/// The binding demo factory, dual-tier mode (the ADR-012 §6.3
/// dispatch-coverage shape, `kv = mem` + `large = local` at the default
/// threshold): a fresh temp directory per `open` so two opens never
/// share state, teardown removing every root it has vended (idempotent
/// — a repeated teardown is a no-op) and safe against abandoned
/// instances (each root is private to its open, so a half-open
/// instance's root is removable the same way).
struct DualTierBinding {
    roots: Mutex<Vec<PathBuf>>,
}

impl Default for DualTierBinding {
    fn default() -> Self {
        DualTierBinding {
            roots: Mutex::new(Vec::new()),
        }
    }
}

impl StoreFactory for DualTierBinding {
    fn name(&self) -> &'static str {
        "dual-tier mem+local (binding demo)"
    }

    async fn open(&self) -> Result<Store, Error> {
        let path = fresh_temp_root();
        let store = Store::dual_tier_mem_local(path.clone(), DEFAULT_DISPATCH_THRESHOLD).await?;
        self.roots
            .lock()
            .unwrap_or_else(|e| e.into_inner())
            .push(path);
        Ok(store)
    }

    async fn teardown(&self) -> Result<(), Error> {
        for root in self
            .roots
            .lock()
            .unwrap_or_else(|e| e.into_inner())
            .drain(..)
        {
            match std::fs::remove_dir_all(&root) {
                Ok(()) => {}
                Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
                Err(e) => return Err(Error::Io(e.to_string())),
            }
        }
        Ok(())
    }
}

/// The binding holds: the demo factory vends the concrete facade in
/// the mem-only mode, reports its identity, and tears down idempotently.
#[tokio::test]
async fn binding_factory_vends_the_concrete_store_facade() {
    let factory = MemOnlyBinding;
    assert_eq!(factory.name(), "mem-only (binding demo)");
    let store = factory.open().await.expect("open vends the store");
    assert_eq!(store.mode(), StoreMode::MemOnly);
    factory.teardown().await.expect("teardown is idempotent");
    factory.teardown().await.expect("teardown repeats cleanly");
}

/// The binding holds in dual-tier mode too: every `open` is isolated
/// (fresh backing), the vend store reports the dispatch-coverage
/// shape, and teardown across open-then-teardown cycles is idempotent.
#[tokio::test]
async fn dual_tier_binding_factory_vends_isolated_stores() {
    let factory = DualTierBinding::default();
    assert_eq!(factory.name(), "dual-tier mem+local (binding demo)");

    for _ in 0..2 {
        let store = factory.open().await.expect("open vends the store");
        assert_eq!(store.mode(), StoreMode::DualTier, "dispatch-coverage shape");
    }
    factory
        .teardown()
        .await
        .expect("teardown removes the roots");
    factory.teardown().await.expect("teardown repeats cleanly");
}