//! Recovery SLA integration tests.
//!
//! Asserts hard latency bounds on cold-start recovery time.
//! These tests run on every `cargo test` invocation (the expensive 1M-item
//! variant is marked `#[ignore]` and must be run explicitly).
//!
//! See `benches/recovery.rs` for the matching Criterion microbenchmark.

#![allow(clippy::unwrap_used)]

use std::time::{Duration, Instant};

use tidaldb::TidalDb;
use tidaldb::schema::{DecaySpec, EntityId, EntityKind, SchemaBuilder, Timestamp, Window};

fn bench_schema() -> tidaldb::schema::Schema {
    let mut builder = SchemaBuilder::new();
    let _ = builder
        .signal(
            "view",
            EntityKind::Item,
            DecaySpec::Exponential {
                half_life: Duration::from_secs(7 * 24 * 3600),
            },
        )
        .windows(&[Window::AllTime])
        .velocity(false)
        .add();
    builder.build().expect("valid schema")
}

fn generate_test_data(dir: &std::path::Path, entity_count: u64) {
    let schema = bench_schema();
    let db = TidalDb::builder()
        .with_data_dir(dir)
        .with_schema(schema)
        .open()
        .unwrap();

    let base_ns = 1_000_000_000_000u64;
    for i in 1..=entity_count {
        let ts = Timestamp::from_nanos(base_ns + i * 1_000_000);
        db.signal("view", EntityId::new(i), 1.0, ts).unwrap();

        if entity_count >= 100_000 && i % 100_000 == 0 {
            eprintln!("  setup: {i}/{entity_count} entities written");
        }
    }
    db.close().unwrap();
}

/// Assert that recovery from 1000-item checkpoint completes in under 2 seconds.
#[test]
fn small_scale_recovery_smoke_test() {
    let dir = tempfile::tempdir().unwrap();
    generate_test_data(dir.path(), 1000);

    let schema = bench_schema();
    let start = Instant::now();
    let db = TidalDb::builder()
        .with_data_dir(dir.path())
        .with_schema(schema)
        .open()
        .unwrap();

    let count = db
        .read_windowed_count(EntityId::new(500), "view", Window::AllTime)
        .unwrap();
    assert_eq!(count, 1);

    let elapsed = start.elapsed();
    assert!(
        elapsed < Duration::from_secs(2),
        "1000-entity recovery took {elapsed:?}, expected < 2s"
    );

    db.close().unwrap();
}

/// Assert that recovery from 10K-item checkpoint completes in under 5 seconds.
///
/// This is the CI-safe version of the 1M-item SLA test below.
/// Run the full benchmark with: cargo bench --bench recovery
#[test]
fn recovery_under_5_seconds_10k_items() {
    let dir = tempfile::tempdir().unwrap();
    generate_test_data(dir.path(), 10_000);

    let schema = bench_schema();
    let start = Instant::now();
    let db = TidalDb::builder()
        .with_data_dir(dir.path())
        .with_schema(schema)
        .open()
        .unwrap();

    let count = db
        .read_windowed_count(EntityId::new(5000), "view", Window::AllTime)
        .unwrap();
    assert_eq!(count, 1);

    let elapsed = start.elapsed();
    assert!(
        elapsed < Duration::from_secs(5),
        "10K-entity recovery took {elapsed:?}, expected < 5s"
    );

    db.close().unwrap();
}

/// Assert that recovery from 1M-item checkpoint completes in under 30 seconds.
///
/// This is the spec-minimum SLA test from task-05. It takes ~5-10 minutes
/// to generate the 1M-item dataset (one-time setup). Marked `#[ignore]` so
/// CI does not run it on every commit. Run locally before major changes to
/// the checkpoint format, WAL replay logic, or entity rebuild:
///
/// ```bash
/// cargo test --manifest-path tidal/Cargo.toml --test m7_recovery_sla -- --ignored
/// ```
///
/// NOTE: This measures checkpoint restore + index rebuild only (WAL backlog
/// is ~0 after a clean `db.close()`). See the module-level doc for scope.
#[test]
#[ignore = "expensive: generates 1M items (~5min setup), run with --ignored"]
fn recovery_under_30_seconds() {
    let dir = tempfile::tempdir().unwrap();
    generate_test_data(dir.path(), 1_000_000);
    eprintln!("  setup: checkpoint written, starting recovery timing");

    let schema = bench_schema();
    let start = Instant::now();
    let db = TidalDb::builder()
        .with_data_dir(dir.path())
        .with_schema(schema)
        .open()
        .unwrap();

    let elapsed = start.elapsed();
    eprintln!("Recovery time (1M items): {elapsed:?}");

    let count = db
        .read_windowed_count(EntityId::new(500_000), "view", Window::AllTime)
        .unwrap();
    assert_eq!(count, 1, "entity 500000 should have exactly 1 signal");

    // 30-second SLA from task-05 spec.
    assert!(
        elapsed < Duration::from_secs(30),
        "1M-entity recovery took {elapsed:?}, expected < 30s"
    );

    db.close().unwrap();
}