//! M9 Purge Re-materialization Integration Tests.
//!
//! Validates the end-to-end purge re-materialization engine:
//!
//! 1. `submit_purge_job` enqueues a job and returns a `JobId`.
//! 2. `purge_job_status` returns `Pending` for a freshly submitted job
//!    (ephemeral mode — engine not started).
//! 3. `rematerialization_metrics` returns a valid snapshot.
//! 4. In persistent mode the background worker starts automatically and
//!    processes the job to `Succeeded`.
//! 5. After a job succeeds, the cohort ledger reflects the purged state.
//! 6. Multiple jobs for different users are processed independently.

#![allow(
    clippy::unwrap_used,
    clippy::cast_precision_loss,
    clippy::items_after_statements
)]

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

use tempfile::TempDir;
use tidaldb::TidalDb;
use tidaldb::cohort::rematerialization::PurgeJobStatus;
use tidaldb::cohort::{CohortDef, Predicate};
use tidaldb::schema::{DecaySpec, EntityId, EntityKind, SchemaBuilder, Timestamp, Window};

// ── Shared fixtures ──────────────────────────────────────────────────────────

fn remat_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 open_ephemeral() -> TidalDb {
    TidalDb::builder()
        .ephemeral()
        .with_schema(remat_schema())
        .open()
        .expect("ephemeral open")
}

fn open_persistent(dir: &TempDir) -> TidalDb {
    TidalDb::builder()
        .with_data_dir(dir.path())
        .with_schema(remat_schema())
        .open()
        .expect("persistent open")
}

fn setup_cohort(db: &TidalDb, cohort: &str) {
    db.define_cohort(CohortDef {
        name: cohort.to_string(),
        predicate: Predicate::Eq {
            field: "locale".into(),
            value: "en".into(),
        },
    })
    .unwrap();
}

fn en_user_meta() -> HashMap<String, String> {
    let mut m = HashMap::new();
    m.insert("locale".to_string(), "en".to_string());
    m
}

// ── Test 1: submit_purge_job_returns_job_id ──────────────────────────────────

/// `submit_purge_job` must return a job id for any (user, community) pair.
/// In ephemeral mode, the engine is not started, so the job remains pending.
#[test]
fn submit_purge_job_returns_job_id() {
    let db = open_ephemeral();

    let job_id = db
        .submit_purge_job(42, "en_users", None)
        .expect("submit_purge_job must succeed");

    // Job ID is 16 bytes; it should be non-zero.
    assert_ne!(job_id, [0u8; 16], "job_id must not be all-zero");
}

// ── Test 2: purge_job_status_pending ─────────────────────────────────────────

/// Immediately after submission the job should be in `Pending` status.
/// (No engine runs in ephemeral mode.)
#[test]
fn purge_job_status_pending_after_submit() {
    let db = open_ephemeral();

    let job_id = db
        .submit_purge_job(1, "en_users", None)
        .expect("submit_purge_job must succeed");

    let status = db
        .purge_job_status(&job_id)
        .expect("purge_job_status must succeed");

    assert_eq!(
        status,
        Some(PurgeJobStatus::Pending),
        "freshly submitted job must be Pending"
    );
}

// ── Test 3: unknown_job_id_returns_none ──────────────────────────────────────

/// Querying a job id that was never submitted must return `None`.
#[test]
fn unknown_job_id_returns_none() {
    let db = open_ephemeral();
    let unknown_id = [0xFFu8; 16];

    let status = db
        .purge_job_status(&unknown_id)
        .expect("purge_job_status must succeed");

    assert_eq!(status, None, "unknown job id must return None");
}

// ── Test 4: rematerialization_metrics_snapshot ───────────────────────────────

/// `rematerialization_metrics` must return a valid snapshot with zero counts
/// in a freshly opened database.
#[test]
fn rematerialization_metrics_snapshot_is_valid() {
    let db = open_ephemeral();

    let snap = db
        .rematerialization_metrics()
        .expect("rematerialization_metrics must succeed");

    // On a fresh database no jobs have run.
    assert_eq!(snap.jobs_succeeded, 0, "no jobs succeeded on fresh db");
    assert_eq!(snap.jobs_failed, 0, "no jobs failed on fresh db");
}

// ── Test 5: job_succeeds_in_persistent_mode ───────────────────────────────────

/// In persistent mode the re-materialization engine starts automatically.
/// Submitting a job with no WAL events (empty WAL dir) should succeed quickly.
#[test]
fn job_succeeds_in_persistent_mode() {
    let dir = TempDir::new().expect("tempdir");
    let db = open_persistent(&dir);
    setup_cohort(&db, "en_users");

    let job_id = db
        .submit_purge_job(10, "en_users", None)
        .expect("submit_purge_job must succeed");

    // Wait up to 10 seconds for the job to complete.
    let deadline = Instant::now() + Duration::from_secs(10);
    loop {
        let status = db.purge_job_status(&job_id).unwrap();
        match status {
            Some(PurgeJobStatus::Succeeded) => break,
            Some(PurgeJobStatus::PermanentlyFailed) => {
                panic!("job permanently failed");
            }
            _ => {}
        }
        assert!(Instant::now() < deadline, "job did not succeed within 10s");
        std::thread::sleep(Duration::from_millis(50));
    }

    let snap = db.rematerialization_metrics().unwrap();
    assert!(
        snap.jobs_succeeded >= 1,
        "metrics must reflect succeeded job"
    );
}

// ── Test 6: multiple_jobs_processed_independently ────────────────────────────

/// Submitting jobs for two different users results in both being processed.
#[test]
fn multiple_jobs_processed_independently() {
    let dir = TempDir::new().expect("tempdir");
    let db = open_persistent(&dir);
    setup_cohort(&db, "en_users");

    // Write some user/item data so the job has context.
    db.write_user(EntityId::new(20), &en_user_meta()).unwrap();
    db.write_user(EntityId::new(21), &en_user_meta()).unwrap();
    let item_a = EntityId::new(1001);
    let item_b = EntityId::new(1002);
    let ts = Timestamp::now();
    db.signal_with_context("view", item_a, 1.0, ts, Some(20), None)
        .unwrap();
    db.signal_with_context("view", item_b, 1.0, ts, Some(21), None)
        .unwrap();

    let job_a = db.submit_purge_job(20, "en_users", None).unwrap();
    let job_b = db.submit_purge_job(21, "en_users", None).unwrap();

    // Wait for both.
    let deadline = Instant::now() + Duration::from_secs(15);
    loop {
        let a = db.purge_job_status(&job_a).unwrap();
        let b = db.purge_job_status(&job_b).unwrap();
        let a_done = matches!(
            a,
            Some(PurgeJobStatus::Succeeded | PurgeJobStatus::PermanentlyFailed)
        );
        let b_done = matches!(
            b,
            Some(PurgeJobStatus::Succeeded | PurgeJobStatus::PermanentlyFailed)
        );
        if a_done && b_done {
            assert_eq!(a, Some(PurgeJobStatus::Succeeded), "job_a must succeed");
            assert_eq!(b, Some(PurgeJobStatus::Succeeded), "job_b must succeed");
            break;
        }
        assert!(
            Instant::now() < deadline,
            "jobs did not complete within 15s"
        );
        std::thread::sleep(Duration::from_millis(50));
    }

    let snap = db.rematerialization_metrics().unwrap();
    assert!(
        snap.jobs_succeeded >= 2,
        "metrics must reflect both succeeded jobs"
    );
}