#![allow(clippy::unwrap_used)]
//! M4 User Acceptance Test: Agent Session Layer.
//!
//! Proves the full agent session lifecycle: schema-declared policies,
//! session start/close, session signals with policy enforcement, audit log,
//! session snapshot, FOR SESSION ranking boost, and session isolation.

use std::collections::HashMap;
use std::time::Duration;

use tidaldb::AgentId;
use tidaldb::TidalDb;
use tidaldb::query::retrieve::{ProfileRef, RetrieveBuilder};
use tidaldb::schema::{
    AgentPolicy, DecaySpec, EntityId, EntityKind, SchemaBuilder, Timestamp, Window,
};

fn test_schema() -> tidaldb::schema::Schema {
    let mut builder = SchemaBuilder::new();

    // Content signals.
    for sig in &["view", "like", "share", "reward", "skip"] {
        let _ = builder
            .signal(
                sig,
                EntityKind::Item,
                DecaySpec::Exponential {
                    half_life: Duration::from_secs(7 * 24 * 3600),
                },
            )
            .windows(&[Window::OneHour, Window::TwentyFourHours])
            .velocity(true)
            .add();
    }

    // Schema-declared session policy: planner_policy.
    // Allows reward + view signals; denies skip; cap of 100 signals.
    let _ = builder.session_policy(
        "planner_policy",
        AgentPolicy {
            allowed_signals: vec!["reward".to_string(), "view".to_string()],
            denied_signals: vec!["skip".to_string()],
            max_session_duration: Duration::from_secs(3600), // 1 hour
            max_signals_per_session: 100,
        },
    );

    builder.build().unwrap()
}

fn test_db() -> TidalDb {
    TidalDb::builder()
        .ephemeral()
        .with_schema(test_schema())
        .open()
        .unwrap()
}

// ── Step 1: Schema with session_policy compiles ─────────────────────────────

#[test]
fn step1_schema_with_session_policy_builds() {
    // Schema should build cleanly with a declared policy.
    let schema = test_schema();
    let policy = schema.session_policy("planner_policy");
    assert!(policy.is_some(), "planner_policy should be in schema");
    let p = policy.unwrap();
    assert!(p.allowed_signals.contains(&"reward".to_string()));
    assert!(p.denied_signals.contains(&"skip".to_string()));
    assert_eq!(p.max_signals_per_session, 100);
}

// ── Step 2: Session lifecycle — start and close ─────────────────────────────

#[test]
fn step2_session_start_and_close() {
    let db = test_db();

    let mut meta = HashMap::new();
    meta.insert("context".to_string(), "video-feed".to_string());

    let handle = db
        .start_session(42, "planner-agent", "planner_policy", meta)
        .unwrap();

    assert_eq!(handle.user_id, 42);
    assert_eq!(handle.agent_id.as_str(), "planner-agent");
    assert_eq!(handle.policy_name, "planner_policy");

    // Session should appear in active_sessions.
    let active = db.active_sessions();
    assert_eq!(active.len(), 1);
    assert_eq!(active[0].user_id, 42);

    let session_id = handle.id;
    let summary = db.close_session(handle).unwrap();

    assert_eq!(summary.id, session_id);
    assert_eq!(summary.rejections, 0);

    // Session should no longer be active.
    assert!(db.active_sessions().is_empty());
}

// ── Step 3: session_signal writes and audit ─────────────────────────────────

#[test]
fn step3_session_signal_and_audit() {
    let db = test_db();

    // Write some content items.
    for i in 1u64..=5 {
        let mut meta = HashMap::new();
        meta.insert("title".to_string(), format!("item-{i}"));
        db.write_item_with_metadata(EntityId::new(i), &meta)
            .unwrap();
    }

    let handle = db
        .start_session(10, "planner-agent", "planner_policy", HashMap::new())
        .unwrap();

    let session_id = handle.id;
    let ts = Timestamp::now();

    // Write allowed signals.
    db.session_signal(&handle, "reward", EntityId::new(1), 1.0, ts, None)
        .unwrap();
    db.session_signal(&handle, "view", EntityId::new(2), 0.5, ts, None)
        .unwrap();

    // Check snapshot counts.
    let snap = db.session_snapshot(session_id).unwrap();
    assert_eq!(snap.signals_written, 2);
    assert_eq!(snap.signals_rejected, 0);

    // Check audit log.
    let audit = db.session_audit(session_id).unwrap();
    assert_eq!(audit.len(), 2);
    assert!(audit.iter().all(|e| e.accepted));

    db.close_session(handle).unwrap();
}

// ── Step 4: Policy rejects denied signals ──────────────────────────────────

#[test]
fn step4_policy_rejects_denied_signal() {
    let db = test_db();

    let handle = db
        .start_session(20, "test-agent", "planner_policy", HashMap::new())
        .unwrap();

    let session_id = handle.id;
    let ts = Timestamp::now();

    // "skip" is explicitly denied in planner_policy.
    let result = db.session_signal(&handle, "skip", EntityId::new(99), 1.0, ts, None);
    assert!(result.is_err(), "skip should be rejected by policy");
    let err_str = format!("{}", result.unwrap_err());
    assert!(
        err_str.to_lowercase().contains("policy") || err_str.to_lowercase().contains("denied"),
        "error should mention policy: {err_str}"
    );

    // Rejection should be counted.
    let snap = db.session_snapshot(session_id).unwrap();
    assert_eq!(snap.signals_rejected, 1);
    assert_eq!(snap.signals_written, 0);

    // Audit log should show the rejection.
    let audit = db.session_audit(session_id).unwrap();
    assert_eq!(audit.len(), 1);
    assert!(!audit[0].accepted);
    assert!(audit[0].reason.is_some());

    db.close_session(handle).unwrap();
}

// ── Step 5: Policy rejects signals not in allow list ───────────────────────

#[test]
fn step5_policy_rejects_non_allowed_signal() {
    let db = test_db();

    let handle = db
        .start_session(30, "test-agent", "planner_policy", HashMap::new())
        .unwrap();

    let ts = Timestamp::now();

    // "share" is not in the allowed list (which only allows reward + view).
    let result = db.session_signal(&handle, "share", EntityId::new(1), 1.0, ts, None);
    assert!(
        result.is_err(),
        "share should be rejected (not in allowed_signals)"
    );

    db.close_session(handle).unwrap();
}

// ── Step 6: Session annotations and snapshot ──────────────────────────────

#[test]
fn step6_session_annotations_and_snapshot() {
    let db = test_db();

    let handle = db
        .start_session(40, "planner-agent", "planner_policy", HashMap::new())
        .unwrap();

    let session_id = handle.id;
    let ts = Timestamp::now();

    // Write with annotation.
    db.session_signal(
        &handle,
        "reward",
        EntityId::new(5),
        1.0,
        ts,
        Some("rust programming language".to_string()),
    )
    .unwrap();

    let snap = db.session_snapshot(session_id).unwrap();
    assert!(!snap.annotations.is_empty());
    assert!(snap.annotations[0].1.contains("rust"));

    // signaled_entities should include entity 5.
    assert!(snap.signaled_entities.contains(&5));

    db.close_session(handle).unwrap();
}

// ── Step 7: Session snapshot is accessible after close ─────────────────────

#[test]
fn step7_closed_session_snapshot() {
    let db = test_db();

    let handle = db
        .start_session(50, "planner-agent", "planner_policy", HashMap::new())
        .unwrap();

    let session_id = handle.id;
    let ts = Timestamp::now();

    db.session_signal(&handle, "reward", EntityId::new(1), 1.0, ts, None)
        .unwrap();
    db.session_signal(&handle, "view", EntityId::new(2), 0.5, ts, None)
        .unwrap();

    let summary = db.close_session(handle).unwrap();
    assert_eq!(summary.signals_written, 2);

    // Snapshot should be retrievable from closed_sessions.
    let snap = db.session_snapshot(session_id).unwrap();
    assert_eq!(snap.signals_written, 2);
    assert_eq!(snap.signals_rejected, 0);
}

// ── Step 8: FOR SESSION ranking boost ─────────────────────────────────────

#[test]
fn step8_for_session_ranking_boost() {
    let db = test_db();

    // Write 10 content items.
    for i in 1u64..=10 {
        let mut meta = HashMap::new();
        meta.insert("title".to_string(), format!("item-{i}"));
        db.write_item_with_metadata(EntityId::new(i), &meta)
            .unwrap();
    }

    // Write global signals to entity 1 (so it ranks without any session).
    let ts = Timestamp::now();
    for _ in 0..5 {
        db.signal("view", EntityId::new(1), 1.0, ts).unwrap();
    }

    let handle = db
        .start_session(60, "planner-agent", "planner_policy", HashMap::new())
        .unwrap();
    let session_id = handle.id;

    // Signal entity 5 heavily in the session (the "personalized" pick).
    for _ in 0..10 {
        db.session_signal(&handle, "reward", EntityId::new(5), 2.0, ts, None)
            .unwrap();
    }

    // Query WITH for_session: entity 5 should get a boost.
    let query = RetrieveBuilder::new(EntityKind::Item, ProfileRef::new("hot"))
        .limit(10)
        .for_session(session_id)
        .build()
        .unwrap();
    let results_with = db.retrieve(&query).unwrap();

    // Query WITHOUT for_session: entity 5 has no global signals.
    let query_no_session = RetrieveBuilder::new(EntityKind::Item, ProfileRef::new("hot"))
        .limit(10)
        .build()
        .unwrap();
    let results_without = db.retrieve(&query_no_session).unwrap();

    // Both queries should return results.
    assert!(!results_with.items.is_empty());
    assert!(!results_without.items.is_empty());

    // WITH session should have a session_snapshot attached.
    assert!(
        results_with.session_snapshot.is_some(),
        "FOR SESSION query should populate session_snapshot in results"
    );

    // Entity 5 should rank higher with the session boost than without.
    let rank_with = results_with
        .items
        .iter()
        .position(|r| r.entity_id == EntityId::new(5));
    let rank_without = results_without
        .items
        .iter()
        .position(|r| r.entity_id == EntityId::new(5));

    // With session boost, entity 5 should appear (even if entity 1 still leads
    // due to global signals).
    assert!(
        rank_with.is_some(),
        "entity 5 should appear in FOR SESSION results"
    );

    // If entity 5 appears in both, its rank should be better (lower index)
    // with the session boost.
    if let (Some(rw), Some(rwo)) = (rank_with, rank_without) {
        assert!(
            rw <= rwo,
            "entity 5 rank={rw} with session should be at least as good as rank={rwo} without"
        );
    }

    db.close_session(handle).unwrap();
}

// ── Step 9: Session isolation — two sessions don't cross-contaminate ────────

#[test]
fn step9_session_isolation() {
    let db = test_db();

    for i in 1u64..=5 {
        let mut meta = HashMap::new();
        meta.insert("title".to_string(), format!("item-{i}"));
        db.write_item_with_metadata(EntityId::new(i), &meta)
            .unwrap();
    }

    // Session A: signals entity 1.
    let handle_a = db
        .start_session(70, "agent-a", "planner_policy", HashMap::new())
        .unwrap();
    let id_a = handle_a.id;

    // Session B: signals entity 5.
    let handle_b = db
        .start_session(71, "agent-b", "planner_policy", HashMap::new())
        .unwrap();
    let id_b = handle_b.id;

    let ts = Timestamp::now();
    db.session_signal(&handle_a, "reward", EntityId::new(1), 1.0, ts, None)
        .unwrap();
    db.session_signal(&handle_b, "reward", EntityId::new(5), 1.0, ts, None)
        .unwrap();

    // Snapshot A should only see entity 1.
    let snap_a = db.session_snapshot(id_a).unwrap();
    assert!(
        snap_a.signaled_entities.contains(&1),
        "session A should have entity 1"
    );
    assert!(
        !snap_a.signaled_entities.contains(&5),
        "session A should NOT have entity 5"
    );

    // Snapshot B should only see entity 5.
    let snap_b = db.session_snapshot(id_b).unwrap();
    assert!(
        snap_b.signaled_entities.contains(&5),
        "session B should have entity 5"
    );
    assert!(
        !snap_b.signaled_entities.contains(&1),
        "session B should NOT have entity 1"
    );

    db.close_session(handle_a).unwrap();
    db.close_session(handle_b).unwrap();
}

// ── Step 10: Invalid policy name is rejected ────────────────────────────────

#[test]
fn step10_invalid_policy_name_rejected() {
    let db = test_db();

    // "nonexistent_policy" is not declared in the schema.
    let result = db.start_session(80, "test-agent", "nonexistent_policy", HashMap::new());
    assert!(result.is_err(), "unknown policy should be rejected");
    let err_str = format!("{}", result.unwrap_err());
    assert!(
        err_str.contains("policy") || err_str.contains("not found"),
        "error should mention policy: {err_str}"
    );
}

// ── Step 11: AgentId validation ─────────────────────────────────────────────

#[test]
fn step11_agent_id_validation() {
    // Valid AgentId formats.
    assert!(AgentId::new("planner-agent").is_ok());
    assert!(AgentId::new("agent_01").is_ok());
    assert!(AgentId::new("a").is_ok());

    // Invalid formats.
    assert!(AgentId::new("").is_err()); // empty
    assert!(AgentId::new("Agent-ID").is_err()); // uppercase
    assert!(AgentId::new("agent id").is_err()); // space
    assert!(AgentId::new(&"a".repeat(65)).is_err()); // too long
}

// ── Step 12: active_sessions tracks multiple sessions ──────────────────────

#[test]
fn step12_active_sessions_tracking() {
    let db = test_db();

    let h1 = db
        .start_session(90, "agent-1", "planner_policy", HashMap::new())
        .unwrap();
    let h2 = db
        .start_session(91, "agent-2", "planner_policy", HashMap::new())
        .unwrap();

    let active = db.active_sessions();
    assert_eq!(active.len(), 2);

    let id1 = h1.id;
    db.close_session(h1).unwrap();

    let active = db.active_sessions();
    assert_eq!(active.len(), 1);
    assert_eq!(active[0].id, h2.id);

    db.close_session(h2).unwrap();
    assert!(db.active_sessions().is_empty());

    // Closed session snapshot still accessible.
    let snap = db.session_snapshot(id1).unwrap();
    assert_eq!(snap.id, id1);
}