use oa_core::{
    references,
    transitions::*,
    validation::{self, Severity},
    *,
};

fn kinds(layer: Layer) -> (Kind, Kind) {
    match layer {
        Layer::Oa => (Kind::Process, Kind::Activity),
        Layer::Sa => (Kind::FunctionalChain, Kind::Function),
    }
}
fn occurrence(p: &Project, owner: Id, name: &str, body: OccurrenceBody) -> Element {
    let mut element = p
        .make_element(
            Kind::Occurrence,
            p.elements[&owner].layer(),
            name,
            Some(owner),
        )
        .unwrap();
    *element.shared_mut().unwrap() = SharedBody::Occurrence {
        body,
        precondition: String::new(),
        postcondition: String::new(),
    };
    element
}
fn add_occurrence(p: &mut Project, owner: Id, name: &str, body: OccurrenceBody) -> Id {
    let element = occurrence(p, owner, name, body);
    let id = element.id;
    p.elements.insert(id, element);
    p.elements
        .get_mut(&owner)
        .unwrap()
        .steps_mut()
        .unwrap()
        .push(id);
    id
}
fn action(p: &mut Project, owner: Id, name: &str) -> Id {
    let layer = p.elements[&owner].layer();
    let work = p.add_element(kinds(layer).1, layer, name, None).unwrap();
    let id = add_occurrence(
        p,
        owner,
        &format!("Perform {name}"),
        OccurrenceBody::Action {
            action: Some(work),
            lifeline: None,
        },
    );
    p.elements.get_mut(&id).unwrap().description =
        format!("Contribution within {}", p.elements[&owner].name);
    id
}
fn link(p: &mut Project, source: Id, target: Id, guard: &str) -> Id {
    let id = p.relate(
        RelationKind::SequenceLink,
        "Next contribution",
        source,
        target,
    );
    if let RelationBody::SequenceLink { guard: value, .. } =
        &mut p.relations.get_mut(&id).unwrap().body
    {
        *value = guard.into();
    }
    id
}
fn branch_fixture(layer: Layer) -> (Project, Id, Id) {
    let mut p = Project::empty();
    let main = p
        .add_element(kinds(layer).0, layer, "Respond to distress", None)
        .unwrap();
    let reusable = p
        .add_element(kinds(layer).0, layer, "Prepare resources", None)
        .unwrap();
    action(&mut p, reusable, "Mobilize responder");
    let start = action(&mut p, main, "Assess distress");
    let fork = add_occurrence(
        &mut p,
        main,
        "Prepare in parallel",
        OccurrenceBody::Control {
            kind: ControlKind::Fork,
        },
    );
    let locate = action(&mut p, main, "Locate vessel");
    let reuse = add_occurrence(
        &mut p,
        main,
        "Use preparations",
        OccurrenceBody::SequenceReference {
            sequence: Some(reusable),
        },
    );
    let join = add_occurrence(
        &mut p,
        main,
        "Both preparations ready",
        OccurrenceBody::Control {
            kind: ControlKind::Join,
        },
    );
    let choice = add_occurrence(
        &mut p,
        main,
        "Select response",
        OccurrenceBody::Control {
            kind: ControlKind::Choice,
        },
    );
    let direct = action(&mut p, main, "Dispatch rescue");
    let fallback = action(&mut p, main, "Request assistance");
    let merge = add_occurrence(
        &mut p,
        main,
        "Response selected",
        OccurrenceBody::Control {
            kind: ControlKind::Merge,
        },
    );
    let end = action(&mut p, main, "Confirm response");
    for (source, target, guard) in [
        (start, fork, ""),
        (fork, locate, ""),
        (fork, reuse, ""),
        (locate, join, ""),
        (reuse, join, ""),
        (join, choice, ""),
        (choice, direct, "available_resources > 0"),
        (choice, fallback, "else"),
        (direct, merge, ""),
        (fallback, merge, ""),
        (merge, end, ""),
    ] {
        link(&mut p, source, target, guard);
    }
    (p, main, reusable)
}
fn errors(p: &Project) -> Vec<validation::Issue> {
    validation::validate(p)
        .into_iter()
        .filter(|i| i.severity == Severity::Error)
        .collect()
}
fn coherent_path(p: &Project) {
    // These contextual-path fixtures deliberately leave the global system boundary
    // and performer allocation open.
    let unexpected: Vec<_> = validation::validate(p)
        .into_iter()
        .filter(|issue| {
            issue.severity != Severity::Warning
                || !matches!(issue.code.as_str(), "unallocated_leaf" | "missing_system")
        })
        .collect();
    assert!(unexpected.is_empty(), "{unexpected:?}");
}

#[test]
fn branching_reusable_processes_transition_as_contextual_topology_in_both_directions() {
    for direction in [TransitionDirection::OaToSa, TransitionDirection::SaToOa] {
        let (p, main, reusable) = branch_fixture(direction.source_layer());
        coherent_path(&p);
        let mut request = TransitionRequest::new(direction, vec![main]);
        request.scope = DependencyScope::Required;
        let plan = plan_transition(&p, &request).unwrap();
        assert!(plan.conflicts.is_empty(), "{:?}", plan.conflicts);
        let mapped = |id| {
            plan.changes
                .iter()
                .find(|change| change.source == id)
                .unwrap()
                .target
        };
        let candidate = apply_transition(&p, &plan).unwrap();
        assert_eq!(
            candidate.elements[&mapped(main)].kind(),
            kinds(direction.target_layer()).0
        );
        assert_eq!(
            candidate.elements[&mapped(reusable)].kind(),
            kinds(direction.target_layer()).0
        );
        for element in p.elements.values() {
            let counterpart = &candidate.elements[&mapped(element.id)];
            assert_eq!(counterpart.description, element.description);
            let expected: Vec<_> = references::element_references(element)
                .into_iter()
                .map(mapped)
                .collect();
            assert_eq!(references::element_references(counterpart), expected);
            if element.kind() == Kind::Occurrence {
                let trace = candidate
                    .traces
                    .values()
                    .find(|trace| trace.oa == element.id || trace.sa == element.id)
                    .unwrap();
                assert_eq!(trace.kind, TraceKind::Sequence);
            }
        }
        for relation in p.relations.values() {
            let counterpart = &candidate.relations[&mapped(relation.id)];
            let mut expected = relation.body.clone();
            expected.set_endpoints(mapped(relation.source()), mapped(relation.target()));
            assert_eq!(counterpart.body, expected);
        }
        assert!(
            candidate
                .relations
                .values()
                .all(|r| r.kind() == RelationKind::SequenceLink),
            "contextual precedence never fabricates global exchanges"
        );
        let mut session = Session::new(p.clone());
        session.execute_many(&plan.commands).unwrap();
        assert_eq!(session.project(), &candidate);
        session.undo();
        assert_eq!(session.project(), &p);
        session.redo();
        assert_eq!(session.project(), &candidate);
        let mut reverse = TransitionRequest::new(
            if direction == TransitionDirection::OaToSa {
                TransitionDirection::SaToOa
            } else {
                TransitionDirection::OaToSa
            },
            vec![mapped(main)],
        );
        reverse.scope = DependencyScope::Required;
        let repeat = plan_transition(&candidate, &reverse).unwrap();
        assert!(repeat.conflicts.is_empty(), "{:?}", repeat.conflicts);
        assert!(repeat.commands.is_empty());
    }
}

#[test]
fn contextual_links_match_work_exchange_endpoints_and_reject_foreign_owners() {
    for layer in [Layer::Oa, Layer::Sa] {
        let mut p = Project::empty();
        let owner = p
            .add_element(kinds(layer).0, layer, "Context", None)
            .unwrap();
        let a = action(&mut p, owner, "A");
        let b = action(&mut p, owner, "B");
        let wrong = action(&mut p, owner, "Wrong");
        let work = |p: &Project, id| match p.elements[&id].shared().unwrap() {
            SharedBody::Occurrence {
                body:
                    OccurrenceBody::Action {
                        action: Some(work), ..
                    },
                ..
            } => *work,
            _ => unreachable!(),
        };
        let global = p.relate(
            if layer == Layer::Oa {
                RelationKind::Interaction
            } else {
                RelationKind::FunctionalExchange
            },
            "A sends to B",
            work(&p, a),
            work(&p, b),
        );
        let exchange = add_occurrence(
            &mut p,
            owner,
            "Contextual message",
            OccurrenceBody::Exchange {
                operation: None,
                exchange: Some(global),
                sender: None,
                receiver: None,
                message_kind: MessageKind::Asynchronous,
                reply_to: None,
                values: vec![],
            },
        );
        let other = p
            .add_element(kinds(layer).0, layer, "Other context", None)
            .unwrap();
        let foreign = action(&mut p, other, "Foreign");
        for (source, target) in [(a, exchange), (exchange, b)] {
            assert!(validation::can_connect(
                &p,
                RelationKind::SequenceLink,
                source,
                target
            ));
        }
        for (source, target) in [(wrong, exchange), (exchange, wrong), (a, foreign), (a, a)] {
            assert!(!validation::can_connect(
                &p,
                RelationKind::SequenceLink,
                source,
                target
            ));
            assert!(
                execute_batch(
                    &p,
                    &[Command::Connect(
                        RelationKind::SequenceLink,
                        "Invalid".into(),
                        source,
                        target
                    )]
                )
                .is_err()
            );
        }
        let original_exchange = p.relations[&global].clone();
        let accepted = execute_batch(
            &p,
            &[
                Command::Connect(RelationKind::SequenceLink, "Before".into(), a, exchange),
                Command::Connect(RelationKind::SequenceLink, "After".into(), exchange, b),
            ],
        )
        .unwrap();
        assert_eq!(accepted.relations[&global], original_exchange);
        let scenario = p
            .add_element(Kind::Scenario, layer, "Timeline", None)
            .unwrap();
        let invalid = occurrence(
            &p,
            scenario,
            "Wrong control context",
            OccurrenceBody::Control {
                kind: ControlKind::Fork,
            },
        );
        assert!(
            execute_batch(&p, &[Command::CreateElement(invalid)])
                .unwrap_err()
                .0
                .contains("sequence_contribution_owner")
        );
    }
}

#[test]
fn reuse_rejects_recursive_or_cross_layer_targets_and_deleted_targets_become_drafts() {
    let mut p = Project::empty();
    let a = p.add_element(Kind::Process, Layer::Oa, "A", None).unwrap();
    let b = p.add_element(Kind::Process, Layer::Oa, "B", None).unwrap();
    let c = p.add_element(Kind::Process, Layer::Oa, "C", None).unwrap();
    let use_b = add_occurrence(
        &mut p,
        a,
        "Reuse B",
        OccurrenceBody::SequenceReference { sequence: Some(b) },
    );
    add_occurrence(
        &mut p,
        b,
        "Reuse C",
        OccurrenceBody::SequenceReference { sequence: Some(c) },
    );
    let foreign = p
        .add_element(Kind::FunctionalChain, Layer::Sa, "SA sequence", None)
        .unwrap();
    let mut session = Session::new(p.clone());
    for target in [a, c, foreign] {
        let invalid = occurrence(
            session.project(),
            c,
            "Invalid reuse",
            OccurrenceBody::SequenceReference {
                sequence: Some(target),
            },
        );
        assert!(session.execute(Command::CreateElement(invalid)).is_err());
        assert_eq!(session.project(), &p);
    }
    let new_b = Id::new_v4();
    session.execute(Command::Reidentify(b, new_b)).unwrap();
    assert!(references::element_references(&session.project().elements[&use_b]).contains(&new_b));
    let reidentified = session.project().clone();
    session.execute(Command::Delete(new_b)).unwrap();
    assert!(session.project().elements.contains_key(&use_b));
    assert!(matches!(
        session.project().elements[&use_b].shared(),
        Some(SharedBody::Occurrence {
            body: OccurrenceBody::SequenceReference { sequence: None },
            ..
        })
    ));
    assert!(session.project().elements.contains_key(&c));
    assert!(errors(session.project()).is_empty());
    assert!(
        validation::validate(session.project())
            .iter()
            .any(|issue| issue.element == Some(use_b) && issue.code == "incomplete_reference")
    );
    session.undo();
    assert_eq!(session.project(), &reidentified);
    session.undo();
    assert_eq!(session.project(), &p);
}

#[test]
fn loops_are_allowed_while_missing_guards_and_disconnected_paths_are_diagnosed() {
    let mut p = Project::empty();
    let owner = p
        .add_element(Kind::Process, Layer::Oa, "Retry until ready", None)
        .unwrap();
    let start = action(&mut p, owner, "Start");
    let gate = add_occurrence(
        &mut p,
        owner,
        "Ready?",
        OccurrenceBody::Control {
            kind: ControlKind::Loop,
        },
    );
    let repeat = action(&mut p, owner, "Retry");
    let end = action(&mut p, owner, "Finish");
    link(&mut p, start, gate, "");
    link(&mut p, gate, repeat, "!ready");
    link(&mut p, repeat, gate, "");
    let exit = link(&mut p, gate, end, "ready");
    coherent_path(&p);
    if let RelationBody::SequenceLink { guard, .. } = &mut p.relations.get_mut(&exit).unwrap().body
    {
        guard.clear();
    }
    assert!(errors(&p).is_empty());
    assert!(
        validation::validate(&p)
            .iter()
            .any(|i| i.element == Some(exit) && i.code == "missing_sequence_guard")
    );
    let island = action(&mut p, owner, "Disconnected work");
    assert!(
        validation::validate(&p)
            .iter()
            .any(|i| i.element == Some(island) && i.code == "isolated_contribution")
    );
    p.relations.remove(&exit);
    assert!(
        validation::validate(&p)
            .iter()
            .any(|i| i.element == Some(gate) && i.code == "control_cardinality")
    );
    assert!(
        validation::validate(&p)
            .iter()
            .any(|i| i.element == Some(gate) && i.code == "nonterminating_contribution")
    );
}

#[test]
fn topology_identity_edits_and_deletions_preserve_remaining_paths_and_undo() {
    let (p, main, _) = branch_fixture(Layer::Sa);
    for id in p.elements.keys().chain(p.relations.keys()).copied() {
        let mut session = Session::new(p.clone());
        let replacement = Id::new_v4();
        session
            .execute(Command::Reidentify(id, replacement))
            .unwrap();
        let reidentified = session.project().clone();
        assert!(
            !reidentified
                .elements
                .values()
                .any(|e| references::element_references(e).contains(&id))
        );
        assert!(
            !reidentified
                .relations
                .values()
                .any(|r| references::relation_references(r).contains(&id))
        );
        session.execute(Command::Delete(replacement)).unwrap();
        assert!(errors(session.project()).is_empty());
        session.undo();
        assert_eq!(session.project(), &reidentified);
        session.undo();
        assert_eq!(session.project(), &p);
    }
    // List order is presentation order: changing it leaves explicit links untouched.
    let mut session = Session::new(p.clone());
    session.execute(Command::MoveStep(main, 0, 4)).unwrap();
    assert_eq!(session.project().relations, p.relations);
    coherent_path(session.project());
}

#[test]
fn legacy_linear_exchange_only_sequences_keep_their_existing_meaning() {
    let mut p = Project::empty();
    let a = p.add_element(Kind::Activity, Layer::Oa, "A", None).unwrap();
    let b = p.add_element(Kind::Activity, Layer::Oa, "B", None).unwrap();
    let c = p.add_element(Kind::Activity, Layer::Oa, "C", None).unwrap();
    let owner = p
        .add_element(Kind::Process, Layer::Oa, "Legacy order", None)
        .unwrap();
    let ab = p.relate(RelationKind::Interaction, "AB", a, b);
    let ca = p.relate(RelationKind::Interaction, "CA", c, a);
    let mut session = Session::new(p);
    session.execute(Command::AddStep(owner, ab)).unwrap();
    session.execute(Command::AddStep(owner, ca)).unwrap();
    let issues = validation::validate(session.project());
    assert!(issues.iter().any(|i| i.code == "sequence_gap"));
    assert!(
        !issues
            .iter()
            .any(|i| i.code == "isolated_contribution" || i.code == "sequence_starts")
    );
    assert!(
        session
            .project()
            .relations
            .values()
            .all(|r| r.kind() != RelationKind::SequenceLink)
    );
}