use std::cell::{Cell, RefCell};

use wip_host::{
    CallErrorKind, CallRequest, InterfaceRegistry, InterfaceTarget, PublishedObject, Validator,
    WipObject,
};
use wip_interface::{
    CodecError, HostError, NamedValue, OperationResult, TypeDeclaration, TypeExpr, Value, WipType,
    interface,
};
use wip_protocol::{ObjectId, ProtocolErrorCategory};

#[interface]
pub trait Reader {
    /// Returns the reader-qualified label.
    fn label(&self) -> OperationResult<String>;

    /// Adds two integers.
    fn add(&self, left: i64, right: i64) -> OperationResult<i64>;
}

#[interface]
pub trait Writer {
    /// Returns the writer-qualified label.
    fn label(&self) -> OperationResult<String>;
}

#[interface]
pub trait Hidden {
    /// Returns a hidden value.
    fn hidden(&self) -> OperationResult<String>;
}

#[interface]
pub trait Broken {
    /// Returns a deliberately invalid encoded value.
    fn broken(&self) -> OperationResult<BadValue>;
}

#[derive(Debug)]
pub struct BadValue;

impl WipType for BadValue {
    fn type_expr() -> TypeExpr {
        TypeExpr::Integer
    }

    fn collect_declarations(_: &mut Vec<TypeDeclaration>) {}

    fn encode(self) -> Result<Value, CodecError> {
        Ok(Value::String("not an integer".into()))
    }

    fn decode(_: Value) -> Result<Self, CodecError> {
        Ok(Self)
    }
}

struct Document {
    id: String,
    validator: Option<Validator>,
    require_validator: bool,
    calls: Cell<usize>,
    private_backend_handle: RefCell<String>,
}

impl Document {
    fn new(id: &str) -> Self {
        Self {
            id: id.into(),
            validator: None,
            require_validator: false,
            calls: Cell::new(0),
            private_backend_handle: RefCell::new("/private/backend/path".into()),
        }
    }

    fn strict(id: &str, validator: &[u8]) -> Self {
        Self {
            id: id.into(),
            validator: Some(Validator::new(validator)),
            require_validator: true,
            calls: Cell::new(0),
            private_backend_handle: RefCell::new("secret-handle".into()),
        }
    }

    fn record_call(&self) {
        self.calls.set(self.calls.get() + 1);
    }
}

impl WipObject for Document {
    fn id(&self) -> ObjectId {
        ObjectId(self.id.clone())
    }

    fn validator(&self) -> Option<&Validator> {
        self.validator.as_ref()
    }

    fn requires_validator(&self) -> bool {
        self.require_validator
    }
}

impl Reader for Document {
    fn label(&self) -> OperationResult<String> {
        self.record_call();
        Ok("reader".into())
    }

    fn add(&self, left: i64, right: i64) -> OperationResult<i64> {
        self.record_call();
        Ok(left + right)
    }
}

impl Writer for Document {
    fn label(&self) -> OperationResult<String> {
        self.record_call();
        Ok("writer".into())
    }
}

impl Hidden for Document {
    fn hidden(&self) -> OperationResult<String> {
        self.record_call();
        Ok("hidden".into())
    }
}

impl Broken for Document {
    fn broken(&self) -> OperationResult<BadValue> {
        self.record_call();
        Ok(BadValue)
    }
}

fn request(
    object: &str,
    object_validator: Option<&[u8]>,
    reference: &wip_host::InterfaceRef,
    interface_validator: Option<&[u8]>,
    operation: &str,
    arguments: Vec<NamedValue>,
) -> CallRequest {
    CallRequest {
        object: ObjectId(object.into()),
        object_validator: object_validator.map(Validator::new),
        interface: InterfaceTarget {
            reference: reference.clone(),
            validator: interface_validator.map(Validator::new),
        },
        operation: operation.into(),
        arguments,
    }
}

#[test]
fn registry_exposes_opaque_validated_descriptor_observations() {
    let mut registry = InterfaceRegistry::new();
    let reader = registry.register(ReaderDefinition, None).unwrap();

    assert_ne!(reader.reference().as_str(), "Reader");
    assert_eq!(
        registry.resolve(reader.reference().as_str()).as_ref(),
        Some(reader.reference())
    );
    assert!(registry.resolve("wip-interface:unknown:0").is_none());
    let observation = registry.observe(reader.reference()).unwrap();
    assert_eq!(observation.reference, *reader.reference());
    assert_eq!(observation.descriptor.name, reader.reference().as_str());
    assert_eq!(observation.validator, None);
    observation.descriptor.validate().unwrap();

    assert!(registry.register(ReaderDefinition, None).is_err());

    let mut other_registry = InterfaceRegistry::new();
    let other_reader = other_registry.register(ReaderDefinition, None).unwrap();
    assert_ne!(reader.reference(), other_reader.reference());
    assert!(
        registry
            .resolve(other_reader.reference().as_str())
            .is_none()
    );
}

#[test]
fn publication_is_explicit_ordered_qualified_and_request_scoped() {
    let mut registry = InterfaceRegistry::new();
    let reader = registry.register(ReaderDefinition, None).unwrap();
    let writer = registry.register(WriterDefinition, None).unwrap();
    let _hidden = registry.register(HiddenDefinition, None).unwrap();

    let publication = PublishedObject::new(Document::new("document-1"))
        .expose(&writer)
        .unwrap()
        .expose(&reader)
        .unwrap();

    let object = publication.protocol_object();
    assert_eq!(
        object.interfaces,
        vec![
            writer.reference().as_str().to_owned(),
            reader.reference().as_str().to_owned()
        ]
    );
    wip_protocol::InterfaceObservation {
        object: object.clone(),
        descriptors: vec![
            registry.observe(writer.reference()).unwrap().descriptor,
            registry.observe(reader.reference()).unwrap().descriptor,
        ],
    }
    .validate()
    .unwrap();
    assert!(!format!("{object:?}").contains("private/backend/path"));

    let writer_result = publication
        .dispatch(request(
            "document-1",
            None,
            writer.reference(),
            None,
            "label",
            vec![],
        ))
        .unwrap();
    let reader_result = publication
        .dispatch(request(
            "document-1",
            None,
            reader.reference(),
            None,
            "label",
            vec![],
        ))
        .unwrap();
    assert_eq!(writer_result.value, Some(Value::String("writer".into())));
    assert_eq!(reader_result.value, Some(Value::String("reader".into())));
    assert_eq!(publication.implementation().calls.get(), 2);
    assert_eq!(
        publication
            .implementation()
            .private_backend_handle
            .borrow()
            .as_str(),
        "/private/backend/path"
    );
}

#[test]
fn implemented_but_unexposed_interface_is_not_a_member() {
    let mut registry = InterfaceRegistry::new();
    let reader = registry.register(ReaderDefinition, None).unwrap();
    let hidden = registry.register(HiddenDefinition, None).unwrap();
    let publication = PublishedObject::new(Document::new("document-2"))
        .expose(&reader)
        .unwrap();

    let error = publication
        .dispatch(request(
            "document-2",
            None,
            hidden.reference(),
            None,
            "hidden",
            vec![],
        ))
        .unwrap_err();
    assert_eq!(error.kind(), CallErrorKind::InterfaceMismatch);
    assert_eq!(
        error.protocol_error().category,
        ProtocolErrorCategory::InterfaceNotFound
    );
    assert_eq!(publication.implementation().calls.get(), 0);
}

#[test]
fn zero_interface_objects_are_valid() {
    let publication = PublishedObject::new(Document::new("empty"));
    let object = publication.protocol_object();
    assert_eq!(object.id, ObjectId("empty".into()));
    assert!(object.interfaces.is_empty());
    object.validate().unwrap();
}

#[test]
fn duplicate_exposure_is_rejected_without_reordering() {
    let mut registry = InterfaceRegistry::new();
    let reader = registry.register(ReaderDefinition, None).unwrap();
    let publication = PublishedObject::new(Document::new("duplicate"))
        .expose(&reader)
        .unwrap();
    let error = match publication.expose(&reader) {
        Ok(_) => panic!("duplicate exposure unexpectedly succeeded"),
        Err(error) => error,
    };
    assert!(error.to_string().contains(reader.reference().as_str()));
}

#[test]
fn operation_and_argument_failures_are_mapped_without_execution() {
    let mut registry = InterfaceRegistry::new();
    let reader = registry.register(ReaderDefinition, None).unwrap();
    let publication = PublishedObject::new(Document::new("validation"))
        .expose(&reader)
        .unwrap();

    let missing = publication
        .dispatch(request(
            "validation",
            None,
            reader.reference(),
            None,
            "missing",
            vec![],
        ))
        .unwrap_err();
    assert_eq!(missing.kind(), CallErrorKind::OperationNotFound);
    assert_eq!(
        missing.protocol_error().category,
        ProtocolErrorCategory::OperationNotFound
    );

    let invalid = publication
        .dispatch(request(
            "validation",
            None,
            reader.reference(),
            None,
            "add",
            vec![NamedValue {
                name: "left".into(),
                value: Value::String("wrong".into()),
            }],
        ))
        .unwrap_err();
    assert_eq!(invalid.kind(), CallErrorKind::InvalidArguments);
    assert_eq!(
        invalid.protocol_error().category,
        ProtocolErrorCategory::InvalidArguments
    );
    assert_eq!(publication.implementation().calls.get(), 0);
}

#[test]
fn invalid_implementation_result_is_internal_and_not_returned() {
    let mut registry = InterfaceRegistry::new();
    let broken = registry.register(BrokenDefinition, None).unwrap();
    let publication = PublishedObject::new(Document::new("broken"))
        .expose(&broken)
        .unwrap();

    let error = publication
        .dispatch(request(
            "broken",
            None,
            broken.reference(),
            None,
            "broken",
            vec![],
        ))
        .unwrap_err();
    assert_eq!(error.kind(), CallErrorKind::InvalidResult);
    assert_eq!(
        error.protocol_error().category,
        ProtocolErrorCategory::Internal
    );
    assert_eq!(publication.implementation().calls.get(), 1);
}

#[test]
fn object_validator_missing_and_mismatch_are_distinct_and_prevent_execution() {
    let mut registry = InterfaceRegistry::new();
    let reader = registry.register(ReaderDefinition, None).unwrap();
    let publication = PublishedObject::new(Document::strict("strict", b"object-v1"))
        .expose(&reader)
        .unwrap();

    let missing = publication
        .dispatch(request(
            "strict",
            None,
            reader.reference(),
            None,
            "label",
            vec![],
        ))
        .unwrap_err();
    assert_eq!(missing.kind(), CallErrorKind::ValidatorRequired);

    let mismatch = publication
        .dispatch(request(
            "strict",
            Some(b"stale"),
            reader.reference(),
            None,
            "label",
            vec![],
        ))
        .unwrap_err();
    assert_eq!(mismatch.kind(), CallErrorKind::ValidatorMismatch);
    assert_eq!(publication.implementation().calls.get(), 0);

    let result = publication
        .dispatch(request(
            "strict",
            Some(b"object-v1"),
            reader.reference(),
            None,
            "label",
            vec![],
        ))
        .unwrap();
    assert_eq!(result.validator, Some(Validator::new(b"object-v1")));
    assert_eq!(publication.implementation().calls.get(), 1);
}

#[test]
fn interface_validator_missing_and_mismatch_are_distinct_and_prevent_execution() {
    let mut registry = InterfaceRegistry::new();
    let writer = registry
        .register(WriterDefinition, Some(Validator::new(b"schema-v1")))
        .unwrap();
    let publication = PublishedObject::new(Document::new("mutable-interface"))
        .expose(&writer)
        .unwrap();

    let observation = registry.observe(writer.reference()).unwrap();
    assert_eq!(observation.validator, Some(Validator::new(b"schema-v1")));

    let missing = publication
        .dispatch(request(
            "mutable-interface",
            None,
            writer.reference(),
            None,
            "label",
            vec![],
        ))
        .unwrap_err();
    assert_eq!(missing.kind(), CallErrorKind::InterfaceValidatorRequired);

    let mismatch = publication
        .dispatch(request(
            "mutable-interface",
            None,
            writer.reference(),
            Some(b"schema-v0"),
            "label",
            vec![],
        ))
        .unwrap_err();
    assert_eq!(mismatch.kind(), CallErrorKind::InterfaceValidatorMismatch);
    assert_eq!(publication.implementation().calls.get(), 0);

    let result = publication
        .dispatch(request(
            "mutable-interface",
            None,
            writer.reference(),
            Some(b"schema-v1"),
            "label",
            vec![],
        ))
        .unwrap();
    assert_eq!(result.value, Some(Value::String("writer".into())));
}

#[test]
fn host_failures_map_to_internal_without_becoming_domain_values() {
    #[interface]
    pub trait Failing {
        /// Always fails in the host implementation.
        fn fail(&self) -> OperationResult<String>;
    }

    impl Failing for Document {
        fn fail(&self) -> OperationResult<String> {
            Err(HostError::new("backend unavailable"))
        }
    }

    let mut registry = InterfaceRegistry::new();
    let failing = registry.register(FailingDefinition, None).unwrap();
    let publication = PublishedObject::new(Document::new("failure"))
        .expose(&failing)
        .unwrap();
    let error = publication
        .dispatch(request(
            "failure",
            None,
            failing.reference(),
            None,
            "fail",
            vec![],
        ))
        .unwrap_err();
    assert_eq!(error.kind(), CallErrorKind::Implementation);
    assert_eq!(
        error.protocol_error().category,
        ProtocolErrorCategory::Internal
    );
}