gpui-rhai 0.1.8

use std::collections::{BTreeMap, BTreeSet};
use std::sync::{Arc, Mutex};

use rhai::{Dynamic, Map};
use semver::{Version, VersionReq};
use serde::{Deserialize, Serialize};
use thiserror::Error;

use crate::{
    AssetId, ComponentStateSchema, Length, ModuleId, ObjectField, RUNTIME_API_VERSION,
    SchemaValidationError, ScriptCallback, ScriptGeneration, Style, UiEventHandler, UiNode,
    UiValue, UiValueError, ValueSchema,
};

const HEADER_START: &str = "/* gpui-rhai\n";
const HEADER_END: &str = "\n*/";

#[derive(Clone, Copy, Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct RuntimeApiRange {
    pub min_inclusive: u32,
    pub max_exclusive: u32,
}

impl RuntimeApiRange {
    #[must_use]
    pub const fn new(min_inclusive: u32, max_exclusive: u32) -> Self {
        Self {
            min_inclusive,
            max_exclusive,
        }
    }

    #[must_use]
    pub const fn contains(self, version: u32) -> bool {
        self.min_inclusive <= version && version < self.max_exclusive
    }

    #[must_use]
    pub const fn is_valid(self) -> bool {
        self.min_inclusive < self.max_exclusive
    }
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct ComponentMetadata {
    pub id: ModuleId,
    pub export: String,
    pub version: Version,
    pub runtime_api: RuntimeApiRange,
    #[serde(default)]
    pub dependencies: BTreeSet<ModuleId>,
    #[serde(default)]
    pub capabilities: BTreeMap<String, VersionReq>,
    #[serde(default)]
    pub assets: BTreeSet<String>,
}

#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
pub struct ComponentSchema {
    #[serde(default)]
    pub props: BTreeMap<String, crate::ObjectField>,
    #[serde(default)]
    pub state: ComponentStateSchema,
    #[serde(default)]
    pub events: BTreeMap<String, EventSchema>,
    #[serde(default)]
    pub slots: BTreeMap<String, SlotSchema>,
    #[serde(default)]
    pub parts: BTreeSet<String>,
    #[serde(default)]
    pub effects: BTreeSet<String>,
}

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct EventSchema {
    pub payload: ValueSchema,
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct SlotSchema {
    #[serde(default)]
    pub required: bool,
    #[serde(default)]
    pub multiple: bool,
}

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct ComponentDefinition {
    pub metadata: ComponentMetadata,
    pub schema: ComponentSchema,
}

impl ComponentDefinition {
    /// Construct and validate a formal component definition.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentError`] when names, compatibility ranges, defaults,
    /// event callbacks, slots, parts, or capabilities violate the component
    /// contract.
    pub fn new(
        metadata: ComponentMetadata,
        mut schema: ComponentSchema,
    ) -> Result<Self, ComponentError> {
        install_standard_style_props(&mut schema)?;
        validate_metadata(&metadata)?;
        validate_schema(&schema)?;
        Ok(Self { metadata, schema })
    }

    /// Validate and normalize invocation props, applying declared defaults.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentError::MissingKey`] for an unkeyed stateful instance,
    /// or [`ComponentError::InvalidProps`] when props violate the schema.
    pub fn invoke(
        &self,
        key: Option<String>,
        props: Map,
    ) -> Result<ComponentInvocation, ComponentError> {
        self.invoke_with_generation(key, props, ScriptGeneration::default())
    }

    pub(crate) fn invoke_with_generation(
        &self,
        key: Option<String>,
        mut props: Map,
        generation: ScriptGeneration,
    ) -> Result<ComponentInvocation, ComponentError> {
        if !self.schema.state.is_empty() && key.is_none() {
            return Err(ComponentError::MissingKey {
                component: self.metadata.id.clone(),
            });
        }

        for (name, field) in &self.schema.props {
            if !props.contains_key(name.as_str())
                && let Some(default) = &field.default
            {
                props.insert(name.clone().into(), default.clone().into_dynamic());
            }
        }

        ValueSchema::object(self.schema.props.clone())
            .validate(&Dynamic::from_map(props.clone()))
            .map_err(|source| ComponentError::InvalidProps {
                component: self.metadata.id.clone(),
                source,
            })?;

        if let Some(part_styles) = props.get("part_styles") {
            let part_styles = part_styles.clone_cast::<Map>();
            if let Some(part) = part_styles
                .keys()
                .find(|part| !self.schema.parts.contains(part.as_str()))
            {
                return Err(ComponentError::UnknownStylePart {
                    component: self.metadata.id.clone(),
                    part: part.to_string(),
                });
            }
        }

        let retained_props =
            ComponentProps::from_validated(&self.schema.props, &props, generation)?;
        Ok(ComponentInvocation {
            component: self.metadata.id.clone(),
            export: self.metadata.export.clone(),
            key,
            props,
            retained_props,
        })
    }

    /// Validate a declared semantic event payload.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentError::UnknownEvent`] or
    /// [`ComponentError::InvalidEventPayload`].
    pub fn validate_event(&self, event: &str, payload: &Dynamic) -> Result<(), ComponentError> {
        let event_schema =
            self.schema
                .events
                .get(event)
                .ok_or_else(|| ComponentError::UnknownEvent {
                    component: self.metadata.id.clone(),
                    event: event.to_owned(),
                })?;
        event_schema.payload.validate(payload).map_err(|source| {
            ComponentError::InvalidEventPayload {
                component: self.metadata.id.clone(),
                event: event.to_owned(),
                source,
            }
        })
    }

    /// Confirm that the source header describes this exported definition.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentError::HeaderMismatch`] when any metadata differs.
    pub fn validate_header(&self, header: &ComponentMetadata) -> Result<(), ComponentError> {
        if &self.metadata == header {
            Ok(())
        } else {
            Err(ComponentError::HeaderMismatch {
                header: Box::new(header.clone()),
                exported: Box::new(self.metadata.clone()),
            })
        }
    }
}

fn install_standard_style_props(schema: &mut ComponentSchema) -> Result<(), ComponentError> {
    match schema.props.get("key") {
        Some(field) if !matches!(field.schema, ValueSchema::String { .. }) => {
            return Err(ComponentError::InvalidStandardKeyProp);
        }
        Some(_) => {}
        None => {
            schema.props.insert(
                "key".to_owned(),
                ObjectField::optional(ValueSchema::string()),
            );
        }
    }
    let standard = [
        ("style", ObjectField::optional(ValueSchema::Style)),
        (
            "part_styles",
            ObjectField::optional(ValueSchema::Map {
                values: Box::new(ValueSchema::Style),
            }),
        ),
    ];
    for (name, expected) in standard {
        match schema.props.get(name) {
            Some(actual) if actual != &expected => {
                return Err(ComponentError::InvalidStandardStyleProp(name.to_owned()));
            }
            Some(_) => {}
            None => {
                schema.props.insert(name.to_owned(), expected);
            }
        }
    }
    Ok(())
}

#[derive(Clone, Debug)]
pub struct ComponentInvocation {
    pub component: ModuleId,
    pub export: String,
    pub key: Option<String>,
    pub props: Map,
    pub retained_props: ComponentProps,
}

#[derive(Clone, Debug, PartialEq)]
pub enum ComponentPropValue {
    Data(UiValue),
    Array(Vec<ComponentPropValue>),
    Map(BTreeMap<String, ComponentPropValue>),
    Node(Box<UiNode>),
    Nodes(Vec<UiNode>),
    Callback(UiEventHandler),
    Style(Box<Style>),
    Styles(BTreeMap<String, Style>),
    Length(Length),
    Asset(AssetId),
    Signal(crate::NativeSignal),
    Collection(crate::NativeCollection),
    Document(crate::NativeTextDocument),
    #[cfg(feature = "charts")]
    ChartData(crate::NativeChartData),
    Ref(crate::ElementRef),
}

#[derive(Clone, Debug, Default, PartialEq)]
pub struct ComponentProps(BTreeMap<String, ComponentPropValue>);

impl ComponentProps {
    fn from_validated(
        schema: &BTreeMap<String, ObjectField>,
        props: &Map,
        generation: ScriptGeneration,
    ) -> Result<Self, ComponentError> {
        let values = schema
            .iter()
            .filter_map(|(name, field)| {
                props.get(name.as_str()).cloned().map(|value| {
                    convert_component_prop(&field.schema, value, generation)
                        .map(|value| (name.clone(), value))
                        .map_err(|source| ComponentError::PropConversion {
                            prop: name.clone(),
                            source,
                        })
                })
            })
            .collect::<Result<_, _>>()?;
        Ok(Self(values))
    }

    #[must_use]
    pub fn get(&self, name: &str) -> Option<&ComponentPropValue> {
        self.0.get(name)
    }

    pub fn iter(&self) -> impl Iterator<Item = (&str, &ComponentPropValue)> {
        self.0.iter().map(|(name, value)| (name.as_str(), value))
    }

    /// Compare props for component-render reuse.
    ///
    /// Node-valued props are deliberately never reusable. A node or slot can
    /// carry callbacks and component ownership whose structural equality does
    /// not prove that retaining the previous subtree is semantically safe.
    pub(crate) fn reusable_eq(&self, other: &Self) -> bool {
        self.0.len() == other.0.len()
            && self.0.iter().all(|(name, value)| {
                other
                    .0
                    .get(name)
                    .is_some_and(|other| value.reusable_eq(other))
            })
    }
}

impl ComponentPropValue {
    fn reusable_eq(&self, other: &Self) -> bool {
        match (self, other) {
            (Self::Node(_) | Self::Nodes(_), _) | (_, Self::Node(_) | Self::Nodes(_)) => false,
            (Self::Array(left), Self::Array(right)) => {
                left.len() == right.len()
                    && left
                        .iter()
                        .zip(right)
                        .all(|(left, right)| left.reusable_eq(right))
            }
            (Self::Map(left), Self::Map(right)) => {
                left.len() == right.len()
                    && left.iter().all(|(name, value)| {
                        right
                            .get(name)
                            .is_some_and(|other| value.reusable_eq(other))
                    })
            }
            _ => self == other,
        }
    }
}

fn convert_component_prop(
    schema: &ValueSchema,
    value: Dynamic,
    generation: ScriptGeneration,
) -> Result<ComponentPropValue, ComponentPropConversionError> {
    match schema {
        ValueSchema::Optional { value: inner } if value.is_unit() => {
            Ok(ComponentPropValue::Data(UiValue::Null))
        }
        ValueSchema::Optional { value: inner } => convert_component_prop(inner, value, generation),
        ValueSchema::OneOf { variants } => {
            let branch = variants
                .iter()
                .find(|variant| variant.validate(&value).is_ok())
                .expect("validated component one_of prop matches one branch");
            convert_component_prop(branch, value, generation)
        }
        ValueSchema::Node => Ok(ComponentPropValue::Node(Box::new(value.cast::<UiNode>()))),
        ValueSchema::Callback if value.is::<rhai::FnPtr>() => {
            Ok(ComponentPropValue::Callback(UiEventHandler::Script(
                ScriptCallback::try_from_fn_ptr(value.cast::<rhai::FnPtr>(), generation)?,
            )))
        }
        ValueSchema::Callback => Ok(ComponentPropValue::Callback(UiEventHandler::Native(
            value.cast::<crate::NativeHandlerRef>(),
        ))),
        ValueSchema::Array { items, .. } if matches!(items.as_ref(), ValueSchema::Node) => {
            Ok(ComponentPropValue::Nodes(
                value
                    .cast::<rhai::Array>()
                    .into_iter()
                    .map(Dynamic::cast::<UiNode>)
                    .collect(),
            ))
        }
        ValueSchema::Array { items, .. } => Ok(ComponentPropValue::Array(
            value
                .cast::<rhai::Array>()
                .into_iter()
                .map(|value| convert_component_prop(items, value, generation))
                .collect::<Result<_, _>>()?,
        )),
        ValueSchema::Map { values } if matches!(values.as_ref(), ValueSchema::Style) => {
            Ok(ComponentPropValue::Styles(
                value
                    .cast::<Map>()
                    .into_iter()
                    .map(|(name, value)| (name.to_string(), value.cast::<Style>()))
                    .collect(),
            ))
        }
        ValueSchema::Map { values } => Ok(ComponentPropValue::Map(
            value
                .cast::<Map>()
                .into_iter()
                .map(|(name, value)| {
                    convert_component_prop(values, value, generation)
                        .map(|value| (name.to_string(), value))
                })
                .collect::<Result<_, _>>()?,
        )),
        ValueSchema::Object {
            fields,
            allow_unknown,
        } => Ok(ComponentPropValue::Map(
            value
                .cast::<Map>()
                .into_iter()
                .map(|(name, value)| {
                    let name = name.to_string();
                    let converted = if let Some(field) = fields.get(&name) {
                        convert_component_prop(&field.schema, value, generation)
                    } else {
                        debug_assert!(*allow_unknown);
                        UiValue::from_dynamic(value)
                            .map(ComponentPropValue::Data)
                            .map_err(Into::into)
                    };
                    converted.map(|value| (name, value))
                })
                .collect::<Result<_, _>>()?,
        )),
        ValueSchema::Style => Ok(ComponentPropValue::Style(Box::new(value.cast::<Style>()))),
        ValueSchema::Length => Ok(ComponentPropValue::Length(value.cast::<Length>())),
        ValueSchema::Asset => Ok(ComponentPropValue::Asset(value.cast::<AssetId>())),
        ValueSchema::Signal => Ok(ComponentPropValue::Signal(
            value.cast::<crate::NativeSignal>(),
        )),
        ValueSchema::Collection => Ok(ComponentPropValue::Collection(
            value.cast::<crate::NativeCollection>(),
        )),
        ValueSchema::Document => Ok(ComponentPropValue::Document(
            value.cast::<crate::NativeTextDocument>(),
        )),
        #[cfg(feature = "charts")]
        ValueSchema::ChartData => Ok(ComponentPropValue::ChartData(
            value.cast::<crate::NativeChartData>(),
        )),
        ValueSchema::Ref => Ok(ComponentPropValue::Ref(value.cast::<crate::ElementRef>())),
        _ => UiValue::from_dynamic(value)
            .map(ComponentPropValue::Data)
            .map_err(Into::into),
    }
}

#[derive(Debug, Error)]
pub enum ComponentPropConversionError {
    #[error(transparent)]
    Value(#[from] UiValueError),
    #[error(transparent)]
    Callback(#[from] crate::ScriptCallbackDefinitionError),
}

#[derive(Clone, Debug, Default)]
pub struct ComponentRegistry {
    components: BTreeMap<ModuleId, ComponentDefinition>,
}

/// Collects definitions registered by `define_component` during module setup.
#[derive(Clone, Debug, Default)]
pub struct ComponentExportCollector {
    registry: Arc<Mutex<ComponentRegistry>>,
}

impl ComponentExportCollector {
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    pub(crate) fn register_definition(
        &self,
        definition: ComponentDefinition,
    ) -> Result<(), ComponentRegistryError> {
        self.registry
            .lock()
            .map_err(|_| ComponentRegistryError::Poisoned)?
            .register(definition, RUNTIME_API_VERSION)
    }

    /// Clone the current exported-component registry.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentExportError::Poisoned`] if a prior panic poisoned the
    /// collector lock.
    pub fn snapshot(&self) -> Result<ComponentRegistry, ComponentExportError> {
        self.registry
            .lock()
            .map(|registry| registry.clone())
            .map_err(|_| ComponentExportError::Poisoned)
    }

    /// Clear all collected component definitions.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentExportError::Poisoned`] if a prior panic poisoned the
    /// collector lock.
    pub fn clear(&self) -> Result<(), ComponentExportError> {
        *self
            .registry
            .lock()
            .map_err(|_| ComponentExportError::Poisoned)? = ComponentRegistry::new();
        Ok(())
    }

    /// Replace collected exports, used to roll back a failed reload candidate.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentExportError::Poisoned`] if the collector lock is poisoned.
    pub fn replace(&self, registry: ComponentRegistry) -> Result<(), ComponentExportError> {
        *self
            .registry
            .lock()
            .map_err(|_| ComponentExportError::Poisoned)? = registry;
        Ok(())
    }
}

impl ComponentRegistry {
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Register a component compatible with the current runtime API.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentRegistryError`] for duplicate component IDs or an
    /// incompatible runtime API range.
    pub fn register(
        &mut self,
        definition: ComponentDefinition,
        runtime_api: u32,
    ) -> Result<(), ComponentRegistryError> {
        let id = definition.metadata.id.clone();
        if let Some(existing) = self.components.get(&id) {
            return if existing == &definition {
                Ok(())
            } else {
                Err(ComponentRegistryError::Duplicate(id))
            };
        }
        if !definition.metadata.runtime_api.contains(runtime_api) {
            return Err(ComponentRegistryError::IncompatibleRuntime {
                component: id,
                required: definition.metadata.runtime_api,
                actual: runtime_api,
            });
        }
        self.components.insert(id, definition);
        Ok(())
    }

    #[must_use]
    pub fn get(&self, id: &ModuleId) -> Option<&ComponentDefinition> {
        self.components.get(id)
    }

    #[must_use]
    pub fn len(&self) -> usize {
        self.components.len()
    }

    #[must_use]
    pub fn is_empty(&self) -> bool {
        self.components.is_empty()
    }

    pub fn iter(&self) -> impl Iterator<Item = (&ModuleId, &ComponentDefinition)> {
        self.components.iter()
    }

    /// Resolve dependencies in installation order, dependencies first.
    ///
    /// # Errors
    ///
    /// Returns [`ComponentRegistryError::Missing`] or
    /// [`ComponentRegistryError::DependencyCycle`].
    pub fn resolve(
        &self,
        requested: impl IntoIterator<Item = ModuleId>,
    ) -> Result<Vec<ModuleId>, ComponentRegistryError> {
        let mut ordered = Vec::new();
        let mut complete = BTreeSet::new();
        let mut stack = Vec::new();
        for id in requested {
            self.visit(&id, &mut stack, &mut complete, &mut ordered)?;
        }
        Ok(ordered)
    }

    fn visit(
        &self,
        id: &ModuleId,
        stack: &mut Vec<ModuleId>,
        complete: &mut BTreeSet<ModuleId>,
        ordered: &mut Vec<ModuleId>,
    ) -> Result<(), ComponentRegistryError> {
        if complete.contains(id) {
            return Ok(());
        }
        if let Some(start) = stack.iter().position(|active| active == id) {
            let mut cycle = stack[start..].to_vec();
            cycle.push(id.clone());
            return Err(ComponentRegistryError::DependencyCycle(cycle));
        }
        let component = self
            .components
            .get(id)
            .ok_or_else(|| ComponentRegistryError::Missing(id.clone()))?;
        stack.push(id.clone());
        for dependency in &component.metadata.dependencies {
            self.visit(dependency, stack, complete, ordered)?;
        }
        stack.pop();
        complete.insert(id.clone());
        ordered.push(id.clone());
        Ok(())
    }
}

/// Parse the required JSON metadata block at the start of a component script.
///
/// # Errors
///
/// Returns [`ComponentHeaderError`] when the sentinel is absent, the block is
/// unterminated, or the JSON metadata is invalid.
pub fn parse_component_header(source: &str) -> Result<ComponentMetadata, ComponentHeaderError> {
    let source = source.strip_prefix('\u{feff}').unwrap_or(source);
    let body = source
        .strip_prefix(HEADER_START)
        .ok_or(ComponentHeaderError::Missing)?;
    let end = body
        .find(HEADER_END)
        .ok_or(ComponentHeaderError::Unterminated)?;
    serde_json::from_str(&body[..end]).map_err(ComponentHeaderError::InvalidJson)
}

fn validate_metadata(metadata: &ComponentMetadata) -> Result<(), ComponentError> {
    if !is_pascal_case_identifier(&metadata.export) {
        return Err(ComponentError::InvalidExport(metadata.export.clone()));
    }
    if !metadata.runtime_api.is_valid() {
        return Err(ComponentError::InvalidRuntimeRange(metadata.runtime_api));
    }
    if metadata.dependencies.contains(&metadata.id) {
        return Err(ComponentError::SelfDependency(metadata.id.clone()));
    }
    for name in metadata.capabilities.keys() {
        if !is_namespaced_identifier(name) {
            return Err(ComponentError::InvalidCapability(name.clone()));
        }
    }
    for asset in &metadata.assets {
        if !is_component_asset_path(asset) {
            return Err(ComponentError::InvalidAsset(asset.clone()));
        }
    }
    Ok(())
}

fn validate_schema(schema: &ComponentSchema) -> Result<(), ComponentError> {
    for (name, field) in &schema.props {
        if !is_snake_case_identifier(name) {
            return Err(ComponentError::InvalidSchemaName(name.clone()));
        }
        if field.required && field.default.is_some() {
            return Err(ComponentError::RequiredPropHasDefault(name.clone()));
        }
        field.schema.validate_definition().map_err(|source| {
            ComponentError::InvalidSchemaDefinition {
                location: format!("prop `{name}`"),
                source,
            }
        })?;
        if let Some(default) = &field.default {
            field.schema.validate_ui_value(default).map_err(|source| {
                ComponentError::InvalidPropDefault {
                    prop: name.clone(),
                    source,
                }
            })?;
        }
    }
    for (name, event) in &schema.events {
        if !is_snake_case_identifier(name) {
            return Err(ComponentError::InvalidSchemaName(name.clone()));
        }
        let callback_name = format!("on_{name}");
        if !schema
            .props
            .get(&callback_name)
            .is_some_and(|field| schema_accepts_callback(&field.schema))
        {
            return Err(ComponentError::MissingEventCallback {
                event: name.clone(),
                prop: callback_name,
            });
        }
        event.payload.validate_definition().map_err(|source| {
            ComponentError::InvalidSchemaDefinition {
                location: format!("event `{name}`"),
                source,
            }
        })?;
    }
    for (name, slot) in &schema.slots {
        if !is_snake_case_identifier(name) {
            return Err(ComponentError::InvalidSchemaName(name.clone()));
        }
        let valid = schema.props.get(name).is_some_and(|field| {
            if slot.multiple {
                matches!(
                    &field.schema,
                    ValueSchema::Array { items, .. } if matches!(items.as_ref(), ValueSchema::Node)
                )
            } else {
                schema_accepts_node(&field.schema)
            }
        });
        if !valid {
            return Err(ComponentError::MissingSlotProp(name.clone()));
        }
    }
    for part in &schema.parts {
        if !is_snake_case_identifier(part) {
            return Err(ComponentError::InvalidSchemaName(part.clone()));
        }
    }
    for effect in &schema.effects {
        if !is_snake_case_identifier(effect) {
            return Err(ComponentError::InvalidSchemaName(effect.clone()));
        }
    }
    for (name, field) in schema.state.fields() {
        if !is_snake_case_identifier(name) {
            return Err(ComponentError::InvalidSchemaName(name.clone()));
        }
        field.schema.validate_definition().map_err(|source| {
            ComponentError::InvalidSchemaDefinition {
                location: format!("state field `{name}`"),
                source,
            }
        })?;
        field
            .schema
            .validate_ui_value(&field.default)
            .map_err(|source| ComponentError::InvalidStateDefault {
                field: name.clone(),
                source,
            })?;
    }
    Ok(())
}

fn schema_accepts_callback(schema: &ValueSchema) -> bool {
    matches!(schema, ValueSchema::Callback)
        || matches!(schema, ValueSchema::Optional { value } if matches!(value.as_ref(), ValueSchema::Callback))
        || matches!(schema, ValueSchema::OneOf { variants } if variants.iter().any(schema_accepts_callback))
}

fn schema_accepts_node(schema: &ValueSchema) -> bool {
    matches!(schema, ValueSchema::Node)
        || matches!(schema, ValueSchema::Optional { value } if matches!(value.as_ref(), ValueSchema::Node))
        || matches!(schema, ValueSchema::OneOf { variants } if variants.iter().any(schema_accepts_node))
}

fn is_pascal_case_identifier(value: &str) -> bool {
    value
        .chars()
        .next()
        .is_some_and(|first| first.is_ascii_uppercase())
        && value
            .chars()
            .all(|character| character.is_ascii_alphanumeric())
}

fn is_snake_case_identifier(value: &str) -> bool {
    !value.is_empty()
        && !value.starts_with('_')
        && !value.ends_with('_')
        && !value.contains("__")
        && value.chars().all(|character| {
            character.is_ascii_lowercase() || character.is_ascii_digit() || character == '_'
        })
}

fn is_namespaced_identifier(value: &str) -> bool {
    value.split_once('.').is_some_and(|(namespace, name)| {
        is_snake_case_identifier(namespace) && is_snake_case_identifier(name)
    })
}

fn is_component_asset_path(value: &str) -> bool {
    !value.is_empty()
        && !value.starts_with('/')
        && !value.ends_with('/')
        && !value.contains(':')
        && !value.contains('\\')
        && value.split('/').all(|segment| {
            !segment.is_empty()
                && !matches!(segment, "." | "..")
                && segment.chars().all(|character| {
                    character.is_ascii_alphanumeric() || matches!(character, '_' | '-' | '.')
                })
        })
}

#[derive(Debug, Error)]
pub enum ComponentError {
    #[error("component export `{0}` must be a PascalCase identifier")]
    InvalidExport(String),
    #[error("runtime API range {0:?} is empty")]
    InvalidRuntimeRange(RuntimeApiRange),
    #[error("component `{0}` cannot depend on itself")]
    SelfDependency(ModuleId),
    #[error("capability `{0}` must be a namespaced snake_case identifier")]
    InvalidCapability(String),
    #[error("component asset `{0}` must be a safe provider-relative path")]
    InvalidAsset(String),
    #[error("schema name `{0}` must be a snake_case identifier")]
    InvalidSchemaName(String),
    #[error("required prop `{0}` cannot also declare a default")]
    RequiredPropHasDefault(String),
    #[error("invalid schema definition for {location}: {source}")]
    InvalidSchemaDefinition {
        location: String,
        #[source]
        source: crate::SchemaDefinitionError,
    },
    #[error("default for state field `{field}` is invalid: {source}")]
    InvalidStateDefault {
        field: String,
        #[source]
        source: SchemaValidationError,
    },
    #[error("standard style prop `{0}` has an incompatible schema")]
    InvalidStandardStyleProp(String),
    #[error("standard component key prop must be a string")]
    InvalidStandardKeyProp,
    #[error("default for prop `{prop}` is invalid: {source}")]
    InvalidPropDefault {
        prop: String,
        #[source]
        source: SchemaValidationError,
    },
    #[error("event `{event}` requires callback prop `{prop}`")]
    MissingEventCallback { event: String, prop: String },
    #[error("slot `{0}` requires a compatible node prop with the same name")]
    MissingSlotProp(String),
    #[error("stateful component `{component}` requires a stable key")]
    MissingKey { component: ModuleId },
    #[error("props for component `{component}` are invalid: {source}")]
    InvalidProps {
        component: ModuleId,
        #[source]
        source: SchemaValidationError,
    },
    #[error("component prop `{prop}` cannot cross the retained boundary: {source}")]
    PropConversion {
        prop: String,
        source: ComponentPropConversionError,
    },
    #[error("component `{component}` does not declare style part `{part}`")]
    UnknownStylePart { component: ModuleId, part: String },
    #[error("component `{component}` does not declare event `{event}`")]
    UnknownEvent { component: ModuleId, event: String },
    #[error("payload for `{component}` event `{event}` is invalid: {source}")]
    InvalidEventPayload {
        component: ModuleId,
        event: String,
        #[source]
        source: SchemaValidationError,
    },
    #[error("component header metadata does not match exported metadata")]
    HeaderMismatch {
        header: Box<ComponentMetadata>,
        exported: Box<ComponentMetadata>,
    },
}

#[derive(Debug, Error)]
pub enum ComponentRegistryError {
    #[error("component export registry is poisoned")]
    Poisoned,
    #[error("component `{0}` is already registered")]
    Duplicate(ModuleId),
    #[error("component `{component}` requires runtime API {required:?}, current API is {actual}")]
    IncompatibleRuntime {
        component: ModuleId,
        required: RuntimeApiRange,
        actual: u32,
    },
    #[error("component `{0}` is not registered")]
    Missing(ModuleId),
    #[error("component dependency cycle: {0:?}")]
    DependencyCycle(Vec<ModuleId>),
}

#[derive(Debug, Error)]
pub enum ComponentHeaderError {
    #[error("component source must start with `/* gpui-rhai` metadata")]
    Missing,
    #[error("component metadata block is missing its closing `*/`")]
    Unterminated,
    #[error("component metadata JSON is invalid: {0}")]
    InvalidJson(#[source] serde_json::Error),
}

#[derive(Clone, Debug, Error, Eq, PartialEq)]
pub enum ComponentExportError {
    #[error("component export registry lock is poisoned")]
    Poisoned,
    #[error("component render registry is already borrowed")]
    Borrowed,
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{ObjectField, StateField, Style, UiValue};
    use rhai::Engine;

    fn metadata(id: &str, export: &str) -> ComponentMetadata {
        ComponentMetadata {
            id: ModuleId::parse(id).unwrap(),
            export: export.to_owned(),
            version: Version::new(0, 1, 0),
            runtime_api: RuntimeApiRange::new(2, 3),
            dependencies: BTreeSet::new(),
            capabilities: BTreeMap::new(),
            assets: BTreeSet::new(),
        }
    }

    fn button() -> ComponentDefinition {
        ComponentDefinition::new(
            metadata("components/button", "Button"),
            ComponentSchema {
                props: BTreeMap::from([
                    (
                        "text".to_owned(),
                        ObjectField::required(ValueSchema::string()),
                    ),
                    (
                        "variant".to_owned(),
                        ObjectField::optional(ValueSchema::enumeration(["primary", "secondary"]))
                            .with_default(UiValue::String("primary".to_owned())),
                    ),
                    (
                        "on_click".to_owned(),
                        ObjectField::optional(ValueSchema::optional(ValueSchema::Callback)),
                    ),
                ]),
                events: BTreeMap::from([(
                    "click".to_owned(),
                    EventSchema {
                        payload: ValueSchema::Null,
                    },
                )]),
                parts: BTreeSet::from(["root".to_owned(), "label".to_owned()]),
                ..ComponentSchema::default()
            },
        )
        .unwrap()
    }

    #[test]
    fn invocation_applies_defaults_and_rejects_unknown_props() {
        let button = button();
        let invocation = button
            .invoke(
                None,
                Map::from_iter([("text".into(), Dynamic::from("Save"))]),
            )
            .unwrap();
        assert_eq!(
            invocation
                .props
                .get("variant")
                .unwrap()
                .clone_cast::<String>(),
            "primary"
        );

        let error = button
            .invoke(
                None,
                Map::from_iter([
                    ("text".into(), Dynamic::from("Save")),
                    ("lable".into(), Dynamic::from("typo")),
                ]),
            )
            .unwrap_err();
        assert!(matches!(error, ComponentError::InvalidProps { .. }));
    }

    #[test]
    fn invocation_normalizes_data_style_and_callback_props_for_retention() {
        let button = button();
        let invocation = button
            .invoke(
                None,
                Map::from_iter([
                    ("text".into(), Dynamic::from("Save")),
                    ("style".into(), Dynamic::from(Style::new().flex_row())),
                    (
                        "on_click".into(),
                        Dynamic::from(rhai::FnPtr::new("clicked").unwrap()),
                    ),
                ]),
            )
            .unwrap();
        assert!(matches!(
            invocation.retained_props.get("text"),
            Some(ComponentPropValue::Data(UiValue::String(value))) if value == "Save"
        ));
        assert!(matches!(
            invocation.retained_props.get("style"),
            Some(ComponentPropValue::Style(_))
        ));
        assert!(matches!(
            invocation.retained_props.get("on_click"),
            Some(ComponentPropValue::Callback(UiEventHandler::Script(_)))
        ));
    }

    #[test]
    fn invocation_rejects_anonymous_retained_callback_props() {
        let button = button();
        let engine = Engine::new();
        let callback = engine.eval::<rhai::FnPtr>("|| ()").unwrap();
        assert!(matches!(
            button.invoke(
                None,
                Map::from_iter([
                    ("text".into(), Dynamic::from("Save")),
                    ("on_click".into(), Dynamic::from(callback)),
                ]),
            ),
            Err(ComponentError::PropConversion { .. })
        ));
    }

    #[test]
    fn standard_style_props_are_typed_and_reject_unknown_parts() {
        let component = button();
        assert!(matches!(
            component.schema.props["style"].schema,
            ValueSchema::Style
        ));
        let props = Map::from_iter([
            ("text".into(), Dynamic::from("Save")),
            (
                "part_styles".into(),
                Dynamic::from_map(Map::from_iter([(
                    "missing".into(),
                    Dynamic::from(Style::new()),
                )])),
            ),
        ]);
        assert!(matches!(
            component.invoke(None, props),
            Err(ComponentError::UnknownStylePart { part, .. }) if part == "missing"
        ));
    }

    #[test]
    fn stateful_components_require_keys() {
        let state = ComponentStateSchema::new(BTreeMap::from([(
            "open".to_owned(),
            StateField::new(ValueSchema::Bool, UiValue::Bool(false)),
        )]))
        .unwrap();
        let definition = ComponentDefinition::new(
            metadata("components/popover", "Popover"),
            ComponentSchema {
                state,
                ..ComponentSchema::default()
            },
        )
        .unwrap();
        assert!(matches!(
            definition.invoke(None, Map::new()),
            Err(ComponentError::MissingKey { .. })
        ));
        definition
            .invoke(Some("settings".to_owned()), Map::new())
            .unwrap();
    }

    #[test]
    fn registry_resolves_dependencies_first() {
        let mut registry = ComponentRegistry::new();
        registry
            .register(button(), crate::RUNTIME_API_VERSION)
            .unwrap();
        let mut popover_metadata = metadata("components/popover", "Popover");
        popover_metadata
            .dependencies
            .insert(ModuleId::parse("components/button").unwrap());
        registry
            .register(
                ComponentDefinition::new(popover_metadata, ComponentSchema::default()).unwrap(),
                crate::RUNTIME_API_VERSION,
            )
            .unwrap();

        assert_eq!(
            registry
                .resolve([ModuleId::parse("components/popover").unwrap()])
                .unwrap(),
            vec![
                ModuleId::parse("components/button").unwrap(),
                ModuleId::parse("components/popover").unwrap()
            ]
        );
    }

    #[test]
    fn component_header_is_machine_readable() {
        let header = r#"/* gpui-rhai
{
  "id": "components/button",
  "export": "Button",
  "version": "0.1.0",
  "runtime_api": { "min_inclusive": 2, "max_exclusive": 3 },
  "dependencies": [],
  "capabilities": {},
  "assets": []
}
*/
// Human-facing Button documentation follows.
fn render_button(props) { text(props.text) }
"#;
        assert_eq!(
            parse_component_header(header).unwrap(),
            metadata("components/button", "Button")
        );
    }

    #[test]
    fn component_collector_is_idempotent_and_rejects_conflicts() {
        let collector = ComponentExportCollector::new();
        let definition = button();
        collector.register_definition(definition.clone()).unwrap();
        assert_eq!(collector.snapshot().unwrap().len(), 1);
        collector.register_definition(definition.clone()).unwrap();
        assert_eq!(collector.snapshot().unwrap().len(), 1);

        let mut conflicting = definition;
        conflicting.metadata.export = "OtherButton".to_owned();
        assert!(collector.register_definition(conflicting).is_err());
        assert_eq!(
            collector
                .snapshot()
                .unwrap()
                .get(&ModuleId::parse("components/button").unwrap())
                .unwrap()
                .metadata
                .export,
            "Button"
        );
    }

    #[test]
    fn header_and_exported_metadata_must_match() {
        let definition = button();
        let mut header = definition.metadata.clone();
        header.version = Version::new(0, 2, 0);
        assert!(matches!(
            definition.validate_header(&header),
            Err(ComponentError::HeaderMismatch { .. })
        ));
    }

    #[test]
    fn component_schema_round_trips_for_tooling() {
        let definition = button();
        let json = serde_json::to_string_pretty(&definition).unwrap();
        let decoded: ComponentDefinition = serde_json::from_str(&json).unwrap();
        assert_eq!(decoded, definition);
    }

    #[test]
    fn component_assets_are_safe_and_part_of_header_identity() {
        let mut valid = metadata("components/icon_button", "IconButton");
        valid.assets.insert("icons/arrow-next.svg".to_owned());
        let definition =
            ComponentDefinition::new(valid.clone(), ComponentSchema::default()).unwrap();
        definition.validate_header(&valid).unwrap();

        let mut mismatch = valid.clone();
        mismatch.assets.clear();
        assert!(matches!(
            definition.validate_header(&mismatch),
            Err(ComponentError::HeaderMismatch { .. })
        ));

        let mut invalid = metadata("components/icon_button", "IconButton");
        invalid.assets.insert("../secret.svg".to_owned());
        assert!(matches!(
            ComponentDefinition::new(invalid, ComponentSchema::default()),
            Err(ComponentError::InvalidAsset(_))
        ));
    }

    #[test]
    fn invalid_nested_schema_definition_is_rejected_at_export() {
        let schema = ComponentSchema {
            props: BTreeMap::from([(
                "page".to_owned(),
                ObjectField::required(ValueSchema::bounded_integer(Some(3), Some(1))),
            )]),
            ..ComponentSchema::default()
        };
        assert!(matches!(
            ComponentDefinition::new(metadata("components/pager", "Pager"), schema),
            Err(ComponentError::InvalidSchemaDefinition { .. })
        ));
    }

    #[test]
    fn component_reuse_equality_is_conservative_for_nested_nodes() {
        let data = ComponentProps(BTreeMap::from([(
            "label".to_owned(),
            ComponentPropValue::Data(UiValue::String("same".to_owned())),
        )]));
        assert!(data.reusable_eq(&data.clone()));

        let slot = ComponentProps(BTreeMap::from([(
            "content".to_owned(),
            ComponentPropValue::Node(Box::new(UiNode::text("same"))),
        )]));
        assert!(!slot.reusable_eq(&slot.clone()));

        let nested_slot = ComponentProps(BTreeMap::from([(
            "payload".to_owned(),
            ComponentPropValue::Array(vec![ComponentPropValue::Map(BTreeMap::from([(
                "content".to_owned(),
                ComponentPropValue::Node(Box::new(UiNode::text("same"))),
            )]))]),
        )]));
        assert!(!nested_slot.reusable_eq(&nested_slot.clone()));
    }
}