gpui-rhai 0.1.8

use std::cmp::Ordering;
use std::collections::{BTreeMap, BTreeSet};
use std::fmt;

use rhai::{Array, Dynamic, FLOAT, FnPtr, INT, ImmutableString, Map};
use serde::{Deserialize, Serialize};

use crate::{AssetId, ElementRef, Length, NativeSignal, OpaqueHandle, Style, UiNode, UiValue};

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum ValueSchema {
    Null,
    Bool,
    Integer {
        #[serde(default, skip_serializing_if = "Option::is_none")]
        min: Option<INT>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        max: Option<INT>,
    },
    Float {
        #[serde(default, skip_serializing_if = "Option::is_none")]
        min: Option<FLOAT>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        max: Option<FLOAT>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        exclusive_min: Option<FLOAT>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        exclusive_max: Option<FLOAT>,
    },
    Number {
        #[serde(default, skip_serializing_if = "Option::is_none")]
        min: Option<FLOAT>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        max: Option<FLOAT>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        exclusive_min: Option<FLOAT>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        exclusive_max: Option<FLOAT>,
    },
    String {
        #[serde(default, skip_serializing_if = "Vec::is_empty")]
        allowed: Vec<String>,
    },
    Array {
        items: Box<Self>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        max_items: Option<usize>,
    },
    Map {
        values: Box<Self>,
    },
    Object {
        fields: BTreeMap<String, ObjectField>,
        #[serde(default)]
        allow_unknown: bool,
    },
    Optional {
        value: Box<Self>,
    },
    OneOf {
        variants: Vec<Self>,
    },
    Node,
    Callback,
    Style,
    Length,
    UiValue,
    Asset,
    Signal,
    Collection,
    Document,
    #[cfg(feature = "charts")]
    ChartData,
    Ref,
    Handle {
        kind: String,
    },
}

impl ValueSchema {
    #[must_use]
    pub fn string() -> Self {
        Self::String {
            allowed: Vec::new(),
        }
    }

    #[must_use]
    pub const fn integer() -> Self {
        Self::Integer {
            min: None,
            max: None,
        }
    }

    #[must_use]
    pub const fn bounded_integer(min: Option<INT>, max: Option<INT>) -> Self {
        Self::Integer { min, max }
    }

    #[must_use]
    pub const fn float() -> Self {
        Self::Float {
            min: None,
            max: None,
            exclusive_min: None,
            exclusive_max: None,
        }
    }

    #[must_use]
    pub const fn bounded_float(min: Option<FLOAT>, max: Option<FLOAT>) -> Self {
        Self::Float {
            min,
            max,
            exclusive_min: None,
            exclusive_max: None,
        }
    }

    #[must_use]
    pub const fn number() -> Self {
        Self::Number {
            min: None,
            max: None,
            exclusive_min: None,
            exclusive_max: None,
        }
    }

    #[must_use]
    pub const fn bounded_number(min: Option<FLOAT>, max: Option<FLOAT>) -> Self {
        Self::Number {
            min,
            max,
            exclusive_min: None,
            exclusive_max: None,
        }
    }

    #[must_use]
    pub const fn positive_number() -> Self {
        Self::Number {
            min: None,
            max: None,
            exclusive_min: Some(0.0),
            exclusive_max: None,
        }
    }

    #[must_use]
    pub fn enumeration(values: impl IntoIterator<Item = impl Into<String>>) -> Self {
        Self::String {
            allowed: values.into_iter().map(Into::into).collect(),
        }
    }

    #[must_use]
    pub fn optional(value: Self) -> Self {
        Self::Optional {
            value: Box::new(value),
        }
    }

    #[must_use]
    pub fn one_of(variants: impl IntoIterator<Item = Self>) -> Self {
        Self::OneOf {
            variants: variants.into_iter().collect(),
        }
    }

    #[must_use]
    pub fn object(fields: BTreeMap<String, ObjectField>) -> Self {
        Self::Object {
            fields,
            allow_unknown: false,
        }
    }

    /// Validate the schema itself before it is used for props or events.
    ///
    /// # Errors
    ///
    /// Returns [`SchemaDefinitionError`] for inverted/non-finite bounds, an
    /// empty union, duplicate enum values, or an invalid nested definition.
    pub fn validate_definition(&self) -> Result<(), SchemaDefinitionError> {
        self.validate_definition_at("$")
    }

    fn validate_definition_at(&self, path: &str) -> Result<(), SchemaDefinitionError> {
        match self {
            Self::Integer { min, max } => validate_integer_bounds(*min, *max, path),
            Self::Float {
                min,
                max,
                exclusive_min,
                exclusive_max,
            }
            | Self::Number {
                min,
                max,
                exclusive_min,
                exclusive_max,
            } => validate_float_bounds(*min, *max, *exclusive_min, *exclusive_max, path),
            Self::String { allowed } => {
                let mut unique = BTreeSet::new();
                if let Some(duplicate) = allowed.iter().find(|value| !unique.insert(*value)) {
                    return Err(SchemaDefinitionError::new(
                        path,
                        format!("allowed string value `{duplicate}` is duplicated"),
                    ));
                }
                Ok(())
            }
            Self::Array { items, .. } => items.validate_definition_at(&format!("{path}.items")),
            Self::Map { values } => values.validate_definition_at(&format!("{path}.values")),
            Self::Object { fields, .. } => {
                for (name, field) in fields {
                    field
                        .schema
                        .validate_definition_at(&format!("{path}.fields.{name}"))?;
                }
                Ok(())
            }
            Self::Optional { value } => value.validate_definition_at(&format!("{path}.value")),
            Self::OneOf { variants } => {
                if variants.is_empty() {
                    return Err(SchemaDefinitionError::new(
                        path,
                        "one_of must contain at least one variant",
                    ));
                }
                for (index, variant) in variants.iter().enumerate() {
                    variant.validate_definition_at(&format!("{path}.variants[{index}]"))?;
                }
                Ok(())
            }
            Self::Handle { kind } if kind.trim().is_empty() => Err(SchemaDefinitionError::new(
                path,
                "handle kind cannot be empty",
            )),
            Self::Null
            | Self::Bool
            | Self::Node
            | Self::Callback
            | Self::Style
            | Self::Length
            | Self::UiValue
            | Self::Asset
            | Self::Signal
            | Self::Collection
            | Self::Document
            | Self::Ref
            | Self::Handle { .. } => Ok(()),
            #[cfg(feature = "charts")]
            Self::ChartData => Ok(()),
        }
    }

    /// Validate a Rhai runtime value and collect all detectable schema issues.
    ///
    /// # Errors
    ///
    /// Returns [`SchemaValidationError`] with precise value paths when one or
    /// more constraints fail.
    pub fn validate(&self, value: &Dynamic) -> Result<(), SchemaValidationError> {
        let mut issues = Vec::new();
        self.validate_at(value, "$", &mut issues);
        if issues.is_empty() {
            Ok(())
        } else {
            Err(SchemaValidationError { issues })
        }
    }

    /// Validate a durable host value before converting it back into Rhai.
    ///
    /// # Errors
    ///
    /// Returns all detected durable-domain or schema violations.
    pub fn validate_ui_value(&self, value: &UiValue) -> Result<(), SchemaValidationError> {
        value.validate().map_err(|error| SchemaValidationError {
            issues: vec![SchemaIssue::new("$", error.to_string())],
        })?;
        self.validate(&value.clone().into_dynamic())
    }

    /// Validate an online durable payload without constructing an unbounded
    /// issue list or converting the complete value back into `Dynamic`.
    pub(crate) fn validate_ui_value_first(
        &self,
        value: &UiValue,
    ) -> Result<(), SchemaValidationError> {
        value.validate().map_err(|error| SchemaValidationError {
            issues: vec![SchemaIssue::new("$", error.to_string())],
        })?;
        self.validate_ui_value_at_first(value, "$")
            .map_or(Ok(()), |issue| {
                Err(SchemaValidationError {
                    issues: vec![issue],
                })
            })
    }

    #[allow(clippy::too_many_lines)]
    fn validate_ui_value_at_first(&self, value: &UiValue, path: &str) -> Option<SchemaIssue> {
        let expected = |name: &str| {
            Some(SchemaIssue::new(
                path,
                format!("expected {name}, got {}", ui_value_type_name(value)),
            ))
        };
        match self {
            Self::Null => (!matches!(value, UiValue::Null))
                .then(|| expected("null"))
                .flatten(),
            Self::Bool => (!matches!(value, UiValue::Bool(_)))
                .then(|| expected("bool"))
                .flatten(),
            Self::Integer { min, max } => match value {
                UiValue::Integer(value) => {
                    if min.is_some_and(|min| *value < min) {
                        Some(SchemaIssue::new(
                            path,
                            format!("expected integer >= {}, got {value}", min.unwrap()),
                        ))
                    } else if max.is_some_and(|max| *value > max) {
                        Some(SchemaIssue::new(
                            path,
                            format!("expected integer <= {}, got {value}", max.unwrap()),
                        ))
                    } else {
                        None
                    }
                }
                _ => expected("integer"),
            },
            Self::Float {
                min,
                max,
                exclusive_min,
                exclusive_max,
            } => match value {
                UiValue::Float(value) => {
                    first_float_issue(*value, *min, *max, *exclusive_min, *exclusive_max, path)
                }
                _ => expected("float"),
            },
            Self::Number {
                min,
                max,
                exclusive_min,
                exclusive_max,
            } => match value {
                UiValue::Float(value) => {
                    first_float_issue(*value, *min, *max, *exclusive_min, *exclusive_max, path)
                }
                UiValue::Integer(value) => first_float_issue(
                    integer_as_float(*value),
                    *min,
                    *max,
                    *exclusive_min,
                    *exclusive_max,
                    path,
                ),
                _ => expected("number"),
            },
            Self::String { allowed } => match value {
                UiValue::String(value)
                    if !allowed.is_empty() && !allowed.iter().any(|item| item == value) =>
                {
                    Some(SchemaIssue::new(
                        path,
                        format!("expected one of [{}], got `{value}`", allowed.join(", ")),
                    ))
                }
                UiValue::String(_) => None,
                _ => expected("string"),
            },
            Self::Array { items, max_items } => match value {
                UiValue::Array(values) => {
                    if max_items.is_some_and(|max| values.len() > max) {
                        Some(SchemaIssue::new(
                            path,
                            format!(
                                "expected at most {} items, got {}",
                                max_items.unwrap(),
                                values.len()
                            ),
                        ))
                    } else {
                        values.iter().enumerate().find_map(|(index, value)| {
                            items.validate_ui_value_at_first(value, &format!("{path}[{index}]"))
                        })
                    }
                }
                _ => expected("array"),
            },
            Self::Map { values } => match value {
                UiValue::Map(items) => items.iter().find_map(|(key, value)| {
                    values.validate_ui_value_at_first(value, &format!("{path}.{key}"))
                }),
                _ => expected("map"),
            },
            Self::Object {
                fields,
                allow_unknown,
            } => match value {
                UiValue::Map(values) => {
                    let field_issue = fields.iter().find_map(|(name, field)| {
                        values.get(name).map_or_else(
                            || {
                                field.required.then(|| {
                                    SchemaIssue::new(
                                        format!("{path}.{name}"),
                                        "required field is missing",
                                    )
                                })
                            },
                            |value| {
                                field
                                    .schema
                                    .validate_ui_value_at_first(value, &format!("{path}.{name}"))
                            },
                        )
                    });
                    field_issue.or_else(|| {
                        (!*allow_unknown).then(|| {
                            values
                                .keys()
                                .find(|key| !fields.contains_key(*key))
                                .map(|key| {
                                    SchemaIssue::new(format!("{path}.{key}"), "unknown field")
                                })
                        })?
                    })
                }
                _ => expected("object"),
            },
            Self::Optional { value: schema } => {
                if matches!(value, UiValue::Null) {
                    None
                } else {
                    schema.validate_ui_value_at_first(value, path)
                }
            }
            Self::OneOf { variants } => {
                let failures = variants
                    .iter()
                    .map(|variant| variant.validate_ui_value_at_first(value, path))
                    .collect::<Vec<_>>();
                if failures.iter().any(Option::is_none) {
                    None
                } else {
                    Some(SchemaIssue::new(
                        path,
                        format!(
                            "value did not match any one_of variant ({})",
                            failures
                                .into_iter()
                                .enumerate()
                                .filter_map(|(index, issue)| issue
                                    .map(|issue| format!("variant {index}: {}", issue.message)))
                                .collect::<Vec<_>>()
                                .join("; ")
                        ),
                    ))
                }
            }
            Self::UiValue => None,
            Self::Handle { kind } => match value {
                UiValue::Handle(handle) if handle.kind() == kind => None,
                UiValue::Handle(handle) => Some(SchemaIssue::new(
                    path,
                    format!("expected `{kind}` handle, got `{}` handle", handle.kind()),
                )),
                _ => expected(&format!("{kind} handle")),
            },
            Self::Node => expected("UiNode"),
            Self::Callback => expected("callback or NativeHandlerRef"),
            Self::Style => expected("Style"),
            Self::Length => expected("Length"),
            Self::Asset => expected("AssetId"),
            Self::Signal => expected("NativeSignal"),
            Self::Collection => expected("NativeCollection"),
            Self::Document => expected("NativeTextDocument"),
            #[cfg(feature = "charts")]
            Self::ChartData => expected("NativeChartData"),
            Self::Ref => expected("ElementRef"),
        }
    }

    fn validate_at(&self, value: &Dynamic, path: &str, issues: &mut Vec<SchemaIssue>) {
        match self {
            Self::Null => expect_type(value.is_unit(), value, path, "null", issues),
            Self::Bool => expect_type(value.is::<bool>(), value, path, "bool", issues),
            Self::Integer { min, max } => validate_integer(value, *min, *max, path, issues),
            Self::Float {
                min,
                max,
                exclusive_min,
                exclusive_max,
            } => validate_float(
                value,
                *min,
                *max,
                *exclusive_min,
                *exclusive_max,
                path,
                issues,
            ),
            Self::Number {
                min,
                max,
                exclusive_min,
                exclusive_max,
            } => validate_number(
                value,
                *min,
                *max,
                *exclusive_min,
                *exclusive_max,
                path,
                issues,
            ),
            Self::String { allowed } => validate_string(value, allowed, path, issues),
            Self::Array { items, max_items } => {
                validate_array(value, items, *max_items, path, issues);
            }
            Self::Map { values } => validate_map(value, values, path, issues),
            Self::Object {
                fields,
                allow_unknown,
            } => validate_object_value(value, fields, *allow_unknown, path, issues),
            Self::Optional { value: schema } => {
                if !value.is_unit() {
                    schema.validate_at(value, path, issues);
                }
            }
            Self::OneOf { variants } => validate_one_of(value, variants, path, issues),
            Self::Node => expect_type(value.is::<UiNode>(), value, path, "UiNode", issues),
            Self::Callback => expect_type(
                value.is::<FnPtr>() || value.is::<crate::NativeHandlerRef>(),
                value,
                path,
                "callback or NativeHandlerRef",
                issues,
            ),
            Self::Style => expect_type(value.is::<Style>(), value, path, "Style", issues),
            Self::Length => validate_length(value, path, issues),
            Self::UiValue => {
                if let Err(error) = UiValue::from_dynamic(value.clone()) {
                    issues.push(SchemaIssue::new(path, error.to_string()));
                }
            }
            Self::Asset => expect_type(value.is::<AssetId>(), value, path, "AssetId", issues),
            Self::Signal => expect_type(
                value.is::<NativeSignal>(),
                value,
                path,
                "NativeSignal",
                issues,
            ),
            Self::Collection => expect_type(
                value.is::<crate::NativeCollection>(),
                value,
                path,
                "NativeCollection",
                issues,
            ),
            Self::Document => expect_type(
                value.is::<crate::NativeTextDocument>(),
                value,
                path,
                "NativeTextDocument",
                issues,
            ),
            #[cfg(feature = "charts")]
            Self::ChartData => expect_type(
                value.is::<crate::NativeChartData>(),
                value,
                path,
                "NativeChartData",
                issues,
            ),
            Self::Ref => expect_type(value.is::<ElementRef>(), value, path, "ElementRef", issues),
            Self::Handle { kind } => validate_handle(value, kind, path, issues),
        }
    }
}

fn ui_value_type_name(value: &UiValue) -> &'static str {
    match value {
        UiValue::Null => "null",
        UiValue::Bool(_) => "bool",
        UiValue::Integer(_) => "integer",
        UiValue::Float(_) => "float",
        UiValue::String(_) => "string",
        UiValue::Array(_) => "array",
        UiValue::Map(_) => "map",
        UiValue::Handle(_) => "handle",
    }
}

fn first_float_issue(
    value: FLOAT,
    min: Option<FLOAT>,
    max: Option<FLOAT>,
    exclusive_min: Option<FLOAT>,
    exclusive_max: Option<FLOAT>,
    path: &str,
) -> Option<SchemaIssue> {
    if !value.is_finite() {
        Some(SchemaIssue::new(path, "number must be finite"))
    } else if min.is_some_and(|min| value < min) {
        Some(SchemaIssue::new(
            path,
            format!("expected number >= {}, got {value}", min.unwrap()),
        ))
    } else if max.is_some_and(|max| value > max) {
        Some(SchemaIssue::new(
            path,
            format!("expected number <= {}, got {value}", max.unwrap()),
        ))
    } else if exclusive_min.is_some_and(|min| value <= min) {
        Some(SchemaIssue::new(
            path,
            format!("expected number > {}, got {value}", exclusive_min.unwrap()),
        ))
    } else if exclusive_max.is_some_and(|max| value >= max) {
        Some(SchemaIssue::new(
            path,
            format!("expected number < {}, got {value}", exclusive_max.unwrap()),
        ))
    } else {
        None
    }
}

fn validate_integer(
    value: &Dynamic,
    min: Option<INT>,
    max: Option<INT>,
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    if value.is::<INT>() {
        validate_integer_value(value.clone_cast::<INT>(), min, max, path, issues);
    } else {
        expect_type(false, value, path, "integer", issues);
    }
}

fn validate_float(
    value: &Dynamic,
    min: Option<FLOAT>,
    max: Option<FLOAT>,
    exclusive_min: Option<FLOAT>,
    exclusive_max: Option<FLOAT>,
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    if value.is::<FLOAT>() {
        validate_float_value(
            value.clone_cast::<FLOAT>(),
            min,
            max,
            exclusive_min,
            exclusive_max,
            path,
            issues,
        );
    } else {
        expect_type(false, value, path, "float", issues);
    }
}

fn validate_number(
    value: &Dynamic,
    min: Option<FLOAT>,
    max: Option<FLOAT>,
    exclusive_min: Option<FLOAT>,
    exclusive_max: Option<FLOAT>,
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    let number = if value.is::<INT>() {
        Some(integer_as_float(value.clone_cast::<INT>()))
    } else if value.is::<FLOAT>() {
        Some(value.clone_cast::<FLOAT>())
    } else {
        None
    };
    if let Some(number) = number {
        validate_float_value(number, min, max, exclusive_min, exclusive_max, path, issues);
    } else {
        expect_type(false, value, path, "number", issues);
    }
}

fn validate_string(value: &Dynamic, allowed: &[String], path: &str, issues: &mut Vec<SchemaIssue>) {
    if value.is::<ImmutableString>() {
        let actual = value.clone_cast::<ImmutableString>();
        if !allowed.is_empty() && !allowed.iter().any(|allowed| allowed == actual.as_str()) {
            issues.push(SchemaIssue::new(
                path,
                format!("expected one of [{}], got `{actual}`", allowed.join(", ")),
            ));
        }
    } else {
        expect_type(false, value, path, "string", issues);
    }
}

fn validate_array(
    value: &Dynamic,
    items: &ValueSchema,
    max_items: Option<usize>,
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    if !value.is::<Array>() {
        expect_type(false, value, path, "array", issues);
        return;
    }
    let values = value.clone_cast::<Array>();
    if let Some(max_items) = max_items
        && values.len() > max_items
    {
        issues.push(SchemaIssue::new(
            path,
            format!("expected at most {max_items} items, got {}", values.len()),
        ));
    }
    for (index, item) in values.iter().enumerate() {
        items.validate_at(item, &format!("{path}[{index}]"), issues);
    }
}

fn validate_map(value: &Dynamic, values: &ValueSchema, path: &str, issues: &mut Vec<SchemaIssue>) {
    if !value.is::<Map>() {
        expect_type(false, value, path, "map", issues);
        return;
    }
    for (key, item) in value.clone_cast::<Map>() {
        values.validate_at(&item, &format!("{path}.{key}"), issues);
    }
}

fn validate_object_value(
    value: &Dynamic,
    fields: &BTreeMap<String, ObjectField>,
    allow_unknown: bool,
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    if value.is::<Map>() {
        validate_object(
            &value.clone_cast::<Map>(),
            fields,
            allow_unknown,
            path,
            issues,
        );
    } else {
        expect_type(false, value, path, "object", issues);
    }
}

fn validate_one_of(
    value: &Dynamic,
    variants: &[ValueSchema],
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    let mut branch_issues = Vec::with_capacity(variants.len());
    for variant in variants {
        let mut candidate = Vec::new();
        variant.validate_at(value, path, &mut candidate);
        if candidate.is_empty() {
            return;
        }
        branch_issues.push(candidate);
    }
    let summary = branch_issues
        .iter()
        .enumerate()
        .map(|(index, candidate)| {
            let messages = candidate
                .iter()
                .map(|issue| issue.message.as_str())
                .collect::<Vec<_>>()
                .join(", ");
            format!("variant {index}: {messages}")
        })
        .collect::<Vec<_>>()
        .join("; ");
    issues.push(SchemaIssue::new(
        path,
        format!("value did not match any one_of variant ({summary})"),
    ));
}

fn validate_length(value: &Dynamic, path: &str, issues: &mut Vec<SchemaIssue>) {
    if value.is::<Length>() {
        let length = value.clone_cast::<Length>();
        if let Err(error) = length.validate() {
            issues.push(SchemaIssue::new(path, error.to_string()));
        }
    } else {
        expect_type(false, value, path, "Length", issues);
    }
}

fn validate_handle(value: &Dynamic, kind: &str, path: &str, issues: &mut Vec<SchemaIssue>) {
    if value.is::<OpaqueHandle>() {
        let handle = value.clone_cast::<OpaqueHandle>();
        if handle.kind() != kind {
            issues.push(SchemaIssue::new(
                path,
                format!("expected `{kind}` handle, got `{}` handle", handle.kind()),
            ));
        }
    } else {
        expect_type(false, value, path, &format!("{kind} handle"), issues);
    }
}

fn validate_integer_bounds(
    min: Option<INT>,
    max: Option<INT>,
    path: &str,
) -> Result<(), SchemaDefinitionError> {
    if min.zip(max).is_some_and(|(min, max)| min > max) {
        Err(SchemaDefinitionError::new(
            path,
            format!("integer minimum {min:?} exceeds maximum {max:?}"),
        ))
    } else {
        Ok(())
    }
}

fn validate_float_bounds(
    min: Option<FLOAT>,
    max: Option<FLOAT>,
    exclusive_min: Option<FLOAT>,
    exclusive_max: Option<FLOAT>,
    path: &str,
) -> Result<(), SchemaDefinitionError> {
    if min.is_some_and(|value| !value.is_finite())
        || max.is_some_and(|value| !value.is_finite())
        || exclusive_min.is_some_and(|value| !value.is_finite())
        || exclusive_max.is_some_and(|value| !value.is_finite())
    {
        return Err(SchemaDefinitionError::new(
            path,
            "numeric bounds must be finite",
        ));
    }
    if min.is_some() && exclusive_min.is_some() {
        return Err(SchemaDefinitionError::new(
            path,
            "numeric schema cannot define both min and exclusive_min",
        ));
    }
    if max.is_some() && exclusive_max.is_some() {
        return Err(SchemaDefinitionError::new(
            path,
            "numeric schema cannot define both max and exclusive_max",
        ));
    }
    let lower = min.or(exclusive_min);
    let upper = max.or(exclusive_max);
    let empty = lower.zip(upper).is_some_and(|(lower, upper)| {
        matches!(lower.total_cmp(&upper), Ordering::Greater)
            || (matches!(lower.total_cmp(&upper), Ordering::Equal)
                && (exclusive_min.is_some() || exclusive_max.is_some()))
    });
    if empty {
        Err(SchemaDefinitionError::new(
            path,
            format!("numeric lower bound {lower:?} does not precede upper bound {upper:?}"),
        ))
    } else {
        Ok(())
    }
}

fn validate_integer_value(
    value: INT,
    min: Option<INT>,
    max: Option<INT>,
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    if let Some(min) = min
        && value < min
    {
        issues.push(SchemaIssue::new(
            path,
            format!("expected integer >= {min}, got {value}"),
        ));
    }
    if let Some(max) = max
        && value > max
    {
        issues.push(SchemaIssue::new(
            path,
            format!("expected integer <= {max}, got {value}"),
        ));
    }
}

fn validate_float_value(
    value: FLOAT,
    min: Option<FLOAT>,
    max: Option<FLOAT>,
    exclusive_min: Option<FLOAT>,
    exclusive_max: Option<FLOAT>,
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    if !value.is_finite() {
        issues.push(SchemaIssue::new(path, "number must be finite"));
        return;
    }
    if let Some(min) = min
        && value < min
    {
        issues.push(SchemaIssue::new(
            path,
            format!("expected number >= {min}, got {value}"),
        ));
    }
    if let Some(max) = max
        && value > max
    {
        issues.push(SchemaIssue::new(
            path,
            format!("expected number <= {max}, got {value}"),
        ));
    }
    if let Some(min) = exclusive_min
        && value <= min
    {
        issues.push(SchemaIssue::new(
            path,
            format!("expected number > {min}, got {value}"),
        ));
    }
    if let Some(max) = exclusive_max
        && value >= max
    {
        issues.push(SchemaIssue::new(
            path,
            format!("expected number < {max}, got {value}"),
        ));
    }
}

fn integer_as_float(value: INT) -> FLOAT {
    value
        .to_string()
        .parse()
        .expect("an integer always has a finite float representation")
}

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct ObjectField {
    pub schema: ValueSchema,
    #[serde(default)]
    pub required: bool,
    #[serde(default)]
    pub sensitive: bool,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub default: Option<crate::UiValue>,
}

impl ObjectField {
    #[must_use]
    pub fn required(schema: ValueSchema) -> Self {
        Self {
            schema,
            required: true,
            sensitive: false,
            default: None,
        }
    }

    #[must_use]
    pub fn optional(schema: ValueSchema) -> Self {
        Self {
            schema,
            required: false,
            sensitive: false,
            default: None,
        }
    }

    #[must_use]
    pub fn sensitive(mut self) -> Self {
        self.sensitive = true;
        self
    }

    #[must_use]
    pub fn with_default(mut self, default: crate::UiValue) -> Self {
        self.default = Some(default);
        self
    }
}

fn validate_object(
    value: &Map,
    fields: &BTreeMap<String, ObjectField>,
    allow_unknown: bool,
    path: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    let actual_keys = value
        .keys()
        .map(ToString::to_string)
        .collect::<BTreeSet<_>>();

    for (name, field) in fields {
        match value.get(name.as_str()) {
            Some(value) => field
                .schema
                .validate_at(value, &format!("{path}.{name}"), issues),
            None if field.required => issues.push(SchemaIssue::new(
                format!("{path}.{name}"),
                "required field is missing",
            )),
            None => {}
        }
    }

    if !allow_unknown {
        for unknown in actual_keys.difference(&fields.keys().cloned().collect()) {
            issues.push(SchemaIssue::new(
                format!("{path}.{unknown}"),
                "unknown field",
            ));
        }
    }
}

fn expect_type(
    valid: bool,
    value: &Dynamic,
    path: &str,
    expected: &str,
    issues: &mut Vec<SchemaIssue>,
) {
    if !valid {
        issues.push(SchemaIssue::new(
            path,
            format!("expected {expected}, got {}", value.type_name()),
        ));
    }
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct SchemaIssue {
    pub path: String,
    pub message: String,
}

impl SchemaIssue {
    #[must_use]
    pub fn new(path: impl Into<String>, message: impl Into<String>) -> Self {
        Self {
            path: path.into(),
            message: message.into(),
        }
    }
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct SchemaValidationError {
    pub issues: Vec<SchemaIssue>,
}

impl fmt::Display for SchemaValidationError {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        for (index, issue) in self.issues.iter().enumerate() {
            if index > 0 {
                formatter.write_str("; ")?;
            }
            write!(formatter, "{}: {}", issue.path, issue.message)?;
        }
        Ok(())
    }
}

impl std::error::Error for SchemaValidationError {}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct SchemaDefinitionError {
    pub path: String,
    pub message: String,
}

impl SchemaDefinitionError {
    #[must_use]
    pub fn new(path: impl Into<String>, message: impl Into<String>) -> Self {
        Self {
            path: path.into(),
            message: message.into(),
        }
    }
}

impl fmt::Display for SchemaDefinitionError {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(formatter, "{}: {}", self.path, self.message)
    }
}

impl std::error::Error for SchemaDefinitionError {}

#[cfg(test)]
mod tests {
    use super::*;

    fn button_schema() -> ValueSchema {
        ValueSchema::object(BTreeMap::from([
            (
                "text".to_owned(),
                ObjectField::required(ValueSchema::string()),
            ),
            (
                "variant".to_owned(),
                ObjectField::optional(ValueSchema::enumeration(["primary", "secondary"])),
            ),
            (
                "on_click".to_owned(),
                ObjectField::optional(ValueSchema::Callback),
            ),
        ]))
    }

    #[test]
    fn objects_report_all_precise_paths() {
        let value = Dynamic::from_map(Map::from_iter([
            ("variant".into(), Dynamic::from("danger")),
            ("lable".into(), Dynamic::from("Save")),
        ]));
        let error = button_schema().validate(&value).unwrap_err();

        assert_eq!(
            error.issues,
            vec![
                SchemaIssue::new("$.text", "required field is missing"),
                SchemaIssue::new(
                    "$.variant",
                    "expected one of [primary, secondary], got `danger`",
                ),
                SchemaIssue::new("$.lable", "unknown field"),
            ]
        );
    }

    #[test]
    fn node_callback_and_handle_types_are_distinct() {
        ValueSchema::Node
            .validate(&Dynamic::from(UiNode::text("content")))
            .unwrap();
        ValueSchema::Callback
            .validate(&Dynamic::from(FnPtr::new("clicked").unwrap()))
            .unwrap();
        ValueSchema::Handle {
            kind: "image".to_owned(),
        }
        .validate(&Dynamic::from(OpaqueHandle::new("image", 42)))
        .unwrap();

        let error = ValueSchema::Handle {
            kind: "image".to_owned(),
        }
        .validate(&Dynamic::from(OpaqueHandle::new("task", 42)))
        .unwrap_err();
        assert_eq!(error.issues[0].path, "$".to_owned());
    }

    #[test]
    fn bounds_and_unions_report_precise_failures() {
        let schema = ValueSchema::one_of([
            ValueSchema::bounded_integer(Some(1), Some(3)),
            ValueSchema::enumeration(["auto"]),
        ]);
        schema.validate_definition().unwrap();
        schema.validate(&Dynamic::from(2_i64)).unwrap();
        schema.validate(&Dynamic::from("auto")).unwrap();

        let error = schema.validate(&Dynamic::from(9_i64)).unwrap_err();
        assert_eq!(error.issues.len(), 1);
        assert!(error.issues[0].message.contains("integer <= 3"));
        assert!(error.issues[0].message.contains("expected string"));
    }

    #[test]
    fn invalid_definitions_are_rejected() {
        assert!(matches!(
            ValueSchema::bounded_integer(Some(4), Some(2)).validate_definition(),
            Err(SchemaDefinitionError { ref path, .. }) if path == "$"
        ));
        assert!(ValueSchema::one_of([]).validate_definition().is_err());
        assert!(
            ValueSchema::bounded_number(Some(f64::NAN), None)
                .validate_definition()
                .is_err()
        );
        ValueSchema::positive_number()
            .validate(&Dynamic::from(0.5_f64))
            .unwrap();
        assert!(
            ValueSchema::positive_number()
                .validate(&Dynamic::from(0_i64))
                .is_err()
        );
    }

    #[test]
    fn length_ui_value_and_asset_are_distinct() {
        ValueSchema::Length
            .validate(&Dynamic::from(Length::pixels(12.0).unwrap()))
            .unwrap();
        ValueSchema::UiValue
            .validate(&Dynamic::from_map(Map::from_iter([(
                "nested".into(),
                Dynamic::from_array(vec![Dynamic::from(1_i64)]),
            )])))
            .unwrap();
        ValueSchema::Asset
            .validate(&Dynamic::from(AssetId::parse("app/check").unwrap()))
            .unwrap();
        assert!(
            ValueSchema::UiValue
                .validate(&Dynamic::from(UiNode::text("not data")))
                .is_err()
        );
    }

    #[test]
    fn online_ui_value_validation_stops_after_the_first_issue() {
        let value = UiValue::Map(
            (0..100_000)
                .map(|index| (format!("field-{index}"), UiValue::Null))
                .collect(),
        );
        let error = ValueSchema::Map {
            values: Box::new(ValueSchema::integer()),
        }
        .validate_ui_value_first(&value)
        .unwrap_err();
        assert_eq!(error.issues.len(), 1);
        assert_eq!(error.issues[0].path, "$.field-0");
    }

    #[test]
    fn online_and_complete_durable_validation_agree_on_acceptance() {
        let cases = [
            (ValueSchema::integer(), UiValue::Integer(2)),
            (ValueSchema::integer(), UiValue::Null),
            (
                ValueSchema::Array {
                    items: Box::new(ValueSchema::string()),
                    max_items: Some(2),
                },
                UiValue::Array(vec![UiValue::String("ok".to_owned())]),
            ),
            (
                ValueSchema::Array {
                    items: Box::new(ValueSchema::string()),
                    max_items: Some(2),
                },
                UiValue::Array(vec![UiValue::Integer(1)]),
            ),
            (
                button_schema(),
                UiValue::Map(BTreeMap::from([(
                    "text".to_owned(),
                    UiValue::String("Save".to_owned()),
                )])),
            ),
            (
                button_schema(),
                UiValue::Map(BTreeMap::from([(
                    "variant".to_owned(),
                    UiValue::String("danger".to_owned()),
                )])),
            ),
        ];
        for (schema, value) in cases {
            assert_eq!(
                schema.validate_ui_value(&value).is_ok(),
                schema.validate_ui_value_first(&value).is_ok(),
                "schema={schema:?}, value={value:?}"
            );
        }
    }
}