mago-analyzer 1.18.1

use mago_atom::Atom;

use mago_codex::metadata::class_like::ClassLikeMetadata;
use mago_codex::ttype::atomic::TAtomic;
use mago_codex::ttype::atomic::generic::TGenericParameter;
use mago_codex::ttype::atomic::object::TObject;
use mago_codex::ttype::atomic::object::r#enum::TEnum;
use mago_codex::ttype::atomic::scalar::TScalar;
use mago_codex::ttype::atomic::scalar::class_like_string::TClassLikeString;
use mago_codex::ttype::atomic::scalar::class_like_string::TClassLikeStringKind;
use mago_codex::ttype::expander;
use mago_codex::ttype::expander::StaticClassType;
use mago_codex::ttype::expander::TypeExpansionOptions;
use mago_codex::ttype::get_class_string;
use mago_codex::ttype::get_mixed;
use mago_codex::ttype::union::TUnion;
use mago_codex::ttype::wrap_atomic;
use mago_reporting::Annotation;
use mago_reporting::Issue;
use mago_span::HasSpan;
use mago_span::Span;
use mago_syntax::ast::ClassLikeConstantSelector;
use mago_syntax::ast::Expression;

use crate::artifacts::AnalysisArtifacts;
use crate::code::IssueCode;
use crate::context::Context;
use crate::context::block::BlockContext;
use crate::error::AnalysisError;
use crate::resolver::class_name::ResolutionOrigin;
use crate::resolver::class_name::ResolvedClassname;
use crate::resolver::class_name::resolve_classnames_from_expression;
use crate::resolver::selector::ResolvedSelector;
use crate::resolver::selector::resolve_constant_selector;

/// Represents a successfully resolved class constant or enum case.
#[derive(Debug)]
pub struct ResolvedConstant {
    /// The type of the constant's value or the enum case itself.
    pub const_type: TUnion,
}

/// Holds the results of a constant resolution attempt.
#[derive(Debug, Default)]
pub struct ConstantResolutionResult {
    /// A list of successfully resolved constants and their types.
    pub constants: Vec<ResolvedConstant>,
    /// Flag indicating if any part of the resolution was ambiguous or dynamic.
    pub has_ambiguous_path: bool,
    /// Flag indicating if any part of the resolution was definitively invalid.
    pub has_invalid_path: bool,
}

/// Resolves all possible class constants from a class expression and a constant selector.
pub fn resolve_class_constants<'ctx, 'ast, 'arena>(
    context: &mut Context<'ctx, 'arena>,
    block_context: &mut BlockContext<'ctx>,
    artifacts: &mut AnalysisArtifacts,
    class_expr: &'ast Expression<'arena>,
    constant_selector: &'ast ClassLikeConstantSelector<'arena>,
    class_expr_is_analyzed: bool,
) -> Result<ConstantResolutionResult, AnalysisError> {
    let mut result = ConstantResolutionResult::default();

    // 1. Resolve all possible class names from the expression.
    let classnames =
        resolve_classnames_from_expression(context, block_context, artifacts, class_expr, class_expr_is_analyzed)?;

    // 2. Resolve all possible constant names from the selector.
    let selectors = resolve_constant_selector(context, block_context, artifacts, constant_selector)?;

    // 3. Iterate through each combination of class and constant to find valid constants.
    'resolved_classes: for class_resolution in &classnames {
        if class_resolution.is_possibly_invalid() {
            result.has_ambiguous_path = true;
            if class_resolution.origin == ResolutionOrigin::Invalid {
                result.has_invalid_path = true;
            }

            continue;
        }

        for selector_resolution in &selectors {
            // Handle `::class` magic constant
            if let ResolvedSelector::Identifier(const_name) = selector_resolution
                && const_name.eq_ignore_ascii_case("class")
            {
                if let Some(const_type) = handle_class_magic_constant(
                    context,
                    block_context,
                    artifacts,
                    class_resolution,
                    class_expr,
                    constant_selector,
                ) {
                    result.constants.push(ResolvedConstant { const_type });
                } else {
                    result.has_invalid_path = true;
                }

                continue;
            }

            let Some(fq_class_id) = class_resolution.fqcn else {
                result.has_ambiguous_path = true;
                report_ambiguous_constant_access(context, class_expr);
                continue 'resolved_classes;
            };

            if selector_resolution.is_dynamic() {
                result.has_ambiguous_path = true;
                continue;
            }

            let Some(const_name) = selector_resolution.name() else {
                result.has_invalid_path = true;
                continue;
            };

            // Handle regular constants and enum cases
            let Some(metadata) = context.codebase.get_class_like(&fq_class_id) else {
                result.has_invalid_path = true;
                report_non_existent_class(context, fq_class_id, class_expr.span());
                continue;
            };

            artifacts.symbol_references.add_reference_to_class_member(
                &block_context.scope,
                (fq_class_id, const_name),
                false,
            );

            if let Some(resolved_const) = find_constant_in_class(
                context,
                metadata,
                const_name,
                class_expr.span(),
                constant_selector.span(),
                &class_resolution.origin,
            ) {
                result.constants.push(resolved_const);
            } else {
                result.has_invalid_path = true;
            }
        }
    }

    Ok(result)
}

/// Specific handler for the `::class` magic constant.
fn handle_class_magic_constant<'ctx, 'ast, 'arena>(
    context: &mut Context<'ctx, 'arena>,
    block_context: &mut BlockContext<'ctx>,
    artifacts: &mut AnalysisArtifacts,
    class_resolution: &ResolvedClassname,
    class_expr: &'ast Expression<'arena>,
    selector: &'ast ClassLikeConstantSelector<'arena>,
) -> Option<TUnion> {
    if matches!(class_resolution.origin, ResolutionOrigin::AnyString) {
        context.collector.report_with_code(
            IssueCode::InvalidClassConstantOnString,
            Issue::error("Cannot use `::class` on an expression of type string.")
                .with_annotation(
                    Annotation::primary(class_expr.span()).with_message("This expression is a string here"),
                )
                .with_annotation(Annotation::secondary(selector.span()).with_message("`::class` used here"))
                .with_note("The `::class` magic constant requires a direct class name or an object instance."),
        );

        return None;
    }

    let class_string = match class_resolution.fqcn {
        Some(fq_class_id) => {
            artifacts.symbol_references.add_reference_to_symbol(&block_context.scope, fq_class_id, false);

            if class_resolution.is_final
                || class_resolution.is_from_literal_class_string()
                || class_resolution.is_named()
            {
                TScalar::ClassLikeString(TClassLikeString::literal(fq_class_id))
            } else {
                TScalar::ClassLikeString(TClassLikeString::of_type(
                    TClassLikeStringKind::Class,
                    class_resolution.get_object_type(context.codebase),
                ))
            }
        }
        None => {
            if let Some(expr_type) = artifacts.get_expression_type(class_expr) {
                for atomic in expr_type.types.as_ref() {
                    if let TAtomic::GenericParameter(TGenericParameter {
                        parameter_name,
                        defining_entity,
                        constraint,
                        ..
                    }) = atomic
                    {
                        return Some(wrap_atomic(TAtomic::Scalar(TScalar::ClassLikeString(
                            TClassLikeString::generic(
                                TClassLikeStringKind::Class,
                                *parameter_name,
                                *defining_entity,
                                constraint.get_single().clone(),
                            ),
                        ))));
                    }
                }
            }

            return Some(get_class_string());
        }
    };

    Some(TUnion::from_atomic(TAtomic::Scalar(class_string)))
}

/// Checks if a trait constant access is valid based on how the trait is referenced.
/// Valid accesses are via self, static, or $this (which resolve the trait in context).
/// Direct trait name access (e.g., `TraitName::CONSTANT`) is invalid.
fn is_valid_trait_constant_access(origin: &ResolutionOrigin) -> bool {
    matches!(
        origin,
        // self::CONSTANT
        ResolutionOrigin::Named { is_self: true, .. }
        // parent::CONSTANT
        | ResolutionOrigin::Named { is_parent: true, .. }
        // static::CONSTANT
        | ResolutionOrigin::Static { .. }
        // $this::CONSTANT
        | ResolutionOrigin::Object { is_this: true }
    )
}

/// Finds a constant or enum case by name within a class.
fn find_constant_in_class<'ctx>(
    context: &mut Context<'ctx, '_>,
    metadata: &'ctx ClassLikeMetadata,
    const_name: Atom,
    class_span: Span,
    const_span: Span,
    resolution_origin: &ResolutionOrigin,
) -> Option<ResolvedConstant> {
    if metadata.kind.is_trait() && !is_valid_trait_constant_access(resolution_origin) {
        context.collector.report_with_code(
            IssueCode::DirectTraitConstantAccess,
            Issue::error(format!(
                "Cannot access trait constant `{}::{}` directly.",
                metadata.original_name, const_name
            ))
            .with_annotation(
                Annotation::primary(class_span).with_message(format!("`{}` is a trait", metadata.original_name)),
            )
            .with_annotation(Annotation::secondary(const_span).with_message("Constant accessed here"))
            .with_note("Trait constants can only be accessed through classes that use the trait, or via self, static, or $this within the trait.")
            .with_help(format!("Access this constant through a class that uses `{}`, or use `self::{}`, `static::{}`, or `$this::{}` instead.", metadata.original_name, const_name, const_name, const_name)),
        );
    }

    // Check for a defined constant
    if let Some(constant_metadata) = metadata.constants.get(&const_name) {
        // Prefer the docblock type (@var) when it exists, as it reflects the user's
        // intended type. When type_metadata was merely copied from the type declaration
        // (they are equal), fall back to the more specific inferred type.
        let mut const_type = if let Some(type_metadata) = &constant_metadata.type_metadata
            && type_metadata.from_docblock
        {
            type_metadata.type_union.clone()
        } else {
            constant_metadata
                .inferred_type
                .clone()
                .map(wrap_atomic)
                .or_else(|| constant_metadata.type_metadata.clone().map(|s| s.type_union))
                .unwrap_or_else(get_mixed)
        };

        expander::expand_union(
            context.codebase,
            &mut const_type,
            &TypeExpansionOptions {
                self_class: Some(metadata.name),
                static_class_type: StaticClassType::Name(metadata.name),
                parent_class: metadata.direct_parent_class,
                function_is_final: metadata.flags.is_final(),
                ..Default::default()
            },
        );

        return Some(ResolvedConstant { const_type });
    }

    // Check for an enum case
    if metadata.kind.is_enum() && metadata.enum_cases.contains_key(&const_name) {
        let const_type =
            TUnion::from_atomic(TAtomic::Object(TObject::Enum(TEnum::new_case(metadata.original_name, const_name))));

        return Some(ResolvedConstant { const_type });
    }

    for required_class in metadata.require_extends.iter().chain(metadata.require_implements.iter()) {
        let Some(required_metadata) = context.codebase.get_class_like(required_class) else {
            continue;
        };

        if let Some(constant_metadata) = required_metadata.constants.get(&const_name) {
            let mut const_type = if let Some(type_metadata) = &constant_metadata.type_metadata
                && type_metadata.from_docblock
            {
                type_metadata.type_union.clone()
            } else {
                constant_metadata
                    .inferred_type
                    .clone()
                    .map(wrap_atomic)
                    .or_else(|| constant_metadata.type_metadata.clone().map(|s| s.type_union))
                    .unwrap_or_else(get_mixed)
            };

            expander::expand_union(
                context.codebase,
                &mut const_type,
                &TypeExpansionOptions {
                    self_class: Some(required_metadata.name),
                    static_class_type: StaticClassType::Name(required_metadata.name),
                    parent_class: required_metadata.direct_parent_class,
                    function_is_final: required_metadata.flags.is_final(),
                    ..Default::default()
                },
            );

            return Some(ResolvedConstant { const_type });
        }

        if required_metadata.kind.is_enum() && required_metadata.enum_cases.contains_key(&const_name) {
            let const_type = TUnion::from_atomic(TAtomic::Object(TObject::Enum(TEnum::new_case(
                required_metadata.original_name,
                const_name,
            ))));

            return Some(ResolvedConstant { const_type });
        }
    }

    // Not found, report error.
    report_non_existent_constant(context, metadata, const_name, class_span, const_span);
    None
}

/// Reports an error for a class-like that cannot be found in the codebase.
fn report_non_existent_class(context: &mut Context<'_, '_>, classname: Atom, class_span: Span) {
    context.collector.report_with_code(
        IssueCode::NonExistentClassLike,
        Issue::error(format!("Class, interface, enum, or trait `{classname}` not found."))
            .with_annotation(
                Annotation::primary(class_span)
                    .with_message(format!("`{classname}` is not defined or cannot be found")),
            )
            .with_help(
                "Ensure the name is correct, including its namespace, and that it's properly defined and autoloadable.",
            ),
    );
}

fn report_non_existent_constant<'ctx>(
    context: &mut Context<'ctx, '_>,
    metadata: &'ctx ClassLikeMetadata,
    const_name: Atom,
    class_span: Span,
    const_span: Span,
) {
    let class_kind_str = metadata.kind.as_str();
    let class_str = &metadata.original_name;

    let (main_message, primary_annotation_message) = if metadata.kind.is_enum() {
        (
            format!("Enum constant or case `{const_name}` does not exist."),
            format!("Constant or case `{const_name}` not found in enum `{class_str}`"),
        )
    } else {
        (
            format!("Class-like constant `{const_name}` does not exist."),
            format!("Constant `{const_name}` not found in `{class_str}`"),
        )
    };

    context.collector.report_with_code(
        IssueCode::NonExistentClassConstant,
        Issue::error(main_message)
            .with_annotation(Annotation::primary(const_span).with_message(primary_annotation_message))
            .with_annotation(
                Annotation::secondary(class_span).with_message(format!("On this {class_kind_str} `{class_str}`")),
            )
            .with_help(format!(
                "Check for typos or ensure `{const_name}` is defined in `{class_str}` or its ancestors/interfaces.",
            )),
    );
}

/// Reports a warning when a constant is accessed on an ambiguous type like `object` or `class-string`.
fn report_ambiguous_constant_access<'arena>(context: &mut Context<'_, 'arena>, class_expr: &Expression<'arena>) {
    context.collector.report_with_code(
        IssueCode::AmbiguousClassLikeConstantAccess,
        Issue::warning("Cannot reliably determine class for constant access due to an ambiguous type.")
            .with_annotation(
                Annotation::primary(class_expr.span())
                    .with_message("This expression does not specify a concrete class"),
            )
            .with_note("To fetch a class constant, the specific class must be known. General types like `object` or a generic `class-string` are too ambiguous for static analysis to verify constant existence.")
            .with_help("Provide a more specific type for the class expression (e.g., `MyClass`), or use `instanceof` checks to narrow it down before accessing constants."),
    );
}