type-inference

enum TypeData {
    Unknown,              // Inference not implemented
    UnknownKeyword,       // Explicit 'unknown' keyword
    String,               // String type
    Number,               // Number type
    Function(FunctionType), // Function with parameters
    Object(ObjectType),   // Object with properties
    Reference,            // Reference to another type
    // ... many more variants
}

enum TypeReference {
    Qualifier(TypeReferenceQualifier),  // Name-based reference
    Resolved(ResolvedTypeId),            // Resolved to type ID
    Import(TypeImportQualifier),         // Import reference
    Unknown,                             // Could not resolve
}

TypeData::TypeofExpression(TypeofExpression::Addition {
    left: TypeReference::from(TypeReferenceQualifier::from_name("a")),
    right: TypeReference::from(TypeReferenceQualifier::from_name("b"))
})

// 1. For tests
HardcodedSymbolResolver

// 2. For globals (Array, Promise, etc.)
GlobalsResolver

// 3. For thin inference (single module)
JsModuleInfoCollector

// 4. For full inference (across modules)
ModuleResolver

use biome_js_type_info::{TypeResolver, ResolvedTypeData};

fn analyze_type(resolver: &impl TypeResolver, type_ref: TypeReference) {
    // Resolve the reference
    let resolved_data: ResolvedTypeData = resolver.resolve_type(type_ref);
    
    // Get raw data for pattern matching
    match resolved_data.as_raw_data() {
        TypeData::String => { /* handle string */ },
        TypeData::Number => { /* handle number */ },
        TypeData::Function(func) => { /* handle function */ },
        _ => { /* handle others */ }
    }
    
    // Resolve nested references
    if let TypeData::Reference(inner_ref) = resolved_data.as_raw_data() {
        let inner_data = resolver.resolve_type(*inner_ref);
        // Process inner type
    }
}

use biome_analyze::Semantic;
use biome_js_type_info::{TypeResolver, TypeData};

impl Rule for MyTypeRule {
    type Query = Semantic<JsCallExpression>;
    
    fn run(ctx: &RuleContext<Self>) -> Self::Signals {
        let node = ctx.query();
        let model = ctx.model();
        
        // Get type resolver from model
        let resolver = model.type_resolver();
        
        // Get type of expression
        let expr_type = node.callee().ok()?.infer_type(resolver);
        
        // Check the type
        match expr_type.as_raw_data() {
            TypeData::Function(_) => { /* valid */ },
            TypeData::Unknown => { /* might be valid, can't tell */ },
            _ => { return Some(()); /* not callable */ }
        }
        
        None
    }
}

fn is_array_type(resolver: &impl TypeResolver, type_ref: TypeReference) -> bool {
    let resolved = resolver.resolve_type(type_ref);
    
    // Follow references
    let data = match resolved.as_raw_data() {
        TypeData::Reference(ref_to) => resolver.resolve_type(*ref_to),
        other => resolved,
    };
    
    // Check if it's an Array
    matches!(data.as_raw_data(), TypeData::Array(_))
}

fn analyze_function(resolver: &impl TypeResolver, type_ref: TypeReference) {
    let resolved = resolver.resolve_type(type_ref);
    
    if let TypeData::Function(func_type) = resolved.as_raw_data() {
        // Access parameters
        for param in func_type.parameters() {
            let param_type = resolver.resolve_type(param.type_ref());
            // Analyze parameter type
        }
        
        // Access return type
        let return_type = resolver.resolve_type(func_type.return_type());
    }
}

struct ResolvedTypeId(ResolverId, TypeId)

// Good - tracks resolver context
let resolved_data: ResolvedTypeData = resolver.resolve_type(type_ref);

// Be careful - loses resolver context
let raw_data: &TypeData = resolved_data.as_raw_data();
// Can't resolve nested TypeReferences without ResolverId!

// Pattern 1: Resolve and flatten
let type_ref = expr.infer_type(resolver);
let flattened = type_ref.flatten(resolver);

// Pattern 2: Check if type matches
fn is_string_type(resolver: &impl TypeResolver, type_ref: TypeReference) -> bool {
    let resolved = resolver.resolve_type(type_ref);
    matches!(resolved.as_raw_data(), TypeData::String)
}

// Pattern 3: Handle unknown gracefully
match resolved.as_raw_data() {
    TypeData::Unknown | TypeData::UnknownKeyword => {
        // Can't verify, assume valid
        return None;
    }
    TypeData::String => { /* handle */ }
    _ => { /* handle */ }
}