<?php

namespace Ktrix;

use ReflectionClass;
use ReflectionParameter;
use KTXC\Server;

/**
 * Dynamic Class Resolver
 * Resolves and instantiates classes with their dependencies dynamically
 */
class Resolver
{
    private array $instanceCache = [];
    private array $contextInstances = [];
    private static array $globalContext = [];

    /**
     * Set a global context instance that will be used for all resolutions
     */
    public static function setGlobalContext(string $className, object $instance): void
    {
        self::$globalContext[$className] = $instance;
    }

    /**
     * Clear global context
     */
    public static function clearGlobalContext(): void
    {
        self::$globalContext = [];
    }

    /**
     * Resolve and instantiate a class with its dependencies
     */
    public function resolve(string $className): object
    {
        return $this->resolveWithContext($className, []);
    }

    /**
     * Resolve and instantiate a class with specific context instances
     */
    public function resolveWithContext(string $className, array $contextInstances = []): object
    {
        // Store context instances temporarily
        $originalContext = $this->contextInstances;
        $this->contextInstances = array_merge($this->contextInstances, $contextInstances);

        try {
            // Check cache first (but not when we have context overrides)
            if (empty($contextInstances) && isset($this->instanceCache[$className])) {
                return $this->instanceCache[$className];
            }

            // Check if class exists
            if (!class_exists($className)) {
                throw new \InvalidArgumentException("Class {$className} does not exist");
            }

            $reflectionClass = new ReflectionClass($className);

            // If class cannot be instantiated
            if (!$reflectionClass->isInstantiable()) {
                throw new \InvalidArgumentException("Class {$className} is not instantiable");
            }

            $constructor = $reflectionClass->getConstructor();

            // If no constructor, just instantiate
            if ($constructor === null) {
                $instance = new $className();
                if (empty($contextInstances)) {
                    $this->instanceCache[$className] = $instance;
                }
                return $instance;
            }

            // Resolve constructor dependencies
            $dependencies = [];
            foreach ($constructor->getParameters() as $parameter) {
                $dependencies[] = $this->resolveParameter($parameter);
            }

            // Create instance with resolved dependencies
            $instance = $reflectionClass->newInstanceArgs($dependencies);
            
            // Only cache if no context overrides
            if (empty($contextInstances)) {
                $this->instanceCache[$className] = $instance;
            }

            return $instance;
        } finally {
            // Restore original context
            $this->contextInstances = $originalContext;
        }
    }

    /**
     * Resolve a single parameter dependency
     */
    private function resolveParameter(ReflectionParameter $parameter): mixed
    {
        $type = $parameter->getType();

        // If no type hint, check if it has a default value
        if ($type === null) {
            if ($parameter->isDefaultValueAvailable()) {
                return $parameter->getDefaultValue();
            }
            throw new \InvalidArgumentException("Cannot resolve parameter {$parameter->getName()} without type hint");
        }

        // Handle union types (PHP 8+)
        if ($type instanceof \ReflectionUnionType) {
            throw new \InvalidArgumentException("Union types are not supported for parameter {$parameter->getName()}");
        }

        $typeName = $type->getName();

        // Check if we have a context instance for this type
        if (isset($this->contextInstances[$typeName])) {
            return $this->contextInstances[$typeName];
        }

        // Check global context
        if (isset(self::$globalContext[$typeName])) {
            return self::$globalContext[$typeName];
        }

        // Handle built-in types
        if ($type->isBuiltin()) {
            if ($parameter->isDefaultValueAvailable()) {
                return $parameter->getDefaultValue();
            }
            throw new \InvalidArgumentException("Cannot resolve built-in type {$typeName} for parameter {$parameter->getName()}");
        }

        // Always try to get from container first for all non-builtin types
        try {
            $container = Server::getContainer();
            if ($container->has($typeName)) {
                return $container->get($typeName);
            }
        } catch (\Exception $e) {
            // Fall through to manual resolution
        }

        // Only try manual resolution for classes in our namespace
        if (strpos($typeName, 'KTXC\\') === 0) {
            try {
                return $this->resolve($typeName);
            } catch (\Exception $e) {
                // If still can't resolve and has default value, use it
                if ($parameter->isDefaultValueAvailable()) {
                    return $parameter->getDefaultValue();
                }

                // If parameter is nullable, return null
                if ($parameter->allowsNull()) {
                    return null;
                }

                throw new \InvalidArgumentException("Cannot resolve dependency {$typeName} for parameter {$parameter->getName()}: " . $e->getMessage());
            }
        }

        // For non-Ktrix classes that aren't in the container, fail gracefully
        if ($parameter->isDefaultValueAvailable()) {
            return $parameter->getDefaultValue();
        }

        if ($parameter->allowsNull()) {
            return null;
        }

        throw new \InvalidArgumentException("Cannot resolve external dependency {$typeName} for parameter {$parameter->getName()}. This service should be registered in the container.");
    }

    /**
     * Resolve and instantiate a class with automatic context detection
     */
    public function resolveWithAutoContext(string $className, object $contextSource = null): object
    {
        $contextInstances = [];
        
        if ($contextSource !== null) {
            // Use reflection to get all properties of the context source
            $reflection = new ReflectionClass($contextSource);
            $properties = $reflection->getProperties();
            
            foreach ($properties as $property) {
                $property->setAccessible(true);
                $value = $property->getValue($contextSource);
                
                if (is_object($value)) {
                    $contextInstances[get_class($value)] = $value;
                }
            }
        }
        
        return $this->resolveWithContext($className, $contextInstances);
    }

    /**
     * Smart resolve - automatically finds dependencies from the call stack
     */
    public function smartResolve(string $className): object
    {
        $contextInstances = [];
        
        // Get the call stack to find potential context sources
        $backtrace = debug_backtrace(DEBUG_BACKTRACE_PROVIDE_OBJECT, 10);
        
        foreach ($backtrace as $frame) {
            if (isset($frame['object']) && is_object($frame['object'])) {
                $sourceObject = $frame['object'];
                $reflection = new ReflectionClass($sourceObject);
                $properties = $reflection->getProperties();
                
                foreach ($properties as $property) {
                    $property->setAccessible(true);
                    $value = $property->getValue($sourceObject);
                    
                    if (is_object($value)) {
                        $contextInstances[get_class($value)] = $value;
                    }
                }
            }
        }
        
        return $this->resolveWithContext($className, $contextInstances);
    }

    /**
     * Clear the instance cache
     */
    public function clearCache(): void
    {
        $this->instanceCache = [];
    }

    /**
     * Check if a class is cached
     */
    public function isCached(string $className): bool
    {
        return isset($this->instanceCache[$className]);
    }
}