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| 1 | +<?php | |
| 2 | + | |
| 3 | +declare(strict_types=1); | |
| 4 | + | |
| 5 | +namespace Metricool\Bootstrap; | |
| 6 | + | |
| 7 | +/** | |
| 8 | + * Container class that provides dependency injection capabilities to manage | |
| 9 | + * object creation and resolution. Class is used for retrieving and injecting | |
| 10 | + * dependencies in a structured and reusable way. This is important because it | |
| 11 | + * decouples classes from concrete implementations (new..) and makes the | |
| 12 | + * codebase easier to test and maintain. | |
| 13 | + */ | |
| 14 | +final class App | |
| 15 | +{ | |
| 16 | + /** | |
| 17 | + * Singleton instance holder. Ensures a single container is shared across | |
| 18 | + * the plugin without globals. | |
| 19 | + */ | |
| 20 | + private static ?App $instance = null; | |
| 21 | + | |
| 22 | + /** | |
| 23 | + * Registry of service factories indexed by identifier. Allows registering | |
| 24 | + * lazy factory closures for services. | |
| 25 | + * @var array<string, \Closure> $registry | |
| 26 | + */ | |
| 27 | + private array $registry = []; | |
| 28 | + | |
| 29 | + /** | |
| 30 | + * Instances of resolved services, indexed by identifier. Used to prevent | |
| 31 | + * multiple instantiations and store created services. | |
| 32 | + * @var array<string, object> $instances | |
| 33 | + */ | |
| 34 | + private array $instances = []; | |
| 35 | + | |
| 36 | + /** | |
| 37 | + * Private constructor to enforce the singleton pattern. Prevents direct | |
| 38 | + * instantiation; use getInstance() instead. | |
| 39 | + */ | |
| 40 | + private function __construct() | |
| 41 | + { | |
| 42 | + } | |
| 43 | + | |
| 44 | + /** | |
| 45 | + * Retrieve the shared container instance. Provides a central access point | |
| 46 | + * to the container for the plugin. | |
| 47 | + */ | |
| 48 | + public static function getInstance(): self | |
| 49 | + { | |
| 50 | + if (self::$instance === null) { | |
| 51 | + self::$instance = new self(); | |
| 52 | + } | |
| 53 | + | |
| 54 | + return self::$instance; | |
| 55 | + } | |
| 56 | + | |
| 57 | + /** | |
| 58 | + * Register a service factory. Defers service creation until first use. The | |
| 59 | + * provided Closure will be called with no arguments when the service is | |
| 60 | + * resolved. | |
| 61 | + */ | |
| 62 | + public function set(string $name, \Closure $value): void | |
| 63 | + { | |
| 64 | + $this->registry[$name] ??= $value; | |
| 65 | + } | |
| 66 | + | |
| 67 | + /** | |
| 68 | + * Resolve an identifier to a mixed instance. It first checks the registry | |
| 69 | + * for a factory. If none is found, it calls {@see make} to perform | |
| 70 | + * constructor autowiring. | |
| 71 | + * | |
| 72 | + * @param class-string $class | |
| 73 | + * @return mixed | |
| 74 | + * @throws \Exception If the target is not instantiable or cannot resolve a dependency. | |
| 75 | + * @throws \ReflectionException If reflection fails. | |
| 76 | + */ | |
| 77 | + public function get(string $class) | |
| 78 | + { | |
| 79 | + // Makes sure we memoize the Closure responses | |
| 80 | + if (array_key_exists($class, $this->instances)) { | |
| 81 | + return $this->instances[$class]; | |
| 82 | + } | |
| 83 | + | |
| 84 | + if (array_key_exists($class, $this->registry)) { | |
| 85 | + $instance = ($this->registry[$class])(); | |
| 86 | + $this->instances[$class] = $instance; // See above | |
| 87 | + return $instance; | |
| 88 | + } | |
| 89 | + | |
| 90 | + return $this->make($class); | |
| 91 | + } | |
| 92 | + | |
| 93 | + /** | |
| 94 | + * Method is used for on-demand construction of an object using constructor | |
| 95 | + * autowiring without touching the registry. When a constructor parameter | |
| 96 | + * asks for the Container itself, the current Container instance is injected | |
| 97 | + * instead of creating a new Container. Class-typed dependencies are | |
| 98 | + * resolved via {@see get} so factories from the registry are honored, while | |
| 99 | + * scalars or unresolved parameters require defaults or will result in an | |
| 100 | + * exception. This keeps "make" safe for ad-hoc instances you may later | |
| 101 | + * choose to register manually. | |
| 102 | + * | |
| 103 | + * @param class-string $class The class to make. Dependencies are injected. | |
| 104 | + * @param bool $register Made classes are registered in the container on | |
| 105 | + * true. Useful for optimization on multi-used classes. | |
| 106 | + * @param bool $registerDependencies Made dependency classes are registered | |
| 107 | + * in the container on true. Useful for optimization on multi-used classes. | |
| 108 | + * | |
| 109 | + * @throws \Exception If the target is not instantiable or a dependency cannot be resolved. | |
| 110 | + * @throws \ReflectionException If reflection fails. | |
| 111 | + */ | |
| 112 | + public function make(string $class, bool $register = true, bool $registerDependencies = true): object | |
| 113 | + { | |
| 114 | + $reflector = new \ReflectionClass($class); | |
| 115 | + | |
| 116 | + if ($reflector->isInstantiable() === false) { | |
| 117 | + throw new \Exception(esc_html("Target [{$class}] is not instantiable.")); | |
| 118 | + } | |
| 119 | + | |
| 120 | + $constructor = $reflector->getConstructor(); | |
| 121 | + | |
| 122 | + if ($constructor === null) { | |
| 123 | + return new $class(); | |
| 124 | + } | |
| 125 | + | |
| 126 | + $arguments = []; | |
| 127 | + $parameters = $constructor->getParameters(); | |
| 128 | + | |
| 129 | + foreach ($parameters as $parameter) { | |
| 130 | + $type = $parameter->getType(); | |
| 131 | + | |
| 132 | + // No type hinted: allow default value, otherwise we cannot resolve. | |
| 133 | + if ($type === null) { | |
| 134 | + if ($parameter->isDefaultValueAvailable()) { | |
| 135 | + $arguments[] = $parameter->getDefaultValue(); | |
| 136 | + continue; | |
| 137 | + } | |
| 138 | + | |
| 139 | + throw new \Exception(esc_html(sprintf( | |
| 140 | + 'Cannot resolve untyped parameter $%s for [%s] without a default value.', | |
| 141 | + $parameter->getName(), | |
| 142 | + $class | |
| 143 | + ))); | |
| 144 | + } | |
| 145 | + | |
| 146 | + // For PHP 7.4 only ReflectionNamedType exists (no unions). | |
| 147 | + if ($type instanceof \ReflectionNamedType === false) { | |
| 148 | + throw new \Exception(esc_html(sprintf( | |
| 149 | + 'Unsupported parameter type for $%s in [%s].', | |
| 150 | + $parameter->getName(), | |
| 151 | + $class | |
| 152 | + ))); | |
| 153 | + } | |
| 154 | + | |
| 155 | + // If nullable and no default, we still must supply something; | |
| 156 | + if ($type->isBuiltin()) { | |
| 157 | + if ($parameter->isDefaultValueAvailable()) { | |
| 158 | + $arguments[] = $parameter->getDefaultValue(); | |
| 159 | + continue; | |
| 160 | + } | |
| 161 | + | |
| 162 | + throw new \Exception(esc_html(sprintf( | |
| 163 | + 'Cannot autowire builtin parameter $%s (%s) for [%s]. Provide a default or register a factory.', | |
| 164 | + $parameter->getName(), | |
| 165 | + $type->getName(), | |
| 166 | + $class | |
| 167 | + ))); | |
| 168 | + } | |
| 169 | + | |
| 170 | + /** @var class-string $dependencyClass */ | |
| 171 | + $dependencyClass = $type->getName(); | |
| 172 | + | |
| 173 | + if ($dependencyClass === self::class) { | |
| 174 | + throw new \Exception(esc_html(sprintf( | |
| 175 | + 'Cannot resolve App container dependency for $%s in [%s] to prevent circular dependencies.', | |
| 176 | + $parameter->getName(), | |
| 177 | + $class | |
| 178 | + ))); | |
| 179 | + } | |
| 180 | + | |
| 181 | + // Using get() will also resolve dependencies of dependencies | |
| 182 | + $dependency = $this->get($dependencyClass); | |
| 183 | + | |
| 184 | + // Note: the registry is untouched here as that is only for deferred | |
| 185 | + // factories (closures). The instances prop is used in get() too. | |
| 186 | + if ($registerDependencies === true) { | |
| 187 | + $this->instances[$dependencyClass] = $dependency; | |
| 188 | + } | |
| 189 | + | |
| 190 | + $arguments[] = $dependency; | |
| 191 | + } | |
| 192 | + | |
| 193 | + $made = new $class(...$arguments); | |
| 194 | + | |
| 195 | + // Note: the registry is untouched here as that is only for deferred | |
| 196 | + // factories (closures). The instances prop is used in get() too. | |
| 197 | + if ($register) { | |
| 198 | + $this->instances[$class] = $made; | |
| 199 | + } | |
| 200 | + | |
| 201 | + return $made; | |
| 202 | + } | |
| 203 | +} | |
