Check WordPress and PHP requirements before installing a theme or plugin

This matches the behavior of WordPress core which will refuse to install
a plugin if the local copy of WordPress or PHP don't meet the minimum
requirements for the most recent version as listed by the plugin
authors.

Unfortunately the api is limited and only provides these requirement
details for the most recent version, so it isn't possible to find an
older version that might work. As a compromise, this code doesn't check
requirements if a user provides a specific --version since we can't know
the requirements for anything other than the latest version and assume
if somebody specifies a version they know it will work or want to try
anyway.

Author: mrsdizzie

features/plugin-install.feature

@@ -237,3 +237,35 @@ Feature: Install WordPress plugins
     Plugin 'site-secrets' activated.
     Success: Plugin already installed.
     """
+
+  Scenario: Can't install plugin that requires a newer version of WordPress
+    Given a WP install
+
+    When I run `wp core download --version=6.4 --force`
+    And I run `rm -r wp-content/themes/*`
+
+    And I try `wp plugin install wp-super-cache`
+    Then STDERR should contain:
+    """
+    Warning: wp-super-cache: This plugin does not work with your version of WordPress
+    """
+
+    And STDERR should contain:
+    """
+    Error: No plugins installed.
+    """
+
+  @less-than-php-7.4
+  Scenario: Can't install plugin that requires a newer version of PHP
+    Given a WP install
+
+    And I try `wp plugin install contact-form-7`
+    Then STDERR should contain:
+    """
+    Warning: contact-form-7: This plugin does not work with your version of PHP
+    """
+
+    And STDERR should contain:
+    """
+    Error: No plugins installed.
+    """

features/theme-install.feature

@@ -125,3 +125,35 @@ Feature: Install WordPress themes
       """
       twentyeleven
       """
+
+  Scenario: Can't install theme that requires a newer version of WordPress
+    Given a WP install
+
+    When I run `wp core download --version=6.4 --force`
+    And I run `rm -r wp-content/themes/*`
+
+    And I try `wp theme install twentytwentyfive`
+    Then STDERR should contain:
+    """
+    Warning: twentytwentyfive: This theme does not work with your version of WordPress.
+    """
+
+    And STDERR should contain:
+    """
+    Error: No themes installed.
+    """
+
+  @less-than-php-7.4
+  Scenario: Can't install theme that requires a newer version of PHP
+    Given a WP install
+
+    And I try `wp theme install oceanwp`
+    Then STDERR should contain:
+    """
+    Warning: oceanwp: This theme does not work with your version of PHP.
+    """
+
+    And STDERR should contain:
+    """
+    Error: No themes installed.
+    """

src/Plugin_Command.php

@@ -590,6 +590,20 @@ protected function install_from_repo( $slug, $assoc_args ) {
 
 		if ( isset( $assoc_args['version'] ) ) {
 			self::alter_api_response( $api, $assoc_args['version'] );
+		} else {
+			$requires_php = isset( $api->requires_php ) ? $api->requires_php : null;
+			$requires_wp  = isset( $api->requires ) ? $api->requires : null;
+
+			$compatible_php = is_php_version_compatible( $requires_php );
+			$compatible_wp  = is_wp_version_compatible( $requires_wp );
+
+			if ( ! $compatible_wp ) {
+				return new WP_Error( 'requirements_not_met', "This plugin does not work with your version of WordPress. Minimum WordPress requirement is $requires_wp" );
+			}
+
+			if ( ! $compatible_php ) {
+				return new WP_Error( 'requirements_not_met', "This plugin does not work with your version of PHP. Minimum PHP required is $compatible_php" );
+			}
 		}
 
 		$status = install_plugin_install_status( $api );

src/Theme_Command.php

@@ -403,6 +403,20 @@ protected function install_from_repo( $slug, $assoc_args ) {
 
 		if ( isset( $assoc_args['version'] ) ) {
 			self::alter_api_response( $api, $assoc_args['version'] );
+		} else {
+			$requires_php = isset( $api->requires_php ) ? $api->requires_php : null;
+			$requires_wp  = isset( $api->requires ) ? $api->requires : null;
+
+			$compatible_php = is_php_version_compatible( $requires_php );
+			$compatible_wp  = is_wp_version_compatible( $requires_wp );
+
+			if ( ! $compatible_wp ) {
+				return new WP_Error( 'requirements_not_met', "This theme does not work with your version of WordPress. Minimum WordPress requirement is $requires_wp" );
+			}
+
+			if ( ! $compatible_php ) {
+				return new WP_Error( 'requirements_not_met', "This theme does not work with your version of PHP. Minimum PHP required is $requires_php" );
+			}
 		}
 
 		if ( ! Utils\get_flag_value( $assoc_args, 'force' ) ) {