<?php

declare(strict_types=1);

namespace DI\Definition;

/**
 * Defines a reference to an environment variable, with fallback to a default
 * value if the environment variable is not defined.
 *
 * @author James Harris <james.harris@icecave.com.au>
 */
class EnvironmentVariableDefinition implements Definition
{
    /**
     * Entry name.
     * @var string
     */
    private $name = '';

    /**
     * The name of the environment variable.
     * @var string
     */
    private $variableName;

    /**
     * Whether or not the environment variable definition is optional.
     *
     * If true and the environment variable given by $variableName has not been
     * defined, $defaultValue is used.
     *
     * @var bool
     */
    private $isOptional;

    /**
     * The default value to use if the environment variable is optional and not provided.
     * @var mixed
     */
    private $defaultValue;

    /**
     * @param string $variableName The name of the environment variable
     * @param bool $isOptional Whether or not the environment variable definition is optional
     * @param mixed $defaultValue The default value to use if the environment variable is optional and not provided
     */
    public function __construct(string $variableName, bool $isOptional = false, $defaultValue = null)
    {
        $this->variableName = $variableName;
        $this->isOptional = $isOptional;
        $this->defaultValue = $defaultValue;
    }

    public function getName() : string
    {
        return $this->name;
    }

    public function setName(string $name)
    {
        $this->name = $name;
    }

    /**
     * @return string The name of the environment variable
     */
    public function getVariableName() : string
    {
        return $this->variableName;
    }

    /**
     * @return bool Whether or not the environment variable definition is optional
     */
    public function isOptional() : bool
    {
        return $this->isOptional;
    }

    /**
     * @return mixed The default value to use if the environment variable is optional and not provided
     */
    public function getDefaultValue()
    {
        return $this->defaultValue;
    }

    public function replaceNestedDefinitions(callable $replacer)
    {
        $this->defaultValue = $replacer($this->defaultValue);
    }

    public function __toString()
    {
        $str = '    variable = ' . $this->variableName . \PHP_EOL
            . '    optional = ' . ($this->isOptional ? 'yes' : 'no');

        if ($this->isOptional) {
            if ($this->defaultValue instanceof Definition) {
                $nestedDefinition = (string) $this->defaultValue;
                $defaultValueStr = str_replace(\PHP_EOL, \PHP_EOL . '    ', $nestedDefinition);
            } else {
                $defaultValueStr = var_export($this->defaultValue, true);
            }

            $str .= \PHP_EOL . '    default = ' . $defaultValueStr;
        }

        return sprintf('Environment variable (' . \PHP_EOL . '%s' . \PHP_EOL . ')', $str);
    }
}
