<?php

namespace Kirby\Form;

use Kirby\Cms\App;
use Kirby\Cms\Model;
use Kirby\Data\Data;
use Kirby\Exception\NotFoundException;
use Kirby\Toolkit\Str;
use Throwable;

/**
 * The main form class, that is being
 * used to create a list of form fields
 * and handles global form validation
 * and submission
 *
 * @package   Kirby Form
 * @author    Bastian Allgeier <bastian@getkirby.com>
 * @link      https://getkirby.com
 * @copyright Bastian Allgeier GmbH
 * @license   https://opensource.org/licenses/MIT
 */
class Form
{
    /**
     * An array of all found errors
     *
     * @var array|null
     */
    protected $errors;

    /**
     * Fields in the form
     *
     * @var \Kirby\Form\Fields|null
     */
    protected $fields;

    /**
     * All values of form
     *
     * @var array
     */
    protected $values = [];

    /**
     * Form constructor
     *
     * @param array $props
     */
    public function __construct(array $props)
    {
        $fields = $props['fields'] ?? [];
        $values = $props['values'] ?? [];
        $input  = $props['input']  ?? [];
        $strict = $props['strict'] ?? false;
        $inject = $props;

        // prepare field properties for multilang setups
        $fields = static::prepareFieldsForLanguage(
            $fields,
            $props['language'] ?? null
        );

        // lowercase all value names
        $values = array_change_key_case($values);
        $input  = array_change_key_case($input);

        unset($inject['fields'], $inject['values'], $inject['input']);

        $this->fields = new Fields();
        $this->values = [];

        foreach ($fields as $name => $props) {

            // inject stuff from the form constructor (model, etc.)
            $props = array_merge($inject, $props);

            // inject the name
            $props['name'] = $name = strtolower($name);

            // check if the field is disabled
            $disabled = $props['disabled'] ?? false;

            // overwrite the field value if not set
            if ($disabled === true) {
                $props['value'] = $values[$name] ?? null;
            } else {
                $props['value'] = $input[$name] ?? $values[$name] ?? null;
            }

            try {
                $field = Field::factory($props['type'], $props, $this->fields);
            } catch (Throwable $e) {
                $field = static::exceptionField($e, $props);
            }

            if ($field->save() !== false) {
                $this->values[$name] = $field->value();
            }

            $this->fields->append($name, $field);
        }

        if ($strict !== true) {

            // use all given values, no matter
            // if there's a field or not.
            $input = array_merge($values, $input);

            foreach ($input as $key => $value) {
                if (isset($this->values[$key]) === false) {
                    $this->values[$key] = $value;
                }
            }
        }
    }

    /**
     * Returns the data required to write to the content file
     * Doesn't include default and null values
     *
     * @return array
     */
    public function content(): array
    {
        return $this->data(false, false);
    }

    /**
     * Returns data for all fields in the form
     *
     * @param false $defaults
     * @param bool $includeNulls
     * @return array
     */
    public function data($defaults = false, bool $includeNulls = true): array
    {
        $data = $this->values;

        foreach ($this->fields as $field) {
            if ($field->save() === false || $field->unset() === true) {
                if ($includeNulls === true) {
                    $data[$field->name()] = null;
                } else {
                    unset($data[$field->name()]);
                }
            } else {
                $data[$field->name()] = $field->data($defaults);
            }
        }

        return $data;
    }

    /**
     * An array of all found errors
     *
     * @return array
     */
    public function errors(): array
    {
        if ($this->errors !== null) {
            return $this->errors;
        }

        $this->errors = [];

        foreach ($this->fields as $field) {
            if (empty($field->errors()) === false) {
                $this->errors[$field->name()] = [
                    'label'   => $field->label(),
                    'message' => $field->errors()
                ];
            }
        }

        return $this->errors;
    }

    /**
     * Shows the error with the field
     *
     * @param \Throwable $exception
     * @param array $props
     * @return \Kirby\Form\Field
     */
    public static function exceptionField(Throwable $exception, array $props = [])
    {
        $message = $exception->getMessage();

        if (App::instance()->option('debug') === true) {
            $message .= ' in file: ' . $exception->getFile() . ' line: ' . $exception->getLine();
        }

        $props = array_merge($props, [
            'label' => 'Error in "' . $props['name'] . '" field.',
            'theme' => 'negative',
            'text'  => strip_tags($message),
        ]);

        return Field::factory('info', $props);
    }

    /**
     * Get the field object by name
     * and handle nested fields correctly
     *
     * @param string $name
     * @throws \Kirby\Exception\NotFoundException
     * @return \Kirby\Form\Field
     */
    public function field(string $name)
    {
        $form       = $this;
        $fieldNames = Str::split($name, '+');
        $index      = 0;
        $count      = count($fieldNames);
        $field      = null;

        foreach ($fieldNames as $fieldName) {
            $index++;

            if ($field = $form->fields()->get($fieldName)) {
                if ($count !== $index) {
                    $form = $field->form();
                }
            } else {
                throw new NotFoundException('The field "' . $fieldName . '" could not be found');
            }
        }

        // it can get this error only if $name is an empty string as $name = ''
        if ($field === null) {
            throw new NotFoundException('No field could be loaded');
        }

        return $field;
    }

    /**
     * Returns form fields
     *
     * @return \Kirby\Form\Fields|null
     */
    public function fields()
    {
        return $this->fields;
    }

    /**
     * @param \Kirby\Cms\Model $model
     * @param array $props
     * @return static
     */
    public static function for(Model $model, array $props = [])
    {
        // get the original model data
        $original = $model->content($props['language'] ?? null)->toArray();
        $values   = $props['values'] ?? [];

        // convert closures to values
        foreach ($values as $key => $value) {
            if (is_a($value, 'Closure') === true) {
                $values[$key] = $value($original[$key] ?? null);
            }
        }

        // set a few defaults
        $props['values']   = array_merge($original, $values);
        $props['fields'] ??= [];
        $props['model']    = $model;

        // search for the blueprint
        if (method_exists($model, 'blueprint') === true && $blueprint = $model->blueprint()) {
            $props['fields'] = $blueprint->fields();
        }

        $ignoreDisabled = $props['ignoreDisabled'] ?? false;

        // REFACTOR: this could be more elegant
        if ($ignoreDisabled === true) {
            $props['fields'] = array_map(function ($field) {
                $field['disabled'] = false;
                return $field;
            }, $props['fields']);
        }

        return new static($props);
    }

    /**
     * Checks if the form is invalid
     *
     * @return bool
     */
    public function isInvalid(): bool
    {
        return empty($this->errors()) === false;
    }

    /**
     * Checks if the form is valid
     *
     * @return bool
     */
    public function isValid(): bool
    {
        return empty($this->errors()) === true;
    }

    /**
     * Disables fields in secondary languages when
     * they are configured to be untranslatable
     *
     * @param array $fields
     * @param string|null $language
     * @return array
     */
    protected static function prepareFieldsForLanguage(array $fields, ?string $language = null): array
    {
        $kirby = App::instance(null, true);

        // only modify the fields if we have a valid Kirby multilang instance
        if (!$kirby || $kirby->multilang() === false) {
            return $fields;
        }

        if ($language === null) {
            $language = $kirby->language()->code();
        }

        if ($language !== $kirby->defaultLanguage()->code()) {
            foreach ($fields as $fieldName => $fieldProps) {
                // switch untranslatable fields to readonly
                if (($fieldProps['translate'] ?? true) === false) {
                    $fields[$fieldName]['unset']    = true;
                    $fields[$fieldName]['disabled'] = true;
                }
            }
        }

        return $fields;
    }

    /**
     * Converts the data of fields to strings
     *
     * @param false $defaults
     * @return array
     */
    public function strings($defaults = false): array
    {
        $strings = [];

        foreach ($this->data($defaults) as $key => $value) {
            if ($value === null) {
                $strings[$key] = null;
            } elseif (is_array($value) === true) {
                $strings[$key] = Data::encode($value, 'yaml');
            } else {
                $strings[$key] = $value;
            }
        }

        return $strings;
    }

    /**
     * Converts the form to a plain array
     *
     * @return array
     */
    public function toArray(): array
    {
        $array = [
            'errors' => $this->errors(),
            'fields' => $this->fields->toArray(function ($item) {
                return $item->toArray();
            }),
            'invalid' => $this->isInvalid()
        ];

        return $array;
    }

    /**
     * Returns form values
     *
     * @return array
     */
    public function values(): array
    {
        return $this->values;
    }
}