<?php

declare(strict_types=1);

namespace App\Services\FormBuilder;

use App\Enums\FormBuilder\FormFieldType;
use App\Models\FormBuilder\FormField;
use App\Models\FormBuilder\FormSchema;

/**
 * Build Laravel validation rules dynamically from a schema's form_fields.
 *
 * Two modes (S2c D8):
 *   - strict(): for the final submit pipeline. is_required fields are
 *     required; SELECT/RADIO values must be in options; multi-value
 *     types must be arrays; type rules (email/url/date/numeric/boolean)
 *     are enforced.
 *   - relaxed(): for auto-save drafts. Every rule becomes nullable;
 *     options lists still constrain (a SELECT can't silently accept
 *     garbage, even mid-draft), but required stays off.
 *
 * Rule shape returned targets `values.{slug}` and `values.{slug}.*` keys
 * so FormRequests can merge this into their own `values` wrapper:
 *
 *     return array_merge(['values' => ['required', 'array']], $ruleBuilder->strict($schema));
 */
final class FormFieldRuleBuilder
{
    public function __construct(
        private readonly FormFieldValidationRuleService $validationRuleService,
    ) {}

    /**
     * @return array<string, array<int, string>>
     */
    public function strict(FormSchema $schema): array
    {
        return $this->build($schema, strict: true);
    }

    /**
     * @return array<string, array<int, string>>
     */
    public function relaxed(FormSchema $schema): array
    {
        return $this->build($schema, strict: false);
    }

    /**
     * @return array<string, array<int, string>>
     */
    private function build(FormSchema $schema, bool $strict): array
    {
        $fields = $schema->fields()->get();
        $rules = [];

        foreach ($fields as $field) {
            if (! (bool) $field->is_portal_visible || (bool) $field->is_admin_only) {
                continue;
            }

            if (in_array($field->field_type, [FormFieldType::HEADING->value, FormFieldType::PARAGRAPH->value], true)) {
                continue;
            }

            $key = 'values.'.$field->slug;
            $isMulti = $this->isMultiValue($field);
            $primaryRules = [];

            if ($strict && (bool) $field->is_required) {
                $primaryRules[] = $isMulti ? 'present' : 'required';
            } else {
                $primaryRules[] = 'sometimes';
                $primaryRules[] = 'nullable';
            }

            if ($isMulti) {
                $primaryRules[] = 'array';
                $rules[$key] = $primaryRules;

                foreach ($this->itemRulesFor($field, $strict) as $itemRule) {
                    $rules[$key.'.*'][] = $itemRule;
                }
                continue;
            }

            foreach ($this->scalarTypeRules($field) as $r) {
                $primaryRules[] = $r;
            }
            foreach ($this->validationRuleShortcuts($field) as $r) {
                $primaryRules[] = $r;
            }

            $rules[$key] = $primaryRules;
        }

        return $rules;
    }

    private function isMultiValue(FormField $field): bool
    {
        return in_array($field->field_type, [
            FormFieldType::MULTISELECT->value,
            FormFieldType::CHECKBOX_LIST->value,
            FormFieldType::TAG_PICKER->value,
            FormFieldType::AVAILABILITY_PICKER->value,
            FormFieldType::SECTION_PRIORITY->value,
            FormFieldType::TABLE_ROWS->value,
        ], true);
    }

    /**
     * @return array<int, string>
     */
    private function scalarTypeRules(FormField $field): array
    {
        return match ($field->field_type) {
            FormFieldType::EMAIL->value => ['email:rfc'],
            FormFieldType::URL->value => ['url'],
            FormFieldType::NUMBER->value => ['numeric'],
            FormFieldType::DATE->value => ['date_format:Y-m-d'],
            FormFieldType::DATETIME->value => ['date'],
            FormFieldType::BOOLEAN->value => ['boolean'],
            FormFieldType::PHONE->value => ['regex:/^[+]?[0-9\s\-()]{4,25}$/'],
            FormFieldType::SELECT->value, FormFieldType::RADIO->value => $this->inOptionsRule($field),
            default => ['string'],
        };
    }

    /**
     * @return array<int, string>
     */
    private function itemRulesFor(FormField $field, bool $strict): array
    {
        $rules = [];
        if ($strict && (bool) $field->is_required) {
            $rules[] = 'required';
        } else {
            $rules[] = 'nullable';
        }

        return match ($field->field_type) {
            FormFieldType::MULTISELECT->value, FormFieldType::CHECKBOX_LIST->value => array_merge($rules, $this->inOptionsRule($field)),
            FormFieldType::TAG_PICKER->value => array_merge($rules, ['string', 'max:30']),
            FormFieldType::AVAILABILITY_PICKER->value => array_merge($rules, ['string', 'max:30']),
            FormFieldType::SECTION_PRIORITY->value => array_merge($rules, ['array:section_id,priority']),
            FormFieldType::TABLE_ROWS->value => array_merge($rules, ['array']),
            default => $rules,
        };
    }

    /**
     * @return array<int, string>
     */
    private function inOptionsRule(FormField $field): array
    {
        $options = $this->scalarOptions($field);
        if ($options === []) {
            return [];
        }

        return ['in:'.implode(',', $options)];
    }

    /**
     * @return array<int, string>
     */
    private function scalarOptions(FormField $field): array
    {
        $options = is_array($field->options) ? $field->options : [];
        $out = [];
        foreach ($options as $opt) {
            if (is_scalar($opt)) {
                $out[] = (string) $opt;
            } elseif (is_array($opt) && isset($opt['value']) && is_scalar($opt['value'])) {
                $out[] = (string) $opt['value'];
            } elseif (is_array($opt) && isset($opt['label']) && is_scalar($opt['label'])) {
                $out[] = (string) $opt['label'];
            }
        }

        return $out;
    }

    /**
     * Shortcuts picked up from the relational validation-rules table.
     * Service-layer FormValueService does the deeper min/max/regex/unique
     * enforcement — these are quick boundary checks surfaced at the
     * Request layer when cheap.
     *
     * Laravel's `min:N` / `max:N` already do the right thing for both
     * numeric inputs (value comparison) and strings (length check), so
     * `min_length`/`min_value` both emit the same `min:N` rule.
     *
     * @return array<int, string>
     */
    private function validationRuleShortcuts(FormField $field): array
    {
        $rules = [];
        $v = $this->validationRuleService->toJsonShape($field->validationRules);
        if (! is_array($v)) {
            return $rules;
        }

        if (isset($v['min_value']) && is_numeric($v['min_value'])) {
            $rules[] = 'min:'.(string) $v['min_value'];
        }
        if (isset($v['max_value']) && is_numeric($v['max_value'])) {
            $rules[] = 'max:'.(string) $v['max_value'];
        }
        if (isset($v['min_length']) && is_numeric($v['min_length'])) {
            $rules[] = 'min:'.(string) $v['min_length'];
        }
        if (isset($v['max_length']) && is_numeric($v['max_length'])) {
            $rules[] = 'max:'.(string) $v['max_length'];
        }
        if (isset($v['regex']) && is_string($v['regex'])) {
            $rules[] = 'regex:'.$v['regex'];
        }

        return $rules;
    }
}