<?php

declare(strict_types=1);

namespace App\Services\FormBuilder;

use App\Enums\FormBuilder\FormPurpose;
use App\Enums\FormBuilder\FormSubmissionStatus;
use App\Exceptions\FormBuilder\DestructiveConfirmationRequiredException;
use App\Exceptions\FormBuilder\EditLockConflictException;
use App\Exceptions\FormBuilder\PublishGuardViolationException;
use App\Exceptions\FormBuilder\PurposeRequirementsNotMetException;
use App\FormBuilder\Publishing\PublishGuardResult;
use App\FormBuilder\Purposes\PurposeRegistry;
use App\Models\FormBuilder\FormField;
use App\Models\FormBuilder\FormFieldBinding;
use App\Models\FormBuilder\FormSchema;
use App\Models\FormBuilder\FormSchemaSection;
use App\Models\FormBuilder\FormSubmission;
use App\Models\Organisation;
use App\Models\User;
use Carbon\Carbon;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;

/**
 * Schema CRUD + lifecycle per ARCH §4.1, §14, §18.1.
 */
final class FormSchemaService
{
    public function __construct(
        private readonly PurposeRegistry $purposeRegistry,
    ) {}

    public function create(Organisation $organisation, array $data, User $actor): FormSchema
    {
        return DB::transaction(function () use ($organisation, $data, $actor): FormSchema {
            $purpose = $this->resolvePurpose($data['purpose'] ?? null);
            $data['organisation_id'] = $organisation->id;
            $data['slug'] = $this->ensureUniqueSlug($organisation, $data['slug'] ?? Str::slug($data['name'] ?? 'formulier'));
            $data['purpose'] = $purpose->value;
            $data['submission_mode'] ??= $purpose->defaultSubmissionMode()->value;
            $data['version'] = 1;
            $data['created_by_user_id'] = $actor->id;
            $data['last_updated_by_user_id'] = $actor->id;

            /** @var FormSchema $schema */
            $schema = FormSchema::create($data);

            $schema->logSchemaChange('schema.created', ['purpose' => $purpose->value]);

            return $schema->refresh();
        });
    }

    public function update(FormSchema $schema, array $data, User $actor): FormSchema
    {
        return DB::transaction(function () use ($schema, $data, $actor): FormSchema {
            if (isset($data['slug']) && $data['slug'] !== $schema->slug) {
                $data['slug'] = $this->ensureUniqueSlug($schema->organisation, $data['slug'], $schema->id);
            }

            $before = $schema->toArray();
            $schema->fill($data);

            if ($this->isStructuralChange($schema)) {
                $schema->version = (int) $schema->version + 1;
            }

            $schema->last_updated_by_user_id = $actor->id;
            $schema->save();

            $schema->logSchemaChange('schema.updated', [
                'old_version' => $before['version'] ?? null,
                'new_version' => $schema->version,
            ]);

            return $schema->refresh();
        });
    }

    public function duplicate(FormSchema $source, User $actor, ?string $nameOverride = null): FormSchema
    {
        return DB::transaction(function () use ($source, $actor, $nameOverride): FormSchema {
            $name = $nameOverride ?? ($source->name.' (kopie)');
            $copy = $source->replicate([
                'public_token', 'public_token_previous', 'public_token_rotated_at',
                'edit_lock_user_id', 'edit_lock_expires_at',
            ]);
            $copy->name = $name;
            $copy->slug = $this->ensureUniqueSlug($source->organisation, Str::slug($name));
            $copy->version = 1;
            $copy->is_published = false;
            $copy->created_by_user_id = $actor->id;
            $copy->last_updated_by_user_id = $actor->id;
            $copy->save();

            // Copy sections (id mapping) then fields (pointing at new section ids).
            $sectionIdMap = [];
            foreach ($source->sections as $section) {
                $newSection = $section->replicate();
                $newSection->form_schema_id = $copy->id;
                $newSection->save();
                $sectionIdMap[$section->id] = $newSection->id;
            }

            foreach ($source->fields as $field) {
                $newField = $field->replicate();
                $newField->form_schema_id = $copy->id;
                if ($field->form_schema_section_id && isset($sectionIdMap[$field->form_schema_section_id])) {
                    $newField->form_schema_section_id = $sectionIdMap[$field->form_schema_section_id];
                }
                $newField->save();
            }

            $copy->logSchemaChange('schema.duplicated', ['source_schema_id' => $source->id]);

            return $copy->refresh();
        });
    }

    public function publish(FormSchema $schema, User $actor): FormSchema
    {
        $this->assertRequiredBindingsPresent($schema);
        $this->assertPublishGuardsSatisfied($schema);

        $schema->is_published = true;
        $schema->last_updated_by_user_id = $actor->id;
        $schema->save();
        $schema->logSchemaChange('schema.published');

        return $schema->refresh();
    }

    /**
     * RFC-WS-6 §3 (Q13) — runs after assertRequiredBindingsPresent().
     * Collects every guard violation (not first-fail) so the builder UI
     * can surface all problems in one 422 response.
     */
    private function assertPublishGuardsSatisfied(FormSchema $schema): void
    {
        $purposeValue = $schema->purpose->value;

        if (! $this->purposeRegistry->has($purposeValue)) {
            return;
        }

        // Eager-load relations needed by guards (avoid N+1).
        $schema->loadMissing(['fields.bindings', 'fields.configs', 'sections']);

        $provider = $this->purposeRegistry->guardProviderFor($purposeValue);

        $violations = [];
        foreach ($provider->publishGuards() as $guard) {
            $result = $guard->evaluate($schema);
            if (! $result->passed) {
                $violations[] = $result;
            }
        }

        if ($violations === []) {
            return;
        }

        usort(
            $violations,
            static fn (PublishGuardResult $a, PublishGuardResult $b): int => strcmp($a->guardCode, $b->guardCode),
        );

        throw new PublishGuardViolationException($purposeValue, $violations);
    }

    /**
     * Verify that every `required_bindings` path declared by the schema's
     * purpose is bound by at least one field on the schema.
     *
     * Binding paths follow Pattern A notation (`{entity}.{attribute}`).
     * Sourced from the relational `form_field_bindings` table (WS-5a;
     * ARCH §6.7, §17.3).
     */
    private function assertRequiredBindingsPresent(FormSchema $schema): void
    {
        $purposeValue = $schema->purpose instanceof FormPurpose
            ? $schema->purpose->value
            : (string) $schema->purpose;

        if (! $this->purposeRegistry->has($purposeValue)) {
            return;
        }

        $required = $this->purposeRegistry->get($purposeValue)->requiredBindings;
        if ($required === []) {
            return;
        }

        $fieldIds = $schema->fields()->pluck('id');

        $bound = FormFieldBinding::query()
            ->withoutGlobalScopes()
            ->where('owner_type', 'form_field')
            ->whereIn('owner_id', $fieldIds)
            ->get(['target_entity', 'target_attribute'])
            ->map(fn (FormFieldBinding $b) => $b->target_entity.'.'.$b->target_attribute)
            ->unique()
            ->all();

        $missing = array_values(array_diff($required, $bound));
        if ($missing !== []) {
            throw new PurposeRequirementsNotMetException($purposeValue, $missing);
        }
    }

    public function unpublish(FormSchema $schema, User $actor): FormSchema
    {
        $schema->is_published = false;
        $schema->last_updated_by_user_id = $actor->id;
        $schema->save();
        $schema->logSchemaChange('schema.unpublished');

        return $schema->refresh();
    }

    public function rotatePublicToken(FormSchema $schema, User $actor, int $graceDays = 7): FormSchema
    {
        return DB::transaction(function () use ($schema, $actor, $graceDays): FormSchema {
            $previous = $schema->public_token;
            $schema->public_token = (string) Str::ulid();
            $schema->public_token_previous = $previous;
            $schema->public_token_rotated_at = now();
            $schema->last_updated_by_user_id = $actor->id;
            $schema->save();

            $schema->logSchemaChange('schema.public_token_rotated', [
                'grace_days' => $graceDays,
                'previous_token_present' => $previous !== null,
            ]);

            return $schema->refresh();
        });
    }

    public function acquireEditLock(FormSchema $schema, User $user, int $ttlMinutes = 10): FormSchema
    {
        return DB::transaction(function () use ($schema, $user, $ttlMinutes): FormSchema {
            $now = now();
            $holderId = $schema->edit_lock_user_id;
            $expiresAt = $schema->edit_lock_expires_at;

            if ($holderId !== null && $holderId !== $user->id && $expiresAt !== null && $expiresAt->greaterThan($now)) {
                throw new EditLockConflictException(
                    User::query()->find($holderId),
                    $expiresAt,
                );
            }

            $schema->edit_lock_user_id = $user->id;
            $schema->edit_lock_expires_at = $now->copy()->addMinutes($ttlMinutes);
            $schema->save();

            return $schema->refresh();
        });
    }

    public function releaseEditLock(FormSchema $schema, User $user): FormSchema
    {
        if ($schema->edit_lock_user_id !== null && $schema->edit_lock_user_id !== $user->id && ! $user->hasRole('org_admin')) {
            throw new EditLockConflictException(
                User::query()->find($schema->edit_lock_user_id),
                $schema->edit_lock_expires_at,
            );
        }

        $schema->edit_lock_user_id = null;
        $schema->edit_lock_expires_at = null;
        $schema->save();

        return $schema->refresh();
    }

    public function delete(FormSchema $schema, User $actor, ?string $confirmedName = null): void
    {
        $hasSubmissions = FormSubmission::query()
            ->where('form_schema_id', $schema->id)
            ->exists();

        if ($hasSubmissions) {
            if ($confirmedName !== $schema->name) {
                throw DestructiveConfirmationRequiredException::forName($schema->name);
            }
        }

        DB::transaction(function () use ($schema, $actor): void {
            $schema->last_updated_by_user_id = $actor->id;
            $schema->save();
            $schema->logSchemaChange('schema.deleted');
            $schema->delete();
        });
    }

    public function bumpVersion(FormSchema $schema): void
    {
        $schema->version = (int) $schema->version + 1;
        $schema->save();
    }

    public function hasSubmittedSubmissions(FormSchema $schema): bool
    {
        return FormSubmission::query()
            ->where('form_schema_id', $schema->id)
            ->where('status', FormSubmissionStatus::SUBMITTED->value)
            ->exists();
    }

    private function resolvePurpose(mixed $purpose): FormPurpose
    {
        if ($purpose instanceof FormPurpose) {
            return $purpose;
        }

        return FormPurpose::from((string) $purpose);
    }

    private function ensureUniqueSlug(?Organisation $organisation, string $slug, ?string $excludeId = null): string
    {
        $orgId = $organisation?->id;
        if ($orgId === null) {
            return $slug;
        }

        $base = Str::slug($slug);
        $candidate = $base;
        $i = 2;
        while (FormSchema::withoutGlobalScopes()
            ->where('organisation_id', $orgId)
            ->where('slug', $candidate)
            ->when($excludeId !== null, fn ($q) => $q->where('id', '!=', $excludeId))
            ->exists()
        ) {
            $candidate = $base.'-'.$i;
            $i++;
        }

        return $candidate;
    }

    private function isStructuralChange(FormSchema $schema): bool
    {
        return $schema->isDirty(['purpose', 'submission_mode', 'locale', 'freeze_on_submit', 'snapshot_mode', 'section_level_submit', 'consent_version']);
    }
}