<?php

namespace MintyPHP\Module\Helpdesk\Service;

use MintyPHP\Module\Helpdesk\Repository\HandoverRepository;

/** @api Called from pages/helpdesk/handovers action files */
class HandoverService
{
    /** @api Used in pages and templates for status checks */
    public const STATUS_DRAFT = 'draft';
    /** @api Used in pages and templates for status checks */
    public const STATUS_IN_PROGRESS = 'in_progress';
    /** @api Used in pages and templates for status checks */
    public const STATUS_COMPLETED = 'completed';
    /** @api Used in pages and templates for status checks */
    public const STATUS_ARCHIVED = 'archived';

    /** @api Used in validation */
    public const ALL_STATUSES = [
        self::STATUS_DRAFT,
        self::STATUS_IN_PROGRESS,
        self::STATUS_COMPLETED,
        self::STATUS_ARCHIVED,
    ];

    public const PERMISSION_CREATE = 'create';
    public const PERMISSION_MANAGE = 'manage';

    /**
     * Status transitions allowed per permission level.
     * create-level: can set draft, in_progress, completed.
     * manage-level: can set any status.
     */
    private const ALLOWED_STATUS_BY_PERMISSION = [
        self::PERMISSION_CREATE => [self::STATUS_DRAFT, self::STATUS_IN_PROGRESS, self::STATUS_COMPLETED],
        self::PERMISSION_MANAGE => [self::STATUS_DRAFT, self::STATUS_IN_PROGRESS, self::STATUS_COMPLETED, self::STATUS_ARCHIVED],
    ];

    /**
     * Statuses in which a create-level user may edit field values.
     */
    private const EDITABLE_STATUSES_CREATE = [self::STATUS_DRAFT, self::STATUS_IN_PROGRESS];

    public function __construct(
        private readonly HandoverRepository $repository,
        private readonly SoftwareProductService $softwareProductService,
    ) {
    }

    /**
     * Create a new handover with a schema snapshot from the software product.
     *
     * @return array{ok: bool, id: int|null, errors: array<string, string>}
     */
    /**
     * @param array<string, mixed> $fieldValues
     */
    public function create(
        int $tenantId,
        string $debitorNo,
        string $debitorName,
        string $productCode,
        int $userId,
        array $fieldValues = [],
    ): array {
        $errors = [];

        $debitorNo = trim($debitorNo);
        if ($debitorNo === '') {
            $errors['debitor_no'] = t('Debitor number is required');
        }

        $productCode = trim($productCode);
        if ($productCode === '') {
            $errors['product_code'] = t('Software product is required');
        }

        if ($errors !== []) {
            return ['ok' => false, 'id' => null, 'errors' => $errors];
        }

        $product = $this->softwareProductService->findByCode($productCode);
        if ($product === null) {
            return ['ok' => false, 'id' => null, 'errors' => ['product_code' => t('Software product not found')]];
        }

        $schemaRaw = $product['handover_protocol_schema'] ?? null;
        if ($schemaRaw === null || $schemaRaw === '') {
            return ['ok' => false, 'id' => null, 'errors' => ['product_code' => t('Software product has no handover protocol schema')]];
        }

        $schema = json_decode($schemaRaw, true);
        if (!is_array($schema) || empty($schema['fields'])) {
            return ['ok' => false, 'id' => null, 'errors' => ['product_code' => t('Software product has no handover protocol schema')]];
        }

        // Validate field values against schema if provided
        if ($fieldValues !== []) {
            $validationErrors = $this->validateFieldValues($fieldValues, $schema['fields']);
            if ($validationErrors !== []) {
                return ['ok' => false, 'id' => null, 'errors' => $validationErrors];
            }
        }

        $fieldValuesJson = $fieldValues !== []
            ? json_encode($fieldValues, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE)
            : json_encode(new \stdClass(), JSON_FORCE_OBJECT);

        $id = $this->repository->insert([
            'tenant_id' => $tenantId,
            'debitor_no' => $debitorNo,
            'debitor_name' => trim($debitorName),
            'product_code' => $productCode,
            'status' => self::STATUS_DRAFT,
            'schema_snapshot' => $schemaRaw,
            'field_values' => $fieldValuesJson,
            'created_by' => $userId,
        ]);

        if ($id === null) {
            return ['ok' => false, 'id' => null, 'errors' => ['general' => t('Failed to create handover')]];
        }

        return ['ok' => true, 'id' => $id, 'errors' => []];
    }

    /**
     * Update field values for a handover.
     *
     * @param array<string, mixed> $fieldValues
     * @return array{ok: bool, errors: array<string, string>}
     */
    public function updateFields(
        int $tenantId,
        int $id,
        array $fieldValues,
        int $userId,
        string $permissionLevel,
    ): array {
        $handover = $this->repository->findById($tenantId, $id);
        if ($handover === null) {
            return ['ok' => false, 'errors' => ['general' => t('Handover not found')]];
        }

        if (!$this->canEdit($handover['status'], $permissionLevel)) {
            return ['ok' => false, 'errors' => ['general' => t('You do not have permission to edit this handover')]];
        }

        $schema = json_decode((string) ($handover['schema_snapshot'] ?? '{}'), true);
        $schemaFields = is_array($schema) ? ($schema['fields'] ?? []) : [];

        $validationErrors = $this->validateFieldValues($fieldValues, $schemaFields);
        if ($validationErrors !== []) {
            return ['ok' => false, 'errors' => $validationErrors];
        }

        $json = json_encode($fieldValues, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
        $updated = $this->repository->updateFieldValues($tenantId, $id, $json, $userId);

        if (!$updated) {
            return ['ok' => false, 'errors' => ['general' => t('Failed to save')]];
        }

        return ['ok' => true, 'errors' => []];
    }

    /**
     * Change the status of a handover.
     *
     * @return array{ok: bool, errors: array<string, string>}
     */
    public function changeStatus(
        int $tenantId,
        int $id,
        string $newStatus,
        int $userId,
        string $permissionLevel,
    ): array {
        if (!in_array($newStatus, self::ALL_STATUSES, true)) {
            return ['ok' => false, 'errors' => ['status' => t('Invalid status')]];
        }

        $handover = $this->repository->findById($tenantId, $id);
        if ($handover === null) {
            return ['ok' => false, 'errors' => ['general' => t('Handover not found')]];
        }

        $allowed = self::ALLOWED_STATUS_BY_PERMISSION[$permissionLevel] ?? [];
        if (!in_array($newStatus, $allowed, true)) {
            return ['ok' => false, 'errors' => ['status' => t('You do not have permission to set this status')]];
        }

        $updated = $this->repository->updateStatus($tenantId, $id, $newStatus, $userId);
        if (!$updated) {
            return ['ok' => false, 'errors' => ['general' => t('Failed to update status')]];
        }

        return ['ok' => true, 'errors' => []];
    }

    /**
     * @return array{total: int, rows: list<array<string, mixed>>}
     */
    public function listPaged(int $tenantId, array $filters): array
    {
        return $this->repository->listPaged($tenantId, $filters);
    }

    public function findById(int $tenantId, int $id): ?array
    {
        return $this->repository->findById($tenantId, $id);
    }

    /**
     * Check if a user with the given permission level can edit a handover in the given status.
     */
    public function canEdit(string $status, string $permissionLevel): bool
    {
        if ($permissionLevel === self::PERMISSION_MANAGE) {
            return true;
        }

        if ($permissionLevel === self::PERMISSION_CREATE) {
            return in_array($status, self::EDITABLE_STATUSES_CREATE, true);
        }

        return false;
    }

    /**
     * Get the list of statuses a user with the given permission level can set.
     *
     * @return list<string>
     */
    public function getAllowedStatuses(string $permissionLevel): array
    {
        return self::ALLOWED_STATUS_BY_PERMISSION[$permissionLevel] ?? [];
    }

    /**
     * Validate field values against the schema snapshot.
     *
     * @param array<string, mixed> $fieldValues
     * @param list<array<string, mixed>> $schemaFields
     * @return array<string, string>
     */
    private function validateFieldValues(array $fieldValues, array $schemaFields): array
    {
        $errors = [];
        $allowedKeys = [];
        $requiredKeys = [];

        foreach ($schemaFields as $field) {
            $key = $field['key'] ?? null;
            if ($key === null) {
                continue;
            }
            $allowedKeys[$key] = true;
            if (!empty($field['required'])) {
                $requiredKeys[$key] = $field['label'] ?? $key;
            }
        }

        foreach ($fieldValues as $key => $value) {
            if (!isset($allowedKeys[$key])) {
                $errors[$key] = t('Unknown field: %s', $key);
            }
        }

        foreach ($requiredKeys as $key => $label) {
            $value = $fieldValues[$key] ?? '';
            if (is_string($value) && trim($value) === '') {
                $errors[$key] = t('%s is required', $label);
            }
        }

        return $errors;
    }

    /**
     * Get the human-readable label for a status.
     */
    public static function statusLabel(string $status): string
    {
        return match ($status) {
            self::STATUS_DRAFT => t('Draft'),
            self::STATUS_IN_PROGRESS => t('In progress'),
            self::STATUS_COMPLETED => t('Completed'),
            self::STATUS_ARCHIVED => t('Archived'),
            default => $status,
        };
    }

    /**
     * Get the badge variant for a status.
     */
    public static function statusVariant(string $status): string
    {
        return match ($status) {
            self::STATUS_DRAFT => 'neutral',
            self::STATUS_IN_PROGRESS => 'warning',
            self::STATUS_COMPLETED => 'success',
            self::STATUS_ARCHIVED => 'neutral',
            default => 'neutral',
        };
    }
}