/*
|--------------------------------------------------------------------------
| Preloaded File - node ace make:preload rules/orcid
| ❯ Do you want to register the preload file in .adonisrc.ts file? (y/N) · true
| DONE:    create start/rules/orcid.ts
| DONE:    update adonisrc.ts file
|--------------------------------------------------------------------------
*/

import vine, { VineString } from '@vinejs/vine';
import { FieldContext } from '@vinejs/vine/types';

/**
 * ORCID Validator Implementation
 *
 * Validates ORCID identifiers using both format validation and checksum verification.
 * ORCID (Open Researcher and Contributor ID) is a persistent digital identifier
 * that distinguishes researchers and supports automated linkages between them
 * and their professional activities.
 *
 * Format: 0000-0000-0000-0000 (where the last digit can be X for checksum 10)
 * Algorithm: MOD-11-2 checksum validation as per ISO/IEC 7064:2003
 *
 * @param value - The ORCID value to validate
 * @param _options - Unused options parameter (required by VineJS signature)
 * @param field - VineJS field context for error reporting
 */
async function orcidValidator(value: unknown, _options: undefined, field: FieldContext) {
    /**
     * Type guard: We only validate string values
     * The "string" rule should handle type validation before this rule runs
     */
    if (typeof value !== 'string') {
        return;
    }

    /**
     * Handle optional fields: Skip validation for empty strings
     * This allows the field to be truly optional when used with .optional()
     */
    if (value.trim() === '') {
        return;
    }

    /**
     * Normalize the ORCID value:
     * - Remove any whitespace characters
     * - Convert to uppercase (for potential X check digit)
     */
    const cleanOrcid = value.replace(/\s/g, '').toUpperCase();

    /**
     * Format Validation
     *
     * ORCID format regex breakdown:
     * ^(\d{4}-){3}  - Three groups of exactly 4 digits followed by hyphen
     * \d{3}         - Three more digits
     * [\dX]$        - Final character: either digit or 'X' (for checksum 10)
     *
     * Valid examples: 0000-0002-1825-0097, 0000-0002-1825-009X
     */
    const orcidRegex = /^(\d{4}-){3}\d{3}[\dX]$/;

    if (!orcidRegex.test(cleanOrcid)) {
        field.report('ORCID must be in format: 0000-0000-0000-0000 or 0000-0000-0000-000X', 'orcid', field);
        return;
    }

    /**
     * Checksum Validation - MOD-11-2 Algorithm
     *
     * This implements the official ORCID checksum algorithm based on ISO/IEC 7064:2003
     * to verify mathematical validity and detect typos or invalid identifiers.
     */

    // Step 1: Extract digits and separate check digit
    const digits = cleanOrcid.replace(/-/g, ''); // Remove hyphens: "0000000218250097"
    const baseDigits = digits.slice(0, -1); // First 15 digits: "000000021825009"
    const checkDigit = digits.slice(-1); // Last character: "7"

    /**
     * Step 2: Calculate checksum using MOD-11-2 algorithm
     *
     * For each digit from left to right:
     * 1. Add the digit to running total
     * 2. Multiply result by 2
     *
     * Example for "000000021825009":
     * - Start with total = 0
     * - Process each digit: total = (total + digit) * 2
     * - Continue until all 15 digits are processed
     */
    let total = 0;
    for (const digit of baseDigits) {
        total = (total + parseInt(digit)) * 2;
    }

    /**
     * Step 3: Calculate expected check digit
     *
     * Formula: (12 - (total % 11)) % 11
     * - Get remainder when total is divided by 11
     * - Subtract from 12 and take modulo 11 again
     * - If result is 10, use 'X' (since we need single character)
     *
     * Example: total = 1314
     * - remainder = 1314 % 11 = 5
     * - result = (12 - 5) % 11 = 7
     * - expectedCheckDigit = "7"
     */
    const remainder = total % 11;
    const result = (12 - remainder) % 11;
    const expectedCheckDigit = result === 10 ? 'X' : result.toString();

    /**
     * Step 4: Verify checksum matches
     *
     * Compare the actual check digit with the calculated expected value.
     * If they don't match, the ORCID is invalid (likely contains typos or is fabricated).
     */
    if (checkDigit !== expectedCheckDigit) {
        field.report('Invalid ORCID checksum', 'orcid', field);
        return;
    }

    // If we reach this point, the ORCID is valid (both format and checksum)
}

/**
 * Create the VineJS validation rule
 *
 * This creates a reusable rule that can be chained with other VineJS validators
 */
const orcidRule = vine.createRule(orcidValidator);

/**
 * TypeScript module declaration
 *
 * Extends the VineString interface to include our custom orcid() method.
 * This enables TypeScript autocompletion and type checking when using the rule.
 */
declare module '@vinejs/vine' {
    interface VineString {
        /**
         * Validates that a string is a valid ORCID identifier
         *
         * Checks both format (0000-0000-0000-0000) and mathematical validity
         * using the MOD-11-2 checksum algorithm.
         *
         * @example
         * ```typescript
         * // Usage in validation schema
         * identifier_orcid: vine.string().trim().maxLength(255).orcid().optional()
         * ```
         *
         * @returns {this} The VineString instance for method chaining
         */
        orcid(): this;
    }
}

/**
 * Register the macro with VineJS
 *
 * This adds the .orcid() method to all VineString instances,
 * allowing it to be used in validation schemas.
 *
 * Usage example:
 * ```typescript
 * vine.string().orcid().optional()
 * ```
 */
VineString.macro('orcid', function (this: VineString) {
    return this.use(orcidRule());
});