/**
 * Validation Module
 * 
 * Provides standalone validation system for fields, forms, and data.
 * Features:
 * - Schema-based validation
 * - Field-level validation
 * - Async validation
 * - Custom validation rules
 * - Integration with form-handling
 * - Integration with LiveComponents
 */

import { Logger } from '../../core/logger.js';

/**
 * Built-in validation rules
 */
const builtInRules = {
    required: (value, options = {}) => {
        if (value === null || value === undefined || value === '') {
            return options.message || 'This field is required';
        }
        return true;
    },
    
    email: (value, options = {}) => {
        if (!value) return true; // Optional if not required
        const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
        if (!emailRegex.test(value)) {
            return options.message || 'Invalid email address';
        }
        return true;
    },
    
    url: (value, options = {}) => {
        if (!value) return true;
        try {
            new URL(value);
            return true;
        } catch {
            return options.message || 'Invalid URL';
        }
    },
    
    min: (value, options = {}) => {
        if (!value && value !== 0) return true;
        const min = parseFloat(options.value);
        const numValue = typeof value === 'string' ? parseFloat(value) : value;
        if (isNaN(numValue) || numValue < min) {
            return options.message || `Value must be at least ${min}`;
        }
        return true;
    },
    
    max: (value, options = {}) => {
        if (!value && value !== 0) return true;
        const max = parseFloat(options.value);
        const numValue = typeof value === 'string' ? parseFloat(value) : value;
        if (isNaN(numValue) || numValue > max) {
            return options.message || `Value must be at most ${max}`;
        }
        return true;
    },
    
    minLength: (value, options = {}) => {
        if (!value) return true;
        const min = parseInt(options.value, 10);
        if (typeof value !== 'string' || value.length < min) {
            return options.message || `Must be at least ${min} characters`;
        }
        return true;
    },
    
    maxLength: (value, options = {}) => {
        if (!value) return true;
        const max = parseInt(options.value, 10);
        if (typeof value !== 'string' || value.length > max) {
            return options.message || `Must be at most ${max} characters`;
        }
        return true;
    },
    
    pattern: (value, options = {}) => {
        if (!value) return true;
        const regex = new RegExp(options.value);
        if (!regex.test(value)) {
            return options.message || 'Invalid format';
        }
        return true;
    },
    
    number: (value, options = {}) => {
        if (!value && value !== 0) return true;
        if (isNaN(parseFloat(value))) {
            return options.message || 'Must be a number';
        }
        return true;
    },
    
    integer: (value, options = {}) => {
        if (!value && value !== 0) return true;
        if (!Number.isInteger(parseFloat(value))) {
            return options.message || 'Must be an integer';
        }
        return true;
    },
    
    phone: (value, options = {}) => {
        if (!value) return true;
        const phoneRegex = /^[\d\s\-\+\(\)]+$/;
        if (!phoneRegex.test(value)) {
            return options.message || 'Invalid phone number';
        }
        return true;
    },
    
    postalCode: (value, options = {}) => {
        if (!value) return true;
        const country = options.country || 'DE';
        const patterns = {
            DE: /^\d{5}$/,
            US: /^\d{5}(-\d{4})?$/,
            UK: /^[A-Z]{1,2}\d{1,2}[A-Z]?\s?\d[A-Z]{2}$/i,
            FR: /^\d{5}$/
        };
        const pattern = patterns[country] || patterns.DE;
        if (!pattern.test(value)) {
            return options.message || `Invalid postal code for ${country}`;
        }
        return true;
    },
    
    custom: (value, options = {}) => {
        if (!options.validator || typeof options.validator !== 'function') {
            return 'Custom validator function required';
        }
        return options.validator(value, options);
    }
};

/**
 * Validator - Schema-based validation
 */
export class Validator {
    constructor(schema = {}) {
        this.schema = schema;
        this.customRules = new Map();
        this.errors = {};
        this.validatedFields = new Set();
    }
    
    /**
     * Create a new Validator instance
     */
    static create(schema = {}) {
        return new Validator(schema);
    }
    
    /**
     * Register a custom validation rule
     */
    registerRule(name, rule) {
        if (typeof rule !== 'function') {
            throw new Error('Validation rule must be a function');
        }
        this.customRules.set(name, rule);
    }
    
    /**
     * Validate a single field
     */
    async validateField(fieldName, value, schema = null) {
        const fieldSchema = schema || this.schema[fieldName];
        
        if (!fieldSchema) {
            return { valid: true, errors: [] };
        }
        
        const errors = [];
        
        // Handle array of rules
        const rules = Array.isArray(fieldSchema) ? fieldSchema : [fieldSchema];
        
        for (const ruleConfig of rules) {
            const result = await this.validateRule(value, ruleConfig);
            if (result !== true) {
                errors.push(result);
            }
        }
        
        // Store errors
        if (errors.length > 0) {
            this.errors[fieldName] = errors;
        } else {
            delete this.errors[fieldName];
        }
        
        this.validatedFields.add(fieldName);
        
        return {
            valid: errors.length === 0,
            errors
        };
    }
    
    /**
     * Validate a single rule
     */
    async validateRule(value, ruleConfig) {
        if (typeof ruleConfig === 'function') {
            // Custom validator function
            const result = await ruleConfig(value);
            return result === true ? true : (result || 'Validation failed');
        }
        
        if (typeof ruleConfig === 'string') {
            // Rule name only
            return this.executeRule(ruleConfig, value, {});
        }
        
        if (typeof ruleConfig === 'object' && ruleConfig !== null) {
            // Rule with options
            const ruleName = ruleConfig.rule || ruleConfig.type || Object.keys(ruleConfig)[0];
            const options = ruleConfig.options || ruleConfig[ruleName] || {};
            
            // Check for async validation
            if (ruleConfig.async && typeof ruleConfig.validator === 'function') {
                const result = await ruleConfig.validator(value, options);
                return result === true ? true : (result || options.message || 'Validation failed');
            }
            
            return this.executeRule(ruleName, value, options);
        }
        
        return true;
    }
    
    /**
     * Execute a validation rule
     */
    executeRule(ruleName, value, options) {
        // Check custom rules first
        if (this.customRules.has(ruleName)) {
            const result = this.customRules.get(ruleName)(value, options);
            return result === true ? true : (result || options.message || 'Validation failed');
        }
        
        // Check built-in rules
        if (builtInRules[ruleName]) {
            const result = builtInRules[ruleName](value, options);
            return result === true ? true : (result || options.message || 'Validation failed');
        }
        
        Logger.warn(`[Validator] Unknown validation rule: ${ruleName}`);
        return true; // Unknown rules pass by default
    }
    
    /**
     * Validate entire schema
     */
    async validate(data) {
        this.errors = {};
        this.validatedFields.clear();
        
        const results = {};
        let isValid = true;
        
        for (const fieldName in this.schema) {
            const value = data[fieldName];
            const result = await this.validateField(fieldName, value);
            results[fieldName] = result;
            
            if (!result.valid) {
                isValid = false;
            }
        }
        
        return {
            valid: isValid,
            errors: this.errors,
            results
        };
    }
    
    /**
     * Validate specific fields
     */
    async validateFields(data, fieldNames) {
        this.errors = {};
        
        const results = {};
        let isValid = true;
        
        for (const fieldName of fieldNames) {
            if (!(fieldName in this.schema)) {
                continue;
            }
            
            const value = data[fieldName];
            const result = await this.validateField(fieldName, value);
            results[fieldName] = result;
            
            if (!result.valid) {
                isValid = false;
            }
        }
        
        return {
            valid: isValid,
            errors: this.errors,
            results
        };
    }
    
    /**
     * Get errors for a specific field
     */
    getFieldErrors(fieldName) {
        return this.errors[fieldName] || [];
    }
    
    /**
     * Get all errors
     */
    getErrors() {
        return { ...this.errors };
    }
    
    /**
     * Check if field is valid
     */
    isFieldValid(fieldName) {
        return !this.errors[fieldName] || this.errors[fieldName].length === 0;
    }
    
    /**
     * Check if all fields are valid
     */
    isValid() {
        return Object.keys(this.errors).length === 0;
    }
    
    /**
     * Clear errors
     */
    clearErrors(fieldName = null) {
        if (fieldName) {
            delete this.errors[fieldName];
        } else {
            this.errors = {};
        }
    }
    
    /**
     * Reset validator
     */
    reset() {
        this.errors = {};
        this.validatedFields.clear();
    }
    
    /**
     * Create validator from HTML form
     */
    static fromForm(form) {
        const schema = {};
        const fields = form.querySelectorAll('input, textarea, select');
        
        fields.forEach(field => {
            if (!field.name) return;
            
            const rules = [];
            
            // Required
            if (field.hasAttribute('required')) {
                rules.push('required');
            }
            
            // Type-based validation
            if (field.type === 'email') {
                rules.push('email');
            } else if (field.type === 'url') {
                rules.push('url');
            } else if (field.type === 'number') {
                rules.push('number');
            }
            
            // Min/Max length
            if (field.hasAttribute('minlength')) {
                rules.push({
                    rule: 'minLength',
                    options: { value: field.getAttribute('minlength') }
                });
            }
            if (field.hasAttribute('maxlength')) {
                rules.push({
                    rule: 'maxLength',
                    options: { value: field.getAttribute('maxlength') }
                });
            }
            
            // Min/Max (for numbers)
            if (field.hasAttribute('min')) {
                rules.push({
                    rule: 'min',
                    options: { value: field.getAttribute('min') }
                });
            }
            if (field.hasAttribute('max')) {
                rules.push({
                    rule: 'max',
                    options: { value: field.getAttribute('max') }
                });
            }
            
            // Pattern
            if (field.hasAttribute('pattern')) {
                rules.push({
                    rule: 'pattern',
                    options: {
                        value: field.getAttribute('pattern'),
                        message: field.getAttribute('data-error-pattern') || 'Invalid format'
                    }
                });
            }
            
            // Custom validation
            if (field.hasAttribute('data-validate')) {
                const validateAttr = field.getAttribute('data-validate');
                try {
                    const customRule = JSON.parse(validateAttr);
                    rules.push(customRule);
                } catch {
                    // Treat as rule name
                    rules.push(validateAttr);
                }
            }
            
            if (rules.length > 0) {
                schema[field.name] = rules;
            }
        });
        
        return new Validator(schema);
    }
}

/**
 * ValidationRule - Individual validation rule
 */
export class ValidationRule {
    constructor(name, validator, options = {}) {
        this.name = name;
        this.validator = validator;
        this.options = options;
    }
    
    async validate(value) {
        if (typeof this.validator === 'function') {
            const result = await this.validator(value, this.options);
            return result === true ? true : (result || this.options.message || 'Validation failed');
        }
        return true;
    }
}