import * as fs from 'fs';
import * as path from 'path';
import { Schema, AttributeInfo, EnhancedAttributeInfo, AttributeValidationResult } from './Schema';
import { XsdDetector } from './XsdDetector';

// Re-export interfaces from Schema for public API
export type { AttributeInfo, EnhancedAttributeInfo, AttributeValidationResult };

/**
 * Interface for attribute name validation results
 */
export interface AttributeNameValidationResult {
  wrongAttributes: string[];
  missingRequiredAttributes: string[];
}

export class XsdReference {
  private schemas: Map<string, Schema> = new Map();
  private xsdDirectory: string;

  constructor(xsdDirectory: string) {
    this.xsdDirectory = xsdDirectory;
  }

  /**
   * Discover and parse XSD includes from a schema file
   * @param xsdFilePath The path to the XSD file to scan for includes
   * @returns Array of absolute paths to included XSD files that exist
   */
  private discoverIncludes(xsdFilePath: string): string[] {
    try {
      const content = fs.readFileSync(xsdFilePath, 'utf8');
      const includes: string[] = [];

      // Find all xs:include elements with schemaLocation
      const includeMatches = content.matchAll(/xs:include\s+schemaLocation\s*=\s*["']([^"']+)["']/g);

      for (const match of includeMatches) {
        const includeFile = match[1];
        const includePath = path.join(this.xsdDirectory, includeFile);

        if (fs.existsSync(includePath)) {
          includes.push(includePath);
        }
      }

      return includes;
    } catch (error) {
      console.warn(`Warning: Could not parse includes from ${xsdFilePath}:`, error);
      return [];
    }
  }

  /**
   * Load a schema dynamically based on schema name
   * @param schemaName The name of the schema to load (without .xsd extension)
   * @returns The loaded Schema instance, or null if loading failed
   */
  private loadSchema(schemaName: string): Schema | null {
    // Check if already loaded
    if (this.schemas.has(schemaName)) {
      return this.schemas.get(schemaName)!;
    }

    // Try to find the XSD file
    const xsdPath = path.join(this.xsdDirectory, `${schemaName}.xsd`);

    if (!fs.existsSync(xsdPath)) {
      console.warn(`Schema file not found: ${xsdPath}`);
      return null;
    }

    try {
      // Discover includes
      const includes = this.discoverIncludes(xsdPath);

      // Create and cache the schema
      const schema = new Schema(xsdPath, includes);
      this.schemas.set(schemaName, schema);

      return schema;
    } catch (error) {
      console.error(`Error loading schema ${schemaName}:`, error);
      return null;
    }
  }

    /**
   * Get the appropriate schema for a given XML file (legacy method)
   * @deprecated Use XsdDetector.detectSchemaFromXml() and then getSchema() instead
   */
  public getSchemaForFile(xmlFilePath: string): Schema | null {
    const fileInfo = XsdDetector.detectSchemaFromXml(xmlFilePath);
    if (!fileInfo.schemaType) {
      return null;
    }

    // Try to load the schema dynamically
    return this.loadSchema(fileInfo.schemaType);
  }

  /**
   * Get schema by type name (loads on demand)
   * @param schemaType The type/name of the schema to retrieve
   * @returns The Schema instance if found and loaded successfully, null otherwise
   */
  public getSchema(schemaType: string): Schema | null {
    return this.loadSchema(schemaType);
  }

  /**
   * Get all currently loaded schema types
   * @returns Array of schema type names that are currently loaded in memory
   */
  public getAvailableSchemas(): string[] {
    return Array.from(this.schemas.keys());
  }

  /**
   * Get all discoverable schema files in the XSD directory
   * @returns Array of schema names (without .xsd extension) found in the XSD directory
   */
  public getDiscoverableSchemas(): string[] {
    try {
      const files = fs.readdirSync(this.xsdDirectory);
      return files
        .filter(file => file.endsWith('.xsd'))
        .map(file => path.basename(file, '.xsd'));
    } catch (error) {
      console.warn(`Could not read XSD directory ${this.xsdDirectory}:`, error);
      return [];
    }
  }
  /**
   * Get element definition using a specific schema by name
   * @param schemaName The schema to use
   * @param elementName The element name to find
   * @param hierarchy The element hierarchy in bottom-up order (parent → root)
   */
  public getElementDefinition(schemaName: string, elementName: string, hierarchy: string[] = []): Element | undefined {
    const schema = this.loadSchema(schemaName);
    if (!schema) {
      return undefined;
    }

    return schema.getElementDefinition(elementName, hierarchy);
  }

  /**
   * Get element attributes using a specific schema by name
   * @param schemaName The schema to use
   * @param elementName The element name to find
   * @param hierarchy The element hierarchy in bottom-up order (parent → root)
   */
  public getElementAttributes(schemaName: string, elementName: string, hierarchy: string[] = []): AttributeInfo[] {
    const schema = this.loadSchema(schemaName);
    if (!schema) {
      return [];
    }

    return schema.getElementAttributes(elementName, hierarchy);
  }

  /**
   * Get element attributes with type information
   * @param schemaName The schema to use
   * @param elementName The element name to find
   * @param hierarchy The element hierarchy in bottom-up order (parent → root)
   */
  public getElementAttributesWithTypes(schemaName: string, elementName: string, hierarchy: string[] = []): EnhancedAttributeInfo[] {
    const schema = this.loadSchema(schemaName);
    if (!schema) {
      return [];
    }

    return schema.getElementAttributesWithTypes(elementName, hierarchy);
  }

  /**
   * Validate an attribute value against the schema
   * @param schemaName The schema to use
   * @param elementName The element name
   * @param attributeName The attribute name
   * @param attributeValue The attribute value to validate
   * @param hierarchy The element hierarchy in bottom-up order (parent → root)
   */
  public validateAttributeValue(schemaName: string, elementName: string, attributeName: string, attributeValue: string, hierarchy: string[] = []): AttributeValidationResult {
    const schema = this.loadSchema(schemaName);
    if (!schema) {
      return { isValid: false, errorMessage: 'Schema not found' };
    }

    return schema.validateAttributeValue(elementName, attributeName, attributeValue, hierarchy);
  }

  /**
   * Validate attributes against a list of provided attribute names
   * @param attributeInfos The attribute info array from getElementAttributesWithTypes
   * @param providedAttributes Array of attribute names that are provided
   * @returns Object containing wrong attributes and missing required attributes
   */
  public static validateAttributeNames(
    attributeInfos: EnhancedAttributeInfo[],
    providedAttributes: string[]
  ): AttributeNameValidationResult {
    // Filter out XML infrastructure attributes from provided attributes
    const filteredProvidedAttributes = this.filterOutInfrastructureAttributes(providedAttributes);

    // Get all valid attribute names from schema
    const validAttributeNames = new Set(attributeInfos.map(attr => attr.name));

    // Get required attribute names
    const requiredAttributeNames = new Set(
      attributeInfos.filter(attr => attr.required).map(attr => attr.name)
    );

    // Find wrong attributes (provided but not in schema)
    const wrongAttributes = filteredProvidedAttributes.filter(attr => !validAttributeNames.has(attr));

    // Find missing required attributes (required in schema but not provided)
    const providedAttributeSet = new Set(filteredProvidedAttributes);
    const missingRequiredAttributes = Array.from(requiredAttributeNames)
      .filter(attr => !providedAttributeSet.has(attr));

    return {
      wrongAttributes,
      missingRequiredAttributes
    };
  }

  /**
   * Filter attributes by type
   * @param attributeInfos The attribute info array from getElementAttributesWithTypes
   * @param attributeType The type to filter by (e.g., 'xs:string', 'xs:int', etc.)
   * @returns Array of attributes that match the specified type
   */
  public static filterAttributesByType(
    attributeInfos: EnhancedAttributeInfo[],
    attributeType: string
  ): string[] {
    return attributeInfos
      .filter(attr => attr.type === attributeType && !this.isXmlInfrastructureAttribute(attr.name))
      .map(attr => attr.name);
  }

  /**
   * Filter attributes by restriction type
   * @param attributeInfos The attribute info array from getElementAttributesWithTypes
   * @param restrictionType The restriction to filter by ('enumeration', 'pattern', 'length', 'range')
   * @returns Array of attributes that have the specified restriction type
   */
  public static filterAttributesByRestriction(
    attributeInfos: EnhancedAttributeInfo[],
    restrictionType: 'enumeration' | 'pattern' | 'length' | 'range'
  ): string[] {
    return attributeInfos
      .filter(attr => {
        // Skip infrastructure attributes
        if (this.isXmlInfrastructureAttribute(attr.name)) {
          return false;
        }

        switch (restrictionType) {
          case 'enumeration':
            return attr.enumValues && attr.enumValues.length > 0;
          case 'pattern':
            return attr.patterns && attr.patterns.length > 0;
          case 'length':
            return (attr.minLength !== undefined) || (attr.maxLength !== undefined);
          case 'range':
            return (attr.minInclusive !== undefined) || (attr.maxInclusive !== undefined) ||
                   (attr.minExclusive !== undefined) || (attr.maxExclusive !== undefined);
          default:
            return false;
        }
      })
      .map(attr => attr.name);
  }

  /**
   * Validate an attribute value against its schema rules
   * @param attributeInfos The attribute info array from getElementAttributesWithTypes
   * @param attributeName The attribute name to validate
   * @param attributeValue The value to validate
   * @returns Validation result with details
   */
  public static validateAttributeValueAgainstRules(
    attributeInfos: EnhancedAttributeInfo[],
    attributeName: string,
    attributeValue: string
  ): { isValid: boolean; errorMessage?: string; violatedRules?: string[] } {
    // Return empty/skip result for XML infrastructure attributes
    if (this.isXmlInfrastructureAttribute(attributeName)) {
      return {
        isValid: true, // Infrastructure attributes are always considered valid but ignored
        errorMessage: undefined
      };
    }

    const attribute = attributeInfos.find(attr => attr.name === attributeName);

    if (!attribute) {
      return {
        isValid: false,
        errorMessage: `Attribute '${attributeName}' not found in attribute info`
      };
    }

    const violatedRules: string[] = [];

    let isPatternsMatched = true;
    // Check patterns
    if (attribute.patterns && attribute.patterns.length > 0) {
      const patternMatches = attribute.patterns.some((pattern: string) => {
        try {
          const regex = new RegExp(pattern);
          return regex.test(attributeValue);
        } catch (e) {
          return false;
        }
      });

      if (!patternMatches) {
        isPatternsMatched = false;
        violatedRules.push(`Value must match pattern(s): ${attribute.patterns.join(' or ')}`);
      }
    } else {
      // If no patterns defined, treat it as not matched for enumeration checks
      isPatternsMatched = ! (attribute.enumValues && attribute.enumValues.length > 0);
    }


    // Check enumeration values
    if (attribute.enumValues && attribute.enumValues.length > 0) {
      if (!attribute.enumValues.includes(attributeValue) && !isPatternsMatched) {
        violatedRules.push(`Value must be one of: ${attribute.enumValues.join(', ')}`);
      }
    }

    // Check length restrictions
    if (attribute.minLength !== undefined && attributeValue.length < attribute.minLength) {
      violatedRules.push(`Value must be at least ${attribute.minLength} characters long`);
    }

    if (attribute.maxLength !== undefined && attributeValue.length > attribute.maxLength) {
      violatedRules.push(`Value must be at most ${attribute.maxLength} characters long`);
    }

    // Check numeric range restrictions (if value is numeric)
    const numericValue = parseFloat(attributeValue);
    if (!isNaN(numericValue)) {
      if (attribute.minInclusive !== undefined && numericValue < attribute.minInclusive) {
        violatedRules.push(`Value must be >= ${attribute.minInclusive}`);
      }

      if (attribute.maxInclusive !== undefined && numericValue > attribute.maxInclusive) {
        violatedRules.push(`Value must be <= ${attribute.maxInclusive}`);
      }

      if (attribute.minExclusive !== undefined && numericValue <= attribute.minExclusive) {
        violatedRules.push(`Value must be > ${attribute.minExclusive}`);
      }

      if (attribute.maxExclusive !== undefined && numericValue >= attribute.maxExclusive) {
        violatedRules.push(`Value must be < ${attribute.maxExclusive}`);
      }
    }

    const isValid = violatedRules.length === 0;

    return {
      isValid,
      errorMessage: isValid ? undefined : violatedRules.join('; '),
      violatedRules: isValid ? undefined : violatedRules
    };
  }

  /**
   * Get possible values for an attribute if it has enumeration restrictions
   * @param attributeInfos The attribute info array from getElementAttributesWithTypes
   * @param attributeName The attribute name
   * @returns Map where key is the enum value and value is its annotation text, or empty map if no enumeration exists
   */
  public static getAttributePossibleValues(
    attributeInfos: EnhancedAttributeInfo[],
    attributeName: string
  ): Map<string, string> {
    // Return empty map for XML infrastructure attributes
    if (this.isXmlInfrastructureAttribute(attributeName)) {
      return new Map();
    }

    const attribute = attributeInfos.find(attr => attr.name === attributeName);

    if (!attribute || !attribute.enumValues) {
      return new Map();
    }

    const result = new Map<string, string>();

    // Build map with enum values and their annotations
    for (const enumValue of attribute.enumValues) {
      const annotation = attribute.enumValuesAnnotations?.get(enumValue) || '';
      result.set(enumValue, annotation);
    }

    return result;
  }

  /**
   * Get all simple types that use a specific type as their base
   * @param schemaName The schema name to search
   * @param baseType The base type to filter by (e.g., 'lvalueexpression')
   * @returns Array of simple type names that use the specified base type
   */
  public getSimpleTypesWithBaseType(
    schemaName: string,
    baseType: string
  ): string[] {
    const schema = this.loadSchema(schemaName);
    if (!schema) {
      return [];
    }

    const results: string[] = [];

    // Access the schema index to get all types
    const schemaIndex = (schema as any).schemaIndex;
    if (!schemaIndex || !schemaIndex.types) {
      return [];
    }

    // Iterate through all types and filter simple types with the specified base type
    Object.entries(schemaIndex.types).forEach(([typeName, typeNode]) => {
      const element = typeNode as Element;
      if (element.nodeName.includes('simpleType')) {
        // Look for xs:restriction element with the specified base
        const restrictions = Array.from(element.childNodes).filter(
          (node): node is Element =>
            node.nodeType === 1 &&
            (node as Element).nodeName.includes('restriction')
        );

        for (const restrictionNode of restrictions) {
          const base = restrictionNode.getAttribute('base');
          if (base === baseType) {
            results.push(typeName);
            break; // Found it, no need to check other restrictions for this type
          }
        }
      }
    });

    return results;
  }

  /**
   * Get enumeration values for a named SimpleType
   * @param schemaName The schema name to search in
   * @param simpleTypeName The name of the SimpleType to get enumeration values from
   * @returns Object containing enumeration values and their annotations, or null if not found or not an enumeration
   */
  public getSimpleTypeEnumerationValues(
    schemaName: string, 
    simpleTypeName: string
  ): { values: string[], annotations: Map<string, string> } | null {
    const schema = this.loadSchema(schemaName);
    if (!schema) {
      return null;
    }

    return schema.getSimpleTypeEnumerationValues(simpleTypeName);
  }

  /**
   * Check if an attribute name is an XML infrastructure attribute that should be ignored
   * @param attributeName The attribute name to check
   * @returns True if it's an infrastructure attribute (xmlns, xsi, etc.)
   */
  private static isXmlInfrastructureAttribute(attributeName: string): boolean {
    return attributeName.startsWith('xmlns:') ||
           attributeName.startsWith('xsi:') ||
           attributeName === 'xmlns';
  }

  /**
   * Filter out XML infrastructure attributes from a list
   * @param attributeNames Array of attribute names to filter
   * @returns Array with infrastructure attributes removed
   */
  private static filterOutInfrastructureAttributes(attributeNames: string[]): string[] {
    return attributeNames.filter(attr => !this.isXmlInfrastructureAttribute(attr));
  }

  /**
   * Get possible child elements for a given element by name and hierarchy
   * @param schemaName The schema to use
   * @param elementName The parent element name
   * @param hierarchy The element hierarchy in bottom-up order (parent → root)
   * @param previousSibling Optional previous sibling element name to filter results based on sequence constraints
   * @returns Map where key is child element name and value is its annotation text
   */
  public getPossibleChildElements(schemaName: string, elementName: string, hierarchy: string[] = [], previousSibling?: string): Map<string, string> {
    const schema = this.loadSchema(schemaName);
    if (!schema) {
      return new Map<string, string>();
    }

    return schema.getPossibleChildElements(elementName, hierarchy, previousSibling);
  }

  /**
   * Extract annotation text from an XML element.
   * This static method provides access to Schema's annotation extraction functionality.
   * @param element The XML element to extract annotation from
   * @returns The annotation text, or undefined if no annotation found
   */
  public static extractAnnotationText(element: Element): string | undefined {
    return Schema.extractAnnotationText(element);
  }

  /**
   * Clear a specific schema from the cache
   * @param schemaName The name of the schema to clear
   */
  private clearSchema(schemaName: string): void {
    // Clear the specific schema from the cache
    if (this.schemas.has(schemaName)) {
      this.schemas.get(schemaName)?.dispose(); // Clear the schema's internal caches
      this.schemas.delete(schemaName);
    }
    // Optionally, you can also clear the XSD directory if needed
    // this.xsdDirectory = '';
  }

  /**
   * Clear all schemas and their caches
   * This method clears all loaded schemas and their internal caches.
   * It can be used to release resources when the XSD reference is no longer needed.
   */
  public dispose(): void {
    // Clear all schemas from the cache
    this.schemas.forEach((schema, name) => this.clearSchema(name)); // Clear each schema's internal caches
    this.schemas.clear();
    this.xsdDirectory = ''; // Reset the directory if needed
  }
}