import { fs, path } from 'zx';
import { PentestError } from './error-handling.js';

// Vulnerability type configuration as immutable data
const VULN_TYPE_CONFIG = Object.freeze({
  injection: Object.freeze({ 
    deliverable: 'injection_analysis_deliverable.md', 
    queue: 'injection_exploitation_queue.json' 
  }),
  xss: Object.freeze({ 
    deliverable: 'xss_analysis_deliverable.md', 
    queue: 'xss_exploitation_queue.json' 
  }),
  auth: Object.freeze({ 
    deliverable: 'auth_analysis_deliverable.md', 
    queue: 'auth_exploitation_queue.json' 
  }),
  ssrf: Object.freeze({ 
    deliverable: 'ssrf_analysis_deliverable.md', 
    queue: 'ssrf_exploitation_queue.json' 
  }),
  authz: Object.freeze({ 
    deliverable: 'authz_analysis_deliverable.md', 
    queue: 'authz_exploitation_queue.json' 
  })
});

// Functional composition utilities - async pipe for promise chain
const pipe = (...fns) => x => fns.reduce(async (v, f) => f(await v), x);
const compose = (...fns) => x => fns.reduceRight((v, f) => f(v), x);

// Pure function to create validation rule
const createValidationRule = (predicate, errorMessage, retryable = true) => 
  Object.freeze({ predicate, errorMessage, retryable });

// Validation rules for file existence (following QUEUE_VALIDATION_FLOW.md)
const fileExistenceRules = Object.freeze([
  // Rule 1: Neither deliverable nor queue exists
  createValidationRule(
    ({ deliverableExists, queueExists }) => deliverableExists || queueExists,
    'Analysis failed: Neither deliverable nor queue file exists. Analysis agent must create both files.'
  ),
  // Rule 2: Queue doesn't exist but deliverable exists
  createValidationRule(
    ({ deliverableExists, queueExists }) => !(!queueExists && deliverableExists),
    'Analysis incomplete: Deliverable exists but queue file missing. Analysis agent must create both files.'
  ),
  // Rule 3: Queue exists but deliverable doesn't exist
  createValidationRule(
    ({ deliverableExists, queueExists }) => !(queueExists && !deliverableExists),
    'Analysis incomplete: Queue exists but deliverable file missing. Analysis agent must create both files.'
  )
]);

// Pure function to create file paths
const createPaths = (vulnType, sourceDir) => {
  const config = VULN_TYPE_CONFIG[vulnType];
  if (!config) {
    return { 
      error: new PentestError(
        `Unknown vulnerability type: ${vulnType}`,
        'validation',
        false,
        { vulnType }
      )
    };
  }
  
  return Object.freeze({
    vulnType,
    deliverable: path.join(sourceDir, 'deliverables', config.deliverable),
    queue: path.join(sourceDir, 'deliverables', config.queue),
    sourceDir
  });
};

// Pure function to check file existence
const checkFileExistence = async (paths) => {
  if (paths.error) return paths;
  
  const [deliverableExists, queueExists] = await Promise.all([
    fs.pathExists(paths.deliverable),
    fs.pathExists(paths.queue)
  ]);
  
  return Object.freeze({
    ...paths,
    existence: Object.freeze({ deliverableExists, queueExists })
  });
};

// Pure function to validate existence rules
const validateExistenceRules = (pathsWithExistence) => {
  if (pathsWithExistence.error) return pathsWithExistence;
  
  const { existence, vulnType } = pathsWithExistence;
  
  // Find the first rule that fails
  const failedRule = fileExistenceRules.find(rule => !rule.predicate(existence));
  
  if (failedRule) {
    return {
      ...pathsWithExistence,
      error: new PentestError(
        `${failedRule.errorMessage} (${vulnType})`,
        'validation',
        failedRule.retryable,
        { 
          vulnType, 
          deliverablePath: pathsWithExistence.deliverable,
          queuePath: pathsWithExistence.queue,
          existence
        }
      )
    };
  }
  
  return pathsWithExistence;
};

// Pure function to validate queue structure
const validateQueueStructure = (content) => {
  try {
    const parsed = JSON.parse(content);
    return Object.freeze({
      valid: parsed.vulnerabilities && Array.isArray(parsed.vulnerabilities),
      data: parsed,
      error: null
    });
  } catch (parseError) {
    return Object.freeze({
      valid: false,
      data: null,
      error: parseError.message
    });
  }
};

// Pure function to read and validate queue content
const validateQueueContent = async (pathsWithExistence) => {
  if (pathsWithExistence.error) return pathsWithExistence;
  
  try {
    const queueContent = await fs.readFile(pathsWithExistence.queue, 'utf8');
    const queueValidation = validateQueueStructure(queueContent);
    
    if (!queueValidation.valid) {
      // Rule 6: Both exist, queue invalid
      return {
        ...pathsWithExistence,
        error: new PentestError(
          queueValidation.error 
            ? `Queue validation failed for ${pathsWithExistence.vulnType}: Invalid JSON structure. Analysis agent must fix queue format.`
            : `Queue validation failed for ${pathsWithExistence.vulnType}: Missing or invalid 'vulnerabilities' array. Analysis agent must fix queue structure.`,
          'validation',
          true, // retryable
          { 
            vulnType: pathsWithExistence.vulnType,
            queuePath: pathsWithExistence.queue,
            originalError: queueValidation.error,
            queueStructure: queueValidation.data ? Object.keys(queueValidation.data) : []
          }
        )
      };
    }
    
    return Object.freeze({
      ...pathsWithExistence,
      queueData: queueValidation.data
    });
  } catch (readError) {
    return {
      ...pathsWithExistence,
      error: new PentestError(
        `Failed to read queue file for ${pathsWithExistence.vulnType}: ${readError.message}`,
        'filesystem',
        false,
        { 
          vulnType: pathsWithExistence.vulnType,
          queuePath: pathsWithExistence.queue,
          originalError: readError.message
        }
      )
    };
  }
};

// Pure function to determine exploitation decision
const determineExploitationDecision = (validatedData) => {
  if (validatedData.error) {
    throw validatedData.error;
  }
  
  const hasVulnerabilities = validatedData.queueData.vulnerabilities.length > 0;
  
  // Rule 4: Both exist, queue valid and populated
  // Rule 5: Both exist, queue valid but empty
  return Object.freeze({
    shouldExploit: hasVulnerabilities,
    shouldRetry: false,
    vulnerabilityCount: validatedData.queueData.vulnerabilities.length,
    vulnType: validatedData.vulnType
  });
};

// Main functional validation pipeline
export const validateQueueAndDeliverable = async (vulnType, sourceDir) => 
  await pipe(
    () => createPaths(vulnType, sourceDir),
    checkFileExistence,
    validateExistenceRules,
    validateQueueContent,
    determineExploitationDecision
  )();

// Pure function to safely validate (returns result instead of throwing)
export const safeValidateQueueAndDeliverable = async (vulnType, sourceDir) => {
  try {
    const result = await validateQueueAndDeliverable(vulnType, sourceDir);
    return { success: true, data: result };
  } catch (error) {
    return { success: false, error };
  }
};