/**
 * Smart Search Tool - Unified search with mode-based execution
 * Modes: auto, exact, fuzzy, semantic, graph
 *
 * Features:
 * - Intent classification (auto mode)
 * - Multi-backend search routing
 * - Result fusion with RRF ranking
 * - Configurable search parameters
 */

import { spawn, execSync } from 'child_process';
import { existsSync, readdirSync, statSync } from 'fs';
import { join, resolve, isAbsolute } from 'path';
import { ensureReady as ensureCodexLensReady, executeCodexLens } from './codex-lens.js';

// Search mode constants
const SEARCH_MODES = ['auto', 'exact', 'fuzzy', 'semantic', 'graph'];

// Classification confidence threshold
const CONFIDENCE_THRESHOLD = 0.7;

/**
 * Detection heuristics for intent classification
 */

/**
 * Detect literal string query (simple alphanumeric or quoted strings)
 */
function detectLiteral(query) {
  return /^[a-zA-Z0-9_-]+$/.test(query) || /^["'].*["']$/.test(query);
}

/**
 * Detect regex pattern (contains regex metacharacters)
 */
function detectRegex(query) {
  return /[.*+?^${}()|[\]\\]/.test(query);
}

/**
 * Detect natural language query (sentence structure, questions, multi-word phrases)
 */
function detectNaturalLanguage(query) {
  return query.split(/\s+/).length >= 3 || /\?$/.test(query);
}

/**
 * Detect file path query (path separators, file extensions)
 */
function detectFilePath(query) {
  return /[/\]/.test(query) || /\.[a-z]{2,4}$/i.test(query);
}

/**
 * Detect relationship query (import, export, dependency keywords)
 */
function detectRelationship(query) {
  return /(import|export|uses?|depends?|calls?|extends?)\s/i.test(query);
}

/**
 * Classify query intent and recommend search mode
 * @param {string} query - Search query string
 * @returns {{mode: string, confidence: number, reasoning: string}}
 */
function classifyIntent(query) {
  // Initialize mode scores
  const scores = {
    exact: 0,
    fuzzy: 0,
    semantic: 0,
    graph: 0
  };

  // Apply detection heuristics with weighted scoring
  if (detectLiteral(query)) {
    scores.exact += 0.8;
  }

  if (detectRegex(query)) {
    scores.fuzzy += 0.7;
  }

  if (detectNaturalLanguage(query)) {
    scores.semantic += 0.9;
  }

  if (detectFilePath(query)) {
    scores.exact += 0.6;
  }

  if (detectRelationship(query)) {
    scores.graph += 0.85;
  }

  // Find mode with highest confidence score
  const mode = Object.keys(scores).reduce((a, b) => scores[a] > scores[b] ? a : b);
  const confidence = scores[mode];

  // Build reasoning string
  const detectedPatterns = [];
  if (detectLiteral(query)) detectedPatterns.push('literal');
  if (detectRegex(query)) detectedPatterns.push('regex');
  if (detectNaturalLanguage(query)) detectedPatterns.push('natural language');
  if (detectFilePath(query)) detectedPatterns.push('file path');
  if (detectRelationship(query)) detectedPatterns.push('relationship');

  const reasoning = `Query classified as ${mode} (confidence: ${confidence.toFixed(2)}, detected: ${detectedPatterns.join(', ')})`;

  return { mode, confidence, reasoning };
}


/**
 * Check if a tool is available in PATH
 * @param {string} toolName - Tool executable name
 * @returns {boolean}
 */
function checkToolAvailability(toolName) {
  try {
    const isWindows = process.platform === 'win32';
    const command = isWindows ? 'where' : 'which';
    execSync(`${command} ${toolName}`, { stdio: 'ignore' });
    return true;
  } catch {
    return false;
  }
}

/**
 * Build ripgrep command arguments
 * @param {Object} params - Search parameters
 * @returns {{command: string, args: string[]}}
 */
function buildRipgrepCommand(params) {
  const { query, paths = ['.'], contextLines = 0, maxResults = 100, includeHidden = false } = params;

  const args = [
    '-n',              // Show line numbers
    '--color=never',   // Disable color output
    '--json'           // Output in JSON format
  ];

  // Add context lines if specified
  if (contextLines > 0) {
    args.push('-C', contextLines.toString());
  }

  // Add max results limit
  if (maxResults > 0) {
    args.push('--max-count', maxResults.toString());
  }

  // Include hidden files if specified
  if (includeHidden) {
    args.push('--hidden');
  }

  // Use literal/fixed string matching for exact mode
  args.push('-F', query);

  // Add search paths
  args.push(...paths);

  return { command: 'rg', args };
}

/**
 * Mode: auto - Intent classification and mode selection
 * Analyzes query to determine optimal search mode
 */
/**
 * Mode: auto - Intent classification and mode selection
 * Analyzes query to determine optimal search mode
 */
async function executeAutoMode(params) {
  const { query } = params;

  // Classify intent
  const classification = classifyIntent(query);

  // Route to appropriate mode based on classification
  switch (classification.mode) {
    case 'exact':
      // Execute exact mode and enrich result with classification metadata
      const exactResult = await executeExactMode(params);
      return {
        ...exactResult,
        metadata: {
          ...exactResult.metadata,
          classified_as: classification.mode,
          confidence: classification.confidence,
          reasoning: classification.reasoning
        }
      };

    case 'fuzzy':
      // Fuzzy mode not yet implemented
      return {
        success: false,
        error: 'Fuzzy mode not yet implemented',
        metadata: {
          classified_as: classification.mode,
          confidence: classification.confidence,
          reasoning: classification.reasoning
        }
      };

    case 'semantic':
      // Execute semantic mode via CodexLens
      const semanticResult = await executeSemanticMode(params);
      return {
        ...semanticResult,
        metadata: {
          ...semanticResult.metadata,
          classified_as: classification.mode,
          confidence: classification.confidence,
          reasoning: classification.reasoning
        }
      };

    case 'graph':
      // Execute graph mode via CodexLens
      const graphResult = await executeGraphMode(params);
      return {
        ...graphResult,
        metadata: {
          ...graphResult.metadata,
          classified_as: classification.mode,
          confidence: classification.confidence,
          reasoning: classification.reasoning
        }
      };

    default:
      // Fallback to exact mode with warning
      const fallbackResult = await executeExactMode(params);
      return {
        ...fallbackResult,
        metadata: {
          ...fallbackResult.metadata,
          classified_as: 'exact',
          confidence: 0.5,
          reasoning: 'Fallback to exact mode due to unknown classification'
        }
      };
  }
}
/**
 * Mode: exact - Precise file path and content matching
 * Uses ripgrep for literal string matching
 */
async function executeExactMode(params) {
  const { query, paths = [], contextLines = 0, maxResults = 100, includeHidden = false } = params;

  // Check ripgrep availability
  if (!checkToolAvailability('rg')) {
    return {
      success: false,
      error: 'ripgrep not available - please install ripgrep (rg) to use exact search mode'
    };
  }

  // Build ripgrep command
  const { command, args } = buildRipgrepCommand({
    query,
    paths: paths.length > 0 ? paths : ['.'],
    contextLines,
    maxResults,
    includeHidden
  });

  return new Promise((resolve) => {
    const child = spawn(command, args, {
      cwd: process.cwd(),
      stdio: ['ignore', 'pipe', 'pipe']
    });

    let stdout = '';
    let stderr = '';

    // Collect stdout
    child.stdout.on('data', (data) => {
      stdout += data.toString();
    });

    // Collect stderr
    child.stderr.on('data', (data) => {
      stderr += data.toString();
    });

    // Handle completion
    child.on('close', (code) => {
      // Parse ripgrep JSON output
      const results = [];

      if (code === 0 || (code === 1 && stdout.trim())) {
        // Code 0: matches found, Code 1: no matches (but may have output)
        const lines = stdout.split('\n').filter(line => line.trim());

        for (const line of lines) {
          try {
            const item = JSON.parse(line);

            // Only process match type items
            if (item.type === 'match') {
              const match = {
                file: item.data.path.text,
                line: item.data.line_number,
                column: item.data.submatches && item.data.submatches[0] ? item.data.submatches[0].start + 1 : 1,
                content: item.data.lines.text.trim()
              };
              results.push(match);
            }
          } catch (err) {
            // Skip malformed JSON lines
            continue;
          }
        }

        resolve({
          success: true,
          results,
          metadata: {
            mode: 'exact',
            backend: 'ripgrep',
            count: results.length,
            query
          }
        });
      } else {
        // Error occurred
        resolve({
          success: false,
          error: `ripgrep execution failed with code ${code}: ${stderr}`,
          results: []
        });
      }
    });

    // Handle spawn errors
    child.on('error', (error) => {
      resolve({
        success: false,
        error: `Failed to spawn ripgrep: ${error.message}`,
        results: []
      });
    });
  });
}

/**
 * Mode: fuzzy - Approximate matching with tolerance
 * Uses fuzzy matching algorithms for typo-tolerant search
 */
async function executeFuzzyMode(params) {
  const { query, paths = [], maxResults = 100 } = params;

  // TODO: Implement fuzzy search
  // - Use fuse.js for content fuzzy matching
  // - Support approximate file path matching
  // - Configure similarity threshold
  // - Return ranked results

  return {
    success: false,
    error: 'Fuzzy mode not implemented - fuzzy matching engine pending'
  };
}

/**
 * Mode: semantic - Natural language understanding search
 * Uses CodexLens embeddings for semantic similarity
 */
async function executeSemanticMode(params) {
  const { query, paths = [], maxResults = 100 } = params;

  // Check CodexLens availability
  const readyStatus = await ensureCodexLensReady();
  if (!readyStatus.ready) {
    return {
      success: false,
      error: `CodexLens not available: ${readyStatus.error}. Run 'ccw tool exec codex_lens {"action":"bootstrap"}' to install.`
    };
  }

  // Determine search path
  const searchPath = paths.length > 0 ? paths[0] : '.';

  // Execute CodexLens semantic search
  const result = await executeCodexLens(
    ['search', query, '--limit', maxResults.toString(), '--json'],
    { cwd: searchPath }
  );

  if (!result.success) {
    return {
      success: false,
      error: result.error,
      metadata: {
        mode: 'semantic',
        backend: 'codexlens'
      }
    };
  }

  // Parse and transform results
  let results = [];
  try {
    // Handle CRLF in output
    const cleanOutput = result.output.replace(/\r\n/g, '\n');
    const parsed = JSON.parse(cleanOutput);
    const data = parsed.result || parsed;
    results = (data.results || []).map(item => ({
      file: item.path || item.file,
      score: item.score || 0,
      content: item.excerpt || item.content || '',
      symbol: item.symbol || null
    }));
  } catch {
    // Return raw output if JSON parsing fails
    return {
      success: true,
      results: [],
      output: result.output,
      metadata: {
        mode: 'semantic',
        backend: 'codexlens',
        count: 0,
        query,
        warning: 'Failed to parse JSON output'
      }
    };
  }

  return {
    success: true,
    results,
    metadata: {
      mode: 'semantic',
      backend: 'codexlens',
      count: results.length,
      query
    }
  };
}

/**
 * Mode: graph - Dependency and relationship traversal
 * Uses CodexLens symbol extraction for code analysis
 */
async function executeGraphMode(params) {
  const { query, paths = [], maxResults = 100 } = params;

  // Check CodexLens availability
  const readyStatus = await ensureCodexLensReady();
  if (!readyStatus.ready) {
    return {
      success: false,
      error: `CodexLens not available: ${readyStatus.error}. Run 'ccw tool exec codex_lens {"action":"bootstrap"}' to install.`
    };
  }

  // First, search for relevant files using text search
  const searchPath = paths.length > 0 ? paths[0] : '.';

  // Execute text search to find files matching the query
  const textResult = await executeCodexLens(
    ['search', query, '--limit', maxResults.toString(), '--json'],
    { cwd: searchPath }
  );

  if (!textResult.success) {
    return {
      success: false,
      error: textResult.error,
      metadata: {
        mode: 'graph',
        backend: 'codexlens'
      }
    };
  }

  // Parse results and extract symbols from top files
  let results = [];
  try {
    const parsed = JSON.parse(textResult.output);
    const files = [...new Set((parsed.results || parsed).map(item => item.path || item.file))].slice(0, 10);

    // Extract symbols from files in parallel
    const symbolPromises = files.map(file =>
      executeCodexLens(['symbol', file, '--json'], { cwd: searchPath })
        .then(result => ({ file, result }))
    );

    const symbolResults = await Promise.all(symbolPromises);

    for (const { file, result } of symbolResults) {
      if (result.success) {
        try {
          const symbols = JSON.parse(result.output);
          results.push({
            file,
            symbols: symbols.symbols || symbols,
            relationships: []
          });
        } catch {
          // Skip files with parse errors
        }
      }
    }
  } catch {
    return {
      success: false,
      error: 'Failed to parse search results',
      metadata: {
        mode: 'graph',
        backend: 'codexlens'
      }
    };
  }

  return {
    success: true,
    results,
    metadata: {
      mode: 'graph',
      backend: 'codexlens',
      count: results.length,
      query,
      note: 'Graph mode provides symbol extraction; full dependency graph analysis pending'
    }
  };
}

/**
 * Main execute function - routes to appropriate mode handler
 */
async function execute(params) {
  const { query, mode = 'auto', paths = [], contextLines = 0, maxResults = 100, includeHidden = false } = params;

  // Validate required parameters
  if (!query || typeof query !== 'string') {
    throw new Error('Parameter "query" is required and must be a string');
  }

  // Validate mode
  if (!SEARCH_MODES.includes(mode)) {
    throw new Error(`Invalid mode: ${mode}. Valid modes: ${SEARCH_MODES.join(', ')}`);
  }

  // Route to mode-specific handler
  switch (mode) {
    case 'auto':
      return executeAutoMode(params);

    case 'exact':
      return executeExactMode(params);

    case 'fuzzy':
      return executeFuzzyMode(params);

    case 'semantic':
      return executeSemanticMode(params);

    case 'graph':
      return executeGraphMode(params);

    default:
      throw new Error(`Unsupported mode: ${mode}`);
  }
}

/**
 * Smart Search Tool Definition
 */
export const smartSearchTool = {
  name: 'smart_search',
  description: `Intelligent code search with multiple modes.

Usage:
  smart_search(query="function main", path=".")           # Auto-select mode
  smart_search(query="def init", mode="exact")            # Exact match
  smart_search(query="authentication logic", mode="semantic")  # NL search

Modes: auto (default), exact, fuzzy, semantic, graph`,
  parameters: {
    type: 'object',
    properties: {
      query: {
        type: 'string',
        description: 'Search query (file pattern, text content, or natural language)'
      },
      mode: {
        type: 'string',
        enum: SEARCH_MODES,
        description: 'Search mode (default: auto)',
        default: 'auto'
      },
      paths: {
        type: 'array',
        description: 'Paths to search within (default: current directory)',
        items: {
          type: 'string'
        },
        default: []
      },
      contextLines: {
        type: 'number',
        description: 'Number of context lines around matches (default: 0)',
        default: 0
      },
      maxResults: {
        type: 'number',
        description: 'Maximum number of results to return (default: 100)',
        default: 100
      },
      includeHidden: {
        type: 'boolean',
        description: 'Include hidden files/directories (default: false)',
        default: false
      }
    },
    required: ['query']
  },
  execute
};