/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import type { MessageBus } from '../confirmation-bus/message-bus.js';
import fs from 'node:fs';
import fsPromises from 'node:fs/promises';
import path from 'node:path';
import { downloadRipGrep } from '@joshua.litt/get-ripgrep';
import type { ToolInvocation, ToolResult } from './tools.js';
import { BaseDeclarativeTool, BaseToolInvocation, Kind } from './tools.js';
import { ToolErrorType } from './tool-error.js';
import { makeRelative, shortenPath } from '../utils/paths.js';
import { getErrorMessage, isNodeError } from '../utils/errors.js';
import type { Config } from '../config/config.js';
import { fileExists } from '../utils/fileUtils.js';
import { Storage } from '../config/storage.js';
import { GREP_TOOL_NAME } from './tool-names.js';
import { debugLogger } from '../utils/debugLogger.js';
import {
  FileExclusions,
  COMMON_DIRECTORY_EXCLUDES,
} from '../utils/ignorePatterns.js';
import { FileDiscoveryService } from '../services/fileDiscoveryService.js';
import { execStreaming } from '../utils/shell-utils.js';
import {
  DEFAULT_TOTAL_MAX_MATCHES,
  DEFAULT_SEARCH_TIMEOUT_MS,
} from './constants.js';

function getRgCandidateFilenames(): readonly string[] {
  return process.platform === 'win32' ? ['rg.exe', 'rg'] : ['rg'];
}

async function resolveExistingRgPath(): Promise<string | null> {
  const binDir = Storage.getGlobalBinDir();
  for (const fileName of getRgCandidateFilenames()) {
    const candidatePath = path.join(binDir, fileName);
    if (await fileExists(candidatePath)) {
      return candidatePath;
    }
  }
  return null;
}

let ripgrepAcquisitionPromise: Promise<string | null> | null = null;

async function ensureRipgrepAvailable(): Promise<string | null> {
  const existingPath = await resolveExistingRgPath();
  if (existingPath) {
    return existingPath;
  }
  if (!ripgrepAcquisitionPromise) {
    ripgrepAcquisitionPromise = (async () => {
      try {
        await downloadRipGrep(Storage.getGlobalBinDir());
        return await resolveExistingRgPath();
      } finally {
        ripgrepAcquisitionPromise = null;
      }
    })();
  }
  return ripgrepAcquisitionPromise;
}

/**
 * Checks if `rg` exists, if not then attempt to download it.
 */
export async function canUseRipgrep(): Promise<boolean> {
  return (await ensureRipgrepAvailable()) !== null;
}

/**
 * Ensures `rg` is downloaded, or throws.
 */
export async function ensureRgPath(): Promise<string> {
  const downloadedPath = await ensureRipgrepAvailable();
  if (downloadedPath) {
    return downloadedPath;
  }
  throw new Error('Cannot use ripgrep.');
}

/**
 * Parameters for the GrepTool
 */
export interface RipGrepToolParams {
  /**
   * The regular expression pattern to search for in file contents
   */
  pattern: string;

  /**
   * The directory to search in (optional, defaults to current directory relative to root)
   */
  dir_path?: string;

  /**
   * File pattern to include in the search (e.g. "*.js", "*.{ts,tsx}")
   */
  include?: string;

  /**
   * Optional: A string that must be present in the file for it to be included (logical AND).
   */
  filter?: string;

  /**
   * If true, searches case-sensitively. Defaults to false.
   */
  case_sensitive?: boolean;

  /**
   * If true, treats pattern as a literal string. Defaults to false.
   */
  fixed_strings?: boolean;

  /**
   * Show num lines of context around each match.
   */
  context?: number;

  /**
   * Show num lines after each match.
   */
  after?: number;

  /**
   * Show num lines before each match.
   */
  before?: number;

  /**
   * If true, does not respect .gitignore or default ignores (like build/dist).
   */
  no_ignore?: boolean;

  /**
   * Optional: Maximum number of matches to return per file.
   */
  max_matches_per_file?: number;
}

/**
 * Result object for a single grep match
 */
interface GrepMatch {
  filePath: string;
  lineNumber: number;
  line: string;
}

class GrepToolInvocation extends BaseToolInvocation<
  RipGrepToolParams,
  ToolResult
> {
  constructor(
    private readonly config: Config,
    private readonly fileDiscoveryService: FileDiscoveryService,
    params: RipGrepToolParams,
    messageBus: MessageBus,
    _toolName?: string,
    _toolDisplayName?: string,
  ) {
    super(params, messageBus, _toolName, _toolDisplayName);
  }

  async execute(signal: AbortSignal): Promise<ToolResult> {
    try {
      // Default to '.' if path is explicitly undefined/null.
      // This forces CWD search instead of 'all workspaces' search by default.
      const pathParam = this.params.dir_path || '.';

      const searchDirAbs = path.resolve(this.config.getTargetDir(), pathParam);
      const validationError = this.config.validatePathAccess(searchDirAbs);
      if (validationError) {
        return {
          llmContent: validationError,
          returnDisplay: 'Error: Path not in workspace.',
          error: {
            message: validationError,
            type: ToolErrorType.PATH_NOT_IN_WORKSPACE,
          },
        };
      }

      // Check existence and type asynchronously
      try {
        const stats = await fsPromises.stat(searchDirAbs);
        if (!stats.isDirectory() && !stats.isFile()) {
          return {
            llmContent: `Path is not a valid directory or file: ${searchDirAbs}`,
            returnDisplay: 'Error: Path is not a valid directory or file.',
          };
        }
      } catch (error: unknown) {
        if (isNodeError(error) && error.code === 'ENOENT') {
          return {
            llmContent: `Path does not exist: ${searchDirAbs}`,
            returnDisplay: 'Error: Path does not exist.',
            error: {
              message: `Path does not exist: ${searchDirAbs}`,
              type: ToolErrorType.FILE_NOT_FOUND,
            },
          };
        }
        return {
          llmContent: `Failed to access path stats for ${searchDirAbs}: ${getErrorMessage(error)}`,
          returnDisplay: 'Error: Failed to access path.',
        };
      }

      const searchDirDisplay = pathParam;

      const totalMaxMatches = DEFAULT_TOTAL_MAX_MATCHES;
      if (this.config.getDebugMode()) {
        debugLogger.log(`[GrepTool] Total result limit: ${totalMaxMatches}`);
      }

      // Create a timeout controller to prevent indefinitely hanging searches
      const timeoutController = new AbortController();
      const timeoutId = setTimeout(() => {
        timeoutController.abort();
      }, DEFAULT_SEARCH_TIMEOUT_MS);

      // Link the passed signal to our timeout controller
      const onAbort = () => timeoutController.abort();
      if (signal.aborted) {
        onAbort();
      } else {
        signal.addEventListener('abort', onAbort, { once: true });
      }

      let allMatches: GrepMatch[];
      try {
        allMatches = await this.performRipgrepSearch({
          pattern: this.params.pattern,
          path: searchDirAbs,
          include: this.params.include,
          filter: this.params.filter,
          case_sensitive: this.params.case_sensitive,
          fixed_strings: this.params.fixed_strings,
          context: this.params.context,
          after: this.params.after,
          before: this.params.before,
          no_ignore: this.params.no_ignore,
          maxMatches: totalMaxMatches,
          maxMatchesPerFile: this.params.max_matches_per_file,
          signal: timeoutController.signal,
        });
      } finally {
        clearTimeout(timeoutId);
        signal.removeEventListener('abort', onAbort);
      }

      if (!this.params.no_ignore) {
        const uniqueFiles = Array.from(
          new Set(allMatches.map((m) => m.filePath)),
        );
        const absoluteFilePaths = uniqueFiles.map((f) =>
          path.resolve(searchDirAbs, f),
        );
        const allowedFiles =
          this.fileDiscoveryService.filterFiles(absoluteFilePaths);
        const allowedSet = new Set(allowedFiles);
        allMatches = allMatches.filter((m) =>
          allowedSet.has(path.resolve(searchDirAbs, m.filePath)),
        );
      }

      const searchLocationDescription = `in path "${searchDirDisplay}"`;
      if (allMatches.length === 0) {
        const noMatchMsg = `No matches found for pattern "${this.params.pattern}" ${searchLocationDescription}${this.params.include ? ` (filter: "${this.params.include}")` : ''}.`;
        return { llmContent: noMatchMsg, returnDisplay: `No matches found` };
      }

      const wasTruncated = allMatches.length >= totalMaxMatches;

      const matchesByFile = allMatches.reduce(
        (acc, match) => {
          const fileKey = match.filePath;
          if (!acc[fileKey]) {
            acc[fileKey] = [];
          }
          acc[fileKey].push(match);
          acc[fileKey].sort((a, b) => a.lineNumber - b.lineNumber);
          return acc;
        },
        {} as Record<string, GrepMatch[]>,
      );

      const matchCount = allMatches.length;
      const matchTerm = matchCount === 1 ? 'match' : 'matches';

      let llmContent = `Found ${matchCount} ${matchTerm} for pattern "${this.params.pattern}" ${searchLocationDescription}${this.params.include ? ` (filter: "${this.params.include}")` : ''}${wasTruncated ? ` (results limited to ${totalMaxMatches} matches for performance)` : ''}:\n---\n`;

      for (const filePath in matchesByFile) {
        llmContent += `File: ${filePath}\n`;
        matchesByFile[filePath].forEach((match) => {
          const trimmedLine = match.line.trim();
          llmContent += `L${match.lineNumber}: ${trimmedLine}\n`;
        });
        llmContent += '---\n';
      }

      return {
        llmContent: llmContent.trim(),
        returnDisplay: `Found ${matchCount} ${matchTerm}${
          wasTruncated ? ' (limited)' : ''
        }`,
      };
    } catch (error) {
      debugLogger.warn(`Error during GrepLogic execution: ${error}`);
      const errorMessage = getErrorMessage(error);
      return {
        llmContent: `Error during grep search operation: ${errorMessage}`,
        returnDisplay: `Error: ${errorMessage}`,
      };
    }
  }

  private async performRipgrepSearch(options: {
    pattern: string;
    path: string;
    include?: string;
    filter?: string;
    case_sensitive?: boolean;
    fixed_strings?: boolean;
    context?: number;
    after?: number;
    before?: number;
    no_ignore?: boolean;
    maxMatches: number;
    maxMatchesPerFile?: number;
    signal: AbortSignal;
  }): Promise<GrepMatch[]> {
    const {
      pattern,
      path: absolutePath,
      include,
      filter,
      case_sensitive,
      fixed_strings,
      context,
      after,
      before,
      no_ignore,
      maxMatches,
      maxMatchesPerFile,
    } = options;

    const rgPath = await ensureRgPath();

    // If filter is provided, first find files matching the filter.
    // This simulates "rg -l 'filter' | xargs rg 'pattern'".
    let matchingFiles: string[] | undefined;

    if (filter) {
      const filterArgs = ['--files-with-matches', '--json'];
      if (!case_sensitive) {
        filterArgs.push('--ignore-case');
      }
      // Treat filter as literal string if fixed_strings is true, or maybe we should always treat filter as regex?
      // The prompt says "must_contain" or "pattern_b".
      // Let's assume filter follows same rules as pattern (regex unless fixed_strings).
      if (fixed_strings) {
        filterArgs.push('--fixed-strings');
        filterArgs.push(filter);
      } else {
        filterArgs.push('--regexp', filter);
      }

      if (no_ignore) {
        filterArgs.push('--no-ignore');
      }
      if (include) {
        filterArgs.push('--glob', include);
      }

      if (!no_ignore) {
        // Add ignore patterns
        const fileExclusions = new FileExclusions(this.config);
        const excludes = fileExclusions.getGlobExcludes([
          ...COMMON_DIRECTORY_EXCLUDES,
          '*.log',
          '*.tmp',
        ]);
        excludes.forEach((exclude) => {
          filterArgs.push('--glob', `!${exclude}`);
        });

        const geminiIgnorePaths =
          this.fileDiscoveryService.getIgnoreFilePaths();
        for (const ignorePath of geminiIgnorePaths) {
          filterArgs.push('--ignore-file', ignorePath);
        }
      }

      filterArgs.push('--threads', '4');
      filterArgs.push(absolutePath);

      try {
        const generator = execStreaming(rgPath, filterArgs, {
          signal: options.signal,
          allowedExitCodes: [0, 1],
        });

        matchingFiles = [];
        for await (const line of generator) {
          try {
            const json = JSON.parse(line);
            if (json.type === 'match') {
              const match = json.data;
              if (match.path?.text) {
                matchingFiles.push(match.path.text);
              }
            }
          } catch (_e) {
            // Ignore parse errors
          }
        }

        if (matchingFiles.length === 0) {
          return [];
        }
      } catch (error: unknown) {
        debugLogger.debug(
          `GrepLogic: ripgrep filter failed: ${getErrorMessage(error)}`,
        );
        throw error;
      }
    }

    const rgArgs = ['--json'];

    if (!case_sensitive) {
      rgArgs.push('--ignore-case');
    }

    if (fixed_strings) {
      rgArgs.push('--fixed-strings');
      rgArgs.push(pattern);
    } else {
      rgArgs.push('--regexp', pattern);
    }

    if (context) {
      rgArgs.push('--context', context.toString());
    }
    if (after) {
      rgArgs.push('--after-context', after.toString());
    }
    if (before) {
      rgArgs.push('--before-context', before.toString());
    }
    if (no_ignore) {
      rgArgs.push('--no-ignore');
    }

    if (maxMatchesPerFile) {
      rgArgs.push('--max-count', maxMatchesPerFile.toString());
    }

    // If we have matchingFiles, we pass them as arguments.
    // Otherwise we use include/exclude args and the path.
    if (matchingFiles) {
      // We don't need --glob include here as we are passing specific files that already matched the include in the filter step.
      // We also don't need ignore files/patterns as we are passing explicit files.
      // However, we should check command line length.
      // If matchingFiles is very large, we might need to batch?
      // For now, let's just spread them.
      rgArgs.push(...matchingFiles);
    } else {
      if (include) {
        rgArgs.push('--glob', include);
      }

      if (!no_ignore) {
        const fileExclusions = new FileExclusions(this.config);
        const excludes = fileExclusions.getGlobExcludes([
          ...COMMON_DIRECTORY_EXCLUDES,
          '*.log',
          '*.tmp',
        ]);
        excludes.forEach((exclude) => {
          rgArgs.push('--glob', `!${exclude}`);
        });

        const geminiIgnorePaths =
          this.fileDiscoveryService.getIgnoreFilePaths();
        for (const ignorePath of geminiIgnorePaths) {
          rgArgs.push('--ignore-file', ignorePath);
        }
      }
      rgArgs.push(absolutePath);
    }

    // Add threads
    rgArgs.push('--threads', '4');

    const results: GrepMatch[] = [];
    try {
      const generator = execStreaming(rgPath, rgArgs, {
        signal: options.signal,
        allowedExitCodes: [0, 1],
      });

      for await (const line of generator) {
        const match = this.parseRipgrepJsonLine(line, absolutePath);
        if (match) {
          results.push(match);
          if (results.length >= maxMatches) {
            break;
          }
        }
      }

      return results;
    } catch (error: unknown) {
      debugLogger.debug(`GrepLogic: ripgrep failed: ${getErrorMessage(error)}`);
      throw error;
    }
  }

  private parseRipgrepJsonLine(
    line: string,
    basePath: string,
  ): GrepMatch | null {
    try {
      const json = JSON.parse(line);
      if (json.type === 'match') {
        const match = json.data;
        // Defensive check: ensure text properties exist (skips binary/invalid encoding)
        if (match.path?.text && match.lines?.text) {
          const absoluteFilePath = path.resolve(basePath, match.path.text);
          const relativeCheck = path.relative(basePath, absoluteFilePath);
          if (
            relativeCheck === '..' ||
            relativeCheck.startsWith(`..${path.sep}`) ||
            path.isAbsolute(relativeCheck)
          ) {
            return null;
          }

          const relativeFilePath = path.relative(basePath, absoluteFilePath);

          return {
            filePath: relativeFilePath || path.basename(absoluteFilePath),
            lineNumber: match.line_number,
            line: match.lines.text.trimEnd(),
          };
        }
      }
    } catch (error) {
      // Only log if it's not a simple empty line or widely invalid
      if (line.trim().length > 0) {
        debugLogger.warn(
          `Failed to parse ripgrep JSON line: ${line.substring(0, 100)}...`,
          error,
        );
      }
    }
    return null;
  }

  /**
   * Gets a description of the grep operation
   * @param params Parameters for the grep operation
   * @returns A string describing the grep
   */
  getDescription(): string {
    let description = `'${this.params.pattern}'`;
    if (this.params.include) {
      description += ` in ${this.params.include}`;
    }
    const pathParam = this.params.dir_path || '.';
    const resolvedPath = path.resolve(this.config.getTargetDir(), pathParam);
    if (resolvedPath === this.config.getTargetDir() || pathParam === '.') {
      description += ` within ./`;
    } else {
      const relativePath = makeRelative(
        resolvedPath,
        this.config.getTargetDir(),
      );
      description += ` within ${shortenPath(relativePath)}`;
    }
    return description;
  }
}

/**
 * Implementation of the Grep tool logic (moved from CLI)
 */
export class RipGrepTool extends BaseDeclarativeTool<
  RipGrepToolParams,
  ToolResult
> {
  static readonly Name = GREP_TOOL_NAME;
  private readonly fileDiscoveryService: FileDiscoveryService;

  constructor(
    private readonly config: Config,
    messageBus: MessageBus,
  ) {
    super(
      RipGrepTool.Name,
      'SearchText',
      'Searches for a regular expression pattern within file contents. Max 100 matches.',
      Kind.Search,
      {
        properties: {
          pattern: {
            description:
              "The pattern to search for. By default, treated as a Rust-flavored regular expression. Use '\\b' for precise symbol matching (e.g., '\\bMatchMe\\b').",
            type: 'string',
          },
          dir_path: {
            description:
              "Directory or file to search. Directories are searched recursively. Relative paths are resolved against current working directory. Defaults to current working directory ('.') if omitted.",
            type: 'string',
          },
          include: {
            description:
              "Glob pattern to filter files (e.g., '*.ts', 'src/**'). Recommended for large repositories to reduce noise. Defaults to all files if omitted.",
            type: 'string',
          },
          filter: {
            description:
              'Optional: A string that must be present in the file for it to be included (logical AND). Use this to filter results to files containing both the `pattern` and this filter.',
            type: 'string',
          },
          case_sensitive: {
            description:
              'If true, search is case-sensitive. Defaults to false (ignore case) if omitted.',
            type: 'boolean',
          },
          fixed_strings: {
            description:
              'If true, treats the `pattern` as a literal string instead of a regular expression. Defaults to false (basic regex) if omitted.',
            type: 'boolean',
          },
          context: {
            description:
              'Show this many lines of context around each match (equivalent to grep -C). Defaults to 0 if omitted.',
            type: 'integer',
          },
          after: {
            description:
              'Show this many lines after each match (equivalent to grep -A). Defaults to 0 if omitted.',
            type: 'integer',
          },
          before: {
            description:
              'Show this many lines before each match (equivalent to grep -B). Defaults to 0 if omitted.',
            type: 'integer',
          },
          no_ignore: {
            description:
              'If true, searches all files including those usually ignored (like in .gitignore, build/, dist/, etc). Defaults to false if omitted.',
            type: 'boolean',
          },
          max_matches_per_file: {
            description:
              'Optional: Maximum number of matches to return per file. Use this to prevent being overwhelmed by repetitive matches in large files.',
            type: 'integer',
            minimum: 1,
          },
        },
        required: ['pattern'],
        type: 'object',
      },
      messageBus,
      true, // isOutputMarkdown
      false, // canUpdateOutput
    );
    this.fileDiscoveryService = new FileDiscoveryService(
      config.getTargetDir(),
      config.getFileFilteringOptions(),
    );
  }

  /**
   * Validates the parameters for the tool
   * @param params Parameters to validate
   * @returns An error message string if invalid, null otherwise
   */
  protected override validateToolParamValues(
    params: RipGrepToolParams,
  ): string | null {
    try {
      new RegExp(params.pattern);
    } catch (error) {
      return `Invalid regular expression pattern provided: ${params.pattern}. Error: ${getErrorMessage(error)}`;
    }

    // Only validate path if one is provided
    if (params.dir_path) {
      const resolvedPath = path.resolve(
        this.config.getTargetDir(),
        params.dir_path,
      );
      const validationError = this.config.validatePathAccess(resolvedPath);
      if (validationError) {
        return validationError;
      }

      // Check existence and type
      try {
        const stats = fs.statSync(resolvedPath);
        if (!stats.isDirectory() && !stats.isFile()) {
          return `Path is not a valid directory or file: ${resolvedPath}`;
        }
      } catch (error: unknown) {
        if (isNodeError(error) && error.code === 'ENOENT') {
          return `Path does not exist: ${resolvedPath}`;
        }
        return `Failed to access path stats for ${resolvedPath}: ${getErrorMessage(error)}`;
      }
    }

    return null; // Parameters are valid
  }

  protected createInvocation(
    params: RipGrepToolParams,
    messageBus: MessageBus,
    _toolName?: string,
    _toolDisplayName?: string,
  ): ToolInvocation<RipGrepToolParams, ToolResult> {
    return new GrepToolInvocation(
      this.config,
      this.fileDiscoveryService,
      params,
      messageBus ?? this.messageBus,
      _toolName,
      _toolDisplayName,
    );
  }
}