import { z } from "zod";
import { Tool } from "./tool";
import { App } from "../app";
import { spawn } from "child_process";
import { promises as fs } from "fs";
import path from "path";

const DESCRIPTION = `Fast content search tool that finds files containing specific text or patterns, returning matching file paths sorted by modification time (newest first).

WHEN TO USE THIS TOOL:
- Use when you need to find files containing specific text or patterns
- Great for searching code bases for function names, variable declarations, or error messages
- Useful for finding all files that use a particular API or pattern

HOW TO USE:
- Provide a regex pattern to search for within file contents
- Set literal_text=true if you want to search for the exact text with special characters (recommended for non-regex users)
- Optionally specify a starting directory (defaults to current working directory)
- Optionally provide an include pattern to filter which files to search
- Results are sorted with most recently modified files first

REGEX PATTERN SYNTAX (when literal_text=false):
- Supports standard regular expression syntax
- 'function' searches for the literal text "function"
- 'log\\..*Error' finds text starting with "log." and ending with "Error"
- 'import\\s+.*\\s+from' finds import statements in JavaScript/TypeScript

COMMON INCLUDE PATTERN EXAMPLES:
- '*.js' - Only search JavaScript files
- '*.{ts,tsx}' - Only search TypeScript files
- '*.go' - Only search Go files

LIMITATIONS:
- Results are limited to 100 files (newest first)
- Performance depends on the number of files being searched
- Very large binary files may be skipped
- Hidden files (starting with '.') are skipped

TIPS:
- For faster, more targeted searches, first use Glob to find relevant files, then use Grep
- When doing iterative exploration that may require multiple rounds of searching, consider using the Agent tool instead
- Always check if results are truncated and refine your search pattern if needed
- Use literal_text=true when searching for exact text containing special characters like dots, parentheses, etc.`;

interface GrepMatch {
  path: string;
  modTime: number;
  lineNum: number;
  lineText: string;
}

function escapeRegexPattern(pattern: string): string {
  const specialChars = [
    "\\",
    ".",
    "+",
    "*",
    "?",
    "(",
    ")",
    "[",
    "]",
    "{",
    "}",
    "^",
    "$",
    "|",
  ];
  let escaped = pattern;

  for (const char of specialChars) {
    escaped = escaped.replaceAll(char, "\\" + char);
  }

  return escaped;
}

function globToRegex(glob: string): string {
  let regexPattern = glob.replaceAll(".", "\\.");
  regexPattern = regexPattern.replaceAll("*", ".*");
  regexPattern = regexPattern.replaceAll("?", ".");

  // Handle {a,b,c} patterns
  regexPattern = regexPattern.replace(/\{([^}]+)\}/g, (match, inner) => {
    return "(" + inner.replace(/,/g, "|") + ")";
  });

  return regexPattern;
}

async function searchWithRipgrep(
  pattern: string,
  searchPath: string,
  include?: string,
): Promise<GrepMatch[]> {
  return new Promise((resolve, reject) => {
    const args = ["-n", pattern];
    if (include) {
      args.push("--glob", include);
    }
    args.push(searchPath);

    const rg = spawn("rg", args);
    let output = "";
    let errorOutput = "";

    rg.stdout.on("data", (data) => {
      output += data.toString();
    });

    rg.stderr.on("data", (data) => {
      errorOutput += data.toString();
    });

    rg.on("close", async (code) => {
      if (code === 1) {
        // No matches found
        resolve([]);
        return;
      }

      if (code !== 0) {
        reject(new Error(`ripgrep failed: ${errorOutput}`));
        return;
      }

      const lines = output.trim().split("\n");
      const matches: GrepMatch[] = [];

      for (const line of lines) {
        if (!line) continue;

        // Parse ripgrep output format: file:line:content
        const parts = line.split(":", 3);
        if (parts.length < 3) continue;

        const filePath = parts[0];
        const lineNum = parseInt(parts[1], 10);
        const lineText = parts[2];

        try {
          const stats = await fs.stat(filePath);
          matches.push({
            path: filePath,
            modTime: stats.mtime.getTime(),
            lineNum,
            lineText,
          });
        } catch {
          // Skip files we can't access
          continue;
        }
      }

      resolve(matches);
    });

    rg.on("error", (err) => {
      reject(err);
    });
  });
}

async function searchFilesWithRegex(
  pattern: string,
  rootPath: string,
  include?: string,
): Promise<GrepMatch[]> {
  const matches: GrepMatch[] = [];
  const regex = new RegExp(pattern);

  let includePattern: RegExp | undefined;
  if (include) {
    const regexPattern = globToRegex(include);
    includePattern = new RegExp(regexPattern);
  }

  async function walkDir(dir: string) {
    if (matches.length >= 200) return;

    try {
      const entries = await fs.readdir(dir, { withFileTypes: true });

      for (const entry of entries) {
        if (matches.length >= 200) break;

        const fullPath = path.join(dir, entry.name);

        if (entry.isDirectory()) {
          // Skip hidden directories
          if (entry.name.startsWith(".")) continue;
          await walkDir(fullPath);
        } else if (entry.isFile()) {
          // Skip hidden files
          if (entry.name.startsWith(".")) continue;

          if (includePattern && !includePattern.test(fullPath)) {
            continue;
          }

          try {
            const content = await fs.readFile(fullPath, "utf-8");
            const lines = content.split("\n");

            for (let i = 0; i < lines.length; i++) {
              if (regex.test(lines[i])) {
                const stats = await fs.stat(fullPath);
                matches.push({
                  path: fullPath,
                  modTime: stats.mtime.getTime(),
                  lineNum: i + 1,
                  lineText: lines[i],
                });
                break; // Only first match per file
              }
            }
          } catch {
            // Skip files we can't read
            continue;
          }
        }
      }
    } catch {
      // Skip directories we can't read
      return;
    }
  }

  await walkDir(rootPath);
  return matches;
}

async function searchFiles(
  pattern: string,
  rootPath: string,
  include?: string,
  limit: number = 100,
): Promise<{ matches: GrepMatch[]; truncated: boolean }> {
  let matches: GrepMatch[];

  try {
    matches = await searchWithRipgrep(pattern, rootPath, include);
  } catch {
    matches = await searchFilesWithRegex(pattern, rootPath, include);
  }

  // Sort by modification time (newest first)
  matches.sort((a, b) => b.modTime - a.modTime);

  const truncated = matches.length > limit;
  if (truncated) {
    matches = matches.slice(0, limit);
  }

  return { matches, truncated };
}

export const grep = Tool.define({
  name: "grep",
  description: DESCRIPTION,
  parameters: z.object({
    pattern: z
      .string()
      .describe("The regex pattern to search for in file contents"),
    path: z
      .string()
      .describe(
        "The directory to search in. Defaults to the current working directory.",
      )
      .optional(),
    include: z
      .string()
      .describe(
        'File pattern to include in the search (e.g. "*.js", "*.{ts,tsx}")',
      )
      .optional(),
    literal_text: z
      .boolean()
      .describe(
        "If true, the pattern will be treated as literal text with special regex characters escaped. Default is false.",
      )
      .optional(),
  }),
  async execute(params) {
    if (!params.pattern) {
      throw new Error("pattern is required");
    }

    const app = await App.use();
    const searchPath = params.path || app.root;

    // If literal_text is true, escape the pattern
    const searchPattern = params.literal_text
      ? escapeRegexPattern(params.pattern)
      : params.pattern;

    const { matches, truncated } = await searchFiles(
      searchPattern,
      searchPath,
      params.include,
      100,
    );

    let output: string;
    if (matches.length === 0) {
      output = "No files found";
    } else {
      const lines = [`Found ${matches.length} matches`];

      let currentFile = "";
      for (const match of matches) {
        if (currentFile !== match.path) {
          if (currentFile !== "") {
            lines.push("");
          }
          currentFile = match.path;
          lines.push(`${match.path}:`);
        }
        if (match.lineNum > 0) {
          lines.push(`  Line ${match.lineNum}: ${match.lineText}`);
        } else {
          lines.push(`  ${match.path}`);
        }
      }

      if (truncated) {
        lines.push("");
        lines.push(
          "(Results are truncated. Consider using a more specific path or pattern.)",
        );
      }

      output = lines.join("\n");
    }

    return {
      metadata: {
        matches: matches.length,
        truncated,
      },
      output,
    };
  },
});