import { readFileSync, writeFileSync } from 'fs';
import type { Tool, ToolResult } from '../types.js';

interface FileEditArgs {
  path: string;
  old_string: string;
  new_string: string;
  replace_all?: boolean;
}

export const fileEditTool: Tool = {
  name: 'file.edit',
  description: 'Edit a file by replacing an exact string match. Fails if old_string is not found or matches multiple times (unless replace_all is true).',
  inputSchema: {
    type: 'object',
    properties: {
      path: { type: 'string', description: 'Absolute path to the file' },
      old_string: { type: 'string', description: 'Exact string to find' },
      new_string: { type: 'string', description: 'Replacement string' },
      replace_all: { type: 'boolean', description: 'Replace all occurrences (default false)' },
    },
    required: ['path', 'old_string', 'new_string'],
  },
  execute: async (rawArgs: unknown): Promise<ToolResult> => {
    const args = rawArgs as FileEditArgs;
    try {
      const content = readFileSync(args.path, 'utf-8');

      if (!content.includes(args.old_string)) {
        return { success: false, output: '', error: `old_string not found in ${args.path}` };
      }

      const count = content.split(args.old_string).length - 1;
      if (count > 1 && !args.replace_all) {
        return { success: false, output: '', error: `old_string found multiple times (${count}). Use replace_all or provide more context.` };
      }

      const newContent = args.replace_all
        ? content.replaceAll(args.old_string, args.new_string)
        : content.replace(args.old_string, args.new_string);

      writeFileSync(args.path, newContent, 'utf-8');
      return { success: true, output: `Edited ${args.path} (${count} replacement${count > 1 ? 's' : ''})` };
    } catch (error) {
      return { success: false, output: '', error: error instanceof Error ? error.message : String(error) };
    }
  },
};