import { createReadStream } from "node:fs";
import { createInterface } from "node:readline";

import path from "node:path";

const virtual_chroot = '/workspaces/aiTools';

// Ensures reads are confined to `virtual_chroot`.

export default {
    type: "function", name: "read_file", description: "read a file", strict: true,
    parameters: {
        type: "object", required: ["path","linesToSkip","linesToRead"], additionalProperties: false, properties: {
            path: { type: "string", description: "The path to the file to read.", },
            linesToSkip: { type: "integer", description: "The number of lines to skip. Use 0 to read from the beginning.", minimum: 0 },
            linesToRead: { type: "integer", description: "1-400 The number of lines to read. Use 0 or more than 400 to read 400 lines.", minimum: 0 }
        }
    }
};

export async function run(args) {
    const { path: filePath, linesToSkip, linesToRead } = args;
    
    // Validate path is within virtual_chroot
    const fullPath = path.resolve(virtual_chroot, filePath.replace(/^\//, ''));
    if (!fullPath.startsWith(virtual_chroot)) {
        return `read_file error: Path outside of allowed directory`;
    }
    
    // Normalize linesToRead (1-400, with 0 or >400 meaning 400)
    const maxLines = (linesToRead <= 0 || linesToRead > 400) ? 400 : linesToRead;
    
    try {

        const rl = createInterface({
            input: createReadStream(fullPath),
            crlfDelay: Infinity
        });
        
        let lines = [];
        let skipped = 0;
        
        for await (const line of rl) {
            if (skipped < linesToSkip) {
                skipped++;
                continue;
            }
            lines.push(line);
            if (lines.length >= maxLines) {
                break;
            }
        }
        
        return lines.join('\n');
    } catch (error) {
        return `read_file error: ${error.message}`;
    }
}