// tools/read.rs — Read file contents

use anyhow::{Context, Result};
use serde_json::json;

use crate::types::ToolDef;

pub fn definition() -> ToolDef {
    ToolDef::new(
        "read_file",
        "Read the contents of a file. Returns the file contents with line numbers.",
        json!({
            "type": "object",
            "properties": {
                "file_path": {
                    "type": "string",
                    "description": "Absolute path to the file to read"
                },
                "offset": {
                    "type": "integer",
                    "description": "Line number to start reading from (1-based). Optional."
                },
                "limit": {
                    "type": "integer",
                    "description": "Maximum number of lines to read. Optional."
                }
            },
            "required": ["file_path"]
        }),
    )
}

pub fn read_file(args: &serde_json::Value) -> Result<String> {
    let path = args["file_path"]
        .as_str()
        .context("file_path is required")?;

    let content =
        std::fs::read_to_string(path).with_context(|| format!("Failed to read {}", path))?;

    let lines: Vec<&str> = content.lines().collect();
    let offset = args["offset"].as_u64().unwrap_or(1).max(1) as usize - 1;
    let limit = args["limit"].as_u64().unwrap_or(lines.len() as u64) as usize;

    let mut output = String::new();
    for (i, line) in lines.iter().skip(offset).take(limit).enumerate() {
        let line_num = offset + i + 1;
        output.push_str(&format!("{:>6}\t{}\n", line_num, line));
    }

    if output.is_empty() {
        output = "(empty file)\n".to_string();
    }

    Ok(output)
}