// tools/grep.rs — Search file contents
//
// Prefers ripgrep (rg) for speed, falls back to grep -r if rg
// isn't installed. Both produce compatible output.

use anyhow::{Context, Result};
use serde_json::json;
use std::process::Command;

use crate::types::ToolDef;

pub fn definition() -> ToolDef {
    ToolDef::new(
        "grep",
        "Search for a pattern in files. Returns matching file paths by default, \
         or matching lines with context.",
        json!({
            "type": "object",
            "properties": {
                "pattern": {
                    "type": "string",
                    "description": "Regex pattern to search for"
                },
                "path": {
                    "type": "string",
                    "description": "Directory or file to search in (default: current directory)"
                },
                "glob": {
                    "type": "string",
                    "description": "Glob pattern to filter files (e.g. '*.rs', '*.py')"
                },
                "show_content": {
                    "type": "boolean",
                    "description": "Show matching lines instead of just file paths"
                },
                "context_lines": {
                    "type": "integer",
                    "description": "Number of context lines around matches (requires show_content)"
                }
            },
            "required": ["pattern"]
        }),
    )
}

/// Check if ripgrep is available (cached after first check).
fn has_rg() -> bool {
    use std::sync::OnceLock;
    static HAS_RG: OnceLock<bool> = OnceLock::new();
    *HAS_RG.get_or_init(|| Command::new("rg").arg("--version").output().is_ok())
}

pub fn grep(args: &serde_json::Value) -> Result<String> {
    let pattern = args["pattern"].as_str().context("pattern is required")?;
    let path = args["path"].as_str().unwrap_or(".");
    let file_glob = args["glob"].as_str();
    let show_content = args["show_content"].as_bool().unwrap_or(false);
    let context = args["context_lines"].as_u64();

    let output = if has_rg() {
        run_rg(pattern, path, file_glob, show_content, context)?
    } else {
        run_grep(pattern, path, file_glob, show_content, context)?
    };

    if output.is_empty() {
        return Ok("No matches found.".to_string());
    }

    let mut result = output;
    const MAX_OUTPUT: usize = 30000;
    if result.len() > MAX_OUTPUT {
        result.truncate(MAX_OUTPUT);
        result.push_str("\n... (output truncated)");
    }

    Ok(result)
}

fn run_rg(
    pattern: &str,
    path: &str,
    file_glob: Option<&str>,
    show_content: bool,
    context: Option<u64>,
) -> Result<String> {
    let mut cmd = Command::new("rg");

    if show_content {
        cmd.arg("-n");
        if let Some(c) = context {
            cmd.arg("-C").arg(c.to_string());
        }
    } else {
        cmd.arg("--files-with-matches");
    }

    if let Some(g) = file_glob {
        cmd.arg("--glob").arg(g);
    }

    cmd.arg(pattern).arg(path);
    let output = cmd.output().context("Failed to run rg")?;
    Ok(String::from_utf8_lossy(&output.stdout).to_string())
}

fn run_grep(
    pattern: &str,
    path: &str,
    file_glob: Option<&str>,
    show_content: bool,
    context: Option<u64>,
) -> Result<String> {
    let mut cmd = Command::new("grep");
    cmd.arg("-r"); // recursive

    if show_content {
        cmd.arg("-n"); // line numbers
        if let Some(c) = context {
            cmd.arg("-C").arg(c.to_string());
        }
    } else {
        cmd.arg("-l"); // files-with-matches
    }

    if let Some(g) = file_glob {
        cmd.arg("--include").arg(g);
    }

    cmd.arg("-E"); // extended regex
    cmd.arg(pattern).arg(path);
    let output = cmd.output().context("Failed to run grep")?;
    Ok(String::from_utf8_lossy(&output.stdout).to_string())
}