//! Edit a file by replacing a text block.

use crate::tools::{resolve_path, Tool, ToolCtx};
use anyhow::Result;
use serde_json::{json, Value};
use std::fs;
use tracing::{info, instrument, warn};

/// Edit a file by replacing `old` text with `new` text.
///
/// Flow: resolve path → read file → ensure `old` exists → perform single
/// replacement → write file.
pub struct Edit;

impl Tool for Edit {
    fn name(&self) -> &'static str {
        "edit"
    }

    fn description(&self) -> &'static str {
        "Edit a file by replacing 'old' text with 'new' text"
    }

    fn parameters(&self) -> Value {
        json!({
            "type": "object",
            "properties": {
                "path": {
                    "type": "string",
                    "description": "Path to the file to edit (relative to workspace root)"
                },
                "old": {
                    "type": "string",
                    "description": "Text to replace (must exist in the file)"
                },
                "new": {
                    "type": "string",
                    "description": "Replacement text"
                },
                "reason": {
                    "type": "string",
                    "description": "Reason for this change"
                }
            },
            "required": ["path", "old", "new"]
        })
    }

    #[instrument(skip(self, ctx, args))]
    fn run(&self, ctx: &ToolCtx, args: &Value) -> Result<String> {
        let rel = crate::tools::arg_str(args, "path")?;
        let old = crate::tools::arg_str(args, "old")?;
        let new = crate::tools::arg_str(args, "new")?;
        let path = resolve_path(&ctx.workspaces, &rel)?;

        if !path.exists() {
            warn!(rel = %rel, "edit target does not exist");
            anyhow::bail!("file '{rel}' does not exist");
        }

        let content = fs::read_to_string(&path)?;
        if !content.contains(&old) {
            warn!(rel = %rel, old_len = old.len(), "old text not found in file");
            anyhow::bail!("old text not found in '{}'", rel);
        }

        let new_content = content.replacen(&old, &new, 1);
        fs::write(&path, &new_content)?;

        info!(rel = %rel, old_len = old.len(), new_len = new.len(), "file edited");
        Ok(format!(
            "Edited '{}': replaced {} bytes with {} bytes",
            rel,
            old.len(),
            new.len()
        ))
    }
}