//! Tool descriptions and file operations for the agent.

use crate::llm::Tool;
use serde_json::{Value, json};
use std::io;

#[path = "overflow.rs"]
pub mod overflow;

/// Human-readable, lossless text representation of tool JSON. String values
/// retain real newlines, with JSON-quoted field/index labels for structure.
fn render(value: &Value) -> String {
    fn visit(value: &Value, label: &str, out: &mut String) {
        match value {
            Value::Object(fields) => {
                if fields.is_empty() {
                    out.push_str(&format!("{label}: {{}}\n"));
                }
                for (key, value) in fields {
                    visit(
                        value,
                        &format!("{label}[{}]", serde_json::to_string(key).unwrap()),
                        out,
                    );
                }
            }
            Value::Array(items) => {
                if items.is_empty() {
                    out.push_str(&format!("{label}: []\n"));
                }
                for (i, value) in items.iter().enumerate() {
                    visit(value, &format!("{label}[{i}]"), out);
                }
            }
            Value::String(text) => {
                out.push_str(&format!("{label} (string, {} bytes):\n", text.len()));
                out.push_str(text);
                out.push('\n');
            }
            _ => {
                out.push_str(&format!("{label}: {value}\n"));
            }
        }
    }
    let mut out = String::new();
    visit(value, "$", &mut out);
    out
}

/// Describe the five tools sent to either inference API.
pub fn definitions() -> Vec<Tool> {
    vec![
        Tool {
            name: "call",
            description: "Call a plugin method through the core. Await its result. Set detach to let its process survive this caller. Large results show an excerpt with a full-output /logs reference.",
            parameters: schema(
                json!({
                    "method": {"type": "string", "description": "Qualified plugin method"},
                    "params": {"type": "object", "description": "Named method parameters"},
                    "detach": {"type": "boolean", "description": "Detach the new process. Default false."}
                }),
                &["method", "params"],
            ),
        },
        Tool {
            name: "read_file",
            description: "Read a text file in the world, including `/proc`. `offset`/`max_bytes` select bytes; `line_offset`/`line_limit` select zero-based lines (default 200). Large results show an excerpt with a full-output /logs reference.",
            parameters: schema(
                json!({
                    "path": {"type": "string"},
                    "offset": {"type": "integer", "description": "Byte offset (default 0)"},
                    "max_bytes": {"type": "integer", "description": "Optional maximum number of bytes to read"},
                    "line_offset": {"type": "integer", "description": "Zero-based starting line; overrides bytes"},
                    "line_limit": {"type": "integer", "description": "Number of lines; default 200"}
                }),
                &["path"],
            ),
        },
        Tool {
            name: "write_file",
            description: "Write a text file in the world. Parent folders are created. Large results show an excerpt with a full-output /logs reference.",
            parameters: schema(
                json!({"path": {"type": "string"}, "content": {"type": "string"}}),
                &["path", "content"],
            ),
        },
        Tool {
            name: "list_dir",
            description: "List entries in a world directory. Returns each name, type, and size. Large results show an excerpt with a full-output /logs reference.",
            parameters: schema(json!({"path": {"type": "string"}}), &["path"]),
        },
        Tool {
            name: "copy_dir",
            description: "Copy a directory tree, for example a plugin source to a draft folder. Skips `target/` folders. Large results show an excerpt with a full-output /logs reference.",
            parameters: schema(
                json!({"from": {"type": "string"}, "to": {"type": "string"}}),
                &["from", "to"],
            ),
        },
    ]
}

/// Create the named-parameter object required by a tool.
fn schema(properties: Value, required: &[&str]) -> Value {
    json!({"type": "object", "properties": properties, "required": required})
}

/// Execute a tool. The chat loop returns errors to the model as tool results.
pub async fn run(name: &str, args: &Value) -> sausage_plugin::Result<Value> {
    if name == "call" {
        let method = args["method"]
            .as_str()
            .ok_or_else(|| sausage_plugin::Error::new(-32602, "missing method"))?;
        let call = sausage_plugin::call(method, args.get("params").cloned().unwrap_or(json!({})));
        return if args["detach"] == true {
            call.detach().await
        } else {
            call.await
        };
    }
    Ok(match name {
        "read_file" => read_file(args),
        "write_file" => write_file(args),
        "list_dir" => list_dir(args),
        "copy_dir" => copy_dir(args),
        other => Ok(json!({"error": format!("unknown tool {other}")})),
    }?)
}

/// Read an optional byte range and report the complete file size.
fn read_file(args: &Value) -> io::Result<Value> {
    let path = args["path"].as_str().unwrap_or_default();
    let bytes = std::fs::read(path)?;
    if path.starts_with("/logs/") {
        return Ok(
            json!({"path":path,"size":bytes.len(),"content":overflow::existing(&bytes, path, args)}),
        );
    }
    if let Some(line) = args["line_offset"].as_u64() {
        return Ok(
            json!({"path":path,"size":bytes.len(),"line_offset":line,"content":overflow::read_lines(&bytes, line as usize, args["line_limit"].as_u64().unwrap_or(200) as usize)}),
        );
    }
    let offset = (args["offset"].as_u64().unwrap_or(0) as usize).min(bytes.len());
    let end = args["max_bytes"].as_u64().map_or(bytes.len(), |max| {
        offset.saturating_add(max as usize).min(bytes.len())
    });
    Ok(json!({
        "path": path,
        "size": bytes.len(),
        "offset": offset,
        "content": String::from_utf8_lossy(&bytes[offset..end]),
        "truncated": end < bytes.len(),
    }))
}

/// Create parent directories and replace a text file.
fn write_file(args: &Value) -> io::Result<Value> {
    let path = args["path"].as_str().unwrap_or_default();
    if let Some(parent) = std::path::Path::new(path).parent() {
        let _ = std::fs::create_dir_all(parent);
    }
    std::fs::write(path, args["content"].as_str().unwrap_or_default())?;
    Ok(json!({"written": path}))
}

/// Return directory metadata in name order.
fn list_dir(args: &Value) -> io::Result<Value> {
    let mut entries: Vec<Value> = std::fs::read_dir(args["path"].as_str().unwrap_or_default())?
        .filter_map(|entry| entry.ok())
        .map(|entry| {
            let metadata = entry.metadata().ok();
            json!({
                "name": entry.file_name().to_string_lossy(),
                "type": if metadata.as_ref().is_some_and(|meta| meta.is_dir()) { "dir" } else { "file" },
                "size": metadata.map(|meta| meta.len()),
            })
        })
        .collect();
    entries.sort_by(|left, right| left["name"].as_str().cmp(&right["name"].as_str()));
    Ok(json!({"entries": entries}))
}

/// Copy a tree and report its file count.
fn copy_dir(args: &Value) -> io::Result<Value> {
    let from = std::fs::canonicalize(args["from"].as_str().unwrap_or_default())?;
    let to = args["to"].as_str().unwrap_or_default();
    std::fs::create_dir_all(to)?;
    if std::fs::canonicalize(to)?.starts_with(&from) {
        return Err(io::Error::new(
            io::ErrorKind::InvalidInput,
            "destination is inside the source",
        ));
    }
    let count = copy_tree(
        args["from"].as_str().unwrap_or_default(),
        args["to"].as_str().unwrap_or_default(),
    )?;
    Ok(json!({"copied_files": count}))
}

/// Copy files recursively without build artifacts in target directories.
fn copy_tree(from: &str, to: &str) -> io::Result<u64> {
    std::fs::create_dir_all(to)?;
    let mut count = 0;
    for entry in std::fs::read_dir(from)? {
        let entry = entry?;
        let name = entry.file_name().to_string_lossy().to_string();
        let src = format!("{from}/{name}");
        let dst = format!("{to}/{name}");
        if entry.file_type()?.is_dir() {
            if name != "target" {
                count += copy_tree(&src, &dst)?;
            }
        } else {
            std::fs::copy(src, dst)?;
            count += 1;
        }
    }
    Ok(count)
}

#[cfg(test)]
mod tests {
    #[test]
    fn overflow_json_can_be_followed_by_line_without_rearchiving() {
        let value = serde_json::json!({"stdout":"hello 😀\n".repeat(4000),"exit":1,"error":{"text":"failure\n".repeat(4000)}});
        let expected = super::render(&value);
        let shown = super::overflow::guard(value.to_string(), "json-test", "call", true);
        assert!(shown.len() <= 50 * 1024 && shown.lines().count() <= 2000);
        let path = shown
            .split("Full output: ")
            .nth(1)
            .unwrap()
            .split(". Read with")
            .next()
            .unwrap();
        assert_eq!(std::fs::read_to_string(path).unwrap(), expected);
        let parent = std::path::Path::new(path).parent().unwrap();
        let count = std::fs::read_dir(parent).unwrap().count();
        let args = serde_json::json!({"path":path,"line_offset":30,"line_limit":5});
        let read = super::read_file(&args).unwrap();
        let read = read["content"].as_str().unwrap();
        assert!(read.contains("Showing lines 31-35"));
        assert!(read.contains(path));
        assert_eq!(std::fs::read_dir(parent).unwrap().count(), count);
        assert!(
            super::overflow::existing(
                expected.as_bytes(),
                path,
                &serde_json::json!({"line_offset":u64::MAX})
            )
            .contains("Full output:")
        );
    }
    #[test]
    fn copy_rejects_a_destination_inside_the_source() {
        let root = if cfg!(target_os = "wasi") {
            std::path::PathBuf::from("/copy-test")
        } else {
            std::env::temp_dir().join(format!("sausage-copy-{}", std::process::id()))
        };
        std::fs::create_dir_all(&root).unwrap();
        let result = super::copy_dir(&serde_json::json!({"from":root,"to":root.join("target")}));
        let _ = std::fs::remove_dir_all(root);
        assert_eq!(result.unwrap_err().kind(), std::io::ErrorKind::InvalidInput);
    }
}