"""Data processing tools: CSV/JSON operations."""

from __future__ import annotations

import csv
import io
import json
from pathlib import Path

from . import tool


@tool("read_csv", "Read a CSV file and return summary or specific rows", category="data")
def read_csv(path: str, max_rows: int = 20) -> str:
    p = Path(path).resolve()
    if not p.exists():
        return f"File not found: {path}"
    try:
        with open(p, newline="", encoding="utf-8-sig") as f:
            reader = csv.reader(f)
            rows = []
            for i, row in enumerate(reader):
                rows.append(row)
                if i >= max_rows:
                    break

        if not rows:
            return "Empty CSV file."

        # Format as table
        header = rows[0]
        lines = [" | ".join(header), " | ".join("---" for _ in header)]
        for row in rows[1:]:
            lines.append(" | ".join(str(c)[:50] for c in row))

        result = "\n".join(lines)
        total_line_count = sum(1 for _ in open(p, encoding="utf-8-sig"))
        if total_line_count > max_rows + 1:
            result += f"\n\n... ({total_line_count - 1} total rows, showing first {max_rows})"
        return result
    except Exception as e:
        return f"Error reading CSV: {e}"


@tool("read_json", "Read and pretty-print a JSON file", category="data")
def read_json(path: str) -> str:
    p = Path(path).resolve()
    if not p.exists():
        return f"File not found: {path}"
    try:
        data = json.loads(p.read_text(encoding="utf-8"))
        formatted = json.dumps(data, indent=2, ensure_ascii=False)
        if len(formatted) > 15000:
            formatted = formatted[:15000] + "\n... (truncated)"
        return formatted
    except Exception as e:
        return f"Error reading JSON: {e}"


@tool("query_json", "Extract data from a JSON file using a dot-notation path", category="data")
def query_json(path: str, json_path: str) -> str:
    """json_path example: 'data.users.0.name' or 'results.*.id'"""
    p = Path(path).resolve()
    if not p.exists():
        return f"File not found: {path}"
    try:
        data = json.loads(p.read_text(encoding="utf-8"))
        result = _navigate(data, json_path.split("."))
        return json.dumps(result, indent=2, ensure_ascii=False) if not isinstance(result, str) else result
    except Exception as e:
        return f"Error: {e}"


def _navigate(data, parts: list[str]):
    for part in parts:
        if part == "*" and isinstance(data, list):
            return data
        elif isinstance(data, dict):
            data = data.get(part, f"Key '{part}' not found")
        elif isinstance(data, list):
            try:
                data = data[int(part)]
            except (ValueError, IndexError):
                return f"Invalid index '{part}'"
        else:
            return f"Cannot navigate into {type(data).__name__}"
    return data