"""Minimal DWG-to-DXF conversion microservice via libredwg."""

import os
import subprocess
import tempfile
import uuid

from flask import Flask, request, send_file, jsonify

app = Flask(__name__)

MAX_FILE_SIZE = 100 * 1024 * 1024  # 100 MB


@app.route("/health", methods=["GET"])
def health():
    """Health check — verifies dwg2dxf binary is callable."""
    try:
        subprocess.run(["dwg2dxf", "--version"], capture_output=True, timeout=5)
        return jsonify({"status": "ok", "dwg2dxf": "available"}), 200
    except Exception as e:
        return jsonify({"status": "error", "detail": str(e)}), 503


@app.route("/convert", methods=["POST"])
def convert():
    """Accept a DWG file via multipart upload, return DXF."""
    if "file" not in request.files:
        return jsonify({"error": "Missing 'file' field in upload."}), 400

    uploaded = request.files["file"]
    original_name = uploaded.filename or "input.dwg"

    if not original_name.lower().endswith(".dwg"):
        return jsonify({"error": "File must have .dwg extension."}), 400

    safe_name = "".join(
        c if c.isalnum() or c in "._-" else "_" for c in original_name
    )

    tmp_dir = os.path.join(tempfile.gettempdir(), f"dwg-{uuid.uuid4().hex}")
    os.makedirs(tmp_dir, exist_ok=True)

    input_path = os.path.join(tmp_dir, safe_name)
    output_path = input_path.rsplit(".", 1)[0] + ".dxf"

    try:
        uploaded.save(input_path)

        file_size = os.path.getsize(input_path)
        if file_size > MAX_FILE_SIZE:
            return jsonify({"error": f"File too large ({file_size} bytes)."}), 413

        result = subprocess.run(
            ["dwg2dxf", input_path],
            capture_output=True,
            timeout=120,
        )

        if not os.path.exists(output_path):
            stderr = result.stderr.decode("utf-8", errors="replace")
            return jsonify({
                "error": f"Conversion failed: {stderr or 'no output file'}"
            }), 500

        dxf_name = safe_name.rsplit(".", 1)[0] + ".dxf"
        return send_file(
            output_path,
            mimetype="application/dxf",
            as_attachment=True,
            download_name=dxf_name,
        )

    except subprocess.TimeoutExpired:
        return jsonify({"error": "Conversion timed out (120s limit)."}), 504

    except Exception as e:
        return jsonify({"error": f"Unexpected error: {str(e)}"}), 500

    finally:
        for f in os.listdir(tmp_dir):
            try:
                os.unlink(os.path.join(tmp_dir, f))
            except OSError:
                pass
        try:
            os.rmdir(tmp_dir)
        except OSError:
            pass


if __name__ == "__main__":
    app.run(host="0.0.0.0", port=5001)