Automating ArcGIS Pro Metadata Export to ISO 19139

from __future__ import annotations

import getpass
import hashlib
import json
from datetime import datetime, timezone
from pathlib import Path

import arcpy  # available only inside ArcGIS Pro's arcgispro-py3 environment
from arcpy import metadata as md


def export_iso19139_with_lineage(
    source_item: str,
    output_dir: str | Path,
    translator: str = "ISO19139_GML32",
) -> dict[str, str]:
    """Export an ArcGIS Pro item's metadata to ISO 19139 XML and emit a lineage record.

    Args:
        source_item: Catalog path to a feature class, raster, or table.
        output_dir: Directory that will hold the .xml export and .lineage.json sidecar.
        translator: arcpy metadata export translation style name.

    Returns:
        The lineage record that was written to disk.
    """
    out_dir = Path(output_dir)
    out_dir.mkdir(parents=True, exist_ok=True)

    if not arcpy.Exists(source_item):
        raise FileNotFoundError(f"ArcGIS item does not exist: {source_item}")

    item_name = Path(source_item).name
    xml_path = out_dir / f"{item_name}.iso19139.xml"

    # Read the item's stored metadata and export it to ISO 19139.
    item_md = md.Metadata(source_item)
    if item_md.isReadOnly:
        raise PermissionError(f"Metadata for {source_item} is read-only")
    item_md.exportMetadata(str(xml_path), translator)

    # Hash the exported XML so drift in the record is detectable later.
    xml_bytes = xml_path.read_bytes()
    xml_sha256 = hashlib.sha256(xml_bytes).hexdigest()

    describe = arcpy.Describe(source_item)
    lineage: dict[str, str] = {
        "event": "metadata_export",
        "source_item": str(source_item),
        "source_catalog_path": describe.catalogPath,
        "dataset_type": describe.dataType,
        "spatial_reference": getattr(describe, "spatialReference", None).name
        if getattr(describe, "spatialReference", None)
        else "UNKNOWN",
        "output_xml": str(xml_path),
        "translator": translator,
        "xml_sha256": xml_sha256,
        "xml_byte_length": str(len(xml_bytes)),
        "operator": getpass.getuser(),
        "exported_at": datetime.now(timezone.utc).isoformat(),
    }

    lineage_path = out_dir / f"{item_name}.lineage.json"
    lineage_path.write_text(json.dumps(lineage, indent=2), encoding="utf-8")
    return lineage


if __name__ == "__main__":
    record = export_iso19139_with_lineage(
        source_item=r"C:\gis\parcels.gdb\parcels_2026",
        output_dir=r"C:\gis\exports\lineage",
    )
    print(f"Exported {record['output_xml']} (sha256={record['xml_sha256'][:12]}...)")

import hashlib
from pathlib import Path
from xml.etree import ElementTree as ET

xml_path = Path(r"C:\gis\exports\lineage\parcels_2026.iso19139.xml")

# 1. The XML must parse and carry the ISO 19139 root namespace (gmd/gco).
root = ET.parse(xml_path).getroot()
assert "isotc211" in root.tag, f"Unexpected root element: {root.tag}"

# 2. The recomputed hash must equal the one stored in the lineage sidecar.
import json
lineage = json.loads(Path(str(xml_path).replace(".iso19139.xml", ".lineage.json")).read_text())
recomputed = hashlib.sha256(xml_path.read_bytes()).hexdigest()
assert recomputed == lineage["xml_sha256"], "Lineage hash drift detected"
print("Export verified:", lineage["exported_at"])