# -*- coding: utf-8 -*-
"""Convert a survey DWG into GIS feature classes and inventory its layers.

Run with ArcGIS Desktop's Python 2.7 (arcpy):
    C:\\Python27\\ArcGIS10.8\\python.exe tools/city-massing/convert-dwg-to-gis.py <input.dwg> <out.gdb>

ArcGIS splits a CAD drawing into Polyline / Polygon / Point / Annotation feature classes and
records the original CAD layer in a `Layer` field. Nothing is filtered here: the script reports
what the drawing actually contains, so a building layer can be chosen from evidence.
"""
import sys
import os
import io
import json
import arcpy


def main():
    if len(sys.argv) < 3:
        print('usage: convert-dwg-to-gis.py <input.dwg> <out.gdb> [referenceScale]')
        return 2
    dwg = os.path.abspath(sys.argv[1])
    gdb = os.path.abspath(sys.argv[2])
    # ArcGIS requires a reference scale; survey drawings here are 1:500 topographic sheets.
    reference_scale = sys.argv[3] if len(sys.argv) > 3 else '500'
    if not os.path.exists(dwg):
        print('missing input: %s' % dwg)
        return 2

    work = os.path.dirname(gdb)
    if not os.path.isdir(work):
        os.makedirs(work)
    inventory_only = '--inventory-only' in sys.argv
    if inventory_only:
        if not arcpy.Exists(gdb):
            print('missing geodatabase: %s' % gdb)
            return 2
    else:
        if arcpy.Exists(gdb):
            arcpy.Delete_management(gdb)
        arcpy.CreateFileGDB_management(work, os.path.basename(gdb))
        print('converting %s -> %s (reference scale 1:%s)' % (dwg, gdb, reference_scale))
        arcpy.CADToGeodatabase_conversion(dwg, gdb, 'cad', reference_scale, '')
    arcpy.env.workspace = gdb

    # CADToGeodatabase puts the feature classes inside a feature dataset, so walk both levels.
    targets = []
    for dataset in arcpy.ListDatasets() or []:
        for name in arcpy.ListFeatureClasses(feature_dataset=dataset) or []:
            targets.append((dataset, name))
    for name in arcpy.ListFeatureClasses() or []:
        targets.append((None, name))

    report = {'input': dwg, 'gdb': gdb, 'featureClasses': []}
    for dataset, name in targets:
        entry = {'name': name, 'dataset': dataset, 'featureType': arcpy.Describe(name).shapeType, 'featureCount': 0, 'layers': {}}
        fields = [f.name for f in arcpy.ListFields(name)]
        entry['fields'] = fields
        hasLayer = 'Layer' in fields
        with arcpy.da.SearchCursor(name, ['Layer'] if hasLayer else ['OID@']) as cursor:
            for row in cursor:
                entry['featureCount'] += 1
                if hasLayer:
                    key = row[0] if row[0] is not None else u'(none)'
                    entry['layers'][key] = entry['layers'].get(key, 0) + 1
        report['featureClasses'].append(entry)
        print('%-10s %-28s %-9s %6d features, %d layers' % (
            dataset or '-', name, entry['featureType'], entry['featureCount'], len(entry['layers'])))
        for layer, count in sorted(entry['layers'].items(), key=lambda kv: -kv[1])[:40]:
            line = u'      %6d  %s' % (count, layer)
            print(line.encode('utf-8'))

    out = os.path.join(work, os.path.basename(gdb) + '-inventory.json')
    with io.open(out, 'w', encoding='utf-8') as handle:
        handle.write(unicode(json.dumps(report, ensure_ascii=False, indent=2, sort_keys=True)))
    print('inventory: %s' % out)
    return 0


if __name__ == '__main__':
    sys.exit(main())