#!/usr/bin/env python3
"""Independent cross-check: extracted CSV vs the raw source JSON.

Usage:
    python3 verify_extraction.py <source_json> <csv_path>

Verifies that every source record appears exactly once in the CSV:
  - row count equals the source record count
  - alpha-2 code sets match exactly
  - name_common values match for every row

Exits 0 only if all checks pass. Evidence, not the formal gate.
"""
import csv
import json
import sys


def main():
    if len(sys.argv) != 3:
        sys.stderr.write('usage: verify_extraction.py <source_json> <csv_path>\n')
        return 2
    source_path, csv_path = sys.argv[1], sys.argv[2]
    try:
        with open(source_path, encoding='utf-8') as fh:
            records = json.load(fh)
    except (OSError, ValueError) as exc:
        sys.stderr.write('cannot read source %s: %s\n' % (source_path, exc))
        return 1
    if not isinstance(records, list):
        sys.stderr.write('source JSON is not a list\n')
        return 1

    source = {}
    for rec in records:
        code = str(rec.get('cca2')) if rec.get('cca2') else None
        name = str((rec.get('name') or {}).get('common')) if rec.get('name') else ''
        if code:
            source[code] = name

    try:
        with open(csv_path, encoding='utf-8') as fh:
            rows = list(csv.reader(fh))
    except OSError as exc:
        sys.stderr.write('cannot read csv %s: %s\n' % (csv_path, exc))
        return 1
    if not rows:
        sys.stderr.write('csv is empty\n')
        return 1
    header, data = rows[0], rows[1:]
    problems = []
    if len(data) != len(source):
        problems.append('row count %d != source count %d'
                        % (len(data), len(source)))

    csv_codes = {}
    for row in data:
        if len(row) != 14:
            problems.append('row with %d fields: %r' % (len(row), row))
            continue
        csv_codes[row[2]] = row[0]

    missing = sorted(set(source) - set(csv_codes))
    extra = sorted(set(csv_codes) - set(source))
    if missing:
        problems.append('alpha-2 missing from csv: %r' % missing)
    if extra:
        problems.append('alpha-2 extra in csv: %r' % extra)
    mismatches = [c for c in source if csv_codes.get(c) != source[c]]
    if mismatches:
        problems.append('name_common mismatches: %r' % mismatches)

    if problems:
        sys.stderr.write('VERIFY FAILED\n')
        for problem in problems:
            sys.stderr.write(' - %s\n' % problem)
        return 1
    print('verify: ok rows=%d codes=%d source=%d header=%r'
          % (len(data), len(csv_codes), len(source), header))
    return 0


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