"""Preserve an INE PDF and prepare a review package; never guess table joins.

The 2012 INE PDF contains independently wrapped columns. A line-based merge
would associate valid codes with the wrong district. This tool deliberately
exports the extracted lines for review instead of manufacturing such joins.
"""
import argparse
import csv
import hashlib
import json
from pathlib import Path
import re
import subprocess


def prepare(source, destination, executable, source_url, source_version):
    source = Path(source).resolve(strict=True)
    destination = Path(destination).resolve()
    original = source.read_bytes()
    if len(original) > 20 * 1024 * 1024 or not original.startswith(b"%PDF-"):
        raise ValueError("Expected a PDF of at most 20 MiB")
    # Never overwrite an earlier review or its preserved original.
    destination.mkdir(parents=True, exist_ok=False)
    (destination / "original.pdf").write_bytes(original)
    version = subprocess.run([executable, "-v"], capture_output=True, timeout=10, check=False)
    # Xpdf 4.00 exits 99 after printing its version; Poppler exits zero.
    if version.returncode not in (0, 99) or b"pdftotext version" not in version.stdout + version.stderr:
        raise RuntimeError("Could not identify the pdftotext executable")
    subprocess.run(
        [executable, "-enc", "UTF-8", "-layout", str(destination / "original.pdf"), str(destination / "layout.txt")],
        capture_output=True, timeout=60, check=True,
    )
    extracted = (destination / "layout.txt").read_text(encoding="utf-8")
    counts = {}
    records = 0
    with (destination / "review.csv").open("w", encoding="utf-8", newline="") as stream:
        writer = csv.writer(stream, delimiter=";")
        writer.writerow(["page", "line", "extracted_text", "issue"])
        for page, contents in enumerate(extracted.split("\f"), 1):
            for line, text in enumerate(contents.splitlines(), 1):
                if not text.strip():
                    continue
                records += 1
                # Preserve text exactly. A code occurrence is not a joined territory.
                code = re.match(r"^\s*([0-9]{6})\s", text)
                if code:
                    prefix = code.group(1)[:2]
                    counts[prefix] = counts.get(prefix, 0) + 1
                writer.writerow([page, line, text, "manual_column_alignment_required"])
    report = {
        "schema_version": 1,
        "source_url": source_url,
        "source_version_declared": source_version,
        "sha256": hashlib.sha256(original).hexdigest(),
        "extraction_sha256": hashlib.sha256((destination / "layout.txt").read_bytes()).hexdigest(),
        "extractor": (version.stdout + version.stderr).decode("utf-8", errors="replace").strip(),
        "status": "requires_steward_review",
        "license_status": "unverified",
        "nonempty_extracted_lines": records,
        "lines_requiring_review": records,
        "automatically_accepted_territories": 0,
        "observed_admin_post_code_lines_by_prefix": dict(sorted(counts.items())),
        "source_totals_comparison": "pending_independent_visual_review",
        "notice": "Code occurrences are not validated totals. No administrative relation or locality was inferred."
    }
    (destination / "report.json").write_text(json.dumps(report, ensure_ascii=False, indent=2), encoding="utf-8")
    return report


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("source")
    parser.add_argument("destination")
    parser.add_argument("--pdftotext", required=True)
    parser.add_argument("--source-url", required=True)
    parser.add_argument("--source-version", required=True)
    args = parser.parse_args()
    report = prepare(args.source, args.destination, args.pdftotext, args.source_url, args.source_version)
    print(json.dumps({"status": report["status"], "sha256": report["sha256"], "review_lines": report["lines_requiring_review"]}))