# SPDX-License-Identifier: MIT
"""Fail-closed metadata preflight before offering a Clark transfer route."""
from __future__ import annotations

import argparse
from datetime import date
from hashlib import sha256
import json
from pathlib import Path

FIELDS = [
    "schema_version", "request_sha256", "task_slug", "subject", "role",
    "worksheet_sha256", "prior_exposure_declared", "attachment_count",
    "requested_transfer_route", "sender_address_redacted", "screened_on",
]
REQUEST_SHA256 = "ab2a8887110cb058d496e0afe1563fe7e42ee260a63608efa2de03a62e58a534"
TOKEN = "[KIWERB-CLARK-RETURN]"
HASH = set("0123456789abcdef")
ROLES = {"first_source_reader", "independent_reproducer"}


def canonical(value):
    return json.dumps(value, ensure_ascii=False, separators=(",", ":"), sort_keys=True).encode()


def validate(value):
    if list(value) != FIELDS:
        raise ValueError("preflight fields drift")
    if value["schema_version"] != "openlab-clark-return-preflight-v1":
        raise ValueError("preflight schema drift")
    if value["request_sha256"] != REQUEST_SHA256 or value["task_slug"] != "clark-table-i":
        raise ValueError("request binding drift")
    subject = value["subject"]
    if not isinstance(subject, str) or not subject.startswith(TOKEN) or subject.count(TOKEN) != 1 or len(subject) > 160:
        raise ValueError("exact leading subject token required")
    if value["role"] not in ROLES:
        raise ValueError("unknown review role")
    worksheet = value["worksheet_sha256"]
    if not isinstance(worksheet, str) or len(worksheet) != 64 or set(worksheet) - HASH:
        raise ValueError("worksheet sha256 invalid")
    if not isinstance(value["prior_exposure_declared"], bool):
        raise ValueError("prior exposure must be explicitly declared")
    if value["attachment_count"] != 0:
        raise ValueError("attachments must not be received before route review")
    if value["requested_transfer_route"] is not True:
        raise ValueError("reviewed transfer route must be requested")
    if value["sender_address_redacted"] is not True:
        raise ValueError("sender address must stay out of preflight evidence")
    try:
        screened = date.fromisoformat(value["screened_on"])
    except (TypeError, ValueError) as error:
        raise ValueError("screened_on must be a real ISO date") from error
    if screened > date.today():
        raise ValueError("future screening date refused")
    digest = sha256(canonical(value)).hexdigest()
    return {
        "schema_version": "openlab-clark-return-preflight-receipt-v1",
        "status": "eligible_for_manual_reply_route_review_not_submission",
        "request_sha256": REQUEST_SHA256,
        "task_slug": "clark-table-i",
        "role": value["role"],
        "worksheet_sha256": worksheet,
        "prior_exposure_declared": value["prior_exposure_declared"],
        "attachments_received": False,
        "sender_identity_verified": False,
        "independence_verified": False,
        "submission_created": False,
        "scientific_validation_claimed": False,
        "preflight_input_sha256": digest,
    }


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("input")
    parser.add_argument("--out", required=True)
    args = parser.parse_args()
    value = json.loads(Path(args.input).read_text(encoding="utf-8"))
    receipt = validate(value)
    Path(args.out).write_text(json.dumps(receipt, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")
    print(json.dumps(receipt, ensure_ascii=False))


if __name__ == "__main__":
    main()