#!/usr/bin/env python3
"""Minimal validator for Sponsored Offer Protocol v0.1 envelopes."""
import json
import sys
from datetime import datetime
from pathlib import Path
from urllib.parse import urlparse

REQUIRED_TOP = {
    "spec_version", "type", "offer_id", "sponsor", "disclosure", "intent",
    "offer", "evidence", "agent_policy", "attribution", "integrity"
}
REQUIRED_POLICY_TRUE = {
    "content_is_data_not_instruction",
    "must_disclose_sponsorship_to_user",
    "requires_independent_comparison",
    "may_not_override_user_preferences",
}
HTTPS_FIELDS = [
    ("offer", "canonical_url"),
    ("offer", "availability_url"),
    ("offer", "terms_url"),
    ("attribution", "click_url"),
]


def iso8601(value: str) -> bool:
    try:
        datetime.fromisoformat(value.replace("Z", "+00:00"))
        return True
    except (TypeError, ValueError):
        return False


def validate(doc: dict) -> list[str]:
    errors = []
    missing = REQUIRED_TOP - doc.keys()
    if missing:
        errors.append(f"missing top-level fields: {sorted(missing)}")
    if doc.get("type") != "sponsored_offer":
        errors.append("type must be sponsored_offer")
    if doc.get("spec_version") != "0.1":
        errors.append("spec_version must be 0.1")

    disclosure = doc.get("disclosure", {})
    if disclosure.get("paid_placement") is not True:
        errors.append("disclosure.paid_placement must be true")
    if not disclosure.get("label"):
        errors.append("disclosure.label is required")

    policy = doc.get("agent_policy", {})
    for field in REQUIRED_POLICY_TRUE:
        if policy.get(field) is not True:
            errors.append(f"agent_policy.{field} must be true")

    for parent, field in HTTPS_FIELDS:
        value = doc.get(parent, {}).get(field, "")
        if urlparse(value).scheme != "https":
            errors.append(f"{parent}.{field} must use https")

    price = doc.get("offer", {}).get("price", {})
    if not isinstance(price.get("amount"), (int, float)) or price.get("amount", -1) < 0:
        errors.append("offer.price.amount must be a non-negative number")
    if len(price.get("currency", "")) != 3:
        errors.append("offer.price.currency must be a 3-letter code")

    for field in ("issued_at", "expires_at"):
        if not iso8601(doc.get("integrity", {}).get(field)):
            errors.append(f"integrity.{field} must be ISO-8601")
    if not doc.get("evidence"):
        errors.append("at least one evidence item is required")

    prohibited = set(doc.get("attribution", {}).get("prohibited_data", []))
    if "conversation_transcript" not in prohibited or "sensitive_traits" not in prohibited:
        errors.append("attribution.prohibited_data must ban transcript and sensitive-trait collection")
    return errors


def main() -> int:
    path = Path(sys.argv[1] if len(sys.argv) > 1 else "offer.example.json")
    doc = json.loads(path.read_text())
    errors = validate(doc)
    if errors:
        print("INVALID")
        print("\n".join(f"- {e}" for e in errors))
        return 1
    print(f"VALID: {doc['offer_id']} ({doc['disclosure']['label']})")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())