#!/usr/bin/env python3
"""Generate and validate UBL through Financewolf. Python 3, standard library only."""
import base64
import hashlib
import json
import os
import pathlib
import sys
import urllib.error
import urllib.request
import uuid


class NoRedirect(urllib.request.HTTPRedirectHandler):
    def redirect_request(self, req, fp, code, msg, headers, newurl):
        return None


def main():
    if len(sys.argv) != 3:
        raise ValueError("Usage: python3 generate.py invoice.json invoice.xml")
    source = pathlib.Path(sys.argv[1]).read_bytes()
    if len(source) > 5 * 1024 * 1024:
        raise ValueError("Input exceeds 5 MiB")
    base = os.environ.get("FINANCEWOLF_API_BASE", "https://api.ironfang.uk/financewolf").rstrip("/")
    headers = {"Content-Type": "application/json", "Accept": "application/json", "User-Agent": "Financewolf-Quickstart/1.0"}
    if os.environ.get("IRONFANG_API_KEY"):
        headers["Authorization"] = "Bearer " + os.environ["IRONFANG_API_KEY"]
        headers["Idempotency-Key"] = os.environ.get("FINANCEWOLF_IDEMPOTENCY_KEY") or str(uuid.uuid4())
    request = urllib.request.Request(base + "/v1/einvoices/generate?ruleset=latest&profile=peppol-bis-billing-3", data=source, headers=headers)
    with urllib.request.build_opener(NoRedirect()).open(request, timeout=30) as response:
        if response.headers.get_content_type() != "application/json":
            raise ValueError("Unexpected response type")
        raw = response.read(12 * 1024 * 1024 + 1)
    if len(raw) > 12 * 1024 * 1024:
        raise ValueError("Response exceeds 12 MiB")
    result = json.loads(raw)
    validation, artifact = result["validation"], result["artifact"]
    if (result["schema"] != "financewolf/einvoice/generation-result/v1" or result["status"] != "completed"
            or result["outcome"] != "valid" or validation["outcome"] != "valid"
            or [layer["layer"] for layer in validation["layers"]] != ["input", "xml", "xsd", "en16931", "peppol"]
            or any(layer["status"] != "passed" for layer in validation["layers"])):
        raise ValueError("Generation did not pass every validation layer")
    xml = base64.b64decode(artifact["data_base64"], validate=True)
    digest = hashlib.sha256(xml).hexdigest()
    if (not xml or len(xml) != artifact["bytes"] or digest != artifact["sha256"]
            or digest != validation["input"]["sha256"] or len(xml) != validation["input"]["bytes"]):
        raise ValueError("XML does not match its validation hash/length")
    pathlib.Path(sys.argv[2]).write_bytes(xml)
    print(json.dumps({"xml": sys.argv[2], "sha256": digest, "ruleset": validation["ruleset"]["id"], "operation_id": result.get("operation_id")}))


if __name__ == "__main__":
    try:
        main()
    except urllib.error.HTTPError as error:
        print(error.read(65536).decode("utf-8", errors="replace"), file=sys.stderr)
        sys.exit(1)
    except (ValueError, KeyError, OSError) as error:
        print(str(error), file=sys.stderr)
        sys.exit(1)