#!/usr/bin/env python3
"""Survey Scaleway IAM names and the backup bucket policy.

Reads the bootstrap and scoped-backup pairs in memory. Writes names, ids and
the bucket policy only. Never prints a credential.
"""

from __future__ import annotations

import datetime as dt
import hashlib
import hmac
import json
import subprocess
import urllib.error
import urllib.parse
import urllib.request
from pathlib import Path

RECEIPT = Path("/home/worsch/.local/state/railiance/receipts/backup-iam-survey.json")
STAGE = Path("/home/worsch/.local/state/railiance/receipts/backup-iam-survey.stage")
BUCKET = "railiance-platform-pg-backup"
HOST = "s3.nl-ams.scw.cloud"


def stage(text):
    STAGE.parent.mkdir(mode=0o700, exist_ok=True)
    STAGE.write_text(text + "\n")
    STAGE.chmod(0o600)


def kv(path):
    proc = subprocess.run(
        ["bao", "kv", "get", "-format=json", path],
        capture_output=True,
    )
    if proc.returncode:
        stage(f"kv_read_failed {path} {proc.returncode}")
        raise SystemExit(41)
    stage(f"kv_read_ok {path}")
    return json.loads(proc.stdout)["data"]["data"]


def scaleway(secret, url):
    request = urllib.request.Request(url, headers={"X-Auth-Token": secret})
    try:
        with urllib.request.urlopen(request, timeout=30) as response:
            return response.status, json.loads(response.read().decode())
    except urllib.error.HTTPError as exc:
        return exc.code, None


def sign(access_key, secret_key, canonical_uri, query):
    now = dt.datetime.now(dt.timezone.utc)
    amz_date = now.strftime("%Y%m%dT%H%M%SZ")
    day = now.strftime("%Y%m%d")
    payload = hashlib.sha256(b"").hexdigest()
    canonical_query = urllib.parse.urlencode(sorted(query.items()))
    canonical = "\n".join(
        [
            "GET",
            canonical_uri,
            canonical_query,
            f"host:{HOST}",
            f"x-amz-content-sha256:{payload}",
            f"x-amz-date:{amz_date}",
            "",
            "host;x-amz-content-sha256;x-amz-date",
            payload,
        ]
    )
    scope = f"{day}/nl-ams/s3/aws4_request"
    to_sign = "\n".join(
        ["AWS4-HMAC-SHA256", amz_date, scope, hashlib.sha256(canonical.encode()).hexdigest()]
    )
    key = ("AWS4" + secret_key).encode()
    for part in (day, "nl-ams", "s3", "aws4_request"):
        key = hmac.new(key, part.encode(), hashlib.sha256).digest()
    signature = hmac.new(key, to_sign.encode(), hashlib.sha256).hexdigest()
    return {
        "Authorization": (
            "AWS4-HMAC-SHA256 "
            f"Credential={access_key}/{scope}, "
            "SignedHeaders=host;x-amz-content-sha256;x-amz-date, "
            f"Signature={signature}"
        ),
        "x-amz-date": amz_date,
        "x-amz-content-sha256": payload,
    }


def bucket_policy(access_key, secret_key):
    query = {"policy": ""}
    headers = sign(access_key, secret_key, f"/{BUCKET}", query)
    url = f"https://{HOST}/{BUCKET}?policy"
    request = urllib.request.Request(url, headers=headers)
    try:
        with urllib.request.urlopen(request, timeout=30) as response:
            return response.status, json.loads(response.read().decode())
    except urllib.error.HTTPError as exc:
        return exc.code, None


def main():
    boot = kv("platform/workloads/railiance/scaleway/bootstrap")
    backup = kv("platform/workloads/railiance/backup/object-storage")
    org = boot["DEFAULT_ORGANIZATION_ID"]
    project = boot["DEFAULT_PROJECT_ID"]
    app_status, applications = scaleway(
        boot["SECRET_KEY"],
        "https://api.scaleway.com/iam/v1alpha1/applications"
        f"?organization_id={urllib.parse.quote(org)}&page_size=100",
    )
    policy_status, policies = scaleway(
        boot["SECRET_KEY"],
        "https://api.scaleway.com/iam/v1alpha1/policies"
        f"?organization_id={urllib.parse.quote(org)}&page_size=100",
    )
    s3_status, document = bucket_policy(backup["ACCESS_KEY"], backup["SECRET_KEY"])
    receipt = {
        "organization_id": org,
        "project_id": project,
        "application_list_status": app_status,
        "applications": [
            {"id": item.get("id"), "name": item.get("name")}
            for item in (applications or {}).get("applications", [])
        ],
        "policy_list_status": policy_status,
        "policies": [
            {
                "id": item.get("id"),
                "name": item.get("name"),
                "application_id": (item.get("application_id") or item.get("principal", {}).get("id")),
            }
            for item in (policies or {}).get("policies", [])
        ],
        "bucket_policy_status": s3_status,
        "bucket_policy": document,
    }
    RECEIPT.parent.mkdir(mode=0o700, exist_ok=True)
    RECEIPT.write_text(json.dumps(receipt, indent=2) + "\n")
    RECEIPT.chmod(0o600)


if __name__ == "__main__":
    try:
        main()
        stage("ok")
    except SystemExit:
        raise
    except Exception as exc:
        stage("failed " + type(exc).__name__)
        raise SystemExit(42) from None