#!/usr/bin/env python3
"""Klassifiziert einen Terraform-Plan als ITIL-Change-Typ.

Aufruf: classify_change.py <plan.json> <stack>
Erzeugt: change-record.md und change.env (für GitLab-dotenv-Reports)
"""
import datetime
import json
import os
import sys

# Änderungen an diesen Typen sind immer ein Normal Change
CRITICAL_TYPES = {
    "azurerm_resource_group",
    "azurerm_virtual_network",
    "azurerm_subnet",
    "azurerm_network_security_group",
    "azurerm_subnet_network_security_group_association",
    "azurerm_shared_image_gallery",
    "azurerm_shared_image",
}


def classify(plan):
    changes, reasons = [], []
    for rc in plan.get("resource_changes", []):
        actions = rc["change"]["actions"]
        if actions in (["no-op"], ["read"]):
            continue
        changes.append((rc["address"], rc["type"], actions))
        if "delete" in actions:
            art = "wird ersetzt" if "create" in actions else "wird gelöscht"
            reasons.append(f"{rc['address']} {art}")
        elif rc["type"] in CRITICAL_TYPES:
            reasons.append(f"{rc['address']}: kritischer Ressourcentyp")

    if not changes:
        return "none", changes, reasons
    return ("normal" if reasons else "standard"), changes, reasons


def main():
    plan_file, stack = sys.argv[1], sys.argv[2]
    with open(plan_file, encoding="utf-8") as fh:
        plan = json.load(fh)

    change_type, changes, reasons = classify(plan)

    lines = [
        f"# Change-Datensatz – Schicht {stack}",
        "",
        f"- Zeitpunkt: {datetime.datetime.now(datetime.timezone.utc):%Y-%m-%d %H:%M} UTC",
        f"- Change-Typ: **{change_type}**",
        f"- Commit: {os.environ.get('CI_COMMIT_SHA', 'lokal')}",
        f"- Merge Request: {os.environ.get('CI_MERGE_REQUEST_IID', '-')}",
        f"- Ausgelöst von: {os.environ.get('GITLAB_USER_LOGIN', 'lokal')}",
        "",
        "## Geplante Änderungen",
    ]
    lines += [f"- `{addr}`: {'/'.join(act)}" for addr, _, act in changes] or ["- keine"]
    if reasons:
        lines += ["", "## Gründe für Normal Change"] + [f"- {r}" for r in reasons]

    with open("change-record.md", "w", encoding="utf-8") as fh:
        fh.write("\n".join(lines) + "\n")
    with open("change.env", "w", encoding="utf-8") as fh:
        fh.write(f"CHANGE_TYPE_{stack.upper()}={change_type}\n")

    print(f"[{stack}] Change-Typ: {change_type}")
    for r in reasons:
        print(f"  - {r}")


if __name__ == "__main__":
    main()