#!/usr/bin/env python3
# Issue-Migration Gitea -> GitLab (gitops#48). Stdlib-only.
#
# Eigenschaften:
# - Dry-Run per Default; --execute schreibt wirklich
# - idempotent: Marker "<!-- gitea-migration: OWNER/REPO#N -->" in der
#   GitLab-Beschreibung; bereits migrierte Issues werden uebersprungen
# - Kommentare werden als Notes uebernommen (Original-Autor + -Zeit im Text,
#   da die API-Autorschaft auf den Token-User laeuft — bekannter, akzeptierter
#   Verlust, siehe gitops#48)
# - Zeitstempel bleiben erhalten: der Admin-Token darf created_at setzen
# - geschlossene Issues werden nach Anlage geschlossen
# - Labels werden namensgleich uebernommen (Gruppen-Labels muessen existieren)
# - PRs werden ausgelassen (Gitea listet sie im Issue-Endpunkt mit)
#
# Aufruf:
#   python3 migrate.py sorb/thread-net-git 18            # Dry-Run
#   python3 migrate.py sorb/thread-net-git 18 --execute
import json
import sys
import urllib.parse
import urllib.request

GITEA = "https://rohana.axion1337.de"
GITLAB = "https://git.lab"
GITEA_TOKEN = open("/Users/thore/.config/gitea-rohana/token").read().strip()
GITLAB_TOKEN = open("/Users/thore/.config/gitlab-lab/token").read().strip()


def gitea(path):
    req = urllib.request.Request(f"{GITEA}/api/v1{path}",
                                 headers={"Authorization": f"token {GITEA_TOKEN}"})
    return json.loads(urllib.request.urlopen(req).read())


def gitlab(method, path, payload=None):
    data = urllib.parse.urlencode(payload).encode() if payload else None
    req = urllib.request.Request(f"{GITLAB}/api/v4{path}", data=data,
                                 headers={"PRIVATE-TOKEN": GITLAB_TOKEN}, method=method)
    return json.loads(urllib.request.urlopen(req).read())


def main():
    repo = sys.argv[1]
    project = sys.argv[2]
    execute = "--execute" in sys.argv

    # Bestehende Migrations-Marker im Zielprojekt einsammeln (Idempotenz)
    existing = set()
    page = 1
    while True:
        batch = gitlab("GET", f"/projects/{project}/issues?per_page=100&page={page}&scope=all&state=all")
        if not batch:
            break
        for i in batch:
            desc = i.get("description") or ""
            for line in desc.splitlines():
                if line.startswith("<!-- gitea-migration: "):
                    existing.add(line.strip())
        page += 1

    # Gitea-Issues (alle Zustaende), PRs ausfiltern
    issues = []
    page = 1
    while True:
        batch = gitea(f"/repos/{repo}/issues?state=all&type=issues&limit=50&page={page}")
        if not batch:
            break
        issues.extend(batch)
        page += 1
    issues.sort(key=lambda i: i["number"])  # aufsteigend = chronologische Anlage

    print(f"{repo}: {len(issues)} Issues gefunden, Ziel-Projekt {project}, "
          f"{'EXECUTE' if execute else 'DRY-RUN'}")

    for i in issues:
        n = i["number"]
        marker = f"<!-- gitea-migration: {repo}#{n} -->"
        if marker in existing:
            print(f"  #{n} bereits migriert - uebersprungen")
            continue
        labels = ",".join(l["name"] for l in i.get("labels", []))
        comments = gitea(f"/repos/{repo}/issues/{n}/comments") if i.get("comments") else []
        footer = (f"\n\n---\n*Migriert aus Gitea [{repo}#{n}]({GITEA}/{repo}/issues/{n}) "
                  f"— dort erstellt am {i['created_at'][:10]} von {i['user']['login']}.*\n{marker}")
        print(f"  #{n} [{i['state']}] {i['title'][:60]} | labels: {labels or '-'} | "
              f"{len(comments)} kommentare")
        if not execute:
            continue
        new = gitlab("POST", f"/projects/{project}/issues", {
            "title": i["title"],
            "description": (i.get("body") or "") + footer,
            "labels": labels,
            "created_at": i["created_at"],
        })
        for c in comments:
            gitlab("POST", f"/projects/{project}/issues/{new['iid']}/notes", {
                "body": f"**{c['user']['login']} am {c['created_at'][:16].replace('T', ' ')} (Gitea):**\n\n{c['body']}",
                "created_at": c["created_at"],
            })
        if i["state"] == "closed":
            gitlab("PUT", f"/projects/{project}/issues/{new['iid']}", {"state_event": "close"})
        print(f"    -> GitLab #{new['iid']} angelegt ({i['state']})")


if __name__ == "__main__":
    main()