#!/usr/bin/env python3
"""File a Tangled pull request as the bot, by reusing a browser session cookie.

WHY: Tangled's appview only indexes a pull when it's created through its
OAuth-authenticated web endpoint (POST /{owner}/{repo}/pulls/), which fetches the
patch from the knot and inserts it into the appview DB directly. Writing the
sh.tangled.repo.pull record straight to the PDS (com.atproto.repo.createRecord)
does NOT get indexed (verified: even a byte-identical knot patch fails). There is
no client CLI. So the automation is: log into tangled.org ONCE in a browser as the
bot, copy the session cookie here (gitignored), and this tool reuses it.

The endpoint needs no CSRF token and no patch upload — just the session cookie and
the branch names; the appview generates the patch (from the knot) and indexes it.
Branch-based PR requires push access to the repo (the bot owns its fork, so OK).

COOKIE FILE (tools/.tangled-session, gitignored), a single line — paste the whole
Cookie header value from the logged-in browser (both appview-* cookies):
  TANGLED_COOKIE=appview-session-v2=<...>; appview-accounts-v2=<...>

USAGE:
  tangled_pr.py --owner notplants-bot.bsky.social --repo lichen.page \
      --target main --source hardening-review \
      [--fork did:plc:<forkRepoDid>] [--title "..."] [--body "..."]
"""
import argparse, os, sys, urllib.request, urllib.parse, urllib.error

BASE = "https://tangled.org"

def load_cookie(path):
    if not os.path.exists(path):
        sys.exit(f"no cookie file at {path} — do the one-time browser login "
                 f"(see machine-docs/tangled-pr-automation.md)")
    for line in open(path):
        line = line.strip()
        if line.startswith("TANGLED_COOKIE="):
            return line[len("TANGLED_COOKIE="):]
    sys.exit("cookie file present but has no TANGLED_COOKIE= line")

def main():
    ap = argparse.ArgumentParser(description="file a Tangled PR via a reused session cookie")
    ap.add_argument("--owner", required=True)
    ap.add_argument("--repo", required=True)
    ap.add_argument("--target", required=True, help="target branch (merge into), e.g. main")
    ap.add_argument("--source", required=True, help="source branch (the changes), e.g. hardening-review")
    ap.add_argument("--fork", default="", help="fork repoDid for a cross-fork PR (omit for same-repo)")
    ap.add_argument("--title", default="")
    ap.add_argument("--body", default="")
    ap.add_argument("--cookie-file", default=os.path.join(os.path.dirname(os.path.abspath(__file__)), ".tangled-session"))
    a = ap.parse_args()

    cookie = load_cookie(a.cookie_file)
    # Tangled's PR form is htmx: it POSTs to /pulls/new (NOT /pulls/, which is 405) and only processes
    # the create when it sees the HX-Request header — otherwise it just re-renders the page (a 200 that
    # creates nothing). Success is signalled by an HX-Redirect header pointing at the new pull.
    new_url = f"{BASE}/{a.owner}/{a.repo}/pulls/new"
    form = {
        "source": "branch",           # branch-compare mode (each PR targets the branch below it)
        "targetBranch": a.target,
        "sourceBranch": a.source,
        "title": a.title, "titleDirty": "true",
        "body": a.body,   "bodyDirty":  "true",
    }
    if a.fork:  form["fork"] = a.fork
    data = urllib.parse.urlencode(form).encode()
    req = urllib.request.Request(new_url, data=data, method="POST", headers={
        "Cookie": cookie,
        "Content-Type": "application/x-www-form-urlencoded",
        "User-Agent": "tangled-pr-bot",
        "HX-Request": "true",
        "HX-Current-URL": new_url,
        "Referer": new_url,
    })

    class NoRedirect(urllib.request.HTTPRedirectHandler):
        def redirect_request(self, *args, **kw):  # capture the redirect instead of following it
            return None
    opener = urllib.request.build_opener(NoRedirect)
    try:
        r = opener.open(req, timeout=90)
        hdrs, code, body = r.headers, r.getcode(), r.read(3000).decode("utf-8", "replace")
    except urllib.error.HTTPError as e:
        hdrs, code, body = e.headers, e.code, e.read(3000).decode("utf-8", "replace")
    # htmx success is signalled by HX-Redirect (…/pulls/<n>), not a normal 3xx Location.
    target = hdrs.get("HX-Redirect", "") or hdrs.get("HX-Location", "") or hdrs.get("Location", "")
    print(f"HTTP {code}" + (f" -> {target}" if target else ""))
    if target and "/pulls/" in target and "/new" not in target:
        print("OK: pull created ->", (BASE + target) if target.startswith("/") else target)
        return
    if ("/login" in target or "oauth" in target.lower()):
        sys.exit("AUTH FAILED: session cookie expired/invalid — refresh engine/.tangled-session "
                 "(scripts/get-tangled-cookie.py)")
    # otherwise surface whatever the page said (a Notice, etc.)
    snippet = " ".join(body.split())[:600]
    print("  no clear success redirect — response snippet:")
    print("  " + snippet)
    sys.exit(2)

if __name__ == "__main__":
    main()