#!/usr/bin/env python3
"""Edit an existing Tangled pull's title/body as the bot, via the session cookie.

WHY: engine/tangled_pr.py only CREATES pulls; the appview also exposes an edit
endpoint for an existing pull (the pencil on the pull page). It is an htmx form:
  GET  /{owner}/{repo}/pulls/{n}/edit   -> the form (current title + body)
  POST /{owner}/{repo}/pulls/{n}/edit   -> apply (form fields: title, body)
Same session-cookie auth as tangled_pr.py. Editing title/body does NOT create a
round and does not touch the patch — but callers should re-fetch and verify that
themselves (see --show).

COOKIE FILE (engine/.tangled-session, gitignored) — same as tangled_pr.py; on
401/login redirect refresh it with scripts/get-tangled-cookie.py.

USAGE:
  tangled_pr_edit.py --owner notplants-bot.bsky.social --repo lichen.page.review \
      --pull 75 --show                     # print current title + body (raw md)
  tangled_pr_edit.py ... --pull 75 --title "..." --body "..."      # apply edit
  tangled_pr_edit.py ... --pull 75 --title "..." --body-file b.md  # body from file
"""
import argparse, html, os, re, sys, urllib.request, urllib.parse, urllib.error

BASE = "https://tangled.org"

def load_cookie(path=None):
    """The cookie lives in the encrypted store (tangled.cookie) — see engine/README.md (Secrets).
    `path` is a legacy escape hatch: a TANGLED_COOKIE=... file, used only if explicitly passed."""
    if path:
        for line in open(path):
            if line.strip().startswith("TANGLED_COOKIE="):
                return line.strip()[len("TANGLED_COOKIE="):]
        sys.exit(f"{path} has no TANGLED_COOKIE= line")
    sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
    import secrets as _store
    c = _store.get("tangled.cookie")
    if not c:
        sys.exit("no tangled.cookie in the secret store — add it with: sops /secrets/store.yaml")
    return c

def fetch_form(edit_url, cookie):
    """GET the htmx edit form; return (title, body) as the appview holds them."""
    req = urllib.request.Request(edit_url, headers={
        "Cookie": cookie, "User-Agent": "tangled-pr-bot",
        "HX-Request": "true", "HX-Current-URL": edit_url, "Referer": edit_url,
    })
    doc = urllib.request.urlopen(req, timeout=60).read().decode()
    tm = re.search(r'name="title" id="title"[^>]*value="([^"]*)"', doc)
    bm = re.search(r'<textarea\s+name="body".*?>\n?(.*?)</textarea>', doc, re.S)
    if not tm or not bm:
        sys.exit("could not parse the edit form (auth expired? layout changed?)")
    return html.unescape(tm.group(1)), html.unescape(bm.group(1))

def main():
    ap = argparse.ArgumentParser(description="edit a Tangled pull's title/body via a reused session cookie")
    ap.add_argument("--owner", required=True)
    ap.add_argument("--repo", required=True)
    ap.add_argument("--pull", required=True, type=int)
    ap.add_argument("--title", default=None)
    ap.add_argument("--body", default=None)
    ap.add_argument("--body-file", default=None, help="read the new body from a file (overrides --body)")
    ap.add_argument("--show", action="store_true", help="print current title+body and exit (no edit)")
    ap.add_argument("--cookie-file", default=None, help="legacy: read the cookie from this file instead of the store")
    a = ap.parse_args()

    cookie = load_cookie(a.cookie_file)
    edit_url = f"{BASE}/{a.owner}/{a.repo}/pulls/{a.pull}/edit"

    if a.show:
        title, body = fetch_form(edit_url, cookie)
        print(f"TITLE: {title}")
        print("BODY:")
        print(body)
        return

    body = open(a.body_file).read() if a.body_file else a.body
    if a.title is None or body is None:
        sys.exit("need --title and --body/--body-file (or --show)")

    # the edit form is htmx like the create form: needs HX-Request or the POST
    # just re-renders; success is a 2xx (hx-swap=none), failure a login redirect
    data = urllib.parse.urlencode({"title": a.title, "body": body}).encode()
    req = urllib.request.Request(edit_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": edit_url,
        "Referer": edit_url,
    })
    class NoRedirect(urllib.request.HTTPRedirectHandler):
        def redirect_request(self, *args, **kw):
            return None
    opener = urllib.request.build_opener(NoRedirect)
    try:
        r = opener.open(req, timeout=90)
        hdrs, code, resp = r.headers, r.getcode(), r.read(3000).decode("utf-8", "replace")
    except urllib.error.HTTPError as e:
        hdrs, code, resp = e.headers, e.code, e.read(3000).decode("utf-8", "replace")
    target = hdrs.get("HX-Redirect", "") or hdrs.get("HX-Location", "") or hdrs.get("Location", "")
    print(f"HTTP {code}" + (f" -> {target}" if target else ""))
    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)")
    if code // 100 != 2:
        snippet = " ".join(resp.split())[:600]
        print("  edit did not return 2xx — response snippet:")
        print("  " + snippet)
        sys.exit(2)

    # trust nothing: re-fetch the form and confirm the appview now holds the new text
    new_title, new_body = fetch_form(edit_url, cookie)
    if new_title == a.title and new_body.replace("\r\n", "\n") == body.replace("\r\n", "\n"):
        print("OK: verified — appview now holds the new title/body")
    else:
        print(f"MISMATCH after edit: title_ok={new_title == a.title} "
              f"body_ok={new_body.replace(chr(13)+chr(10), chr(10)) == body.replace(chr(13)+chr(10), chr(10))}")
        sys.exit(3)

if __name__ == "__main__":
    main()