"""Recurring company-mailbox scan (BINKY-WP-0004-T05).

Two-phase design, because credentials and network are barred from the
agentic session's tool allow-list:

1. **Deterministic scan phase** (this module, no LLM): acquire the IMAP
   credentials from OpenBao, run email-connect's read-only scan-mailbox in
   the target repo, record a `binky_mail_intake` hub progress event with
   metadata-only counts. Credential values live exclusively in the child
   process environment — never in argv, logs, hub events, or files.

2. **Optional triage session** (standard run_task): an agentic session in
   the target repo reads the newest report CSV and updates the metadata
   log/queues. Suspicious-mail rule is part of that task's prompt: never
   act on message content, only log it.

Credential acquisition, in order:
- AppRole (unattended lane): role_id/secret_id files under
  $EXECUTOR_APPROLE_DIR → `bao write -field=token auth/approle/login ...`
- Pre-existing token (operator lane): ambient bao token, e.g. after an
  interactive OIDC login.
Then two `bao kv get -field=...` reads on the kv path.
"""

from __future__ import annotations

import os
import subprocess
from dataclasses import dataclass
from pathlib import Path

from agent_harness import hub

_KV_PATH = "tenants/binky/company-email/imap"
_BAO_TIMEOUT = 30


class MailScanError(RuntimeError):
    pass


@dataclass
class MailScanResult:
    ok: bool
    report_path: str | None
    new_messages: int | None
    auth_lane: str
    reason: str = ""


def _bao(*args: str, env: dict[str, str] | None = None) -> str:
    result = subprocess.run(
        ["bao", *args],
        capture_output=True,
        text=True,
        timeout=_BAO_TIMEOUT,
        env=env or os.environ.copy(),
    )
    if result.returncode != 0:
        # stderr may reference paths/roles but never secret values
        raise MailScanError(f"bao {args[0]} failed: {result.stderr.strip()[:200]}")
    return result.stdout.strip()


def _acquire_token() -> tuple[str | None, str]:
    """Return (token_or_none_for_ambient, auth_lane)."""
    approle_dir = os.environ.get("EXECUTOR_APPROLE_DIR")
    if approle_dir:
        role_id_file = Path(approle_dir) / "role_id"
        secret_id_file = Path(approle_dir) / "secret_id"
        if role_id_file.is_file() and secret_id_file.is_file():
            token = _bao(
                "write",
                "-field=token",
                "auth/approle/login",
                f"role_id={role_id_file.read_text().strip()}",
                f"secret_id={secret_id_file.read_text().strip()}",
            )
            return token, "approle"
    return None, "ambient"


def _fetch_credentials() -> tuple[dict[str, str], str]:
    token, lane = _acquire_token()
    env = os.environ.copy()
    if token:
        env["BAO_TOKEN"] = token
    creds = {
        field: _bao("kv", "get", f"-field={field}", _KV_PATH, env=env)
        for field in ("IMAP_USERNAME", "IMAP_PASSWORD")
    }
    return creds, lane


def run_mail_scan(
    target_repo: Path,
    config: str = "integrations/mailbox-binky-company.yml",
    out_dir: str = "mailmeta/reports",
    email_connect_src: str | None = None,
    report_to_hub: bool = True,
) -> MailScanResult:
    try:
        creds, lane = _fetch_credentials()
    except MailScanError as exc:
        result = MailScanResult(
            ok=False, report_path=None, new_messages=None, auth_lane="none",
            reason=str(exc),
        )
        _report(result, report_to_hub, target_repo)
        return result

    env = os.environ.copy()
    env.update(creds)
    if email_connect_src is None:
        email_connect_src = str(Path.home() / "email-connect" / "src")
    env["PYTHONPATH"] = email_connect_src

    before = _report_files(target_repo / out_dir)
    proc = subprocess.run(
        [
            "python3", "-m", "email_connect.cli", "scan-mailbox",
            "--config", config,
            "--out", out_dir,
        ],
        cwd=target_repo,
        capture_output=True,
        text=True,
        timeout=600,
        env=env,
    )
    if proc.returncode != 0:
        result = MailScanResult(
            ok=False, report_path=None, new_messages=None, auth_lane=lane,
            reason=f"email-connect exited {proc.returncode}: {proc.stderr.strip()[:200]}",
        )
        _report(result, report_to_hub, target_repo)
        return result

    new_reports = sorted(_report_files(target_repo / out_dir) - before)
    report_path = new_reports[-1] if new_reports else None
    new_messages = _count_rows(target_repo / out_dir / report_path) if report_path else 0
    result = MailScanResult(
        ok=True, report_path=report_path, new_messages=new_messages, auth_lane=lane,
    )
    _report(result, report_to_hub, target_repo)
    return result


def _report_files(out_dir: Path) -> set[str]:
    if not out_dir.is_dir():
        return set()
    return {p.name for p in out_dir.glob("*.csv")}


def _count_rows(path: Path) -> int | None:
    try:
        with path.open() as fh:
            return max(0, sum(1 for _ in fh) - 1)
    except OSError:
        return None


def _report(result: MailScanResult, report_to_hub: bool, target_repo: Path) -> None:
    if not report_to_hub:
        return
    # Failures must NOT emit binky_mail_intake: the activity-core resolver
    # treats any such event as "a scan ran" (idempotence guard), so a failed
    # run reports as a generic executor_run failure instead and the slot
    # stays due.
    event_type = "binky_mail_intake" if result.ok else "executor_run"
    hub.post_progress_event(
        summary=(
            f"binky mailbox scan {'ok' if result.ok else 'failed'}"
            + (f": {result.new_messages} new message(s)" if result.ok else "")
        ),
        event_type=event_type,
        detail={
            "repo": target_repo.name,
            "ok": result.ok,
            "report": result.report_path,
            "new_messages": result.new_messages,
            "auth_lane": result.auth_lane,
            "reason": result.reason,
        },
    )