"""The gate chain that decides whether finished work may move forward.

A developer's ``WORK_REPORT`` is a claim, not evidence. Four gates check it:

* **diff guard** — the diff is real, is not empty for a code task, and touches
  nothing the platform forbids (``.git``, CI configuration, symlinks that point
  outside the repo, files over a megabyte).
* **no-progress** — the same diff twice in a row means the agent is spinning;
  the task goes to the manager instead of looping forever.
* **tests** — the app profile's test command runs in the sandbox. Red sends the
  work back to the developer with the failure tail; green lets it continue.
* **green** — the tester's ``TEST_PASS`` is only believed when the tests gate is
  green, or when the tester explicitly *waives* it with a reason. A waiver is
  always stored, never inferred (PLAN-v2 §3).

Every verdict is a ``gate_results`` row **and** a ``task.gate`` event, because a
gate that only exists in a log is a gate nobody can audit.
"""

from __future__ import annotations

import hashlib
from dataclasses import dataclass

from app.application.engine.events import RunFeed
from app.application.ports.sandbox_provider import SandboxProviderPort
from app.core.config import settings
from app.domain.workforce.engine import GateName, GateResult
from app.domain.workforce.models import Task
from app.domain.workforce.pipeline import TaskKind
from app.infrastructure.repositories.app_profile import AppProfileRepository
from app.infrastructure.repositories.engine import GateResultRepository

#: Path prefixes a diff may never touch: git internals and CI configuration.
CI_PATHS: tuple[str, ...] = (".github/", ".gitlab-ci.yml", ".gitea/", ".circleci/")

#: Fail a diff that carries a file larger than this (one megabyte).
MAX_FILE_BYTES = 1_000_000

#: How much of the test output is stored and shown. A traceback is at the end.
TEST_OUTPUT_CHARS = 8_000


def diff_hash(text: str) -> str:
    """A stable fingerprint of a diff, for the no-progress gate."""
    return hashlib.sha256(text.encode("utf-8", "replace")).hexdigest()


def forbidden_paths(changed_files: list[str]) -> list[str]:
    """Changed files the diff guard refuses, in the plan's own words."""
    bad: list[str] = []
    for path in changed_files:
        normalised = path.strip()
        # Strip a leading "./" *prefix*, not the set {".", "/"}: ``lstrip("./")``
        # would turn ".github/ci.yml" into "github/ci.yml" and hide it from the
        # guard entirely.
        if normalised.startswith("./"):
            normalised = normalised[2:]
        if normalised.startswith(".git/") or normalised == ".git":
            bad.append(path)
            continue
        if any(normalised == ci.rstrip("/") or normalised.startswith(ci) for ci in CI_PATHS):
            bad.append(path)
    return bad


@dataclass(slots=True, kw_only=True)
class GateOutcome:
    """One gate verdict, and whether it sends the task back to the developer."""

    gate: GateName
    ok: bool
    detail: str = ""
    #: True when the caller must move the task back to implementation.
    sends_back: bool = False


class GateRunner:
    """Runs the gates and leaves a row + an event behind for each verdict."""

    def __init__(
        self,
        *,
        results: GateResultRepository,
        feed: RunFeed,
        profiles: AppProfileRepository | None = None,
    ) -> None:
        self.results = results
        self.feed = feed
        self.profiles = profiles

    # ------------------------------------------------------------------ #

    async def _record(self, *, task: Task, outcome: GateOutcome) -> GateOutcome:
        await self.results.create(
            GateResult(
                task_id=task.id,
                gate=outcome.gate,
                ok=outcome.ok,
                detail=outcome.detail,
            )
        )
        await self.feed.gate(
            task_id=task.id,
            organization_id=task.organization_id,
            gate=str(outcome.gate),
            ok=outcome.ok,
            detail=outcome.detail,
        )
        return outcome

    async def record(self, *, task: Task, outcome: GateOutcome) -> GateOutcome:
        """Write a verdict the caller already reasoned about.

        The scheduler records merge conflicts through this instead of the
        gate-specific helpers, because a conflict is a diff-guard verdict that
        comes from git rather than from hashing the diff.
        """
        return await self._record(task=task, outcome=outcome)

    # -- diff guard --------------------------------------------------------- #

    async def diff_guard(self, *, task: Task, diff, code_task: bool) -> GateOutcome:
        """Refuse a diff that is empty, forbidden or unreasonably large."""
        problems: list[str] = []
        if diff.is_empty and code_task:
            problems.append("تفاوت خالی است: هیچ تغییری ثبت نشده.")
        forbidden = forbidden_paths(list(diff.changed_files))
        if forbidden:
            problems.append(
                "تغییر در مسیرهای ممنوع: " + ", ".join(sorted(forbidden))
            )
        if diff.escaping_symlinks:
            problems.append(
                "پیوندهای نمادین به بیرون مخزن: " + ", ".join(diff.escaping_symlinks)
            )
        if diff.largest_file_bytes > MAX_FILE_BYTES:
            problems.append(
                f"فایلی بزرگ‌تر از حد مجاز: {diff.largest_file_bytes} بایت."
            )
        detail = "\n".join(problems)
        return await self._record(
            task=task,
            outcome=GateOutcome(
                gate=GateName.DIFF_GUARD,
                ok=not problems,
                detail=detail or "تفاوت قابل قبول است.",
                sends_back=bool(problems),
            ),
        )

    # -- no-progress -------------------------------------------------------- #

    async def no_progress(
        self, *, task: Task, previous_hash: str, same_count: int, diff_text: str
    ) -> tuple[GateOutcome, str, int]:
        """Hash the diff; the same hash twice in a row means no progress.

        Returns the verdict and the new ``(hash, same_count)`` the caller must
        persist, so the decision and the counter live in one place.
        """
        current = diff_hash(diff_text)
        count = same_count + 1 if current and current == previous_hash else 1
        stuck = count >= 2 and bool(current)
        outcome = await self._record(
            task=task,
            outcome=GateOutcome(
                gate=GateName.NO_PROGRESS,
                ok=not stuck,
                detail=(
                    "دو تفاوت یکسان پشت سر هم: پیشرفتی حاصل نشده."
                    if stuck
                    else "پیشرفت تازه‌ای ثبت شد."
                ),
                sends_back=stuck,
            ),
        )
        return outcome, current, count

    # -- tests -------------------------------------------------------------- #

    async def test_command_for(self, task: Task) -> str:
        """The app profile's test command, or ``""`` when there is none."""
        if self.profiles is None or not task.project_id:
            return ""
        profile = await self.profiles.get(
            organization_id=task.organization_id, project_id=task.project_id
        )
        return (profile.test_command or "").strip() if profile else ""

    async def tests(
        self, *, task: Task, sandbox: SandboxProviderPort, session_external_id: str
    ) -> GateOutcome:
        """Run the app profile's tests in the sandbox: red or green."""
        command = await self.test_command_for(task)
        if not command:
            return await self._record(
                task=task,
                outcome=GateOutcome(
                    gate=GateName.TESTS,
                    ok=True,
                    detail="دستور تستی برای این برنامه تعریف نشده است.",
                ),
            )
        if not session_external_id:
            return await self._record(
                task=task,
                outcome=GateOutcome(
                    gate=GateName.TESTS,
                    ok=False,
                    detail="نشست اجرا در دسترس نیست؛ تست‌ها اجرا نشدند.",
                    sends_back=True,
                ),
            )
        result = await sandbox.run_command(
            session_external_id=session_external_id,
            command=command,
            timeout_seconds=settings.engine_tests_timeout_seconds,
            max_output_bytes=TEST_OUTPUT_CHARS,
        )
        ok = result.exit_code == 0
        output = (result.stdout + ("\n" + result.stderr if result.stderr else "")).strip()
        tail = output[-TEST_OUTPUT_CHARS:]
        detail = (
            f"تست‌ها سبز شدند (کد خروج {result.exit_code})."
            if ok
            else f"تست‌ها قرمز شدند (کد خروج {result.exit_code}).\n{tail}"
        )
        return await self._record(
            task=task,
            outcome=GateOutcome(
                gate=GateName.TESTS, ok=ok, detail=detail, sends_back=not ok
            ),
        )

    # -- green -------------------------------------------------------------- #

    async def green(
        self, *, task: Task, waived: bool, waiver_reason: str
    ) -> GateOutcome:
        """Accept a ``TEST_PASS`` only with a green tests gate, or a waiver."""
        passed = await self.results.latest_for(task.id, str(GateName.TESTS))
        tests_ok = passed.ok if passed is not None else False
        reason = waiver_reason.strip()
        if tests_ok:
            return await self._record(
                task=task,
                outcome=GateOutcome(
                    gate=GateName.GREEN, ok=True, detail="دروازهٔ تست سبز است."
                ),
            )
        if waived and reason:
            return await self._record(
                task=task,
                outcome=GateOutcome(
                    gate=GateName.GREEN,
                    ok=True,
                    detail=f"با اعلام صرف‌نظر: {reason}",
                ),
            )
        return await self._record(
            task=task,
            outcome=GateOutcome(
                gate=GateName.GREEN,
                ok=False,
                detail="تست‌ها سبز نیستند و صرف‌نظری با دلیل ثبت نشده است.",
                sends_back=True,
            ),
        )

    # -- helpers the scheduler uses ----------------------------------------- #

    @staticmethod
    def code_task(kind: TaskKind | str) -> bool:
        """``analysis`` produces prose, not a diff: an empty diff is fine."""
        return TaskKind(kind) is not TaskKind.ANALYSIS


__all__ = [
    "CI_PATHS",
    "MAX_FILE_BYTES",
    "TEST_OUTPUT_CHARS",
    "GateOutcome",
    "GateRunner",
    "diff_hash",
    "forbidden_paths",
]