"""Narrow GitHub publishing helpers; credentials stay in the Job environment."""

from __future__ import annotations

import json
import os
import subprocess
from dataclasses import dataclass
from pathlib import Path
from typing import Any

from .validate import ValidationError, validate_scope


class GitHubPublishingError(RuntimeError):
    """Raised when generated changes cannot be safely published."""


def _run(command: list[str], cwd: Path) -> str:
    completed = subprocess.run(command, cwd=cwd, check=True, text=True, capture_output=True)
    return completed.stdout.strip()


@dataclass(frozen=True)
class PullRequestSpec:
    base_repository: str
    base_branch: str
    head_repository: str
    head_branch: str
    title: str
    body: str
    draft: bool = True


def build_pr_body(manifest: dict[str, Any]) -> str:
    """Build a non-secret, reproducible PR description from a run manifest."""

    checks = manifest.get("checks", {})
    counts = manifest.get("inventory", {})
    metrics = manifest.get("metrics", {})
    return "\n".join(
        [
            "## Japanese documentation synchronization",
            "",
            "Machine-generated from the English documentation source of truth; no native Japanese review was performed.",
            "",
            f"- English base SHA: `{manifest.get('transformers_source_sha')}`",
            f"- Model: `{manifest.get('model_id')}` at `{manifest.get('model_revision')}`",
            f"- Runner revision: `{manifest.get('runner_revision')}`",
            f"- Doc-builder revision: `{manifest.get('doc_builder_revision')}`",
            f"- Pages added: `{counts.get('missing_count', 0)}`",
            f"- Pages overwritten: `{counts.get('shared_count', 0)}`",
            f"- Pages deleted: `{counts.get('target_only_count', 0)}`",
            f"- Total pages: `{counts.get('english_count', 0)}`",
            f"- Path parity: `{checks.get('path_parity', 'unknown')}`",
            f"- Cache hits/misses: `{metrics.get('cache_hits', 0)}` / `{metrics.get('cache_misses', 0)}`",
            f"- Input/output tokens per second: `{metrics.get('translation', {}).get('input_tokens_per_second', 0):.2f}` / `{metrics.get('translation', {}).get('output_tokens_per_second', 0):.2f}`",
            f"- Peak GPU memory: `{metrics.get('peak_gpu_memory_bytes', 'not recorded')}`",
            f"- Validation: `{checks.get('validation', 'unknown')}`",
            f"- Doc build: `{checks.get('doc_build', 'not run')}`",
            f"- Job run: `{manifest.get('job_url', 'not recorded')}`",
            f"- Bucket run record: `{manifest.get('run_record', 'not recorded')}`",
        ]
    )


class GitHubPublisher:
    def __init__(self, checkout: Path, target_prefix: str = "docs/source/ja/"):
        self.checkout = checkout
        self.target_prefix = target_prefix

    def require_clean_checkout(self) -> None:
        status = _run(["git", "status", "--porcelain"], self.checkout)
        if status:
            raise GitHubPublishingError("refusing publication from a dirty checkout")

    def require_scope(self, base_ref: str) -> list[str]:
        changed = _run(["git", "diff", "--name-only", f"{base_ref}...HEAD"], self.checkout).splitlines()
        try:
            validate_scope(changed, self.target_prefix)
        except ValidationError as exc:
            raise GitHubPublishingError(str(exc)) from exc
        return changed

    def commit_generated_tree(self, source_sha: str) -> str:
        _run(["git", "add", "--", self.target_prefix], self.checkout)
        changed = _run(["git", "diff", "--cached", "--name-only"], self.checkout).splitlines()
        try:
            validate_scope(changed, self.target_prefix)
        except ValidationError as exc:
            raise GitHubPublishingError(str(exc)) from exc
        if not changed:
            raise GitHubPublishingError("generated tree is unchanged; refusing an empty commit")
        _run(["git", "commit", "-m", f"[i18n-ja] Sync Japanese docs from {source_sha[:12]}"], self.checkout)
        return _run(["git", "rev-parse", "HEAD"], self.checkout)

    def push_with_lease(self, remote: str, local_branch: str, remote_branch: str) -> None:
        if os.environ.get("GH_TOKEN") or os.environ.get("GITHUB_TOKEN"):
            _run(["gh", "auth", "setup-git", "--hostname", "github.com", "--force"], self.checkout)
        _run(["git", "push", "--force-with-lease", remote, f"{local_branch}:{remote_branch}"], self.checkout)

    def find_open_pr(self, base_repository: str, base_branch: str, head: str) -> dict[str, Any] | None:
        output = _run(
            [
                "gh",
                "pr",
                "list",
                "--repo",
                base_repository,
                "--state",
                "open",
                "--base",
                base_branch,
                "--head",
                head,
                "--json",
                "number,url,state,headRefName,baseRefName",
            ],
            self.checkout,
        )
        values = json.loads(output or "[]")
        return values[0] if values else None

    def read_pr(self, repository: str, number: int) -> dict[str, Any]:
        output = _run(
            [
                "gh",
                "pr",
                "view",
                str(number),
                "--repo",
                repository,
                "--json",
                "number,state,mergedAt,baseRefName,headRefName",
            ],
            self.checkout,
        )
        return json.loads(output)

    def create_or_update_pr(self, spec: PullRequestSpec) -> dict[str, Any]:
        head = f"{spec.head_repository}:{spec.head_branch}"
        existing = self.find_open_pr(spec.base_repository, spec.base_branch, head)
        if existing:
            _run(["gh", "pr", "edit", str(existing["number"]), "--body", spec.body, "--title", spec.title], self.checkout)
            return existing
        command = [
            "gh",
            "pr",
            "create",
            "--repo",
            spec.base_repository,
            "--base",
            spec.base_branch,
            "--head",
            head,
            "--title",
            spec.title,
            "--body",
            spec.body,
        ]
        if spec.draft:
            command.append("--draft")
        url = _run(command, self.checkout)
        return {"url": url, "state": "OPEN", "headRefName": spec.head_branch, "baseRefName": spec.base_branch}