import asyncio
import os
import shlex
from typing import Any
from urllib.parse import urlsplit

import httpx

GITEA_URL = os.getenv("GITEA_URL", "http://127.0.0.1:3000").rstrip("/")
GITEA_TOKEN = os.getenv("GITEA_TOKEN", "")
REVIEW_DIFF_MAX_BYTES = 64 * 1024
REVIEW_DIFF_MAX_LINES = 400
_client: httpx.AsyncClient | None = None


def _auth() -> dict[str, str]:
    headers: dict[str, str] = {"Accept": "application/json"}
    if GITEA_TOKEN:
        headers["Authorization"] = f"token {GITEA_TOKEN}"
    return headers


def start_client(**kwargs) -> httpx.AsyncClient:
    """Create the application-lifetime Gitea transport."""
    global _client
    _client = httpx.AsyncClient(base_url=GITEA_URL, timeout=10, **kwargs)
    return _client


def _get_client() -> httpx.AsyncClient:
    if _client is None or _client.is_closed:
        return start_client()
    return _client


async def stop_client() -> None:
    global _client
    if _client is not None and not _client.is_closed:
        await _client.aclose()


async def fetch(path: str) -> Any:
    r = await _get_client().get(f"/api/v1/{path}", headers=_auth())
    r.raise_for_status()
    return r.json()


async def fetch_text(path: str, max_bytes: int) -> tuple[str, bool]:
    chunks: list[bytes] = []
    size = 0
    truncated = False
    async with _get_client().stream(
        "GET", f"/api/v1/{path}", headers={**_auth(), "Accept": "text/plain"}
    ) as response:
        response.raise_for_status()
        async for chunk in response.aiter_bytes():
            remaining = max_bytes - size
            if len(chunk) > remaining:
                chunks.append(chunk[:remaining])
                truncated = True
                break
            chunks.append(chunk)
            size += len(chunk)
    return b"".join(chunks).decode("utf-8", errors="replace"), truncated


def _diff_previews(diff: str, stream_truncated: bool) -> dict[str, dict]:
    previews: dict[str, dict] = {}
    current: dict | None = None
    in_hunk = False
    remaining = REVIEW_DIFF_MAX_LINES
    for line in diff.splitlines():
        if line.startswith("diff --git "):
            try:
                target = shlex.split(line)[3]
                filename = target[2:] if target.startswith("b/") else target
            except (IndexError, ValueError):
                current = None
                continue
            current = {
                "diff_lines": [],
                "diff_available": False,
                "diff_binary": False,
                "diff_truncated": stream_truncated,
            }
            previews[filename] = current
            in_hunk = False
            continue
        if current is None:
            continue
        if line.startswith("Binary files ") or line == "GIT binary patch":
            current["diff_binary"] = True
            in_hunk = False
            continue
        if line.startswith("@@"):
            in_hunk = True
        if in_hunk and not line.startswith("\\ No newline at end of file"):
            if remaining:
                current["diff_lines"].append(line)
                current["diff_available"] = True
                remaining -= 1
            else:
                current["diff_truncated"] = True
    return previews


async def current_user() -> dict:
    return await fetch("user")


async def repos() -> list[dict]:
    return await fetch("user/repos?limit=50")


async def issues() -> list[dict]:
    return await fetch(
        "repos/issues/search?state=open&assigned=true&type=issues&limit=50"
    )


def _safe_web_url(value: Any) -> str:
    if not isinstance(value, str):
        return ""
    parsed = urlsplit(value)
    return value if parsed.scheme in {"http", "https"} and parsed.netloc else ""


def _normalize_notifications(threads: Any) -> list[dict]:
    if not isinstance(threads, list):
        raise ValueError("Gitea notification response was not a list")
    normalized = []
    for thread in threads:
        if not isinstance(thread, dict):
            continue
        repository = thread.get("repository")
        subject = thread.get("subject")
        repository = repository if isinstance(repository, dict) else {}
        subject = subject if isinstance(subject, dict) else {}
        subject_url = _safe_web_url(subject.get("html_url"))
        latest_url = _safe_web_url(subject.get("latest_comment_html_url"))
        number_text = (
            urlsplit(subject_url).path.rstrip("/").rsplit("/", 1)[-1]
            if subject_url
            else ""
        )
        normalized.append(
            {
                "id": thread.get("id"),
                "unread": thread.get("unread") is True,
                "updated_at": (
                    thread.get("updated_at")
                    if isinstance(thread.get("updated_at"), str)
                    else ""
                ),
                "repository": (
                    repository.get("full_name")
                    if isinstance(repository.get("full_name"), str)
                    else ""
                ),
                "number": int(number_text) if number_text.isdigit() else None,
                "title": (
                    subject.get("title")
                    if isinstance(subject.get("title"), str) and subject.get("title")
                    else "Untitled update"
                ),
                "subject_type": (
                    subject.get("type")
                    if isinstance(subject.get("type"), str) and subject.get("type")
                    else "Update"
                ),
                "state": (
                    subject.get("state")
                    if isinstance(subject.get("state"), str)
                    else ""
                ),
                "url": latest_url or subject_url,
                "subject_url": subject_url,
            }
        )
    return normalized


async def notifications() -> dict:
    return await notification_page(1)


async def notification_page(page: int, limit: int = 50) -> dict:
    response = await _get_client().get(
        f"/api/v1/notifications?status-types=unread&limit={limit}&page={page}",
        headers=_auth(),
    )
    response.raise_for_status()
    items = _normalize_notifications(response.json())
    try:
        total = max(len(items), int(response.headers.get("X-Total-Count", len(items))))
    except (TypeError, ValueError):
        total = len(items)
    return {
        "items": items,
        "page": page,
        "total": total,
        "has_more": page * limit < total,
    }


async def mark_notification_read(thread_id: int) -> None:
    response = await _get_client().patch(
        f"/api/v1/notifications/threads/{thread_id}?to-status=read",
        headers=_auth(),
    )
    response.raise_for_status()


def _gitea_api_path(value: Any) -> str:
    if not isinstance(value, str):
        return ""
    parsed = urlsplit(value)
    configured = urlsplit(GITEA_URL)
    prefix = "/api/v1/"
    if (
        parsed.scheme not in {"http", "https"}
        or parsed.netloc != configured.netloc
        or not parsed.path.startswith(prefix)
    ):
        return ""
    return parsed.path[len(prefix):] + (("?" + parsed.query) if parsed.query else "")


async def notification_detail(thread_id: int) -> dict:
    thread = await fetch(f"notifications/threads/{thread_id}")
    if not isinstance(thread, dict):
        raise ValueError("Gitea notification thread response was not an object")
    repository_value = thread.get("repository")
    repository = repository_value if isinstance(repository_value, dict) else {}
    subject_value = thread.get("subject")
    subject = subject_value if isinstance(subject_value, dict) else {}
    subject_path = _gitea_api_path(subject.get("url"))
    comment_path = _gitea_api_path(subject.get("latest_comment_url"))
    subject_detail = await fetch(subject_path) if subject_path else {}
    comment = await fetch(comment_path) if comment_path else {}
    subject_detail = subject_detail if isinstance(subject_detail, dict) else {}
    comment = comment if isinstance(comment, dict) else {}
    user_value = comment.get("user")
    user = user_value if isinstance(user_value, dict) else {}
    subject_url = _safe_web_url(subject.get("html_url"))
    latest_url = _safe_web_url(comment.get("html_url")) or _safe_web_url(
        subject.get("latest_comment_html_url")
    )
    return {
        "id": thread_id,
        "repository": repository.get("full_name", "")
        if isinstance(repository.get("full_name"), str)
        else "",
        "title": subject.get("title", "")
        if isinstance(subject.get("title"), str)
        else "",
        "subject_type": subject.get("type", "Update")
        if isinstance(subject.get("type"), str)
        else "Update",
        "state": subject.get("state", "")
        if isinstance(subject.get("state"), str)
        else "",
        "url": latest_url or subject_url,
        "subject_body": subject_detail.get("body", "")
        if isinstance(subject_detail.get("body"), str)
        else "",
        "latest_comment": {
            "author": user.get("login", "")
            if isinstance(user.get("login"), str)
            else "",
            "body": comment.get("body", "")
            if isinstance(comment.get("body"), str)
            else "",
            "created_at": comment.get("created_at", "")
            if isinstance(comment.get("created_at"), str)
            else "",
            "url": latest_url,
        },
    }


async def pull_requests() -> list[dict]:
    assigned, review_requested = await asyncio.gather(
        fetch("repos/issues/search?state=open&assigned=true&type=pulls&limit=50"),
        fetch(
            "repos/issues/search?state=open&review_requested=true&type=pulls&limit=50"
        ),
    )
    merged: dict[int, dict] = {}
    for reason, pulls in (
        ("assigned_to_me", assigned or []),
        ("review_requested", review_requested or []),
    ):
        for pull in pulls:
            identity = pull.get("id")
            if identity not in merged:
                merged[identity] = {**pull, "work_reasons": []}
            merged[identity]["work_reasons"].append(reason)
    return list(merged.values())


async def is_requested_review(repository: str, number: int) -> bool:
    pulls = await fetch(
        "repos/issues/search?state=open&review_requested=true&type=pulls&limit=50"
    )
    return any(
        isinstance(pull, dict)
        and pull.get("number") == number
        and isinstance(pull.get("repository"), dict)
        and pull["repository"].get("full_name") == repository
        for pull in (pulls or [])
    )


async def pull_review_detail(repository: str, number: int) -> dict:
    base = f"repos/{repository}/pulls/{number}"
    pull = await fetch(base)
    if not isinstance(pull, dict):
        raise ValueError("Gitea pull request response was not an object")
    head_value = pull.get("head")
    head: dict = head_value if isinstance(head_value, dict) else {}
    sha_value = head.get("sha")
    sha = sha_value if isinstance(sha_value, str) else ""
    files, status, reviews, diff_result = await asyncio.gather(
        fetch(f"{base}/files"),
        fetch(f"repos/{repository}/commits/{sha}/status"),
        fetch(f"{base}/reviews"),
        fetch_text(
            f"repos/{repository}/pulls/{number}.diff", REVIEW_DIFF_MAX_BYTES
        ),
    )
    diff, diff_truncated = diff_result
    previews = _diff_previews(diff, diff_truncated)
    user_value = pull.get("user")
    user: dict = user_value if isinstance(user_value, dict) else {}
    normalized_files = [
        {
            "filename": file["filename"],
            "status": file.get("status") or "changed",
            "additions": file.get("additions") or 0,
            "deletions": file.get("deletions") or 0,
            **previews.get(
                file["filename"],
                {
                    "diff_lines": [],
                    "diff_available": False,
                    "diff_binary": False,
                    "diff_truncated": diff_truncated,
                },
            ),
        }
        for file in (files if isinstance(files, list) else [])[:100]
        if isinstance(file, dict) and isinstance(file.get("filename"), str)
    ]
    normalized_reviews = [
        {
            "user": {
                "login": (
                    review["user"].get("login", "")
                    if isinstance(review.get("user"), dict)
                    else ""
                )
            },
            "state": review.get("state") or "COMMENT",
            "body": review.get("body") or "",
        }
        for review in (reviews if isinstance(reviews, list) else [])[:50]
        if isinstance(review, dict)
    ]
    return {
        "repository": repository,
        "number": number,
        "title": pull.get("title", ""),
        "body": pull.get("body") or "",
        "url": pull.get("html_url", ""),
        "author": user.get("login", ""),
        "head_sha": sha,
        "ci_state": status.get("state", "unknown") if isinstance(status, dict) else "unknown",
        "files": normalized_files,
        "reviews": normalized_reviews,
    }


async def activity_events(user: dict | None = None) -> list[dict]:
    if user is None:
        user = await current_user()
    events = await fetch(f"users/{user['login']}/activities/feeds?limit=20")
    if events is None:
        events = []
    elif not isinstance(events, list):
        raise ValueError("Gitea activity feed response was not a list")
    return [
        {
            "type": (
                event.get("op_type")
                if isinstance(event.get("op_type"), str) and event.get("op_type")
                else "activity"
            ),
            "actor": (
                event.get("act_user")
                if isinstance(event.get("act_user"), dict)
                else {}
            ),
            "repo": (
                event.get("repo")
                if isinstance(event.get("repo"), dict)
                else {}
            ),
            "created_at": (
                event.get("created")
                if isinstance(event.get("created"), str)
                else ""
            ),
        }
        for event in (events or [])
        if isinstance(event, dict)
    ]