from __future__ import annotations

import json
import socket
import time
from dataclasses import dataclass
from urllib.error import HTTPError, URLError
from urllib.parse import urlencode
import urllib.request
from typing import Any


UA = "Mozilla/5.0 (compatible; ai-daily-report/1.0)"


@dataclass
class FetchTextError(Exception):
    error_type: str
    message: str
    http_status: int | None = None
    attempts: int = 1

    def __str__(self) -> str:
        return self.message


def _classify_fetch_exception(exc: Exception) -> tuple[str, int | None, bool]:
    if isinstance(exc, HTTPError):
        if exc.code == 404:
            return "http_404", exc.code, False
        if exc.code in {429, 500, 502, 503, 504}:
            return f"http_{exc.code}", exc.code, True
        return f"http_{exc.code}", exc.code, False
    if isinstance(exc, TimeoutError | socket.timeout):
        return "timeout", None, True
    if isinstance(exc, URLError):
        reason = exc.reason
        if isinstance(reason, TimeoutError | socket.timeout):
            return "timeout", None, True
        return "network_error", None, True
    return "fetch_error", None, False


def fetch_text(
    url: str,
    timeout_seconds: int,
    *,
    retries: int = 0,
    backoff_seconds: float = 0.5,
) -> str:
    req = urllib.request.Request(url, headers={"User-Agent": UA})
    attempts = max(1, retries + 1)
    last_error: FetchTextError | None = None
    for attempt in range(1, attempts + 1):
        try:
            with urllib.request.urlopen(req, timeout=timeout_seconds) as response:
                return response.read().decode("utf-8", "ignore")
        except Exception as exc:
            error_type, http_status, retryable = _classify_fetch_exception(exc)
            last_error = FetchTextError(
                error_type=error_type,
                message=f"{type(exc).__name__}: {exc}",
                http_status=http_status,
                attempts=attempt,
            )
            if not retryable or attempt >= attempts:
                raise last_error from exc
            if backoff_seconds > 0:
                time.sleep(backoff_seconds * (2 ** (attempt - 1)))
    raise last_error or FetchTextError("fetch_error", "unknown fetch error", attempts=attempts)


class OpenAICompatibleClient:
    def __init__(self, *, api_key: str, base_url: str, model: str, timeout_seconds: int = 600):
        self.api_key = api_key
        self.base_url = base_url.rstrip("/")
        self.model = model
        self.timeout_seconds = timeout_seconds

    def chat(self, prompt: str) -> str:
        payload = json.dumps(
            {
                "model": self.model,
                "messages": [{"role": "user", "content": prompt}],
                "temperature": 0.2,
                "max_tokens": 8000,
            },
            ensure_ascii=False,
        ).encode("utf-8")
        req = urllib.request.Request(
            f"{self.base_url}/chat/completions",
            data=payload,
            headers={"Authorization": f"Bearer {self.api_key}", "Content-Type": "application/json"},
        )
        with urllib.request.urlopen(req, timeout=self.timeout_seconds) as response:
            data = json.loads(response.read().decode("utf-8"))
        return data["choices"][0]["message"]["content"].strip()


class BlogApiClient:
    def __init__(self, *, base_url: str, token: str, timeout_seconds: int = 25):
        self.base_url = base_url.rstrip("/")
        self.token = token
        self.timeout_seconds = timeout_seconds

    def _request(self, method: str, path: str, payload: dict[str, Any] | None = None) -> dict[str, Any]:
        data = None
        headers = {"Authorization": f"Bearer {self.token}", "User-Agent": UA}
        if payload is not None:
            data = json.dumps(payload, ensure_ascii=False).encode("utf-8")
            headers["Content-Type"] = "application/json"
        req = urllib.request.Request(f"{self.base_url}{path}", data=data, headers=headers, method=method)
        with urllib.request.urlopen(req, timeout=self.timeout_seconds) as response:
            return json.loads(response.read().decode("utf-8"))

    def create_post(self, payload: dict[str, Any]) -> dict[str, Any]:
        return self._request("POST", "/api/service/posts", payload)

    def _normalize_post_response(self, value: Any, slug: str) -> dict[str, Any] | None:
        if isinstance(value, dict):
            if isinstance(value.get("post"), dict):
                value = value["post"]
            elif isinstance(value.get("data"), dict):
                value = value["data"]
            elif isinstance(value.get("items"), list):
                for item in value["items"]:
                    if isinstance(item, dict) and item.get("slug") == slug:
                        return item
                return None
            if value.get("slug") == slug or value.get("id") or value.get("content") or value.get("markdown"):
                return value
        if isinstance(value, list):
            for item in value:
                if isinstance(item, dict) and item.get("slug") == slug:
                    return item
        return None

    def _request_optional(self, method: str, path: str, payload: dict[str, Any] | None = None) -> dict[str, Any] | list[Any] | None:
        try:
            return self._request(method, path, payload)
        except HTTPError as exc:
            if exc.code in {403, 404}:
                return None
            raise
        except FetchTextError as exc:
            if exc.error_type in {"http_403", "http_404"}:
                return None
            raise

    def get_post_by_slug(self, slug: str) -> dict[str, Any] | None:
        paths = [
            f"/api/service/posts/{slug}",
            f"/api/service/posts?{urlencode({'slug': slug})}",
            f"/api/service/posts/slug/{slug}",
        ]
        for path in paths:
            value = self._request_optional("GET", path)
            post = self._normalize_post_response(value, slug)
            if post is not None:
                return post
        return None

    def publish_post(self, slug: str) -> None:
        self._request("POST", f"/api/service/posts/{slug}/publish")