import base64
import hashlib
import html
import os
import re
from urllib.parse import parse_qs, urlparse

import httpx

from .base import ImageAttachment, Notifier
from .image_utils import compressed_preview


def _truncate_utf8(value: str, limit: int) -> str:
    data = value.encode("utf-8")
    if len(data) <= limit:
        return value
    return data[:limit - 3].decode("utf-8", errors="ignore") + "..."


def _format_plain_text(title: str, text: str) -> str:
    plain = re.sub(r"<br\s*/?>", "\n", text, flags=re.IGNORECASE)
    plain = re.sub(r"<[^>]+>", "", plain)
    plain = html.unescape(plain)
    if not title:
        return plain.strip()

    field_icons = {
        "发送人：": "👤",
        "类别：": "🗂",
        "待行动：": "✅",
        "截止：": "⏰",
    }
    section_icons = {
        "摘要：": "📌",
        "原因：": "📝",
        "原文：": "💬",
    }
    output: list[str] = []
    for line in plain.splitlines():
        stripped = line.strip()
        matched = False
        for label, icon in field_icons.items():
            if stripped.startswith(label):
                output.append(f"{icon} {stripped}")
                matched = True
                break
        if matched:
            continue
        for label, icon in section_icons.items():
            if stripped.startswith(label):
                if output and output[-1] != "":
                    output.append("")
                output.append(f"{icon} {label[:-1]}")
                value = stripped[len(label):].strip()
                if value:
                    output.append(value)
                matched = True
                break
        if not matched:
            output.append(line)

    body = "\n".join(output).strip()
    if not title:
        return body
    icon = "🔴" if "重要" in title else "🔔"
    return f"{icon} {title}\n━━━━━━━━━━━━\n\n{body}" if body else f"{icon} {title}"


class WecomWebhookNotifier(Notifier):
    name = "wecom_webhook"

    def __init__(self, urls: list[str] | None = None) -> None:
        configured = urls or []
        if not configured:
            configured = [part.strip() for part in os.getenv(
                "WECOM_WEBHOOK_URLS", ""
            ).split(";") if part.strip()]
        self.urls = [self._validate_url(url) for url in configured]
        if not self.urls:
            raise RuntimeError("WECOM_WEBHOOK_URLS is not configured")

    @staticmethod
    def _validate_url(value: str) -> str:
        parsed = urlparse(value.strip())
        key = parse_qs(parsed.query).get("key", [])
        if (parsed.scheme != "https" or parsed.hostname != "qyapi.weixin.qq.com"
                or parsed.path != "/cgi-bin/webhook/send" or not key or not key[0]):
            raise RuntimeError("invalid Enterprise WeChat webhook URL")
        return value.strip()

    async def send(self, title: str, text: str,
                   images: list[ImageAttachment] | None = None) -> None:
        content = _truncate_utf8(_format_plain_text(title, text), 2048)
        failures = 0
        async with httpx.AsyncClient(timeout=90, trust_env=False) as client:
            for url in self.urls:
                try:
                    response = await client.post(
                        url,
                        json={"msgtype": "text", "text": {"content": content}},
                    )
                    data = response.json()
                    ok = response.status_code < 400 and data.get("errcode") == 0
                    if ok:
                        for image in images or []:
                            preview = compressed_preview(image)
                            encoded = base64.b64encode(preview.data).decode("ascii")
                            digest = hashlib.md5(preview.data).hexdigest()
                            response = await client.post(
                                url,
                                json={
                                    "msgtype": "image",
                                    "image": {"base64": encoded, "md5": digest},
                                },
                            )
                            data = response.json()
                            if response.status_code >= 400 or data.get("errcode") != 0:
                                ok = False
                                break
                except Exception:
                    ok = False
                if not ok:
                    failures += 1
        if failures:
            raise RuntimeError(f"Enterprise WeChat webhook failed for {failures} target(s)")