from __future__ import annotations

import os
import re
import html as html_lib
from typing import List, Tuple, Union

import requests
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel

APP_NAME = "pr-tool-backend"

VK_API_VERSION = os.getenv("VK_API_VERSION", "5.131")
VK_ACCESS_TOKEN = os.getenv("VK_ACCESS_TOKEN", "")
REQUEST_TIMEOUT = float(os.getenv("REQUEST_TIMEOUT", "15"))

app = FastAPI(title=APP_NAME)

# Для простоты разрешаем все источники. Можно сузить список доменов в проде.
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=False,
    allow_methods=["POST", "GET", "OPTIONS"],
    allow_headers=["*"]
)


class ParseRequest(BaseModel):
    links: Union[List[str], str]


class ParseResponse(BaseModel):
    html: str
    text: str
    telegram_total: int
    vk_total: int
    errors: List[str]


# ---------- Вспомогательные функции ----------

def human_format_views(num: int) -> str:
    if num >= 1_000_000:
        value = num / 1_000_000
        suffix = "M"
    else:
        value = num / 1000
        suffix = "K"

    if value.is_integer():
        formatted = f"{int(value)}{suffix}"
    else:
        formatted = f"{value:.1f}{suffix}"

    return formatted.replace(".", ",")


def detect_platform(link: str) -> str:
    link = link.strip().lower()
    if "t.me/" in link or "telegram.me/" in link:
        return "telegram"
    if "vk.com/wall" in link:
        return "vk"
    return ""


def canonicalize_tg_link(link: str) -> Tuple[str | None, str | None, str | None]:
    link = link.strip()
    m = re.match(r"https?://(?:t(?:elegram)?\.me)/(?:s/)?([^/]+)/(?P<id>\d+)", link, re.IGNORECASE)
    if not m:
        return None, None, None
    username = m.group(1)
    message_id = m.group("id")
    canonical = f"https://t.me/{username}/{message_id}"
    return canonical, username, message_id


def canonicalize_vk_link(link: str) -> Tuple[str | None, int | None, str | None]:
    link = link.strip()
    m = re.search(r"vk\.com/wall(-?\d+)_(\d+)", link)
    if not m:
        return None, None, None
    owner_id = int(m.group(1))
    post_id = m.group(2)
    canonical = f"https://vk.com/wall{owner_id}_{post_id}"
    return canonical, owner_id, post_id


def process_telegram_link(channel_username: str, message_id: str, canonical_link: str) -> Tuple[str, int]:
    # Набор альтернативных адресов (если t.me не резолвится)
    urls = [
        f"https://t.me/{channel_username}/{message_id}?embed=1",
        f"https://t.me/s/{channel_username}/{message_id}",
        f"https://telegram.me/{channel_username}/{message_id}?embed=1",
        f"https://r.jina.ai/http://t.me/{channel_username}/{message_id}?embed=1",
        f"https://r.jina.ai/http://t.me/s/{channel_username}/{message_id}",
        f"https://r.jina.ai/http://telegram.me/{channel_username}/{message_id}?embed=1",
    ]
    headers = {"User-Agent": "Mozilla/5.0"}

    def _parse_views_number(s: str) -> int:
        if not s:
            return 0
        s = s.strip().replace(" ", "").replace(",", ".")
        m2 = re.match(r"([\d\.]+)\s*([kKmM]?)", s)
        if not m2:
            return 0
        val = float(m2.group(1))
        suf = m2.group(2).lower()
        if suf == "k":
            val *= 1_000
        elif suf == "m":
            val *= 1_000_000
        return int(val)

    def _fetch_first_ok(url_list):
        last_err = None
        for u in url_list:
            try:
                resp = requests.get(u, headers=headers, timeout=REQUEST_TIMEOUT)
                if resp.status_code == 200 and resp.text:
                    return resp.text
            except Exception as exc:
                last_err = exc
        raise last_err or Exception("Не удалось получить страницу Telegram")

    try:
        html = _fetch_first_ok(urls)

        title = None
        m_title_meta = re.search(
            r"<meta[^>]*property=[\"']og:title[\"'][^>]*content=[\"']([^\"']+)[\"']",
            html,
            re.IGNORECASE,
        )
        if m_title_meta:
            title = m_title_meta.group(1).strip()
        if not title:
            m_title = re.search(
                r'class="tgme_widget_message_owner_name".*?<span[^>]*>(.*?)</span>',
                html,
                re.IGNORECASE | re.DOTALL,
            )
            if m_title:
                title = m_title.group(1).strip()
        if not title:
            title = channel_username

        views = 0
        m_views = re.search(
            r'class="tgme_widget_message_views[^"]*">([\d\s\.,kKmM]+)<',
            html,
            re.IGNORECASE,
        )
        if m_views:
            views = _parse_views_number(m_views.group(1))
        else:
            candidates = re.findall(
                r'(\d[\d\s\.,]*)([kKmM]?)\s*(?:views|просмотр|просмотра|просмотров|переглядів|visualizações|visualizzazioni|ansichten|visninger|visitas)?',
                html,
                re.IGNORECASE,
            )
            if candidates:
                last_num, last_suf = candidates[-1]
                views = _parse_views_number(last_num + last_suf)

        return title, views

    except Exception as exc:
        return f"Ошибка (TG) при обработке {canonical_link}: {exc}", 0


def process_vk_link(owner_id: int, post_id: str, canonical_link: str) -> Tuple[str, int]:
    posts_param = f"{owner_id}_{post_id}"
    api_url = "https://api.vk.com/method/wall.getById"

    params = {
        "posts": posts_param,
        "v": VK_API_VERSION,
        "extended": 1,
    }
    if VK_ACCESS_TOKEN:
        params["access_token"] = VK_ACCESS_TOKEN

    try:
        resp = requests.get(api_url, params=params, timeout=REQUEST_TIMEOUT)
    except Exception as exc:
        return f"**Ошибка (VK)**: {exc} — {canonical_link}", 0

    if resp.status_code != 200:
        return f"**Ошибка (VK)**: HTTP {resp.status_code} — {canonical_link}", 0

    data = resp.json()
    if "error" in data:
        error_msg = data["error"].get("error_msg", "")
        return f"**Ошибка (VK)**: {error_msg or 'API error'} — {canonical_link}", 0

    response_data = data.get("response", {})
    items = response_data.get("items", [])
    if not items:
        return f"**Ошибка (VK)**: пост не найден — {canonical_link}", 0

    post = items[0]
    views = post.get("views", {}).get("count", 0)
    post_owner_id = post.get("owner_id", owner_id)

    title = None
    if post_owner_id < 0:
        group_id = -post_owner_id
        for group in response_data.get("groups", []):
            if group.get("id") == group_id:
                title = group.get("name")
                break
    else:
        user_id = post_owner_id
        for profile in response_data.get("profiles", []):
            if profile.get("id") == user_id:
                first_name = profile.get("first_name", "")
                last_name = profile.get("last_name", "")
                title = (first_name + " " + last_name).strip()
                break
    if not title:
        title = "VK пост"

    return title, views


def normalize_links(links: Union[List[str], str]) -> List[str]:
    if isinstance(links, str):
        raw = links.splitlines()
    else:
        raw = []
        for item in links:
            raw.extend(str(item).splitlines())
    return [line.strip() for line in raw if line.strip()]


def _escape(text: str) -> str:
    return html_lib.escape(text, quote=True)


def build_output(lines: List[Tuple[str, str, object, object]]) -> Tuple[str, str, int, int, List[str]]:
    errors: List[str] = []

    tg_groups = {}
    vk_groups = {}

    for plat, canonical, a, b in lines:
        if plat == "telegram":
            username, mid = a, b
            if not username or not mid:
                key = canonical
                tg_groups.setdefault(key, {"title": "Telegram", "items": []})
                tg_groups[key]["items"].append((canonical, 0))
            else:
                title, views = process_telegram_link(username, mid, canonical)
                key = username
                if key not in tg_groups:
                    tg_groups[key] = {"title": title, "items": []}
                if not tg_groups[key].get("title") or str(tg_groups[key]["title"]).startswith("**Ошибка"):
                    tg_groups[key]["title"] = title
                tg_groups[key]["items"].append((canonical, views))

        elif plat == "vk":
            owner_id, post_id = a, b
            if owner_id is None or post_id is None:
                key = canonical
                vk_groups.setdefault(key, {"title": "VK пост", "items": []})
                vk_groups[key]["items"].append((canonical, 0))
            else:
                title, views = process_vk_link(owner_id, post_id, canonical)
                key = str(owner_id)
                if key not in vk_groups:
                    vk_groups[key] = {"title": title, "items": []}
                if not vk_groups[key].get("title") or str(vk_groups[key]["title"]).startswith("**Ошибка"):
                    vk_groups[key]["title"] = title
                vk_groups[key]["items"].append((canonical, views))
        else:
            errors.append(f"Неизвестная платформа: {canonical}")

    tg_total_views = sum(v for g in tg_groups.values() for _, v in g["items"])
    vk_total_views = sum(v for g in vk_groups.values() for _, v in g["items"])

    tg_sorted = sorted(
        tg_groups.items(),
        key=lambda kv: sum(v for _, v in kv[1]["items"]),
        reverse=True,
    )
    vk_sorted = sorted(
        vk_groups.items(),
        key=lambda kv: sum(v for _, v in kv[1]["items"]),
        reverse=True,
    )

    html_lines: List[str] = []
    text_lines: List[str] = []

    # --- Telegram ---
    html_lines.append("<h2>Telegram</h2>")
    html_lines.append(f"<b>Суммарный охват постов — {human_format_views(tg_total_views)} просмотров</b>")
    text_lines.append("Telegram")
    text_lines.append(f"Суммарный охват постов — {human_format_views(tg_total_views)} просмотров")
    if tg_sorted:
        html_lines.append("<ol>")
        for idx, (_, data) in enumerate(tg_sorted, start=1):
            title = data["title"] or "Telegram"
            items = data["items"]
            first_link, _first_views = items[0]

            title_html = _escape(title)
            first_link_html = _escape(first_link)
            line_html = f'<li><a href="{first_link_html}">{title_html}</a>'
            if len(items) > 1:
                for link2, _v in items[1:]:
                    line_html += f' + <a href="{_escape(link2)}">ещё</a>'
            views_str = " + ".join(human_format_views(v) for _, v in items)
            line_html += f" — {views_str}</li>"
            html_lines.append(line_html)

            line_text = f"{idx}. {title} ({first_link})"
            if len(items) > 1:
                extra_links = ", ".join(link2 for link2, _v in items[1:])
                line_text += f" + ещё: {extra_links}"
            line_text += f" — {views_str}"
            text_lines.append(line_text)
        html_lines.append("</ol>")
    else:
        html_lines.append("<i>Нет ссылок на Telegram</i>")
        text_lines.append("Нет ссылок на Telegram")
    html_lines.append("<br/>")
    text_lines.append("")

    # --- VK ---
    html_lines.append("<h2>ВКонтакте</h2>")
    html_lines.append(f"<b>Суммарный охват постов — {human_format_views(vk_total_views)} просмотров</b>")
    text_lines.append("ВКонтакте")
    text_lines.append(f"Суммарный охват постов — {human_format_views(vk_total_views)} просмотров")
    if vk_sorted:
        html_lines.append("<ol>")
        for idx, (_, data) in enumerate(vk_sorted, start=1):
            title = data["title"] or "VK пост"
            items = data["items"]
            first_link, _first_views = items[0]

            title_html = _escape(title)
            first_link_html = _escape(first_link)
            line_html = f'<li><a href="{first_link_html}">{title_html}</a>'
            if len(items) > 1:
                for link2, _v in items[1:]:
                    line_html += f' + <a href="{_escape(link2)}">ещё</a>'
            views_str = " + ".join(human_format_views(v) for _, v in items)
            line_html += f" — {views_str}</li>"
            html_lines.append(line_html)

            line_text = f"{idx}. {title} ({first_link})"
            if len(items) > 1:
                extra_links = ", ".join(link2 for link2, _v in items[1:])
                line_text += f" + ещё: {extra_links}"
            line_text += f" — {views_str}"
            text_lines.append(line_text)
        html_lines.append("</ol>")
    else:
        html_lines.append("<i>Нет ссылок на ВКонтакте</i>")
        text_lines.append("Нет ссылок на ВКонтакте")
    html_lines.append("<br/>")
    text_lines.append("")

    if errors:
        html_lines.append("<h2>Ошибки</h2>")
        html_lines.append("<ul>")
        for err in errors:
            html_lines.append(f"<li>{_escape(err)}</li>")
            text_lines.append(f"- {err}")
        html_lines.append("</ul>")
        html_lines.append("<br/>")
        text_lines.append("")

    return "\n".join(html_lines), "\n".join(text_lines), tg_total_views, vk_total_views, errors


@app.get("/health")
def health_check():
    return {"status": "ok"}


@app.post("/parse", response_model=ParseResponse)
def parse_links(payload: ParseRequest):
    raw_lines = normalize_links(payload.links)
    if not raw_lines:
        return ParseResponse(html="", text="", telegram_total=0, vk_total=0, errors=["Нет ссылок для обработки."])

    seen = set()
    lines: List[Tuple[str, str, object, object]] = []
    for link in raw_lines:
        plat = detect_platform(link)
        if plat == "telegram":
            canonical, username, mid = canonicalize_tg_link(link)
            if not canonical:
                canonical = link
                username = None
                mid = None
            if canonical in seen:
                continue
            seen.add(canonical)
            lines.append(("telegram", canonical, username, mid))
        elif plat == "vk":
            canonical, owner_id, post_id = canonicalize_vk_link(link)
            if not canonical:
                canonical = link
            if canonical in seen:
                continue
            seen.add(canonical)
            lines.append(("vk", canonical, owner_id, post_id))
        else:
            lines.append(("unknown", link, None, None))

    html, text, tg_total, vk_total, errors = build_output(lines)
    return ParseResponse(
        html=html,
        text=text,
        telegram_total=tg_total,
        vk_total=vk_total,
        errors=errors,
    )