"""سئوی سمت سرور — robots.txt، sitemap.xml و سرو HTML صفحات وبلاگ/پروژه با متای تزریق‌شده.

فرانت‌اند یک SPA است؛ خزنده‌های اجتماعی (تلگرام، واتس‌اپ و...) جاوااسکریپت اجرا نمی‌کنند.
این ماژول همان index.html بیلد فرانت‌اند را می‌خواند و پیش از ارسال، تگ‌های
title / description / OG / canonical / JSON-LD را از دیتابیس داخل آن تزریق می‌کند —
بازدیدکننده‌های عادی همان SPA همیشگی را می‌بینند و خزنده‌ها متای درست را می‌خوانند.
"""

import html
import json
import re
from pathlib import Path

from fastapi import APIRouter, Depends, Response
from fastapi.responses import HTMLResponse
from sqlalchemy.orm import Session

from . import models
from .config import settings
from .database import get_db

router = APIRouter()

STATIC_PATHS = ["/", "/about", "/services", "/projects", "/investment", "/blog", "/faq", "/contact"]


def _absolute(path: str) -> str:
    if not path:
        return ""
    if path.startswith(("http://", "https://")):
        return path
    site = settings.site_url.rstrip("/")
    return f"{site}{path}" if site else path


def _read_index() -> str | None:
    try:
        return (Path(settings.frontend_dist) / "index.html").read_text(encoding="utf-8")
    except OSError:
        return None


def _doc_text(doc: object, limit: int = 300) -> str:
    """متن ساده سند TipTap — برای noscript و پیش‌نمایش."""
    words: list[str] = []

    def walk(node: object) -> None:
        if not isinstance(node, dict):
            return
        if node.get("type") == "text" and isinstance(node.get("text"), str):
            words.append(node["text"])
        for child in node.get("content") or []:
            walk(child)

    if isinstance(doc, dict):
        for block in doc.get("content") or []:
            walk(block)
    text = " ".join(words).strip()
    return text[:limit] + ("…" if len(text) > limit else "")


def _shell(
    *,
    title: str,
    description: str,
    path: str,
    og_image: str = "",
    og_type: str = "website",
    jsonld: dict | None = None,
    noscript: str = "",
) -> HTMLResponse:
    """index.html فرانت‌اند با متای تزریق‌شده؛ اگر بیلد در دسترس نبود، صفحه حداقلی."""
    title = title.strip() or "گروه ساختمانی آرامش"
    description = description.strip()
    canonical = _absolute(path)
    image = _absolute(og_image)
    esc = html.escape

    # تگ title جای تگ موجود index.html را می‌گیرد و در بلوک تکرار نمی‌شود
    tags = [
        f'<meta name="description" content="{esc(description)}" />',
        f'<meta property="og:title" content="{esc(title)}" />',
        f'<meta property="og:description" content="{esc(description)}" />',
        f'<meta property="og:type" content="{esc(og_type)}" />',
        f'<meta property="og:url" content="{esc(canonical)}" />',
        f'<meta name="twitter:card" content="summary_large_image" />',
    ]
    if image:
        tags.append(f'<meta property="og:image" content="{esc(image)}" />')
    if jsonld:
        payload = json.dumps(jsonld, ensure_ascii=False).replace("</", "<\\/")
        tags.append(f'<script type="application/ld+json">{payload}</script>')
    block = "\n    ".join(tags)

    raw = _read_index()
    if raw is None:
        # بیلد فرانت‌اند سوار نشده — صفحه حداقلی با خودِ متا تا خزنده‌ها دست خالی نمانند
        body = f"<h1>{esc(title)}</h1><p>{esc(description)}</p>"
        return HTMLResponse(
            f'<!doctype html><html lang="fa" dir="rtl"><head><meta charset="utf-8">'
            f"<title>{esc(title)}</title>{block}</head><body>{body}</body></html>"
        )

    raw = re.sub(r"<title>.*?</title>", f"<title>{esc(title)}</title>", raw, count=1, flags=re.S)
    raw = raw.replace("</head>", f"    {block}\n  </head>", 1)
    if noscript:
        raw = raw.replace("</body>", f"<noscript>{noscript}</noscript>\n  </body>", 1)
    return HTMLResponse(raw)


def _brand_name(db: Session) -> str:
    brand = db.query(models.Brand).first()
    return brand.name if brand else "گروه ساختمانی آرامش"


def _page_meta(db: Session, page_key: str) -> models.SeoMeta | None:
    return db.query(models.SeoMeta).filter(models.SeoMeta.page_key == page_key).first()


# ---------- robots.txt و sitemap.xml ----------


@router.get("/robots.txt", response_class=Response)
def robots(db: Session = Depends(get_db)):
    lines = ["User-agent: *", "Disallow: /admin", "Disallow: /api", ""]
    if settings.site_url:
        lines.append(f"Sitemap: {_absolute('/sitemap.xml')}")
    return Response(content="\n".join(lines), media_type="text/plain; charset=utf-8")


@router.get("/sitemap.xml", response_class=Response)
def sitemap(db: Session = Depends(get_db)):
    urls = list(STATIC_PATHS)
    urls += [
        f"/blog/{a.slug}"
        for a in db.query(models.Article)
        .filter(models.Article.status == "published")
        .order_by(models.Article.position, models.Article.id)
        .all()
    ]
    urls += [
        f"/projects/{p.slug}"
        for p in db.query(models.Project).order_by(models.Project.position, models.Project.id).all()
    ]
    items = "\n".join(
        f"    <url><loc>{html.escape(_absolute(u))}</loc></url>" for u in urls
    )
    xml = (
        '<?xml version="1.0" encoding="UTF-8"?>\n'
        '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">\n'
        f"{items}\n</urlset>\n"
    )
    return Response(content=xml, media_type="application/xml; charset=utf-8")


# ---------- صفحات وبلاگ ----------


@router.get("/blog", response_class=HTMLResponse)
def blog_list(db: Session = Depends(get_db)):
    meta = _page_meta(db, "blog")
    return _shell(
        title=meta.title if meta and meta.title else "وبلاگ | " + _brand_name(db),
        description=meta.description if meta else "",
        path="/blog",
        og_image=meta.image if meta else "",
    )


@router.get("/blog/{slug}", response_class=HTMLResponse)
def blog_detail(slug: str, db: Session = Depends(get_db)):
    article = (
        db.query(models.Article)
        .filter(models.Article.slug == slug, models.Article.status == "published")
        .first()
    )
    if article is None:
        # مقاله ناموجود یا پیش‌نویس — پوسته ساده بدون متا؛ SPA پیام «یافت نشد» را نشان می‌دهد
        return _shell(title=_brand_name(db), description="", path=f"/blog/{slug}")

    brand = _brand_name(db)
    first_text = _doc_text(article.body) if not isinstance(article.body, list) else " ".join(article.body[:2])
    jsonld = {
        "@context": "https://schema.org",
        "@type": "Article",
        "headline": article.title,
        "description": article.excerpt,
        "image": _absolute(article.image),
        "inLanguage": "fa",
        "author": {"@type": "Organization", "name": brand},
        "publisher": {"@type": "Organization", "name": brand},
        "mainEntityOfPage": _absolute(f"/blog/{article.slug}"),
    }
    noscript = f"<h1>{html.escape(article.title)}</h1><p>{html.escape(first_text)}</p>"
    return _shell(
        title=f"{article.title} | {brand}",
        description=article.excerpt,
        path=f"/blog/{article.slug}",
        og_image=article.image,
        og_type="article",
        jsonld=jsonld,
        noscript=noscript,
    )


# ---------- صفحات پروژه ----------


@router.get("/projects", response_class=HTMLResponse)
def projects_list(db: Session = Depends(get_db)):
    meta = _page_meta(db, "projects")
    return _shell(
        title=meta.title if meta and meta.title else "پروژه‌ها | " + _brand_name(db),
        description=meta.description if meta else "",
        path="/projects",
    )


@router.get("/projects/{slug}", response_class=HTMLResponse)
def project_detail(slug: str, db: Session = Depends(get_db)):
    project = db.query(models.Project).filter(models.Project.slug == slug).first()
    if project is None:
        return _shell(title=_brand_name(db), description="", path=f"/projects/{slug}")

    brand = _brand_name(db)
    return _shell(
        title=f"{project.title} | {brand}",
        description=project.summary,
        path=f"/projects/{project.slug}",
        og_image=project.image,
        jsonld={
            "@context": "https://schema.org",
            "@type": "WebPage",
            "name": project.title,
            "description": project.summary,
            "image": _absolute(project.image),
            "inLanguage": "fa",
        },
    )