"""Fetch retail list prices for verified platform listings.

API-first where possible (Google Books, Apple iTunes). HTML fallback with
US-locale headers for Amazon and other US retailers. Open Library shows Free.
"""

from __future__ import annotations

import json
import re
from dataclasses import dataclass

import httpx
import structlog

from app.services.book_url_scraper import (
    _API_TIMEOUT,
    _browser_headers,
    _google_books_api_params,
    _parse_amazon_html,
    _score_itunes_item,
)

logger = structlog.get_logger(__name__)

_PRICE_TIMEOUT = 12.0

# Goodreads is discovery-only — no single list price on the page.
_NO_PRICE_PLATFORMS = frozenset({"goodreads"})


@dataclass
class PriceContext:
    """Optional catalog hints when listing URL alone is insufficient."""

    isbn13: str | None = None
    title: str | None = None
    author: str | None = None


@dataclass
class PlatformPrice:
    """Normalized list price for a retailer listing."""

    formatted: str
    amount: float | None = None
    currency: str = "USD"
    source: str = "unknown"


def format_price(amount: float, currency: str = "USD") -> str:
    """Format amount with a common currency symbol when known."""
    currency = (currency or "USD").upper()
    symbols = {"USD": "$", "GBP": "£", "EUR": "€", "CAD": "CA$", "AUD": "A$", "PKR": "PKR "}
    sym = symbols.get(currency)
    if sym == "$":
        return f"${amount:.2f}"
    if sym and sym != "PKR ":
        return f"{sym}{amount:.2f}"
    if sym == "PKR ":
        return f"PKR {amount:.2f}"
    return f"{amount:.2f} {currency}"


def _retailer_headers(platform_id: str, variant: str = "us") -> dict[str, str]:
    """Browser headers tuned per retailer (US locale for Amazon pricing)."""
    headers = _browser_headers()
    headers["Accept-Language"] = "en-US,en;q=0.9"

    if platform_id == "amazon" or variant == "us":
        headers["Cookie"] = "i18n-prefs=USD; lc-main=en_US; sp-cdn=J4F7"

    if variant == "mobile":
        headers["User-Agent"] = (
            "Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) "
            "AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1"
        )
    return headers


def _extract_amazon_price(html: str) -> PlatformPrice | None:
    """Parse Amazon list price — USD and international currency labels."""
    parsed = _parse_amazon_html(html)
    raw = (parsed.get("price") or "").strip()
    if raw:
        m = re.search(r"([0-9]+(?:\.[0-9]{2})?)", raw.replace(",", ""))
        if m:
            amount = float(m.group(1))
            return PlatformPrice(
                formatted=raw if raw.startswith("$") else format_price(amount, "USD"),
                amount=amount,
                currency="USD",
                source="html",
            )

    patterns: list[tuple[str, str]] = [
        (r'class="[^"]*a-offscreen[^"]*"[^>]*>\s*\$([0-9]+\.[0-9]{2})', "USD"),
        (r'apex-pricetopay-accessibility-label">\s*USD ([0-9,.]+)', "USD"),
        (r'apex-pricetopay-accessibility-label">\s*([A-Z]{3}) ([0-9,.]+)', "MULTI"),
        (r'"priceToPay"\s*:\s*\{[^}]*"amount"\s*:\s*([0-9.]+)', "USD"),
        (r'"priceAmount"\s*:\s*([0-9.]+)', "USD"),
        (r'class="a-price-whole">(\d+)</span><span class="a-price-fraction">(\d+)', "SPLIT"),
    ]
    for pat, kind in patterns:
        m = re.search(pat, html, re.IGNORECASE | re.DOTALL)
        if not m:
            continue
        if kind == "SPLIT":
            amount = float(f"{m.group(1)}.{m.group(2)}")
            return PlatformPrice(formatted=format_price(amount, "USD"), amount=amount, currency="USD", source="html")
        if kind == "MULTI":
            currency = m.group(1).upper()
            amount = float(m.group(2).replace(",", ""))
            return PlatformPrice(formatted=format_price(amount, currency), amount=amount, currency=currency, source="html")
        amount = float(m.group(1).replace(",", ""))
        return PlatformPrice(formatted=format_price(amount, kind), amount=amount, currency=kind, source="html")
    return None


def _price_from_json_ld(html: str) -> PlatformPrice | None:
    """Extract offer price from schema.org JSON-LD on retailer pages."""
    for m in re.finditer(
        r'<script[^>]*type=["\']application/ld\+json["\'][^>]*>(.*?)</script>',
        html,
        re.DOTALL | re.IGNORECASE,
    ):
        try:
            data = json.loads(m.group(1))
        except json.JSONDecodeError:
            continue
        items = data if isinstance(data, list) else [data]
        for item in items:
            offers = item.get("offers")
            if isinstance(offers, dict):
                offers = [offers]
            for offer in offers or []:
                if not isinstance(offer, dict):
                    continue
                raw = offer.get("price")
                if raw is None:
                    continue
                try:
                    amount = float(str(raw).replace(",", ""))
                except ValueError:
                    continue
                currency = str(offer.get("priceCurrency") or "USD").upper()
                return PlatformPrice(
                    formatted=format_price(amount, currency),
                    amount=amount,
                    currency=currency,
                    source="html",
                )
    return None


def _price_from_patterns(platform_id: str, html: str) -> PlatformPrice | None:
    """Platform-specific HTML price patterns (after JSON-LD)."""
    patterns: dict[str, list[str]] = {
        "barnes_noble": [
            r'"currentPrice"\s*:\s*([0-9]+\.?[0-9]*)',
            r'"salePrice"\s*:\s*([0-9]+\.?[0-9]*)',
            r'"listPrice"\s*:\s*([0-9]+\.?[0-9]*)',
            r'"price"\s*:\s*"?([0-9]+\.[0-9]{2})"?',
            r'class="[^"]*price[^"]*"[^>]*>\s*\$([0-9]+\.[0-9]{2})',
            r'itemprop="price"[^>]*content="([0-9.]+)"',
        ],
        "abebooks": [
            r'itemprop="price"[^>]*content="([0-9.]+)"',
            r'class="[^"]*item-price[^"]*"[^>]*>\s*US\$\s*([0-9]+\.[0-9]{2})',
        ],
        "kobo": [
            r'itemprop="price"[^>]*content="([0-9.]+)"',
            r'"Price"\s*:\s*"?([0-9]+\.?[0-9]*)"?',
            r'"price"\s*:\s*"?([0-9]+\.[0-9]{2})"?',
        ],
        "thriftbooks": [
            r'class="[^"]*Item-price[^"]*">\s*\$([0-9]+\.[0-9]{2})',
            r'class="[^"]*AllEditionsItem-price[^"]*">\s*\$([0-9]+\.[0-9]{2})',
            r'"price"\s*:\s*"?([0-9]+\.[0-9]{2})"?',
        ],
        "bookshop": [
            r'itemprop="price"[^>]*content="([0-9.]+)"',
            r'"price"\s*:\s*"?([0-9]+\.[0-9]{2})"?',
            r'data-price="([0-9.]+)"',
        ],
    }
    for pat in patterns.get(platform_id, []):
        m = re.search(pat, html, re.IGNORECASE | re.DOTALL)
        if m:
            amount = float(m.group(1))
            return PlatformPrice(
                formatted=format_price(amount, "USD"),
                amount=amount,
                currency="USD",
                source="html",
            )
    return None


def extract_price_from_html(platform_id: str, html: str) -> PlatformPrice | None:
    """Parse list price from retailer HTML."""
    if platform_id == "amazon":
        return _extract_amazon_price(html)

    return _price_from_json_ld(html) or _price_from_patterns(platform_id, html)


def _google_volume_id(listing_url: str) -> str | None:
    m = re.search(r"[?&]id=([^&]+)", listing_url)
    return m.group(1) if m else None


def _apple_book_id(listing_url: str) -> str | None:
    m = re.search(r"/id(\d+)", listing_url)
    return m.group(1) if m else None


def _sale_info_price(sale: dict) -> PlatformPrice | None:
    """Parse Google Books saleInfo block."""
    for key in ("listPrice", "retailPrice"):
        lp = sale.get(key) or {}
        if lp.get("amount") is None:
            continue
        amount = float(lp["amount"])
        currency = str(lp.get("currencyCode") or "USD").upper()
        return PlatformPrice(
            formatted=format_price(amount, currency),
            amount=amount,
            currency=currency,
            source="api",
        )
    return None


async def fetch_google_books_price(
    client: httpx.AsyncClient,
    listing_url: str,
    ctx: PriceContext | None = None,
) -> PlatformPrice | None:
    """Google Books API saleInfo — volume ID then ISBN search fallback."""
    volume_id = _google_volume_id(listing_url)
    isbn = (ctx.isbn13 if ctx else None) or ""

    try:
        if volume_id:
            r = await client.get(
                f"https://www.googleapis.com/books/v1/volumes/{volume_id}",
                params={**_google_books_api_params(), "country": "US"},
                timeout=_API_TIMEOUT,
            )
            if r.status_code == 200:
                hit = _sale_info_price(r.json().get("saleInfo") or {})
                if hit:
                    return hit

        if isbn:
            r = await client.get(
                "https://www.googleapis.com/books/v1/volumes",
                params={
                    **_google_books_api_params(q=f"isbn:{isbn}", maxResults="5"),
                    "country": "US",
                },
                timeout=_API_TIMEOUT,
            )
            if r.status_code == 200:
                for item in r.json().get("items", []):
                    hit = _sale_info_price(item.get("saleInfo") or {})
                    if hit:
                        return hit
    except Exception as exc:
        logger.debug("Google Books price fetch failed", error=str(exc))
    return None


async def fetch_apple_books_price(
    client: httpx.AsyncClient,
    listing_url: str,
    ctx: PriceContext | None = None,
) -> PlatformPrice | None:
    """Apple iTunes Lookup API with title search fallback."""
    book_id = _apple_book_id(listing_url)

    def _from_item(item: dict) -> PlatformPrice | None:
        if item.get("formattedPrice"):
            formatted = str(item["formattedPrice"])
            m = re.search(r"([0-9]+(?:\.[0-9]{2})?)", formatted.replace(",", ""))
            amount = float(m.group(1)) if m else None
            return PlatformPrice(
                formatted=formatted,
                amount=amount,
                currency=str(item.get("currency") or "USD").upper(),
                source="api",
            )
        if item.get("trackPrice") is not None:
            amount = float(item["trackPrice"])
            currency = str(item.get("currency") or "USD").upper()
            return PlatformPrice(
                formatted=format_price(amount, currency),
                amount=amount,
                currency=currency,
                source="api",
            )
        return None

    try:
        if book_id:
            for params in ({"id": book_id, "entity": "ebook"}, {"id": book_id}):
                r = await client.get(
                    "https://itunes.apple.com/lookup",
                    params=params,
                    timeout=_API_TIMEOUT,
                )
                if r.status_code != 200:
                    continue
                results = r.json().get("results") or []
                if results:
                    hit = _from_item(results[0])
                    if hit:
                        return hit

        title = (ctx.title if ctx else None) or ""
        author = (ctx.author if ctx else None) or ""
        if title:
            term = f"{title} {author}".strip()
            r = await client.get(
                "https://itunes.apple.com/search",
                params={"term": term, "entity": "ebook", "limit": "8", "country": "US"},
                timeout=_API_TIMEOUT,
            )
            if r.status_code == 200:
                results = r.json().get("results") or []
                if book_id:
                    for item in results:
                        if str(item.get("trackId")) == book_id:
                            hit = _from_item(item)
                            if hit:
                                return hit
                if results:
                    best = max(results, key=lambda i: _score_itunes_item(i, title, author))
                    if _score_itunes_item(best, title, author) >= 4.0:
                        hit = _from_item(best)
                        if hit:
                            return hit
    except Exception as exc:
        logger.debug("Apple Books price fetch failed", error=str(exc))
    return None


async def _fetch_html_price(
    client: httpx.AsyncClient,
    platform_id: str,
    listing_url: str,
) -> PlatformPrice | None:
    """GET product page with US then mobile headers."""
    variants = ("us", "mobile") if platform_id in {
        "amazon", "kobo", "thriftbooks", "bookshop",
    } else ("us",)

    for variant in variants:
        try:
            r = await client.get(
                listing_url,
                headers=_retailer_headers(platform_id, variant),
                timeout=_PRICE_TIMEOUT,
            )
            if r.status_code != 200 or len(r.text) < 500:
                continue
            hit = extract_price_from_html(platform_id, r.text)
            if hit:
                return hit
        except Exception as exc:
            logger.debug(
                "HTML price fetch failed",
                platform=platform_id,
                variant=variant,
                error=str(exc)[:120],
            )
    return None


async def fetch_listing_price(
    client: httpx.AsyncClient,
    platform_id: str,
    listing_url: str,
    ctx: PriceContext | None = None,
    credential: "EffectiveCredential | None" = None,
) -> PlatformPrice | None:
    """Fetch list price for one verified platform listing."""
    if not listing_url:
        return None

    if platform_id == "open_library":
        return PlatformPrice(formatted="Free", amount=0.0, currency="USD", source="catalog")

    if platform_id in _NO_PRICE_PLATFORMS:
        return None

    # Priority 1: SuperAdmin / environment API credential
    if credential is not None:
        from app.services.platform_api_registry import fetch_price_via_credential
        hit = await fetch_price_via_credential(
            client, credential, platform_id, listing_url, ctx,
        )
        if hit:
            return hit

    # Priority 2: built-in free logic
    if platform_id == "google_books":
        return await fetch_google_books_price(client, listing_url, ctx)

    if platform_id == "apple_books":
        return await fetch_apple_books_price(client, listing_url, ctx)

    return await _fetch_html_price(client, platform_id, listing_url)