from asyncio import Semaphore
import re
from urllib.parse import quote_plus
from playwright.async_api import Browser

from serp.base import PlaywrightSerpBackendBase, SerpQuery, SerpResultItem, playwright_open_page


class GPatentsSerpBackend(PlaywrightSerpBackendBase):
    """GPatents SERP backend for scraping patent data."""

    def __init__(self):
        super().__init__()
        self.MAX_CONCURRENCY_SEMAPHORE = Semaphore(2)
        pass

    @property
    def name(self) -> str:
        """Name of the backend. Used for identification in slugs."""
        return "gpatents"

    async def query_serp_page(self, browser: Browser, query: SerpQuery) -> list[SerpResultItem]:
        """Query the GPatents SERP page and return a list of SerpResultItem."""

        # regex to locate a patent id
        PATENT_ID_REGEX = r"\b[A-Z]{2}\d{6,}(?:[A-Z]\d?)?\b"

        async with playwright_open_page(browser, self.MAX_CONCURRENCY_SEMAPHORE) as page:

            async def _block_resources(route, request):
                if request.resource_type in ["stylesheet", "image"]:
                    await route.abort()
                else:
                    await route.continue_()

            await page.route("**/*", _block_resources)

            url = f"https://patents.google.com/?q={quote_plus(query.query)}&num={query.n_results}"
            await page.goto(url)

            # Wait for at least one search result item to appear
            # This ensures the page has loaded enough to start scraping
            await page.wait_for_function(
                f"""() => document.querySelectorAll('search-result-item').length >= 1""",
                timeout=30_000
            )

            items = await page.locator("search-result-item").all()
            results = []
            for item in items:
                text = " ".join(await item.locator("span").all_inner_texts())
                match = re.search(PATENT_ID_REGEX, text)
                if not match:
                    continue

                patent_id = match.group()

                try:
                    title = await item.locator("h3, h4").first.inner_text(timeout=1000)
                    body = await item.locator("div.abstract, div.result-snippet, .snippet, .result-text").first.inner_text(timeout=1000)
                except:
                    continue  # If we can't get title or body, skip this item

                results.append(SerpResultItem(
                    href=f"https://patents.google.com/patent/{patent_id}/en",
                    title=title,
                    body=body,
                    patent_id=patent_id,
                    content_slug=f"{self.name}:{patent_id}"
                ))

        return results

    @property
    def category(self):
        return "patent"