scraper_api_client.py

#!/usr/bin/env python3
"""medium-scraper — 2captcha Scraper API edition (fourth engine)

One HTTP request per page, no local browser, no Playwright install. The
2captcha Scraper API fetches the page from its own infrastructure and returns
the HTML; this client parses it with the same `product_parser` the browser
engines use, so the rows and columns are identical.

MEASURED 2026-09-16, $0.0005 A REQUEST
-------------------------------------
All four modes, one request each, no browser anywhere and no proxy:

    --mode tag        HTTP 200,   361,092 bytes,   53 rows,  5.4s
    --mode archive    HTTP 200, 2,305,814 bytes,  128 rows,  8.3s
    --mode author     HTTP 200,   229,266 bytes,   10 rows, 59.5s
    --mode post       HTTP 200,   219,654 bytes,    1 row,   6.8s

The rows are not merely present, they are IDENTICAL to what a local browser
produced on the same URLs: the same 128 stories on the archive day with 100%
coverage of claps, reading time, word count and language, the same 248 claps
/ 15.54 minutes / 3,801 words on the same story, and the same
18,352-character body in post mode.

So this is the cheapest complete path on this site, and the archive day is
what it is best at — one request returns the whole 2.3 MB legacy payload,
which is the richest thing Medium publishes.

WHAT IT CANNOT DO, and it costs nothing here
--------------------------------------------
It returns the SERVED response rather than a rendered DOM, so it cannot
scroll. On a tag feed that costs nothing: the feed does not extend from an
ordinary address anyway. On an AUTHOR page it does cost something — the same
page over the Scraping Browser (`--cdp-endpoint` on a browser engine) scrolls
10 cards up to 60 and yields 55 rows against this path's 10.

So: reach for this for `--mode archive` and `--mode post`, where it is
complete and cheapest; reach for a browser engine over `--cdp-endpoint` when
you want an author page's whole output.

    python3 scraper_api_client.py \\
        --url "https://medium.com/tag/python/archive/2026/09/10"

    python3 scraper_api_client.py --url "https://medium.com/tag/python"

    # $TWOCAPTCHA_KEY is read from the environment or .env, so a key never
    # has to be typed — a secret in argv is readable by anything that can run
    # `ps` and lands in shell history.
"""

import argparse
import json
import logging
import os
import re
import sys
import time
from typing import Optional

import requests

from product_parser import (parse_posts, detect_bot_challenge,
                            detect_page_state, listing_kind, normalize_url,
                            BOT_CHALLENGE_MARKERS)
from output_writer import save
import env_config
import page_flow

logging.basicConfig(level=logging.INFO, format="%(asctime)s [%(levelname)s] %(message)s")
logger = logging.getLogger("scraper_api_client")

API_BASE = "https://scraper.2captcha.com"
SYNC_ENDPOINT = f"{API_BASE}/tasks/sync"

# The API caps `timeout` at 120s and rejects bodies over 10,000 bytes.
MAX_API_TIMEOUT = 120

# Exit codes. Kept distinct from 2 (bad usage) on purpose: a remote API
# failing is not the operator passing wrong arguments, and a harness that
# lumps them together sends you looking in the wrong place. An early run
# reported `exit=2` for an HTTP 422 from the API — which reads as "you called
# it wrong".
#
# Imported rather than redefined: the browser engines return the same code for
# a Scraping Browser that will not accept a connection, and two definitions
# of one exit code is how a family's contract drifts.
from output_writer import EXIT_API_ERROR  # noqa: E402

def _mask_credentials(url: str) -> str:
    """Never print a username:password embedded in a ws://... or http://... URL."""
    if "@" not in url:
        return url
    scheme_sep = url.find("://")
    if scheme_sep == -1:
        return url
    scheme, rest = url[:scheme_sep + 3], url[scheme_sep + 3:]
    _, _, host_part = rest.partition("@")
    return f"{scheme}***:***@{host_part}"


# Credentials embedded ANYWHERE in a blob of text, not just in a string that
# is entirely a URL — and every occurrence, not the first. A masker that
# handles one occurrence prints the password the other four times and looks
# like it is working.
_CREDS_IN_TEXT_RE = re.compile(r"([a-z][a-z0-9+.-]*://)[^/\s'\"@]+@", re.IGNORECASE)
# Same shape as captcha_solver's and fingerprint_client's. A third copy is
# one too many and they should be unified in a family pass; reaching into
# another module's private name to avoid it would be worse.
_KEY_IN_TEXT_RE = re.compile(
    r"((?:client)?key|token|api[_-]?key)=([^&\s'\"]{6,})", re.IGNORECASE)


def _redact_debug_header(value: str) -> str:
    """The x-debug header, safe to log.

    SECURITY.md names this header as one of three places credentials reach a
    log unmasked, and it was logged verbatim: the API echoes back the task it
    ran, so a run driven through a credentialed CDP endpoint put that
    endpoint's username and password into the log, and a key passed as a
    query parameter would go the same way.

    Redaction rather than an allowlist of fields, deliberately: the header is
    the API's own metadata and its shape is not ours to pin, so an allowlist
    would silently drop the cost and timing figures this is logged FOR the
    first time the API adds a field.
    """
    return _KEY_IN_TEXT_RE.sub(r"\1=***",
                               _CREDS_IN_TEXT_RE.sub(r"\1***:***@", value))


def _build_wait_for(args) -> Optional[dict]:
    """`waitFor` is sent as an OBJECT. Measured 2026-09-23: the
    JSON-encoded string form is answered with HTTP 422 and still billed
    ($0.0005); the object form gets HTTP 200.

    Default (no flag): wait for the DOM. On a challenge-protected page
    that resolves instantly against the challenge page itself — which is
    exactly the trap documented in this module's docstring, so
    --wait-text/--wait-element exist to wait on something only the real
    page can contain."""
    if args.wait_text:
        return {"text": args.wait_text}
    if args.wait_element:
        return {"element": args.wait_element, "checkVisible": True}
    if args.wait_state:
        return {"state": args.wait_state}
    return None


def fetch_html(args) -> str:
    payload = {
        "task_type": "scrape",
        "url": args.url,
        "data_format": "raw",   # we want HTML; product_parser does the rest
        "format": "json",       # so we get {"status", "http_code", "headers", "body"}
        "timeout": min(args.timeout, MAX_API_TIMEOUT),
    }

    wait_for = _build_wait_for(args)
    if wait_for:
        payload["waitFor"] = wait_for
        logger.info("waitFor: %s", json.dumps(wait_for))

    if args.cdp_url:
        payload["cdpurl"] = args.cdp_url
        logger.info("Routing through an existing browser session: %s",
                    _mask_credentials(args.cdp_url))

    logger.info("POST %s (url=%s)", SYNC_ENDPOINT, args.url)
    resp = requests.post(
        SYNC_ENDPOINT,
        headers={"Authorization": f"Bearer {args.key}", "Content-Type": "application/json"},
        json=payload,
        # Give the HTTP call more headroom than the API-side task timeout,
        # otherwise a task that legitimately runs the full 120s looks like
        # a client-side network failure.
        timeout=min(args.timeout, MAX_API_TIMEOUT) + 30,
    )

    # The API returns its own per-task metadata (price, timings, status)
    # in an x-debug header — worth logging, it's the only place the real
    # cost of the call shows up.
    debug = resp.headers.get("x-debug")
    if debug:
        logger.info("x-debug: %s", _redact_debug_header(debug))

    if resp.status_code != 200:
        # 422 = task ran but errored (this is what a bad/unreachable
        # cdpurl produces: "CDP connect failed (user cdpurl) after N
        # attempts"); 402 = out of balance; 408 = sync wait exceeded.
        raise RuntimeError(
            f"Scraper API returned HTTP {resp.status_code}: {resp.text[:500]}"
        )

    body = resp.json()
    html = body.get("body") or ""
    # The TARGET's HTTP code is `http_code`. `status` is the API's own
    # verdict string ("success", measured 2026-09-23), and passing it on
    # meant the page classifier never saw a 403. Fall back to `status` only
    # if some response shape carries an int there.
    upstream_status = body.get("http_code")
    if not isinstance(upstream_status, int):
        legacy = body.get("status")
        upstream_status = legacy if isinstance(legacy, int) else None
    logger.info("Upstream page HTTP %s (API status %r), %d bytes of HTML.",
                upstream_status, body.get("status"), len(html))
    # The STATUS is returned alongside the HTML, not thrown away. It used to
    # be, and that cost this engine the family's central distinction. On this
    # site a refusal carries no markup at all — nothing a challenge check
    # on it, so the challenge check below finds nothing and the run fell
    # through to "0 products" and exit 4. A pipeline branching on the exit
    # code then reads a block as an empty category. See detect_page_state,
    # which the three browser engines already reach through page_flow.
    return html, upstream_status


def main() -> int:
    args = parse_args()

    if not args.key:
        logger.error("No 2captcha API key. Pass --key, or better, export TWOCAPTCHA_KEY.")
        return 2

    # A challenge page is not necessarily final (see _run_once), so a
    # single attempt is not evidence. Each retry is a fresh billable task —
    # $0.0005 at the observed rate — so the default is deliberately low.
    attempts = max(1, args.retries + 1)
    for attempt in range(1, attempts + 1):
        rc = _run_once(args, attempt, attempts)
        if rc != 3 or attempt == attempts:
            return rc
        logger.info("Challenge page on attempt %d/%d — retrying in %ds.",
                    attempt, attempts, args.retry_delay)
        time.sleep(args.retry_delay)
    return rc


def _run_once(args, attempt: int = 1, attempts: int = 1) -> int:
    if attempts > 1:
        logger.info("Attempt %d/%d", attempt, attempts)

    try:
        html, upstream_status = fetch_html(args)
    except requests.RequestException as e:
        logger.error("Network error talking to the Scraper API: %s", e)
        return EXIT_API_ERROR
    except RuntimeError as e:
        # HTTP 4xx/5xx from the API, including the 422 that a busy or
        # unreachable cdpurl produces.
        logger.error("%s", e)
        return EXIT_API_ERROR

    if args.dump_html:
        with open(args.dump_html, "w", encoding="utf-8") as f:
            f.write(html)
        logger.info("Raw HTML written to %s", args.dump_html)

    # Same policy as the browser engines: the status decides the blocked
    # case, because this site's refusal has no marker to detect.
    state = detect_page_state(html, status=upstream_status, url=args.url)
    if state == "blocked":
        dump = f"{args.out}_scraperapi_debug.html"
        with open(dump, "w", encoding="utf-8") as f:
            f.write(html)
        logger.error(
            "The site did not serve the Scraper API's request (upstream "
            "HTTP %s, %d bytes) — saved to %s. On 2026-09-16 this path was "
            "served on all four modes, so a refusal is not the usual "
            "answer; the dump shows which of Medium's two refusal pages it "
            "was. Retry later, or route the task through a Scraping Browser "
            "session with --cdp-url. "
            "This is exit 3, distinct from an empty result (exit 4).", upstream_status, len(html), dump)
        return 3

    vendor = detect_bot_challenge(html)
    if vendor:
        logger.error(
            "The Scraper API returned a %s bot-challenge page (%d bytes), not real content.",
            vendor, len(html),
        )
        logger.error("A challenge page is not a final answer — retry before concluding "
                     "anything (--retries): Medium's managed challenge was measured "
                     "clearing on the next attempt. If it persists, pass "
                     "--cdp-url, or use playwright_scraper.py / "
                     "puppeteer_scraper.py directly.")
        return 3

    products = parse_posts(html, args.url, mode=listing_kind(args.url))
    logger.info("Parsed %d stor(ies).", len(products))

    if not products:
        dump = f"{args.out}_scraperapi_debug.html"
        with open(dump, "w", encoding="utf-8") as f:
            f.write(html)
        logger.warning("0 stories parsed — saved the raw response to %s so "
                       "you can see what actually came back. Medium "
                       "server-renders both of its payloads, so a served "
                       "page should never parse to zero here: check the dump "
                       "for Cloudflare's block page (5 KB, 'you have been "
                       "blocked') or its managed challenge (28 KB, 'Just a "
                       "moment'). All four modes were measured returning "
                       "HTTP 200 and full rows on 2026-09-16, so zero here "
                       "is worth an issue.", dump)
        return 4

    return save(products, args.out, args.format, allow_empty=args.allow_empty)


def parse_args():
    p = argparse.ArgumentParser(
        description="Medium story scraper — 2captcha Scraper API edition "
                    "(no local browser). Measured 2026-09-16 at $0.0005 a "
                    "request: all four modes returned HTTP 200 and rows "
                    "identical to a local browser's, including the whole "
                    "2.3 MB archive-day payload in one request. It cannot "
                    "scroll, which costs nothing except on an author page — "
                    "see the module docstring.")
    # NOT required: prefer the TWOCAPTCHA_KEY env var. A key passed on the
    # command line is visible to anyone who can run `ps`, and it lands in
    # shell history and in any log that echoes the command line.
    p.add_argument("--key", default=os.environ.get("TWOCAPTCHA_KEY"),
                   help="2captcha.com API key (sent as a Bearer token). "
                        "Defaults to $TWOCAPTCHA_KEY, which is the safer way to pass it.")
    p.add_argument("--url", default=None,
                   help="A Medium URL: a tag feed (/tag/{slug}), a tag's day "
                        "archive (/tag/{slug}/archive/{yyyy}/{mm}/{dd}), an "
                        "author (/@{username}) or a story (/p/{id}). "
                        "Required, unless MEDIUM_URL is set in the "
                        "environment or in .env.")
    p.add_argument("--category", default=None,
                   help="Accepted so a command line shared with the other "
                        "scrapers in this family still parses, and NOT used: "
                        "a Medium row has no category column (its tags are in "
                        "`tags`). A warning says so when it is passed.")
    p.add_argument("--format", choices=["json", "csv", "both"], default="both")
    p.add_argument("--out", default="medium_posts_scraperapi", help="Output file prefix")
    p.add_argument("--timeout", type=int, default=60,
                   help=f"API-side task timeout in seconds (1-{MAX_API_TIMEOUT}, default 60)")
    p.add_argument("--cdp-url", default=None,
                   help="Route the fetch through an existing browser session over CDP "
                        "(sent as the API's `cdpurl` param), e.g. ws://user:pass@host:port")
    wait = p.add_mutually_exclusive_group()
    wait.add_argument("--wait-text", default=None,
                      help="Wait until this string appears on the page, e.g. '$'. Use this "
                           "on protected sites — a DOM/load wait is satisfied instantly by "
                           "the challenge page itself.")
    wait.add_argument("--wait-element", default=None,
                      help="Wait until this CSS selector is visible, e.g. 'a[href*=\"-item-\"]'")
    wait.add_argument("--wait-state", choices=["load", "domcontentloaded"], default=None,
                      help="Wait for a page load state instead of specific content")
    p.add_argument("--allow-empty", action="store_true",
                   help="Write output files even when 0 products were parsed. Off by "
                        "default so a failed fetch can't overwrite a good result.")
    p.add_argument("--retries", type=page_flow.at_least("--retries", 0), default=1,
                   help="Extra attempts if a bot-challenge page comes back. One retry is "
                        "usually worth it. Each attempt is a separate billable task, so "
                        "this defaults to 1.")
    p.add_argument("--retry-delay", type=page_flow.at_least("--retry-delay", 0),
                   default=10,
                   help="Seconds between retries (default 10)")
    p.add_argument("--dump-html", default=None,
                   help="Also write the raw returned HTML to this path (always, even on success)")
    args = p.parse_args()
    # This client uses --key and --cdp-url rather than --twocaptcha-key and
    # --cdp-endpoint, so the env mapping is spelled out instead of defaulted.
    env_config.apply(args, keys={
        "TWOCAPTCHA_KEY": "key",
        "MEDIUM_CDP_ENDPOINT": "cdp_url",
        "MEDIUM_URL": "url",
    })
    if not args.url:
        p.error("no --url given, and MEDIUM_URL is not set in the environment "
                "or in .env.")
    if args.category:
        logger.warning("--category %r is accepted and ignored: a Medium row has "
                       "no category column. The story's own tags are in the "
                       "`tags` column.", args.category)
    return args


if __name__ == "__main__":
    try:
        sys.exit(main())
    except KeyboardInterrupt:
        sys.exit(1)