scraper_api_client.py

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

A fourth way to run this scraper. Unlike playwright_scraper.py /
puppeteer_scraper.py / selenium_scraper.py, this one manages **no browser and
no CDP session of its own**: it POSTs a URL to 2captcha's separate **Scraper
API** (https://scraper.2captcha.com -- a different product from the Scraping
Browser API the other three reach through --cdp-endpoint), gets HTML back over
plain HTTPS, and feeds it to this project's product_parser.

ON THIS SITE IT IS A FIRST-CLASS PATH, which is unusual
-------------------------------------------------------
A sibling repo's copy of this file opens by warning that its site is a poor
fit for a browserless fetch, and returns five products where a browser
returns sixty. The opposite is true here, and for the same structural reason
read the other way round: Craigslist serves a COMPLETE result list in its
first response, with the page's JSON-LD beside it, and only afterwards
replaces it with a JavaScript grid. A single fetch gets the whole thing.

Measured 2026-09-14, `tasks/sync` with NO CDP routing at all:

    upstream status      200
    HTML                 510,928 bytes
    rows parsed          350
    with a price         346
    with structured data 302
    with coordinates     302
    wall clock           ~5s
    cost                 $0.0005

Against 353 / 349 / 314 / 314 from `playwright_scraper.py` on the same URL:
the same columns, the same currency, within a percent of the same coverage.
Two runs forty seconds apart returned all 350 of the same ids, so the path is
stable rather than lucky.

What it cannot do is walk. `--pages` does not exist here, because batches
beyond the first live behind the site's virtualised grid and need a browser
to slide. If you want more than the first ~350 rows of a listing, use
`playwright_scraper.py --pages N`, or narrow the URL with the site's own
filters and fetch each narrowed URL with this client -- which is cheap enough
that doing so is reasonable.

`--cdp-url` routes the fetch through a Scraping Browser session. It is NOT
needed on this site: the Scraper API's own exit was served without it,
measured above. Use it when you want a specific exit country.

Usage
-----
    python3 scraper_api_client.py \\
        --url "https://www.craigslist.org/search/area/newyork?cat=sss"

    # a price band, which is how you cover more than one fetch can hold
    python3 scraper_api_client.py \\
        --url "https://www.craigslist.org/search/area/newyork?cat=sss&min_price=0&max_price=100"

    # the key comes from $TWOCAPTCHA_KEY and the endpoint from
    # $CRAIGSLIST_CDP_ENDPOINT, so neither needs to be typed -- a secret in
    # argv is readable by anything that can run `ps`

Requires: pip install -r requirements.txt
"""

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_products, detect_bot_challenge,
                            detect_page_state, 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 an OBJECT. Measured 2026-09-23 against the live
    /tasks/sync endpoint: the JSON-encoded string form this client used to
    send was answered with HTTP 422 ("params.waitFor must be an object")
    and was still billed ($0.0005); the same request with an object
    answered HTTP 200. The earlier note here, that the API wanted a
    double-encoded string, no longer describes the API.

    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",       # {"status": verdict, "http_code": target status, "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 status is `http_code`. `status` is the API's own
    # verdict string ("success"), measured 2026-09-23 -- passing it on
    # handed the page classifier a string, so a target 403/503 was never
    # seen. Fall back to `status` only if it is itself an integer.
    upstream_status = body.get("http_code")
    if not isinstance(upstream_status, int):
        legacy = body.get("status")
        upstream_status = legacy if isinstance(legacy, int) and not isinstance(legacy, bool) else None
    logger.info("Upstream page HTTP status %s, %d bytes of HTML.", upstream_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 and the structural
    # served-by-Craigslist test decide the blocked case, because no refusal
    # has been observed on this site to take a marker from.
    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(
            "Craigslist did not serve the Scraper API's request (upstream "
            "HTTP %s, %d bytes) — saved to %s. This has not been observed "
            "here: the Scraper API's own exit was served during this repo's "
            "development. If it persists, --cdp-url routes the fetch "
            "through a Scraping Browser session with a chosen exit. 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). No challenge has been observed on "
                     "Craigslist, so if this persists, compare with a browser "
                     "engine (playwright_scraper.py) or route the fetch through "
                     "a Scraping Browser session with --cdp-url.")
        return 3

    products = parse_products(html, args.url, category=args.category)
    logger.info("Parsed %d products.", 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 products parsed — saved the raw response to %s so you can see "
                       "what actually came back.", dump)
        return 4

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


def parse_args():
    p = argparse.ArgumentParser(
        description="Craigslist scraper -- 2captcha Scraper API edition (no "
                    "local browser). On THIS site that is a first-class path "
                    "rather than a fallback: Craigslist serves a complete "
                    "result list in its first response, so one fetch returned "
                    "350 rows -- against 353 from playwright_scraper.py on "
                    "the same URL, same columns, within a percent of the same "
                    "coverage, for $0.0005 in about five seconds. What it "
                    "cannot do is WALK: there is no --pages here, because "
                    "batches beyond the first live behind the site's "
                    "virtualised grid. --cdp-url is optional -- the API's own "
                    "exit was served without it.")
    # 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 $TWOCAPTCHA_KEY, which is the safer way to pass it.")
    p.add_argument("--url", default=None,
                   help="Craigslist result-list URL, e.g. "
                        "/search/area/newyork?cat=sss -- the first response "
                        "carries the complete first batch, which is all this "
                        "path reads. Required, unless "
                        "CRAIGSLIST_URL is set in the environment or in .env.")
    p.add_argument("--category", default=None, help="Label to tag output rows with. Defaults to the category segment of the URL, so the column is never empty just because the flag was omitted.")
    p.add_argument("--format", choices=["json", "csv", "both"], default="both")
    p.add_argument("--out", default="craigslist_products_scraperapi", help="Output file prefix")
    p.add_argument("--timeout", type=int, default=60,
                   help=f"API-side task timeout in seconds (1-{MAX_API_TIMEOUT}, default 60)")
    p.add_argument("--cdp-url", default=None,
                   help="Route the fetch through an existing browser session over CDP "
                        "(sent as the API's `cdpurl` param), e.g. ws://user:pass@host:port")
    wait = p.add_mutually_exclusive_group()
    wait.add_argument("--wait-text", default=None,
                      help="Wait until this string appears on the page, e.g. '$'. 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. 'li.cl-static-search-result'")
    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(0, "--retries"), 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(0, "--retry-delay"), 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",
        "CRAIGSLIST_CDP_ENDPOINT": "cdp_url",
        "CRAIGSLIST_URL": "url",
    })
    if not args.url:
        p.error("no --url given, and CRAIGSLIST_URL is not set in the environment "
                "or in .env.")
    return args


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