#!/usr/bin/env python3

import asyncio
import io
import json
import re
import zipfile
from datetime import datetime

import httpx

from .base import BaseScraper
from .models import (ContestListResult, ContestSummary, MetadataResult,
                     ProblemSummary, SubmitResult, TestCase)

BASE_URL = "https://open.kattis.com"
HEADERS = {
    "User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"
}
TIMEOUT_S = 15.0
CONNECTIONS = 8

TIME_RE = re.compile(
    r"CPU Time limit</span>\s*<span[^>]*>\s*(\d+)\s*seconds?\s*</span>",
    re.DOTALL,
)
MEM_RE = re.compile(
    r"Memory limit</span>\s*<span[^>]*>\s*(\d+)\s*MB\s*</span>",
    re.DOTALL,
)


async def _fetch_text(client: httpx.AsyncClient, url: str) -> str:
    r = await client.get(url, headers=HEADERS, timeout=TIMEOUT_S)
    r.raise_for_status()
    return r.text


async def _fetch_bytes(client: httpx.AsyncClient, url: str) -> bytes:
    r = await client.get(url, headers=HEADERS, timeout=TIMEOUT_S)
    r.raise_for_status()
    return r.content


def _parse_limits(html: str) -> tuple[int, int]:
    tm = TIME_RE.search(html)
    mm = MEM_RE.search(html)
    timeout_ms = int(tm.group(1)) * 1000 if tm else 1000
    memory_mb = int(mm.group(1)) if mm else 1024
    return timeout_ms, memory_mb


def _parse_samples_html(html: str) -> list[TestCase]:
    tests: list[TestCase] = []
    tables = re.finditer(r'<table\s+class="sample"[^>]*>.*?</table>', html, re.DOTALL)
    for table_match in tables:
        table_html = table_match.group(0)
        pres = re.findall(r"<pre>(.*?)</pre>", table_html, re.DOTALL)
        if len(pres) >= 2:
            inp = pres[0].strip()
            out = pres[1].strip()
            tests.append(TestCase(input=inp, expected=out))
    return tests


def _parse_samples_zip(data: bytes) -> list[TestCase]:
    try:
        zf = zipfile.ZipFile(io.BytesIO(data))
    except zipfile.BadZipFile:
        return []
    inputs: dict[str, str] = {}
    outputs: dict[str, str] = {}
    for name in zf.namelist():
        content = zf.read(name).decode("utf-8").strip()
        if name.endswith(".in"):
            key = name[: -len(".in")]
            inputs[key] = content
        elif name.endswith(".ans"):
            key = name[: -len(".ans")]
            outputs[key] = content
    tests: list[TestCase] = []
    for key in sorted(set(inputs) & set(outputs)):
        tests.append(TestCase(input=inputs[key], expected=outputs[key]))
    return tests


def _is_interactive(html: str) -> bool:
    return "This is an interactive problem" in html


def _parse_contests_page(html: str) -> list[ContestSummary]:
    results: list[ContestSummary] = []
    seen: set[str] = set()
    for row_m in re.finditer(r"<tr[^>]*>(.*?)</tr>", html, re.DOTALL):
        row = row_m.group(1)
        link_m = re.search(r'href="/contests/([a-z0-9]+)"[^>]*>([^<]+)</a>', row)
        if not link_m:
            continue
        cid = link_m.group(1)
        name = link_m.group(2).strip()
        if cid in seen:
            continue
        seen.add(cid)
        start_time: int | None = None
        ts_m = re.search(r'data-timestamp="(\d+)"', row)
        if ts_m:
            start_time = int(ts_m.group(1))
        else:
            time_m = re.search(r'<time[^>]+datetime="([^"]+)"', row)
            if time_m:
                try:
                    dt = datetime.fromisoformat(time_m.group(1).replace("Z", "+00:00"))
                    start_time = int(dt.timestamp())
                except Exception:
                    pass
        results.append(ContestSummary(id=cid, name=name, start_time=start_time))
    return results


def _parse_contest_problem_list(html: str) -> list[tuple[str, str]]:
    if "The problems will become available when the contest starts" in html:
        return []
    results: list[tuple[str, str]] = []
    seen: set[str] = set()
    for row_m in re.finditer(r"<tr[^>]*>(.*?)</tr>", html, re.DOTALL):
        row = row_m.group(1)
        link_m = re.search(
            r'href="/contests/[^/]+/problems/([^"]+)"[^>]*>([^<]+)</a>', row
        )
        if not link_m:
            continue
        slug = link_m.group(1)
        name = link_m.group(2).strip()
        if slug in seen:
            continue
        seen.add(slug)
        label_m = re.search(r"<td[^>]*>\s*([A-Z])\s*</td>", row)
        label = label_m.group(1) if label_m else ""
        display = f"{label} - {name}" if label else name
        results.append((slug, display))
    return results


async def _fetch_contest_slugs(
    client: httpx.AsyncClient, contest_id: str
) -> list[tuple[str, str]]:
    try:
        html = await _fetch_text(client, f"{BASE_URL}/contests/{contest_id}/problems")
        return _parse_contest_problem_list(html)
    except httpx.HTTPStatusError:
        return []
    except Exception:
        return []


async def _stream_single_problem(client: httpx.AsyncClient, slug: str) -> None:
    try:
        html = await _fetch_text(client, f"{BASE_URL}/problems/{slug}")
    except Exception:
        return

    timeout_ms, memory_mb = _parse_limits(html)
    interactive = _is_interactive(html)

    tests: list[TestCase] = []
    try:
        zip_data = await _fetch_bytes(
            client,
            f"{BASE_URL}/problems/{slug}/file/statement/samples.zip",
        )
        tests = _parse_samples_zip(zip_data)
    except Exception:
        tests = _parse_samples_html(html)

    combined_input = "\n".join(t.input for t in tests) if tests else ""
    combined_expected = "\n".join(t.expected for t in tests) if tests else ""

    print(
        json.dumps(
            {
                "problem_id": slug,
                "combined": {
                    "input": combined_input,
                    "expected": combined_expected,
                },
                "tests": [{"input": t.input, "expected": t.expected} for t in tests],
                "timeout_ms": timeout_ms,
                "memory_mb": memory_mb,
                "interactive": interactive,
                "multi_test": False,
            }
        ),
        flush=True,
    )


class KattisScraper(BaseScraper):
    @property
    def platform_name(self) -> str:
        return "kattis"

    async def scrape_contest_metadata(self, contest_id: str) -> MetadataResult:
        try:
            async with httpx.AsyncClient() as client:
                slugs = await _fetch_contest_slugs(client, contest_id)
                if slugs:
                    return MetadataResult(
                        success=True,
                        error="",
                        contest_id=contest_id,
                        problems=[
                            ProblemSummary(id=slug, name=name) for slug, name in slugs
                        ],
                        url=f"{BASE_URL}/problems/%s",
                    )
                try:
                    html = await _fetch_text(
                        client, f"{BASE_URL}/problems/{contest_id}"
                    )
                except Exception as e:
                    return self._metadata_error(str(e))
                title_m = re.search(r"<title>([^<]+)</title>", html)
                name = (
                    title_m.group(1).split("\u2013")[0].strip()
                    if title_m
                    else contest_id
                )
                return MetadataResult(
                    success=True,
                    error="",
                    contest_id=contest_id,
                    problems=[ProblemSummary(id=contest_id, name=name)],
                    url=f"{BASE_URL}/problems/%s",
                )
        except Exception as e:
            return self._metadata_error(str(e))

    async def scrape_contest_list(self) -> ContestListResult:
        try:
            async with httpx.AsyncClient() as client:
                html = await _fetch_text(client, f"{BASE_URL}/contests")
            contests = _parse_contests_page(html)
            if not contests:
                return self._contests_error("No contests found")
            return ContestListResult(success=True, error="", contests=contests)
        except Exception as e:
            return self._contests_error(str(e))

    async def stream_tests_for_category_async(self, category_id: str) -> None:
        async with httpx.AsyncClient(
            limits=httpx.Limits(max_connections=CONNECTIONS)
        ) as client:
            slugs = await _fetch_contest_slugs(client, category_id)
            if slugs:
                sem = asyncio.Semaphore(CONNECTIONS)

                async def emit_one(slug: str, _name: str) -> None:
                    async with sem:
                        await _stream_single_problem(client, slug)

                await asyncio.gather(*(emit_one(s, n) for s, n in slugs))
                return

            await _stream_single_problem(client, category_id)

    async def submit(
        self,
        contest_id: str,
        problem_id: str,
        source_code: str,
        language_id: str,
        credentials: dict[str, str],
    ) -> SubmitResult:
        return SubmitResult(
            success=False,
            error="Kattis submit not yet implemented",
            submission_id="",
            verdict="",
        )


if __name__ == "__main__":
    KattisScraper().run_cli()