main.py

# main.py
import os
import re
import json
import base64
import stat
import shutil
import asyncio
import logging
import sys
from typing import List, Optional
from datetime import datetime

import httpx
import git
from fastapi import FastAPI, HTTPException, Request, Query
from fastapi.responses import JSONResponse, PlainTextResponse
from pydantic import BaseModel, Field
from pydantic_settings import BaseSettings

# ------------------------- Settings -------------------------
class Settings(BaseSettings):
    GEMINI_API_KEY: str = Field("", env="GEMINI_API_KEY")
    GITHUB_TOKEN: str = Field("", env="GITHUB_TOKEN")
    GITHUB_USERNAME: str = Field("", env="GITHUB_USERNAME")
    STUDENT_SECRET: str = Field("", env="STUDENT_SECRET")
    LOG_FILE_PATH: str = Field("logs/app.log", env="LOG_FILE_PATH")
    MAX_CONCURRENT_TASKS: int = Field(2, env="MAX_CONCURRENT_TASKS")
    KEEP_ALIVE_INTERVAL_SECONDS: int = Field(30, env="KEEP_ALIVE_INTERVAL_SECONDS")
    GITHUB_API_BASE: str = Field("https://api.github.com", env="GITHUB_API_BASE")
    GITHUB_PAGES_BASE: Optional[str] = None

    class Config:
        env_file = ".env"
        env_file_encoding = "utf-8"

settings = Settings()
if not settings.GITHUB_PAGES_BASE:
    settings.GITHUB_PAGES_BASE = f"https://{settings.GITHUB_USERNAME}.github.io"

# ------------------------- Logging -------------------------
os.makedirs(os.path.dirname(settings.LOG_FILE_PATH), exist_ok=True)
logger = logging.getLogger("task_receiver")
logger.setLevel(logging.INFO)
console_handler = logging.StreamHandler(sys.stdout)
file_handler = logging.FileHandler(settings.LOG_FILE_PATH, mode="a", encoding="utf-8")
fmt = logging.Formatter("%(asctime)s [%(levelname)s] %(message)s")
console_handler.setFormatter(fmt)
file_handler.setFormatter(fmt)
logger.handlers = []
logger.addHandler(console_handler)
logger.addHandler(file_handler)
logger.propagate = False

def flush_logs():
    try:
        sys.stdout.flush()
        sys.stderr.flush()
        for h in logger.handlers:
            try:
                h.flush()
            except Exception:
                pass
    except Exception:
        pass

# ------------------------- Models -------------------------
class Attachment(BaseModel):
    name: str
    url: str  # data URI or http(s) url

class TaskRequest(BaseModel):
    task: str
    email: str
    round: int
    brief: str
    evaluation_url: str
    nonce: str
    secret: str
    attachments: List[Attachment] = []

# ------------------------- App & Globals -------------------------
app = FastAPI(title="Automated Task Receiver & Processor", description="LLM-driven code generation and deployment")
background_tasks_list: List[asyncio.Task] = []
task_semaphore = asyncio.Semaphore(settings.MAX_CONCURRENT_TASKS)
last_received_task: Optional[dict] = None
GEMINI_API_URL = "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash-preview-05-20:generateContent"

# ------------------------- Utility -------------------------
def verify_secret(secret_from_request: str) -> bool:
    return secret_from_request == settings.STUDENT_SECRET

def safe_makedirs(path: str):
    os.makedirs(path, exist_ok=True)

def remove_local_path(path: str):
    if not os.path.exists(path):
        return
    def onerror(func, path_arg, exc_info):
        try:
            os.chmod(path_arg, stat.S_IWUSR)
            func(path_arg)
        except Exception as exc:
            logger.exception(f"Failed in rmtree on {path_arg}: {exc}")
            raise
    logger.info(f"[CLEANUP] Removing local directory: {path}")
    shutil.rmtree(path, onerror=onerror)
    flush_logs()

# ------------------------- Attachment helpers -------------------------
def is_image_data_uri(data_uri: str) -> bool:
    if not data_uri or not data_uri.startswith("data:"):
        return False
    return re.search(r"data:image/[^;]+;base64,", data_uri, re.IGNORECASE) is not None

def data_uri_to_gemini_part(data_uri: str) -> Optional[dict]:
    if not data_uri or not data_uri.startswith("data:"):
        return None
    match = re.search(r"data:(?P<mime_type>[^;]+);base64,(?P<base64_data>.*)", data_uri, re.IGNORECASE)
    if not match:
        return None
    mime_type = match.group('mime_type')
    base64_data = match.group('base64_data')
    if not mime_type.startswith("image/"):
        return None
    return {"inlineData": {"data": base64_data, "mimeType": mime_type}}

async def attachment_to_gemini_part(attachment_url: str) -> Optional[dict]:
    if not attachment_url:
        return None
    if attachment_url.startswith("data:"):
        return data_uri_to_gemini_part(attachment_url)
    if attachment_url.startswith(("http://", "https://")):
        try:
            async with httpx.AsyncClient(timeout=15) as client:
                resp = await client.get(attachment_url)
                resp.raise_for_status()
                mime = resp.headers.get("Content-Type", "")
                if not mime.startswith("image/"):
                    logger.info(f"[ATTACHMENT] Skipping non-image MIME: {mime}")
                    return None
                b64 = base64.b64encode(resp.content).decode("utf-8")
                return {"inlineData": {"data": b64, "mimeType": mime}}
        except Exception as e:
            logger.warning(f"[ATTACHMENT] Failed to fetch/encode attachment {attachment_url}: {e}")
            return None
    return None

# ------------------------- Filesystem Save Helpers -------------------------
async def save_generated_files_locally(task_id: str, files: dict) -> str:
    base_dir = os.path.join(os.getcwd(), "generated_tasks")
    task_dir = os.path.join(base_dir, task_id)
    safe_makedirs(task_dir)
    logger.info(f"[LOCAL_SAVE] Saving generated files to: {task_dir}")
    for filename, content in files.items():
        file_path = os.path.join(task_dir, filename)
        try:
            with open(file_path, "w", encoding="utf-8") as f:
                f.write(content)
            logger.info(f"   -> Saved: {filename} (bytes: {len(content)})")
        except Exception as e:
            logger.exception(f"Failed to save generated file {filename}: {e}")
            raise
    flush_logs()
    return task_dir

async def save_attachments_locally(task_dir: str, attachments: List[Attachment]) -> List[str]:
    saved_files = []
    logger.info(f"[ATTACHMENTS] Processing {len(attachments)} attachments for {task_dir}")
    async with httpx.AsyncClient(timeout=30) as client:
        for attachment in attachments:
            filename = attachment.name
            url = attachment.url
            file_bytes = None
            if not filename or not url:
                logger.warning(f"Skipping invalid attachment entry: {filename}")
                continue
            try:
                if url.startswith("data:"):
                    m = re.search(r"base64,(.*)", url, re.IGNORECASE)
                    if m:
                        file_bytes = base64.b64decode(m.group(1))
                elif url.startswith(("http://", "https://")):
                    resp = await client.get(url)
                    resp.raise_for_status()
                    file_bytes = resp.content
                if file_bytes is None:
                    logger.warning(f"No content for attachment: {filename}")
                    continue
                file_path = os.path.join(task_dir, filename)
                with open(file_path, "wb") as f:
                    f.write(file_bytes)
                logger.info(f"   -> Saved Attachment: {filename} (bytes: {len(file_bytes)})")
                saved_files.append(filename)
            except Exception as e:
                logger.exception(f"Failed to save attachment {filename}: {e}")
    flush_logs()
    return saved_files

# ------------------------- GitHub helpers -------------------------
async def setup_local_repo(local_path: str, repo_name: str, repo_url_auth: str, repo_url_http: str, round_index: int) -> git.Repo:
    github_token = settings.GITHUB_TOKEN
    headers = {
        "Authorization": f"token {github_token}",
        "Accept": "application/vnd.github.v3+json",
        "X-GitHub-Api-Version": "2022-11-28"
    }
    async with httpx.AsyncClient(timeout=45) as client:
        try:
            if round_index == 1:
                logger.info(f"[GIT] R1: Creating remote repo '{repo_name}'")
                payload = {"name": repo_name, "private": False, "auto_init": True}
                resp = await client.post(f"{settings.GITHUB_API_BASE}/user/repos", json=payload, headers=headers)
                resp.raise_for_status()
                repo = git.Repo.init(local_path)
                repo.create_remote('origin', repo_url_auth)
                logger.info("[GIT] Local repo initialized")
            else:
                logger.info(f"[GIT] R{round_index}: Cloning {repo_url_http}")
                repo = git.Repo.clone_from(repo_url_auth, local_path)
                logger.info("[GIT] Cloned repo")
            flush_logs()
            return repo
        except httpx.HTTPStatusError as e:
            logger.exception(f"GitHub API error: {getattr(e.response, 'text', '')}")
            raise
        except git.GitCommandError as e:
            logger.exception(f"Git command error: {e}")
            raise

async def commit_and_publish(repo: git.Repo, task_id: str, round_index: int, repo_name: str) -> dict:
    github_username = settings.GITHUB_USERNAME
    github_token = settings.GITHUB_TOKEN
    headers = {
        "Authorization": f"token {github_token}",
        "Accept": "application/vnd.github.v3+json",
        "X-GitHub-Api-Version": "2022-11-28"
    }
    repo_url_http = f"https://github.com/{github_username}/{repo_name}"
    async with httpx.AsyncClient(timeout=45) as client:
        try:
            repo.git.add(A=True)
            commit_message = f"Task {task_id} - Round {round_index}: automated update"
            repo.index.commit(commit_message)
            commit_sha = repo.head.object.hexsha
            logger.info(f"[GIT] Committed: {commit_sha}")
            repo.git.branch('-M', 'main')
            repo.git.push('--set-upstream', 'origin', 'main', force=True)
            logger.info("[GIT] Pushed to origin/main")

            # Configure GitHub Pages with retries
            pages_api_url = f"{settings.GITHUB_API_BASE}/repos/{github_username}/{repo_name}/pages"
            pages_payload = {"source": {"branch": "main", "path": "/"}}
            pages_max_retries = 5
            pages_base_delay = 3
            for attempt in range(pages_max_retries):
                try:
                    pages_response = await client.get(pages_api_url, headers=headers)
                    is_configured = (pages_response.status_code == 200)
                    if is_configured:
                        await client.put(pages_api_url, json=pages_payload, headers=headers)
                    else:
                        await client.post(pages_api_url, json=pages_payload, headers=headers)
                    logger.info("[GIT] Pages configured")
                    break
                except httpx.HTTPStatusError as e:
                    text = getattr(e.response, "text", "")
                    if e.response.status_code == 422 and "main branch must exist" in text and attempt < pages_max_retries - 1:
                        delay = pages_base_delay * (2 ** attempt)
                        logger.warning(f"[GIT] Pages timing issue, retrying in {delay}s")
                        await asyncio.sleep(delay)
                        continue
                    logger.exception(f"[GIT] Pages configuration failed: {text}")
                    raise

            await asyncio.sleep(5)  # allow pages to deploy
            pages_url = f"{settings.GITHUB_PAGES_BASE}/{repo_name}/"
            flush_logs()
            return {"repo_url": repo_url_http, "commit_sha": commit_sha, "pages_url": pages_url}
        except git.GitCommandError as e:
            logger.exception("Git operation failed during deployment.")
            raise
        except httpx.HTTPStatusError as e:
            logger.exception("GitHub API error during deployment.")
            raise

# ------------------------- Gemini / LLM helpers -------------------------
async def call_gemini_api(contents: list, system_prompt: str, response_schema: dict, max_retries: int = 3, timeout: int = 60) -> dict:
    payload = {
        "contents": contents,
        "systemInstruction": {"parts": [{"text": system_prompt}]},
        "generationConfig": {
            "responseMimeType": "application/json",
            "responseSchema": response_schema
        }
    }
    base_delay = 1
    for attempt in range(max_retries):
        try:
            if not settings.GEMINI_API_KEY:
                raise Exception("GEMINI_API_KEY not configured.")
            url = f"{GEMINI_API_URL}?key={settings.GEMINI_API_KEY}"
            async with httpx.AsyncClient(timeout=timeout) as client:
                resp = await client.post(url, json=payload, headers={"Content-Type": "application/json"})
                resp.raise_for_status()
                result = resp.json()
                candidates = result.get("candidates", [])
                if not candidates:
                    raise ValueError("No candidates in LLM response")
                content_parts = candidates[0].get("content", {}).get("parts", [])
                if not content_parts:
                    raise ValueError("No content parts in candidate")
                json_text = content_parts[0].get("text")
                return json.loads(json_text)
        except httpx.HTTPStatusError as e:
            logger.warning(f"[GEMINI] HTTP error attempt {attempt+1}: {e}")
        except (httpx.RequestError, KeyError, json.JSONDecodeError, ValueError) as e:
            logger.warning(f"[GEMINI] Processing error attempt {attempt+1}: {e}")
        if attempt < max_retries - 1:
            delay = base_delay * (2 ** attempt)
            logger.info(f"[GEMINI] Retrying in {delay}s...")
            await asyncio.sleep(delay)
    raise Exception("LLM generation failed after retries")

# ------------------------- Round 2 surgical update (Base.py style) -------------------------
async def call_llm_round2_surgical_update(task_id: str, brief: str, existing_index_html: str) -> dict:
    system_prompt = (
        "You are an expert full-stack engineer tasked with making SURGICAL and MINIMAL changes. "
        "Your MOST CRITICAL instruction is to preserve the existing application's core logic and structure. "
        "Only apply the specific changes requested in the 'New Brief'. "
        "Return a JSON object with 'index.html', 'README.md', and 'LICENSE'. "
        "If README.md / LICENSE exist, copy them verbatim unless a change is strictly required."
    )
    response_schema = {
        "type": "OBJECT",
        "properties": {
            "index.html": {"type": "STRING"},
            "README.md": {"type": "STRING"},
            "LICENSE": {"type": "STRING"},
        },
        "required": ["index.html", "README.md", "LICENSE"]
    }
    prompt = (
        f"UPDATE INSTRUCTION (SAFE MODE):\n\n"
        f"New Brief: {brief}\n\n"
        f"--- EXISTING index.html START ---\n{existing_index_html}\n--- EXISTING index.html END ---\n\n"
        "Only make the minimal changes necessary to implement the brief. Do NOT remove or break core scripts, event handlers, or layout. "
        "Return FULL JSON with 'index.html', 'README.md', 'LICENSE'. If you make no changes to README/LICENSE, copy their existing contents."
    )

    contents = [{"parts": [{"text": prompt}]}]

    try:
        result = await call_gemini_api(contents=contents, system_prompt=system_prompt, response_schema=response_schema, max_retries=4, timeout=90)
    except Exception as e:
        logger.exception(f"[ROUND2] LLM call failed: {e}")
        # Fallback: return existing index.html and placeholders for readme/license
        return {"index.html": existing_index_html or "<!-- original index.html preserved due to LLM failure -->",
                "README.md": "", "LICENSE": ""}

    # Safety checks (Safe Mode)
    new_html = (result.get("index.html") or "").strip()
    if not new_html:
        logger.warning("[SAFE] LLM returned empty index.html — reverting to existing.")
        result["index.html"] = existing_index_html
    else:
        # If LLM output is grossly shorter than original (possible destructive rewrite), reject it.
        try:
            orig_len = len(existing_index_html or "")
            new_len = len(new_html)
            if orig_len > 0 and new_len < max(200, int(orig_len * 0.3)):  # threshold: not less than 30% (and at least 200 chars)
                logger.warning("[SAFE] LLM index.html appears destructive (too small). Reverting to existing.")
                result["index.html"] = existing_index_html
        except Exception:
            # if anything goes wrong in safety checks, revert
            result["index.html"] = existing_index_html

    # Ensure README and LICENSE exist (if LLM didn't return them)
    result["README.md"] = result.get("README.md") or ""
    result["LICENSE"] = result.get("LICENSE") or ""
    return result

# ------------------------- Notifier -------------------------
async def notify_evaluation_server(evaluation_url: str, email: str, task_id: str, round_index: int, nonce: str, repo_url: str, commit_sha: str, pages_url: str) -> bool:
    payload = {
        "email": email,
        "task": task_id,
        "round": round_index,
        "nonce": nonce,
        "repo_url": repo_url,
        "commit_sha": commit_sha,
        "pages_url": pages_url
    }
    max_retries = 3
    base_delay = 1
    logger.info(f"[NOTIFY] Notifying evaluation server at {evaluation_url}")
    for attempt in range(max_retries):
        try:
            async with httpx.AsyncClient(timeout=10) as client:
                resp = await client.post(evaluation_url, json=payload)
                resp.raise_for_status()
                logger.info(f"[NOTIFY] Notification succeeded: {resp.status_code}")
                flush_logs()
                return True
        except httpx.HTTPStatusError as e:
            logger.warning(f"[NOTIFY] HTTP error attempt {attempt+1}: {e}")
        except httpx.RequestError as e:
            logger.warning(f"[NOTIFY] Request error attempt {attempt+1}: {e}")
        if attempt < max_retries - 1:
            await asyncio.sleep(base_delay * (2 ** attempt))
    logger.error("[NOTIFY] Failed to notify evaluation server after retries.")
    flush_logs()
    return False

# ------------------------- Main orchestration -------------------------
async def generate_files_and_deploy(task_data: TaskRequest):
    acquired = False
    try:
        await task_semaphore.acquire()
        acquired = True
        logger.info(f"[PROCESS START] Task: {task_data.task} Round: {task_data.round}")
        flush_logs()

        task_id = task_data.task
        email = task_data.email
        round_index = task_data.round
        brief = task_data.brief
        evaluation_url = task_data.evaluation_url
        nonce = task_data.nonce
        attachments = task_data.attachments or []

        repo_name = task_id.replace(" ", "-").lower()
        github_username = settings.GITHUB_USERNAME
        github_token = settings.GITHUB_TOKEN
        repo_url_auth = f"https://{github_username}:{github_token}@github.com/{github_username}/{repo_name}.git"
        repo_url_http = f"https://github.com/{github_username}/{repo_name}"

        base_dir = os.path.join(os.getcwd(), "generated_tasks")
        local_path = os.path.join(base_dir, task_id)

        # Cleanup local path
        if os.path.exists(local_path):
            try:
                remove_local_path(local_path)
            except Exception as e:
                logger.exception(f"Cleanup failed for {local_path}: {e}")
                raise
        safe_makedirs(local_path)

        # Setup repo (init or clone)
        repo = await setup_local_repo(local_path, repo_name, repo_url_auth, repo_url_http, round_index)

        # --- Prepare attachment data for LLM ---
        image_parts = []
        for attachment in attachments:
            part = await attachment_to_gemini_part(attachment.url)
            if part:
                image_parts.append(part)

        # Build explicit file reference list for LLM
        attachment_descriptions = ""
        if attachments:
            attachment_descriptions = "\nThe following attachments are provided (saved in the same folder):\n"
            for att in attachments:
                attachment_descriptions += f"- {att.name}\n"
            attachment_descriptions += (
                "Use these exact file names in your HTML (for example: "
                "<img src='sample.png'>). Do NOT rename or use external links.\n"
            )

        # --- Round 1: Full generation ---
        if round_index == 1:
            logger.info("[WORKFLOW] Round 1: full generation")

            # Add filenames info directly to the LLM prompt
            enriched_brief = f"{brief}\n\n{attachment_descriptions}".strip()

            system_prompt = (
                "You are an expert full-stack engineer. Produce a JSON object with keys 'index.html', 'README.md', and 'LICENSE'. "
                "index.html must be a single-file responsive HTML app using Tailwind CSS. "
                "If image attachments are mentioned below, reference them using <img src='filename'> exactly as provided. "
                "README.md should be professional, LICENSE should contain the full MIT license text."
            )

            response_schema = {
                "type": "OBJECT",
                "properties": {
                    "index.html": {"type": "STRING"},
                    "README.md": {"type": "STRING"},
                    "LICENSE": {"type": "STRING"},
                },
                "required": ["index.html", "README.md", "LICENSE"],
            }

            contents = []
            if image_parts:
                contents.append({"parts": image_parts + [{"text": enriched_brief}]})
            else:
                contents.append({"parts": [{"text": enriched_brief}]})

            generated = await call_gemini_api(
                contents=contents,
                system_prompt=system_prompt,
                response_schema=response_schema,
                max_retries=4,
                timeout=120,
            )

        # --- Round 2+: Surgical Update ---
        else:
            logger.info("[WORKFLOW] Round 2+: surgical update (Base.py style). Loading existing index.html only.")
            existing_index_html = ""
            idx_path = os.path.join(local_path, "index.html")
            if os.path.exists(idx_path):
                try:
                    with open(idx_path, "r", encoding="utf-8") as f:
                        existing_index_html = f.read()
                    logger.info("[WORKFLOW] Read existing index.html for context.")
                except Exception as e:
                    logger.warning(f"[WORKFLOW] Could not read existing index.html: {e}")
                    existing_index_html = ""

            # Add attachments info to round 2 prompt as well
            brief_with_attachments = f"{brief}\n\n{attachment_descriptions}".strip()
            generated = await call_llm_round2_surgical_update(
                task_id=task_id, brief=brief_with_attachments, existing_index_html=existing_index_html
            )

            # Preserve README/LICENSE if LLM didn’t return them
            readme_path = os.path.join(local_path, "README.md")
            license_path = os.path.join(local_path, "LICENSE")
            if not generated.get("README.md") and os.path.exists(readme_path):
                with open(readme_path, "r", encoding="utf-8") as f:
                    generated["README.md"] = f.read()
            if not generated.get("LICENSE") and os.path.exists(license_path):
                with open(license_path, "r", encoding="utf-8") as f:
                    generated["LICENSE"] = f.read()

        # Save generated files locally
        await save_generated_files_locally(task_id, generated)

        # Save attachments into repo folder
        await save_attachments_locally(os.path.join(base_dir, task_id), attachments)

        # Commit and publish
        deployment_info = await commit_and_publish(repo, task_id, round_index, repo_name)

        # Notify evaluation server
        await notify_evaluation_server(
            evaluation_url=evaluation_url,
            email=email,
            task_id=task_id,
            round_index=round_index,
            nonce=nonce,
            repo_url=deployment_info["repo_url"],
            commit_sha=deployment_info["commit_sha"],
            pages_url=deployment_info["pages_url"],
        )

        logger.info(f"[DEPLOYMENT] Success. Repo: {deployment_info['repo_url']} Pages: {deployment_info['pages_url']}")

    except Exception as exc:
        logger.exception(f"[CRITICAL FAILURE] Task {getattr(task_data, 'task', 'unknown')} failed: {exc}")
    finally:
        if acquired:
            task_semaphore.release()
        flush_logs()
        logger.info(
            f"[PROCESS END] Task: {getattr(task_data, 'task', 'unknown')} Round: {getattr(task_data, 'round', 'unknown')}"
        )


# ------------------------- Endpoint handlers -------------------------
def _task_done_callback(task: asyncio.Task):
    try:
        exc = task.exception()
        if exc:
            logger.error(f"[BACKGROUND TASK] Task finished with exception: {exc}")
            logger.exception(exc)
        else:
            logger.info("[BACKGROUND TASK] Task finished successfully.")
    except asyncio.CancelledError:
        logger.warning("[BACKGROUND TASK] Task was cancelled.")
    finally:
        flush_logs()

@app.post("/ready", status_code=200)
async def receive_task(task_data: TaskRequest, request: Request):
    global last_received_task, background_tasks_list
    if not verify_secret(task_data.secret):
        logger.warning(f"Unauthorized attempt for task {task_data.task} from {request.client.host if request.client else 'unknown'}")
        raise HTTPException(status_code=401, detail="Unauthorized: Secret mismatch")

    last_received_task = {
        "task": task_data.task,
        "email": task_data.email,
        "round": task_data.round,
        "brief": (task_data.brief[:250] + "...") if len(task_data.brief) > 250 else task_data.brief,
        "time": datetime.utcnow().isoformat() + "Z"
    }

    bg_task = asyncio.create_task(generate_files_and_deploy(task_data))
    bg_task.add_done_callback(_task_done_callback)
    background_tasks_list.append(bg_task)

    logger.info(f"Received task {task_data.task}. Background processing started.")
    flush_logs()

    return JSONResponse(status_code=200, content={"status": "ready", "message": f"Task {task_data.task} received and processing started."})

@app.get("/")
async def root():
    return {"message": "Task Receiver Service running. POST /ready to submit."}

@app.get("/status")
async def get_status():
    global last_received_task, background_tasks_list
    if last_received_task:
        background_tasks_list[:] = [t for t in background_tasks_list if not t.done()]
        return {"last_received_task": last_received_task, "running_background_tasks": len(background_tasks_list)}
    return {"message": "Awaiting first task submission to /ready"}

@app.get("/health")
async def health():
    return {"status": "ok", "timestamp": datetime.utcnow().isoformat() + "Z"}

@app.get("/logs")
async def get_logs(lines: int = Query(200, ge=1, le=5000)):
    path = settings.LOG_FILE_PATH
    if not os.path.exists(path):
        return PlainTextResponse("Log file not found.", status_code=404)
    try:
        with open(path, "rb") as f:
            f.seek(0, os.SEEK_END)
            file_size = f.tell()
            buffer = bytearray()
            block_size = 1024
            blocks = 0
            # Read from end until we have enough or hit limit
            while file_size > 0 and len(buffer) < lines * 2000 and blocks < 1024:
                read_size = min(block_size, file_size)
                f.seek(file_size - read_size)
                buffer.extend(f.read(read_size))
                file_size -= read_size
                blocks += 1
            text = buffer.decode(errors="ignore").splitlines()
            last_lines = "\n".join(text[-lines:])
            return PlainTextResponse(last_lines)
    except Exception as e:
        logger.exception(f"Error reading log file: {e}")
        return PlainTextResponse(f"Error reading log file: {e}", status_code=500)

# ------------------------- Startup / Shutdown -------------------------
@app.on_event("startup")
async def startup_event():
    async def keep_alive():
        while True:
            try:
                logger.info("[KEEPALIVE] Service heartbeat")
                flush_logs()
            except Exception:
                pass
            await asyncio.sleep(settings.KEEP_ALIVE_INTERVAL_SECONDS)
    asyncio.create_task(keep_alive())

@app.on_event("shutdown")
async def shutdown_event():
    logger.info("[SHUTDOWN] Waiting for background tasks to finish (graceful shutdown)...")
    for t in background_tasks_list:
        if not t.done():
            try:
                t.cancel()
            except Exception:
                pass
    await asyncio.sleep(0.5)
    flush_logs()