"""Web page fetch tool - reads content from URLs (safe and stable)."""
from __future__ import annotations

import requests
from bs4 import BeautifulSoup
from core.state import PlanStep, StepResult, StepStatus


# Configuration limits
MAX_RESPONSE_SIZE = 500 * 1024  # 500KB
MAX_OUTPUT_LENGTH = 4000  # Characters
REQUEST_TIMEOUT = 5  # Seconds


def web_fetch(step: PlanStep) -> StepResult:
    """Fetch and read content from a web page (safe and stable).
    
    Args:
        step: PlanStep with payload containing 'url'
        
    Returns:
        StepResult with extracted page content (max 4000 characters)
    """
    url = step.payload.get("url", "").strip()
    
    # Validation: Basic URL check
    if not url:
        return StepResult(
            step_id=step.step_id,
            status=StepStatus.FAILED,
            error="Fetch error: URL not provided"
        )
    
    if not url.startswith(("http://", "https://")):
        return StepResult(
            step_id=step.step_id,
            status=StepStatus.FAILED,
            error="Fetch error: URL must start with http:// or https://"
        )
    
    try:
        # Request configuration
        headers = {
            "User-Agent": "Mozilla/5.0 (compatible; AgentMaxim/1.0)"
        }
        
        # Streaming response with size limit (follow redirects automatically)
        response = requests.get(
            url, 
            headers=headers, 
            timeout=REQUEST_TIMEOUT, 
            stream=True,
            allow_redirects=True
        )
        
        # Content-type validation
        content_type = response.headers.get("content-type", "")
        if "text/html" not in content_type:
            return StepResult(
                step_id=step.step_id,
                status=StepStatus.FAILED,
                error=f"Fetch error: Invalid content-type: {content_type}"
            )
        
        # Read with size limit
        content = b""
        for chunk in response.iter_content(chunk_size=8192):
            content += chunk
            if len(content) > MAX_RESPONSE_SIZE:
                break
        
        if len(content) == 0:
            return StepResult(
                step_id=step.step_id,
                status=StepStatus.FAILED,
                error="Fetch error: Empty response"
            )
        
        # Parse HTML
        soup = BeautifulSoup(content, "html.parser")
        
        # Smart content extraction
        # Priority: main container → article → content divs → body
        main_content = (
            soup.find("main") or 
            soup.find("article") or 
            soup.find("div", class_=["content", "main-content", "article-content"]) or 
            soup.body
        )
        
        if not main_content:
            main_content = soup.find("body")
        
        # Extract text with cleaning
        text = main_content.get_text(separator="\n", strip=True)
        
        # Remove excessive whitespace
        import re
        text = re.sub(r'\n{3,}', '\n\n', text)
        text = re.sub(r' +', ' ', text)
        
        # Limit output length
        if len(text) > MAX_OUTPUT_LENGTH:
            text = text[:MAX_OUTPUT_LENGTH] + "\n\n... (truncated)"
        
        return StepResult(
            step_id=step.step_id,
            status=StepStatus.DONE,
            output_text=text,
            metadata={
                "source": url,
                "content_type": content_type,
                "original_size": len(content),
                "output_size": len(text)
            }
        )
        
    except requests.exceptions.Timeout:
        return StepResult(
            step_id=step.step_id,
            status=StepStatus.FAILED,
            error=f"Fetch error: Request timed out (>{REQUEST_TIMEOUT}s)"
        )
    
    except requests.exceptions.RequestException as e:
        return StepResult(
            step_id=step.step_id,
            status=StepStatus.FAILED,
            error=f"Fetch error: {str(e)}"
        )
    
    except Exception as e:
        return StepResult(
            step_id=step.step_id,
            status=StepStatus.FAILED,
            error=f"Fetch error: {type(e).__name__}: {str(e)}"
        )