{"""JavaScript code generator."""

import json
from curlconverter.parser import ParsedCurl
from curlconverter.generators import register_generator


def _detect_content_type(headers: dict, data: str) -> str:
    """Detect content type from headers or data."""
    if "Content-Type" in headers:
        return headers["Content-Type"]
    if "content-type" in headers:
        return headers["content-type"]
    if data:
        try:
            json.loads(data)
            return "application/json"
        except (json.JSONDecodeError, TypeError):
            pass
    return "application/x-www-form-urlencoded"


@register_generator("javascript")
def generate_javascript(parsed: ParsedCurl) -> str:
    """Generate JavaScript fetch code from parsed curl data."""
    lines = []
    
    lines.append(f"const url = {repr(parsed.url)};")
    lines.append("")
    
    options = {"method": parsed.method}
    headers = dict(parsed.headers) if parsed.headers else {}
    
    if parsed.user_agent and "User-Agent" not in headers and "user-agent" not in headers:
        headers["User-Agent"] = parsed.user_agent
    
    if parsed.auth:
        encoded = btoa(f"{parsed.auth[0]}:{parsed.auth[1]}")
        headers["Authorization"] = f"Basic {encoded}"
    
    if parsed.data:
        content_type = _detect_content_type(headers, parsed.data)
        
        if content_type == "application/json":
            try:
                json_data = json.loads(parsed.data)
                options["body"] = json.dumps(json_data)
                headers["Content-Type"] = "application/json"
            except (json.JSONDecodeError, TypeError):
                options["body"] = repr(parsed.data)
        else:
            options["body"] = repr(parsed.data)
    
    if parsed.cookies:
        headers["Cookie"] = parsed.cookies
    
    if headers:
        lines.append("const headers = " + json.dumps(headers, indent=2) + ";")
        options["headers"] = "headers"
    
    if len(options) > 1:
        lines.append("const options = " + json.dumps(options, indent=2) + ";")
        lines.append("")
        lines.append("fetch(url, options)")
    else:
        lines.append("fetch(url)")
    
    lines.append("  .then(response => {")
    lines.append("    console.log(response.status);")
    lines.append("    return response.text();")
    lines.append("  })")
    lines.append("  .then(data => console.log(data))")
    lines.append("  .catch(error => console.error(error));")
    
    return "\n".join(lines)