"""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("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.data:
        content_type = _detect_content_type(headers, parsed.data)
        
        if content_type == "application/json":
            try:
                json_data = json.loads(parsed.data)
                lines.append("const jsonData = " + json.dumps(json_data, indent=2) + ";")
                options["body"] = "JSON.stringify(jsonData)"
                if "Content-Type" not in headers and "content-type" not in headers:
                    headers["Content-Type"] = "application/json"
            except (json.JSONDecodeError, TypeError):
                lines.append("const data = " + repr(parsed.data) + ";")
                options["body"] = "data"
        else:
            lines.append("const data = " + repr(parsed.data) + ";")
            options["body"] = "data"
    
    if parsed.cookies:
        if "Cookie" not in headers and "cookie" not in headers:
            headers["Cookie"] = parsed.cookies
    
    if headers:
        lines.append("const headers = " + _format_object(headers) + ";")
        options["headers"] = "headers"
    
    if parsed.auth:
        auth_str = f"{parsed.auth[0]}:{parsed.auth[1]}"
        import base64
        encoded = base64.b64encode(auth_str.encode()).decode()
        lines.append("const auth = " + repr(encoded) + ";")
        if "Authorization" not in headers and "content-type" not in headers:
            lines.append("const headersWithAuth = {")
            lines.append("  ...headers,")
            lines.append('  "Authorization": `Basic ${auth}`')
            lines.append("};")
            options["headers"] = "headersWithAuth"
    
    options_str = _format_options(options)
    lines.append("")
    lines.append(f"fetch(url, {options_str})")
    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)


def _format_object(obj: dict) -> str:
    """Format an object for JavaScript code."""
    if not obj:
        return "{}"
    items = []
    for k, v in obj.items():
        items.append(f'  {repr(k)}: {repr(v)}')
    return "{\n" + ",\n".join(items) + "\n}"


def _format_options(opts: dict) -> str:
    """Format fetch options for JavaScript code."""
    if not opts:
        return "{}"
    items = []
    for k, v in opts.items():
        items.append(f"    {k}: {v}")
    return "{\n" + ",\n".join(items) + "\n  }"