# xbrl_processing/instance_finder.py

import tempfile
import zipfile
import requests
import io

from xbrl_processing.downloader import download_xbrl


def file_contains_ixbrl(text: str) -> bool:
    if not text:
        return False
    t = text.lower()
    return (
        "<ix:" in t or 
        "<ix:non" in t or 
        "<ix:header" in t or
        "xmlns:ix" in t
    )


def file_contains_xbrl_xml(text: str) -> bool:
    if not text:
        return False
    t = text.lower()
    return (
        "<xbrli:" in t or 
        "xmlns:xbrli" in t or 
        "http://www.xbrl.org" in t
    )


def find_esef_xhtml_in_zip(url: str):
    try:
        resp = requests.get(url, timeout=15)
        z = zipfile.ZipFile(io.BytesIO(resp.content))

        candidates = [
            name for name in z.namelist()
            if name.lower().endswith((".xhtml", ".html"))
        ]
        if not candidates:
            return None, None

        for name in candidates:
            try:
                content = z.read(name).decode("utf-8", errors="ignore")
                if file_contains_ixbrl(content):
                    return z, name
            except:
                pass

        for name in candidates:
            if "report" in name.lower():
                return z, name
            if "xbrl" in name.lower():
                return z, name

        largest = max(candidates, key=lambda n: len(z.read(n)))
        return z, largest

    except Exception:
        return None, None


def find_valid_instance(df):
    """
    Returns: (instance_local_path, instance_source_url)
    """
    # ZIP → XHTML
    zip_rows = df[df["Url"].str.contains(".zip", case=False, na=False)]

    if not zip_rows.empty:
        for _, row in zip_rows.iterrows():
            zfile, entry = find_esef_xhtml_in_zip(row["Url"])
            if entry:
                with tempfile.NamedTemporaryFile(suffix=".xhtml", delete=False) as tmp:
                    tmp.write(zfile.read(entry))
                    tmp.flush()
                    return tmp.name, row["Url"]

    # XML → XBRL
    xml_rows = df[
        df["Url"].str.contains(".xml", case=False, na=False) |
        df["Filtype"].str.contains("XBRL", case=False, na=False) |
        df["Url"].str.contains("xbrl", case=False, na=False)
    ]

    if not xml_rows.empty:
        for _, row in xml_rows.iterrows():
            try:
                resp = requests.get(row["Url"], timeout=10)
                chunk = resp.content[:200000].decode("utf-8", errors="ignore")

                if file_contains_xbrl_xml(chunk):
                    with tempfile.NamedTemporaryFile(suffix=".xml", delete=False) as tmp:
                        download_xbrl(row["Url"], tmp.name)
                        return tmp.name, row["Url"]

            except Exception:
                pass

    # Nothing found
    return None, None