"""Zip introspection helpers for category-specific version metadata.

Parsed once at upload time and stored on the Version row, so the detail page
never re-reads large archives. All functions take the on-disk path of an
adopted file (under MEDIA_ROOT) and return plain dicts/values.
"""

import json
import zipfile


def _open_zip(path):
    """Return a ZipFile for the path (None when it's not a zip)."""
    try:
        return zipfile.ZipFile(path)
    except (zipfile.BadZipFile, OSError):
        return None


def read_pack_mcmeta(path):
    """Extract the NoN-relevant data from a datapack's pack.mcmeta.

    Returns (pack_format, description) or (None, '').
    """
    zf = _open_zip(path)
    if zf is None:
        return None, ''
    try:
        try:
            data = json.loads(zf.read('pack.mcmeta').decode('utf-8', 'replace'))
        except (KeyError, json.JSONDecodeError):
            return None, ''
        pack = data.get('pack') or {}
        try:
            pack_format = int(pack.get('pack_format'))
        except (TypeError, ValueError):
            pack_format = None
        description = pack.get('description', '') or ''
        if isinstance(description, (dict, list)):
            description = json.dumps(description)
        return pack_format, str(description)
    finally:
        zf.close()


def parse_mods_manifest(path, filename=''):
    """Inspect a modpack archive and build a manifest for the Mods tab.

    - Modrinth .mrpack: modrinth.index.json → dependencies
    - Curseforge modpack: manifest.json → files array
    - Classic folder layout: minecraft/mods/*.jar
    Returns a dict: {source, files: [...]}.
    """
    zf = _open_zip(path)
    if zf is None:
        return {'source': 'unknown', 'files': []}

    try:
        names = set(zf.namelist())

        if filename.lower().endswith('.mrpack') or 'modrinth.index.json' in names:
            try:
                index = json.loads(zf.read('modrinth.index.json').decode('utf-8', 'replace'))
            except (KeyError, json.JSONDecodeError):
                index = {}
            deps = []
            for dep in index.get('dependencies') or []:
                deps.append({
                    'name': dep.get('file_name') or dep.get('project_id', 'unknown'),
                    'version_id': dep.get('version_id'),
                    'type': dep.get('dependency_type', ''),
                })
            return {'source': 'modrinth', 'files': deps}

        if 'manifest.json' in names:
            try:
                manifest = json.loads(zf.read('manifest.json').decode('utf-8', 'replace'))
            except (KeyError, json.JSONDecodeError):
                manifest = {}
            files = []
            for entry in manifest.get('files') or []:
                files.append({
                    'name': entry.get('fileName', entry.get('projectID', 'unknown')),
                    'project_id': entry.get('projectID'),
                    'file_id': entry.get('fileID'),
                })
            if files:
                return {'source': 'curseforge', 'files': files}

        mods = []
        prefix = 'minecraft/mods/'
        for name in sorted(names):
            if name.startswith(prefix) and not name.endswith('/'):
                mods.append({'name': name[len(prefix):]})
        if mods:
            return {'source': 'folder', 'files': mods}

        return {'source': 'unknown', 'files': []}
    finally:
        zf.close()