"""
HCFS Filesystem - FUSE-based virtual filesystem layer.
"""

import os
import stat
import errno
import time
from typing import Dict, Optional
from pathlib import Path

import pyfuse3
from pyfuse3 import FUSEError

from .context_db import ContextDatabase, Context


class HCFSFilesystem(pyfuse3.Operations):
    """
    HCFS FUSE filesystem implementation.
    
    Maps directory navigation to context scope and provides
    virtual files for context access.
    """
    
    def __init__(self, context_db: ContextDatabase, mount_point: str):
        super().__init__()
        self.context_db = context_db
        self.mount_point = mount_point
        self._inode_counter = 1
        self._inode_to_path: Dict[int, str] = {1: "/"}  # Root inode
        self._path_to_inode: Dict[str, int] = {"/": 1}
        
        # Virtual files
        self.CONTEXT_FILE = ".context"
        self.CONTEXT_LIST_FILE = ".context_list"
        self.CONTEXT_PUSH_FILE = ".context_push"
    
    def _get_inode(self, path: str) -> int:
        """Get or create inode for path."""
        if path in self._path_to_inode:
            return self._path_to_inode[path]
        
        self._inode_counter += 1
        inode = self._inode_counter
        self._inode_to_path[inode] = path
        self._path_to_inode[path] = inode
        return inode
    
    def _get_path(self, inode: int) -> str:
        """Get path for inode."""
        return self._inode_to_path.get(inode, "/")
    
    def _is_virtual_file(self, path: str) -> bool:
        """Check if path is a virtual context file."""
        basename = os.path.basename(path)
        return basename in [self.CONTEXT_FILE, self.CONTEXT_LIST_FILE, self.CONTEXT_PUSH_FILE]
    
    async def getattr(self, inode: int, ctx=None) -> pyfuse3.EntryAttributes:
        """Get file attributes."""
        path = self._get_path(inode)
        entry = pyfuse3.EntryAttributes()
        entry.st_ino = inode
        entry.st_uid = os.getuid()
        entry.st_gid = os.getgid()
        entry.st_atime_ns = int(time.time() * 1e9)
        entry.st_mtime_ns = int(time.time() * 1e9)
        entry.st_ctime_ns = int(time.time() * 1e9)
        
        if self._is_virtual_file(path):
            # Virtual files are readable text files
            entry.st_mode = stat.S_IFREG | 0o644
            entry.st_size = 1024  # Placeholder size
        else:
            # Directories
            entry.st_mode = stat.S_IFDIR | 0o755
            entry.st_size = 0
        
        return entry
    
    async def lookup(self, parent_inode: int, name: bytes, ctx=None) -> pyfuse3.EntryAttributes:
        """Look up a directory entry."""
        parent_path = self._get_path(parent_inode)
        child_path = os.path.join(parent_path, name.decode('utf-8'))
        
        # Normalize path
        if child_path.startswith("//"):
            child_path = child_path[1:]
        
        child_inode = self._get_inode(child_path)
        return await self.getattr(child_inode, ctx)
    
    async def opendir(self, inode: int, ctx=None) -> int:
        """Open directory."""
        return inode
    
    async def readdir(self, inode: int, start_id: int, token) -> None:
        """Read directory contents."""
        path = self._get_path(inode)
        
        # Always show virtual context files in every directory
        entries = [
            (self.CONTEXT_FILE, await self.getattr(self._get_inode(os.path.join(path, self.CONTEXT_FILE)))),
            (self.CONTEXT_LIST_FILE, await self.getattr(self._get_inode(os.path.join(path, self.CONTEXT_LIST_FILE)))),
            (self.CONTEXT_PUSH_FILE, await self.getattr(self._get_inode(os.path.join(path, self.CONTEXT_PUSH_FILE)))),
        ]
        
        # Add subdirectories (you might want to make this dynamic based on context paths)
        # For now, allowing any directory to be created by navigation
        
        for i, (name, attr) in enumerate(entries):
            if i >= start_id:
                if not pyfuse3.readdir_reply(token, name.encode('utf-8'), attr, i + 1):
                    break
    
    async def open(self, inode: int, flags: int, ctx=None) -> int:
        """Open file."""
        path = self._get_path(inode)
        if not self._is_virtual_file(path):
            raise FUSEError(errno.EISDIR)
        return inode
    
    async def read(self, fh: int, offset: int, size: int) -> bytes:
        """Read from virtual files."""
        path = self._get_path(fh)
        basename = os.path.basename(path)
        dir_path = os.path.dirname(path)
        
        if basename == self.CONTEXT_FILE:
            # Return aggregated context for current directory
            contexts = self.context_db.get_context_by_path(dir_path, depth=1)
            content = "\\n".join(f"[{ctx.path}] {ctx.content}" for ctx in contexts)
            
        elif basename == self.CONTEXT_LIST_FILE:
            # List contexts at current path
            contexts = self.context_db.list_contexts_at_path(dir_path)
            content = "\\n".join(f"ID: {ctx.id}, Path: {ctx.path}, Author: {ctx.author}, Created: {ctx.created_at}" 
                               for ctx in contexts)
            
        elif basename == self.CONTEXT_PUSH_FILE:
            # Instructions for pushing context
            content = f"Write to this file to push context to path: {dir_path}\\nFormat: <content>"
            
        else:
            content = "Unknown virtual file"
        
        content_bytes = content.encode('utf-8')
        return content_bytes[offset:offset + size]
    
    async def write(self, fh: int, offset: int, data: bytes) -> int:
        """Write to virtual files (context_push only)."""
        path = self._get_path(fh)
        basename = os.path.basename(path)
        dir_path = os.path.dirname(path)
        
        if basename == self.CONTEXT_PUSH_FILE:
            # Push new context to current directory
            content = data.decode('utf-8').strip()
            context = Context(
                id=None,
                path=dir_path,
                content=content,
                author="fuse_user"
            )
            self.context_db.store_context(context)
            return len(data)
        else:
            raise FUSEError(errno.EACCES)
    
    async def mkdir(self, parent_inode: int, name: bytes, mode: int, ctx=None) -> pyfuse3.EntryAttributes:
        """Create directory (virtual - just for navigation)."""
        parent_path = self._get_path(parent_inode)
        new_path = os.path.join(parent_path, name.decode('utf-8'))
        
        if new_path.startswith("//"):
            new_path = new_path[1:]
        
        new_inode = self._get_inode(new_path)
        return await self.getattr(new_inode, ctx)