from config import AUTO_GEN_SCAN_EXTENSIONS,AUTO_GENERATED_MARKERS,SUPPORTED_TYPES,EXCLUDE_PATTERNS
from pathlib import Path
import pathspec
import json
import os
import pathspec

from langchain_core.documents import Document
from langchain_core.document_loaders.base import BaseLoader
from langchain_community.document_loaders import DirectoryLoader, TextLoader, PyPDFLoader

def is_valid(file_path):
    path = Path(file_path)

    if not path.is_file():
        return False

    name_lower = path.name.lower()
    extension = path.suffix.lower()

    if path.name in {"Dockerfile", "Makefile", "LICENSE", "Procfile", "Rakefile"}:
        return True

    if ".min." in name_lower or ".pb." in name_lower or ".g." in name_lower:
        return False

    if path.name in {".env"} or extension in {".pem", ".key"}:
        return False

    if extension == ".lock":
        return False

    # Reject auto-generated files before touching the size check 
    if extension in AUTO_GEN_SCAN_EXTENSIONS:
        try:
            with open(file_path, "r", errors="ignore") as f:
                header = f.read(512).lower()   # 512 bytes is fast; covers any header
            if any(marker.lower() in header for marker in AUTO_GENERATED_MARKERS):
                return False
        except Exception:
            pass   # If we can't read the header, fall through to normal checks

    size_kb = path.stat().st_size >> 10

    if extension in SUPPORTED_TYPES["no_limit"]:
        return True
    if extension in SUPPORTED_TYPES["limit_2048kb"]:
        return size_kb <= 2048
    if extension in SUPPORTED_TYPES["limit_50kb"]:
        return size_kb <= 50
    if extension in SUPPORTED_TYPES["limit_30kb"]:
        return size_kb <= 30
    if extension in SUPPORTED_TYPES["limit_20kb"]:
        return size_kb <= 20

    if extension != "":
        return False

    try:
        with open(file_path, "rb") as f:
            chunk = f.read(2048)
            if b"\x00" in chunk:
                return False
            chunk.decode("utf-8")
            return True
    except Exception:
        return False


def count_valid_supported_files(directory_path: Path) -> int:
    import os
    import pathspec
    from concurrent.futures import ThreadPoolExecutor

    spec = pathspec.PathSpec.from_lines('gitwildmatch', EXCLUDE_PATTERNS)
    root = str(directory_path)

    # 1. FAST TRAVERSAL: Gather all file paths first
    candidates = []
    stack = [root]
    
    # We define this locally since we can't edit globals. 
    # Checking a set is O(1) and bypasses slow pathspec regex for massive junk folders.
    fast_ignore_dirs = {
        ".git", ".svn", ".hg", "node_modules", "venv", ".venv", "env", "python_env",
        "__pycache__", "dist", "build", "out", "target", "bin", "obj", ".next", 
        ".nuxt", ".vscode", ".idea", "coverage", "tmp", "temp"
    }

    while stack:
        current_dir = stack.pop()

        try:
            with os.scandir(current_dir) as it:
                for entry in it:
                    # Instantly skip giant junk directories before running slow regex
                    if entry.is_dir(follow_symlinks=False) and entry.name in fast_ignore_dirs:
                        continue
                        
                    rel_path = os.path.relpath(entry.path, root)

                    if spec.match_file(rel_path):
                        continue

                    if entry.is_dir(follow_symlinks=False):
                        stack.append(entry.path)
                    elif entry.is_file(follow_symlinks=False):
                        # Do NOT validate here. Just collect the path.
                        candidates.append(entry.path)
                        
        except PermissionError:
            continue

    # At this line, len(candidates) gives you the instant total of 34,645 files!
    
    # 2. MULTITHREADED VALIDATION: Run `is_valid` in parallel
    valid_count = 0
    
    # Using 32 workers is generally a sweet spot for I/O bound disk operations
    with ThreadPoolExecutor(max_workers=32) as executor:
        # executor.map feeds our candidates list into your existing `is_valid` function
        results = executor.map(is_valid, candidates)
        
        # Count how many returned True
        valid_count = sum(1 for is_file_valid in results if is_file_valid)

    return valid_count




def _Custom_ipynbLoader(file_path):
    try:
        with open(file_path, 'r', encoding="utf-8") as f:
            notebook = json.load(f)

        cells = []
        for i, cell in enumerate(notebook.get("cells", [])):
            if cell.get("cell_type") in ["code", "markdown"]:
                source = cell.get("source", "")
                content = "".join(source) if isinstance(source, list) else source
                cells.append(f"[{cell['cell_type'].upper()} CELL {i}]\n{content}")

        extraction = "\n\n".join(cells)
        return [Document(page_content=extraction, metadata={"source": str(file_path)})]
    except Exception:
        return []


class _CustomLoader(BaseLoader):
    def __init__(self, file_path: str):
        self.file_path = file_path

    def load(self):
        if not is_valid(self.file_path):
            return []

        ext = Path(self.file_path).suffix.lower()

        try:
            if ext == ".pdf":
                return PyPDFLoader(self.file_path).load()
            elif ext == ".ipynb":
                return _Custom_ipynbLoader(self.file_path)
            else:
                try:
                    return TextLoader(self.file_path, encoding="utf-8").load()
                except UnicodeDecodeError:
                    # SAFETY: If the file has weird characters, open it manually and ignore errors
                    with open(self.file_path, "r", encoding="utf-8", errors="ignore") as f:
                        text = f.read()
                    return [Document(page_content=text, metadata={"source": self.file_path})]
                    
        except Exception as e:
            print(f"Failed to load {self.file_path}: {e}")
            return []

def load_repository_as_documents(repo_storage_path: Path) -> list[Document]:
    loader = DirectoryLoader(
        repo_storage_path,
        glob="**/*.*",
        exclude=EXCLUDE_PATTERNS,
        loader_cls=_CustomLoader,
        recursive=True,
        silent_errors=True,
        show_progress=True,
        use_multithreading=True,
    )
    
    docs = loader.load()
    print(f"Successfully loaded {len(docs)} documents.")
    return docs