import os
from typing import List
import PyPDF2


class TextFileLoader:
    def __init__(self, path: str, encoding: str = "utf-8"):
        self.documents = []
        self.path = path
        self.encoding = encoding

    def load(self):
        if os.path.isdir(self.path):
            self.load_directory()
        elif os.path.isfile(self.path) and self.path.endswith(".txt"):
            self.load_file()
        else:
            raise ValueError(
                "Provided path is neither a valid directory nor a .txt file."
            )

    def load_file(self):
        with open(self.path, "r", encoding=self.encoding) as f:
            self.documents.append(f.read())

    def load_directory(self):
        for root, _, files in os.walk(self.path):
            for file in files:
                if file.endswith(".txt"):
                    with open(
                        os.path.join(root, file), "r", encoding=self.encoding
                    ) as f:
                        self.documents.append(f.read())

    def load_documents(self):
        self.load()
        return self.documents


class CharacterTextSplitter:
    def __init__(
        self,
        chunk_size: int = 1000,
        chunk_overlap: int = 200,
    ):
        assert (
            chunk_size > chunk_overlap
        ), "Chunk size must be greater than chunk overlap"

        self.chunk_size = chunk_size
        self.chunk_overlap = chunk_overlap

    def split(self, text: str) -> List[str]:
        paragraphs = text.split('\n\n')
        chunks = []
        current_chunk = ""
        
        for paragraph in paragraphs:
            if len(current_chunk) + len(paragraph) > self.chunk_size:
                if current_chunk:
                    chunks.append(current_chunk.strip())
                if len(paragraph) > self.chunk_size:
                    words = paragraph.split()
                    current_chunk = ""
                    for word in words:
                        if len(current_chunk) + len(word) + 1 > self.chunk_size:
                            chunks.append(current_chunk.strip())
                            current_chunk = word
                        else:
                            current_chunk += " " + word if current_chunk else word
                else:
                    current_chunk = paragraph
            else:
                if current_chunk:
                    current_chunk += "\n\n" + paragraph
                else:
                    current_chunk = paragraph
        
        if current_chunk:
            chunks.append(current_chunk.strip())
            
        final_chunks = []
        for chunk in chunks:
            if len(chunk) > 8000:
                words = chunk.split()
                current = ""
                for word in words:
                    if len(current) + len(word) + 1 > 8000:
                        final_chunks.append(current.strip())
                        current = word
                    else:
                        current += " " + word if current else word
                if current:
                    final_chunks.append(current.strip())
            else:
                final_chunks.append(chunk)
                
        return final_chunks

    def split_texts(self, texts: List[str]) -> List[str]:
        chunks = []
        for text in texts:
            chunks.extend(self.split(text))
        return chunks


class PDFLoader:
    def __init__(self, path: str):
        self.documents = []
        self.path = path
        print(f"PDFLoader initialized with path: {self.path}")

    def load(self):
        print(f"Loading PDF from path: {self.path}")
        print(f"Path exists: {os.path.exists(self.path)}")
        print(f"Is file: {os.path.isfile(self.path)}")
        print(f"Is directory: {os.path.isdir(self.path)}")
        print(f"File permissions: {oct(os.stat(self.path).st_mode)[-3:]}")
        
        try:
            # Try to open the file first to verify access
            with open(self.path, 'rb') as test_file:
                pass
            
            # If we can open it, proceed with loading
            self.load_file()
            
        except IOError as e:
            print(f"IOError while accessing file: {str(e)}")
            raise ValueError(f"Cannot access file at '{self.path}': {str(e)}")
        except Exception as e:
            print(f"Unexpected error while processing file: {str(e)}")
            raise ValueError(f"Error processing file at '{self.path}': {str(e)}")

    def load_file(self):
        with open(self.path, 'rb') as file:
            # Create PDF reader object
            pdf_reader = PyPDF2.PdfReader(file)
            print(f"PDF loaded successfully. Number of pages: {len(pdf_reader.pages)}")
            
            # Extract text from each page
            text = ""
            for i, page in enumerate(pdf_reader.pages):
                page_text = page.extract_text()
                if not page_text.strip():
                    print(f"Warning: Page {i+1} appears to be empty or unreadable")
                text += page_text + "\n"
                print(f"Processed page {i+1}, extracted {len(page_text)} characters")
            
            if not text.strip():
                print("Warning: No text was extracted from the PDF")
            else:
                print(f"Successfully extracted {len(text)} characters of text")
            
            self.documents.append(text)

    def load_directory(self):
        for root, _, files in os.walk(self.path):
            for file in files:
                if file.lower().endswith('.pdf'):
                    file_path = os.path.join(root, file)
                    with open(file_path, 'rb') as f:
                        pdf_reader = PyPDF2.PdfReader(f)
                        
                        # Extract text from each page
                        text = ""
                        for page in pdf_reader.pages:
                            text += page.extract_text() + "\n"
                        
                        self.documents.append(text)

    def load_documents(self):
        self.load()
        return self.documents


if __name__ == "__main__":
    loader = TextFileLoader("data/KingLear.txt")
    loader.load()
    splitter = CharacterTextSplitter()
    chunks = splitter.split_texts(loader.documents)
    print(len(chunks))
    print(chunks[0])
    print("--------")
    print(chunks[1])
    print("--------")
    print(chunks[-2])
    print("--------")
    print(chunks[-1])