import os
from typing import List
from PyPDF2 import PdfReader
import re

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]:
        chunks = []
        for i in range(0, len(text), self.chunk_size - self.chunk_overlap):
            chunks.append(text[i : i + self.chunk_size])
        return 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

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

    def load_file(self):
        with open(self.path, 'rb') as file:
            pdf_reader = PdfReader(file)
            text = ""
            for page in pdf_reader.pages:
                text += page.extract_text()
            self.documents.append(text)

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

    def load_documents(self) -> List[str]:
        self.load()
        return self.documents

class SentenceTextSplitter:
    def __init__(
        self,
        chunk_size: int = 1000,
        chunk_overlap: int = 200,
        separator: str = "\n"
    ):
        self.chunk_size = chunk_size
        self.chunk_overlap = chunk_overlap
        self.separator = separator

    def split(self, text: str) -> List[str]:
        # Split the text into sentences
        sentences = re.split(r'(?<=[.!?])\s+', text)
        chunks = []
        current_chunk = []
        current_size = 0

        for sentence in sentences:
            sentence_size = len(sentence)
            
            if current_size + sentence_size > self.chunk_size and current_chunk:
                # If adding this sentence would exceed the chunk size, store the current chunk
                chunks.append(self.separator.join(current_chunk))
                
                # Start a new chunk, keeping some overlap
                overlap_size = 0
                while overlap_size < self.chunk_overlap and current_chunk:
                    overlap_sentence = current_chunk.pop(0)
                    overlap_size += len(overlap_sentence)
                current_chunk = [overlap_sentence] if overlap_size < self.chunk_overlap else []
                current_size = overlap_size
            
            current_chunk.append(sentence)
            current_size += sentence_size

        # Add the last chunk if it's not empty
        if current_chunk:
            chunks.append(self.separator.join(current_chunk))

        return chunks

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


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])