import os
import threading
import multiprocessing
from time import sleep
import numpy as np


class EmbeddingManager:
    def __init__(self, emb_size=1024, cache_file="cache/embedding_cache", save_interval=600):
        self.model = None
        self.emb_size = emb_size
        self.cache_file = cache_file
        self.cache_key_file = f'{self.cache_file}.keys'
        self.save_interval = save_interval
        self.cache = multiprocessing.Manager().dict()  # Shared dictionary for multiprocess use
        self.lock = threading.Lock()  # Thread-safe lock

        npy_filename = f'{self.cache_file}.npy'
        # Load cache from file if it exists
        if os.path.exists(npy_filename):
            embedding_data = np.load(npy_filename)
            embedding_keys = open(self.cache_key_file, "r").readlines()
            embedding_keys = [key.strip("\n") for key in embedding_keys]
            for idx, key in enumerate(embedding_keys):
                self.cache[key] = embedding_data[idx]
        print("cache loaded:")
        print(self.cache)

        # Start the periodic saving thread
        self.saving_thread = threading.Thread(target=self._periodic_save, daemon=True)
        self.saving_thread.start()

    def set_model(self, model):
        """Since each process has its own model, model must be set after process is forked"""
        self.model = model

    def get_embedding(self, text_list):
        """
        Search embedding for a given text. If not found, generate using the model, save to cache, and return it.
        """
        if not isinstance(text_list, list):
            raise Exception(f"Invalid parameter type: text_list {type(text_list)}")
        embedding_list = np.zeros((len(text_list), self.emb_size), np.float32)
        if not text_list:
            return embedding_list
        new_texts = []
        new_texts_ori_idx = []
        for idx, text in enumerate(text_list):
            if text in self.cache:
                print(f"find {text} in cache")
                embedding_list[idx] = self.cache[text]
            else:
                new_texts.append(text)
                new_texts_ori_idx.append(idx)

        new_embeddings = self.model.get_embedding(new_texts)

        # Generate embedding if not found in cache
        with self.lock:  # Ensure thread-safe access
            for idx, text in enumerate(new_texts):
                if text not in self.cache:  # Re-check in case another thread added it
                    self.cache[text] = new_embeddings[idx]
                embedding_list[new_texts_ori_idx[idx]] = new_embeddings[idx]
        return embedding_list

    def _periodic_save(self):
        """Periodically save the cache to disk."""
        while True:
            sleep(self.save_interval)
            self.save_now()

    def save_now(self):
        """Manually trigger a save to disk."""
        if os.path.dirname(self.cache_file):
            os.makedirs(os.path.dirname(self.cache_file), 0o755, True)
        tmp_cache_file = self.cache_file + ".tmp"
        tmp_cache_key_file = self.cache_key_file + ".tmp"
        with self.lock:  # Ensure thread-safe access
            keys = self.cache.keys()
            cache_to_save = np.zeros((len(keys), self.emb_size), np.float32)
            for idx, key in enumerate(keys):
                cache_to_save[idx] = self.cache[key]
            np.save(tmp_cache_file, cache_to_save)
            with open(tmp_cache_key_file, 'w') as fp:
                fp.write('\n'.join(keys))
        if os.path.exists(self.cache_file + ".npy"):
            os.rename(self.cache_file + ".npy", self.cache_file + ".npy.bak")
        if os.path.exists(self.cache_key_file):
            os.rename(self.cache_key_file, self.cache_key_file + ".bak")
        os.rename(tmp_cache_file + ".npy", self.cache_file + ".npy")
        os.rename(tmp_cache_key_file, self.cache_key_file)


# Only for testing
class DummyModel:
    def padding_text(self, text):
        padding_factor = 1024 // len(text)
        text = text * padding_factor
        text += text[:1024 - len(text)]
        return text

    def get_embedding(self, text_list):
        embeddings = np.zeros((len(text_list), 1024), np.float32)
        for idx, text in enumerate(text_list):
            text = self.padding_text(text)
            embedding = np.array([ord(c) for c in text], np.float32)
            embeddings[idx] = embedding
        return embeddings

if __name__ == "__main__":
    model = DummyModel()
    manager = EmbeddingManager()
    manager.set_model(model)
    print(manager.get_embedding(["hello"]))
    print(manager.get_embedding(["world"]))
    print(manager.get_embedding(["hello world"]))
    manager.save_now()
    print(manager.get_embedding(["new", "word"]))
    manager.save_now()