import os
import json
from enum import Enum

class BufferState(Enum):
    READY = "ready"
    EMPTY = "empty"
    PLAYING = "playing"
    RUNNING = "running"
    UNDERRUN = "underrun"

class ClipSlot:
    def __init__(self, audio_data=None, sample_rate=48000, prompt="", clip_index=0):
        self.audio_data = audio_data
        self.sample_rate = sample_rate
        self.prompt = prompt
        self.clip_index = clip_index
        self.state = "empty"

class ClipBuffer:
    MAX_RETAINED_CLIPS = 10

    def __init__(self, min_depth=3):
        self.min_depth = min_depth
        self.slots = []
        self._history = []
        self.state = BufferState.EMPTY
        self.underrun_count = 0

    def enqueue_generated(self, clip):
        self.slots.append(clip)
        if len(self.slots) >= self.min_depth:
            self.state = BufferState.RUNNING

    def promote(self):
        if not self.slots:
            self.state = BufferState.UNDERRUN
            self.underrun_count += 1
            return None

        old_playing = self.slots.pop(0)
        # Prune audio data to save memory as per test expectation
        old_playing.audio_data = None
        self._history.append(old_playing)

        if len(self._history) > self.MAX_RETAINED_CLIPS:
            self._history.pop(0)

        if len(self.slots) < self.min_depth:
             self.state = BufferState.UNDERRUN
             self.underrun_count += 1
        else:
             self.state = BufferState.RUNNING

        return old_playing

    def get_playing(self):
        return self.slots[0] if self.slots else None

    def get_queued(self):
        return self.slots[1] if len(self.slots) > 1 else None

    def depth(self):
        return len(self.slots)