from __future__ import annotations

import asyncio
import base64
from collections import deque
from collections.abc import AsyncIterator
from typing import Any

from ..exceptions import UserError
from ..logger import logger
from ..tracing import Span, SpeechGroupSpanData, speech_group_span, speech_span
from ..tracing.util import time_iso
from .events import (
    VoiceStreamEvent,
    VoiceStreamEventAudio,
    VoiceStreamEventError,
    VoiceStreamEventLifecycle,
)
from .imports import np, npt
from .model import TTSModel, TTSModelSettings
from .pipeline_config import VoicePipelineConfig


def _audio_to_base64(audio_data: list[bytes]) -> str:
    joined_audio_data = b"".join(audio_data)
    return base64.b64encode(joined_audio_data).decode("utf-8")


class StreamedAudioResult:
    """The output of a `VoicePipeline`. Streams events and audio data as they're generated."""

    def __init__(
        self,
        tts_model: TTSModel,
        tts_settings: TTSModelSettings,
        voice_pipeline_config: VoicePipelineConfig,
    ):
        """Create a new `StreamedAudioResult` instance.

        Args:
            tts_model: The TTS model to use.
            tts_settings: The TTS settings to use.
            voice_pipeline_config: The voice pipeline config to use.
        """
        self.tts_model = tts_model
        self.tts_settings = tts_settings
        self.total_output_text = ""
        self.instructions = tts_settings.instructions
        self.text_generation_task: asyncio.Task[Any] | None = None

        self._voice_pipeline_config = voice_pipeline_config
        self._text_buffer = ""
        self._turn_text_buffer = ""
        self._queue: asyncio.Queue[VoiceStreamEvent] = asyncio.Queue()
        self._tasks: list[asyncio.Task[Any]] = []
        self._ordered_tasks: deque[asyncio.Queue[VoiceStreamEvent | None]] = (
            deque()
        )  # New: deque to hold local queues for each text segment
        self._dispatcher_task: asyncio.Task[Any] | None = (
            None  # Task to dispatch audio chunks in order
        )

        self._done_processing = False
        self._buffer_size = tts_settings.buffer_size
        self._started_processing_turn = False
        self._first_byte_received = False
        self._generation_start_time: str | None = None
        self._completed_session = False
        self._stored_exception: BaseException | None = None
        self._tracing_span: Span[SpeechGroupSpanData] | None = None

    async def _start_turn(self):
        if self._started_processing_turn:
            return

        self._tracing_span = speech_group_span()
        self._tracing_span.start()
        self._started_processing_turn = True
        self._first_byte_received = False
        self._generation_start_time = time_iso()
        await self._queue.put(VoiceStreamEventLifecycle(event="turn_started"))

    def _set_task(self, task: asyncio.Task[Any]):
        self.text_generation_task = task

    async def _add_error(self, error: Exception):
        await self._queue.put(VoiceStreamEventError(error))

    def _transform_audio_buffer(
        self, buffer: list[bytes], output_dtype: npt.DTypeLike
    ) -> npt.NDArray[np.int16 | np.float32]:
        combined_buffer = b"".join(buffer)
        if len(combined_buffer) % 2 != 0:
            # np.int16 needs 2-byte alignment; pad odd-length chunks safely.
            combined_buffer += b"\x00"

        np_array = np.frombuffer(combined_buffer, dtype=np.int16)

        if output_dtype == np.int16:
            return np_array
        elif output_dtype == np.float32:
            return (np_array.astype(np.float32) / 32767.0).reshape(-1, 1)
        else:
            raise UserError("Invalid output dtype")

    async def _stream_audio(
        self,
        text: str,
        local_queue: asyncio.Queue[VoiceStreamEvent | None],
        finish_turn: bool = False,
    ):
        with speech_span(
            model=self.tts_model.model_name,
            input=text if self._voice_pipeline_config.trace_include_sensitive_data else "",
            model_config={
                "voice": self.tts_settings.voice,
                "instructions": self.instructions,
                "speed": self.tts_settings.speed,
            },
            output_format="pcm",
            parent=self._tracing_span,
        ) as tts_span:
            try:
                first_byte_received = False
                buffer: list[bytes] = []
                full_audio_data: list[bytes] = []
                pending_byte = b""

                async for chunk in self.tts_model.run(text, self.tts_settings):
                    if not first_byte_received:
                        first_byte_received = True
                        tts_span.span_data.first_content_at = time_iso()

                    if chunk:
                        buffer.append(chunk)
                        full_audio_data.append(chunk)
                        if len(buffer) >= self._buffer_size:
                            combined = pending_byte + b"".join(buffer)
                            if len(combined) % 2 != 0:
                                pending_byte = combined[-1:]
                                combined = combined[:-1]
                            else:
                                pending_byte = b""

                            if combined:
                                audio_np = self._transform_audio_buffer(
                                    [combined], self.tts_settings.dtype
                                )
                                if self.tts_settings.transform_data:
                                    audio_np = self.tts_settings.transform_data(audio_np)
                                await local_queue.put(
                                    VoiceStreamEventAudio(data=audio_np)
                                )  # Use local queue
                            buffer = []
                if buffer:
                    combined = pending_byte + b"".join(buffer)
                else:
                    combined = pending_byte

                if combined:
                    # Final flush: pad the remaining half sample if needed.
                    if len(combined) % 2 != 0:
                        combined += b"\x00"
                    audio_np = self._transform_audio_buffer([combined], self.tts_settings.dtype)
                    if self.tts_settings.transform_data:
                        audio_np = self.tts_settings.transform_data(audio_np)
                    await local_queue.put(VoiceStreamEventAudio(data=audio_np))  # Use local queue

                if self._voice_pipeline_config.trace_include_sensitive_audio_data:
                    tts_span.span_data.output = _audio_to_base64(full_audio_data)
                else:
                    tts_span.span_data.output = ""

                if finish_turn:
                    await local_queue.put(VoiceStreamEventLifecycle(event="turn_ended"))
                else:
                    await local_queue.put(None)  # Signal completion for this segment
            except Exception as e:
                tts_span.set_error(
                    {
                        "message": str(e),
                        "data": {
                            "text": text
                            if self._voice_pipeline_config.trace_include_sensitive_data
                            else "",
                        },
                    }
                )
                logger.error("Error streaming audio: %s", e)

                # Signal completion for whole session because of error
                await local_queue.put(VoiceStreamEventLifecycle(event="session_ended"))
                raise e

    async def _add_text(self, text: str):
        await self._start_turn()

        self._text_buffer += text
        self.total_output_text += text
        self._turn_text_buffer += text

        combined_sentences, self._text_buffer = self.tts_settings.text_splitter(self._text_buffer)

        if combined_sentences:
            local_queue: asyncio.Queue[VoiceStreamEvent | None] = asyncio.Queue()
            self._ordered_tasks.append(local_queue)
            self._tasks.append(
                asyncio.create_task(self._stream_audio(combined_sentences, local_queue))
            )
            if self._dispatcher_task is None:
                self._dispatcher_task = asyncio.create_task(self._dispatch_audio())

    async def _turn_done(self):
        if self._text_buffer:
            local_queue: asyncio.Queue[VoiceStreamEvent | None] = asyncio.Queue()
            self._ordered_tasks.append(local_queue)  # Append the local queue for the final segment
            self._tasks.append(
                asyncio.create_task(
                    self._stream_audio(self._text_buffer, local_queue, finish_turn=True)
                )
            )
            self._text_buffer = ""
        elif self._started_processing_turn:
            local_queue = asyncio.Queue()
            self._ordered_tasks.append(local_queue)
            await local_queue.put(VoiceStreamEventLifecycle(event="turn_ended"))
        self._done_processing = True
        if self._dispatcher_task is None:
            self._dispatcher_task = asyncio.create_task(self._dispatch_audio())
        await asyncio.gather(*self._tasks)

    def _finish_turn(self):
        if self._tracing_span:
            if self._voice_pipeline_config.trace_include_sensitive_data:
                self._tracing_span.span_data.input = self._turn_text_buffer
            else:
                self._tracing_span.span_data.input = ""

            self._tracing_span.finish()
            self._tracing_span = None
        self._turn_text_buffer = ""
        self._started_processing_turn = False

    async def _done(self):
        self._completed_session = True
        await self._wait_for_completion()

    async def _dispatch_audio(self):
        # Dispatch audio chunks from each segment in the order they were added
        while True:
            if len(self._ordered_tasks) == 0:
                if self._completed_session:
                    break
                await asyncio.sleep(0)
                continue
            local_queue = self._ordered_tasks.popleft()
            while True:
                chunk = await local_queue.get()
                if chunk is None:
                    break
                await self._queue.put(chunk)
                if isinstance(chunk, VoiceStreamEventLifecycle):
                    local_queue.task_done()
                    if chunk.event == "turn_ended":
                        self._finish_turn()
                        break
        await self._queue.put(VoiceStreamEventLifecycle(event="session_ended"))

    async def _wait_for_completion(self):
        tasks: list[asyncio.Task[Any]] = self._tasks
        if self._dispatcher_task is not None:
            tasks.append(self._dispatcher_task)
        await asyncio.gather(*tasks)

    def _cleanup_tasks(self):
        self._finish_turn()

        for task in self._tasks:
            if not task.done():
                task.cancel()

        if self._dispatcher_task and not self._dispatcher_task.done():
            self._dispatcher_task.cancel()

        if self.text_generation_task and not self.text_generation_task.done():
            self.text_generation_task.cancel()

    def _check_errors(self):
        for task in self._tasks:
            if task.done():
                if task.exception():
                    self._stored_exception = task.exception()
                    break

    async def stream(self) -> AsyncIterator[VoiceStreamEvent]:
        """Stream the events and audio data as they're generated."""
        saw_session_end = False
        while True:
            try:
                event = await self._queue.get()
            except asyncio.CancelledError:
                break
            if isinstance(event, VoiceStreamEventError):
                self._stored_exception = event.error
                logger.error("Error processing output: %s", event.error)
                break
            if event is None:
                break
            yield event
            if event.type == "voice_stream_event_lifecycle" and event.event == "session_ended":
                saw_session_end = True
                break

        # On the normal completion path, let the producer task finish gracefully so any active
        # trace context can emit `trace_end` before we run cleanup.
        if (
            saw_session_end
            and self.text_generation_task is not None
            and not self.text_generation_task.done()
        ):
            await asyncio.shield(self.text_generation_task)

        self._check_errors()
        self._cleanup_tasks()

        if self._stored_exception:
            raise self._stored_exception
