"""
Routes for data processing and manipulation (Audio/Image).
"""

import time
import re
from collections import defaultdict
from fastapi import APIRouter, File, UploadFile, Form, HTTPException, Request, Depends, status
from fastapi.responses import StreamingResponse
from pydantic import ValidationError
import json
import logging

from app.schemas import AudioAugmentationOptions, AudioConvertOptions, DatasetEntryMetadata
from app.services.audio_processor import process_audio, convert_audio_format
from app.services.dataset_organizer import analyze_for_organization
from app.services.client_ip import client_ip as _client_ip

router = APIRouter(prefix="/api/process", tags=["Data Processing"])
logger = logging.getLogger(__name__)

# Rate limiter for heavy processing endpoints
_process_rate_store: dict[str, list[float]] = defaultdict(list)
_PROCESS_RATE_WINDOW = 60
_PROCESS_RATE_MAX = 10
_PROCESS_MAX_IPS = 10_000


async def _process_rate_limit(request: Request) -> None:
    client_ip = _client_ip(request)
    now = time.time()
    cutoff = now - _PROCESS_RATE_WINDOW

    if len(_process_rate_store) > _PROCESS_MAX_IPS:
        stale = [ip for ip, ts in _process_rate_store.items() if not ts or all(t <= cutoff for t in ts)]
        for ip in stale:
            del _process_rate_store[ip]

    hits = [t for t in _process_rate_store[client_ip] if t > cutoff]
    if len(hits) >= _PROCESS_RATE_MAX:
        raise HTTPException(
            status_code=status.HTTP_429_TOO_MANY_REQUESTS,
            detail={"code": "rate_limit_exceeded", "message": "Too many processing requests. Please wait."}
        )
    hits.append(now)
    _process_rate_store[client_ip] = hits


async def _read_capped(file: UploadFile, max_bytes: int) -> bytes:
    """Read an UploadFile in chunks, raising 413 if it exceeds max_bytes."""
    chunks = []
    total_read = 0
    chunk_size = 1024 * 1024  # 1 MB chunks
    while True:
        chunk = await file.read(chunk_size)
        if not chunk:
            break
        total_read += len(chunk)
        if total_read > max_bytes:
            raise HTTPException(status_code=413, detail={"code": "file_too_large", "message": f"File too large. Maximum size is {max_bytes // (1024*1024)} MB."})
        chunks.append(chunk)
    return b"".join(chunks)


@router.post("/audio", dependencies=[Depends(_process_rate_limit)])
async def process_audio_endpoint(
    file: UploadFile = File(...),
    options: str = Form(default="{}"),
    mix_file: UploadFile | None = File(default=None),
):
    """
    Process an audio file with the given augmentation options.
    Returns the processed WAV file.
    options is a JSON string; if missing or empty, defaults to all-off.
    mix_file: required when options.mixAudio is true — a second audio file
    to blend into the primary track.
    """
    MAX_PAYLOAD_BYTES = 30 * 1024 * 1024  # 30 MB
    logger.info(f"Received audio processing request for file: {file.filename}")

    # Parse options JSON string into validated Pydantic model
    raw_options = options.strip() if options else "{}"
    if not raw_options:
        raw_options = "{}"
    try:
        parsed_options = AudioAugmentationOptions.model_validate_json(raw_options)
    except (ValidationError, json.JSONDecodeError) as e:
        raise HTTPException(
            status_code=422,
            detail={"code": "invalid_options", "message": f"Invalid options format: {e}"}
        )

    if not file.content_type or not file.content_type.startswith("audio/"):
        raise HTTPException(status_code=400, detail={"code": "invalid_file_type", "message": "Invalid file type. Must be audio."})

    if parsed_options.mix_audio and mix_file is None:
        raise HTTPException(
            status_code=400,
            detail={"code": "missing_mix_file", "message": "mixAudio is enabled but no second file was provided."}
        )
    if mix_file is not None and (not mix_file.content_type or not mix_file.content_type.startswith("audio/")):
        raise HTTPException(status_code=400, detail={"code": "invalid_file_type", "message": "Second file for mixing must be audio."})

    try:
        # Sanitize filename to prevent injection attacks
        safe_filename = re.sub(r'[^a-zA-Z0-9._-]', '_', file.filename or 'audio')
        if safe_filename.endswith('.wav'):
            safe_filename = safe_filename[:-4]

        content = await _read_capped(file, MAX_PAYLOAD_BYTES)
        mix_content = await _read_capped(mix_file, MAX_PAYLOAD_BYTES) if mix_file is not None else None

        # Process audio
        processed_audio = process_audio(content, parsed_options, mix_with_bytes=mix_content)

        # Return as downloadable file
        output_filename = f"processed_{safe_filename}.wav"
        return StreamingResponse(
            processed_audio,
            media_type="audio/wav",
            headers={"Content-Disposition": f"attachment; filename={output_filename}"}
        )

    except ValueError as e:
        raise HTTPException(status_code=400, detail={"code": "validation_error", "message": str(e)})
    except HTTPException:
        # Re-raise as-is (e.g. the 413 file_too_large above) — without this,
        # the bare `except Exception` below catches it too (HTTPException IS
        # an Exception) and replaces a correct 413 with a misleading 500.
        raise
    except Exception as e:
        logger.error(f"Unexpected error in audio processing: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail={"code": "internal_error", "message": "Internal server error during audio processing"})


_CONVERT_MEDIA_TYPES = {
    "wav": "audio/wav",
    "mp3": "audio/mpeg",
    "flac": "audio/flac",
    "ogg": "audio/ogg",
}


@router.post("/audio/convert", dependencies=[Depends(_process_rate_limit)])
async def convert_audio_endpoint(
    file: UploadFile = File(...),
    options: str = Form(default="{}")
):
    """
    Convert an audio file to another format (wav/mp3/flac/ogg).
    Returns the converted file for download.
    options is a JSON string; if missing or empty, defaults to wav @ 192kbps.
    """
    MAX_PAYLOAD_BYTES = 30 * 1024 * 1024  # 30 MB
    logger.info(f"Received audio conversion request for file: {file.filename}")

    raw_options = options.strip() if options else "{}"
    if not raw_options:
        raw_options = "{}"
    try:
        parsed_options = AudioConvertOptions.model_validate_json(raw_options)
    except (ValidationError, json.JSONDecodeError) as e:
        raise HTTPException(
            status_code=422,
            detail={"code": "invalid_options", "message": f"Invalid options format: {e}"}
        )

    if not file.content_type or not file.content_type.startswith("audio/"):
        raise HTTPException(status_code=400, detail={"code": "invalid_file_type", "message": "Invalid file type. Must be audio."})

    try:
        safe_filename = re.sub(r'[^a-zA-Z0-9._-]', '_', file.filename or 'audio')
        # Strip any existing extension so we don't end up with e.g. "song.mp3.flac"
        safe_filename = re.sub(r'\.[a-zA-Z0-9]{1,5}$', '', safe_filename)

        chunks = []
        total_read = 0
        chunk_size = 1024 * 1024  # 1 MB chunks
        while True:
            chunk = await file.read(chunk_size)
            if not chunk:
                break
            total_read += len(chunk)
            if total_read > MAX_PAYLOAD_BYTES:
                raise HTTPException(status_code=413, detail={"code": "file_too_large", "message": f"File too large. Maximum size is {MAX_PAYLOAD_BYTES // (1024*1024)} MB."})
            chunks.append(chunk)
        content = b"".join(chunks)

        converted = convert_audio_format(content, parsed_options)

        target = parsed_options.target_format
        output_filename = f"{safe_filename}.{target}"
        return StreamingResponse(
            converted,
            media_type=_CONVERT_MEDIA_TYPES[target],
            headers={"Content-Disposition": f"attachment; filename={output_filename}"}
        )

    except ValueError as e:
        raise HTTPException(status_code=400, detail={"code": "validation_error", "message": str(e)})
    except HTTPException:
        # Re-raise as-is — see the matching comment in the /audio endpoint
        # above for why this is needed before the bare `except Exception`.
        raise
    except Exception as e:
        logger.error(f"Unexpected error in audio conversion: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail={"code": "internal_error", "message": "Internal server error during audio conversion"})


@router.post("/audio/organize", response_model=DatasetEntryMetadata, dependencies=[Depends(_process_rate_limit)])
async def organize_audio_endpoint(file: UploadFile = File(...)):
    """
    Analyze an audio file and return real acoustic metadata (duration,
    tempo, key, loudness) plus auto-generated tags for dataset tagging
    and categorization. No transformation — read-only analysis.
    """
    MAX_PAYLOAD_BYTES = 30 * 1024 * 1024  # 30 MB
    logger.info(f"Received audio organization request for file: {file.filename}")

    if not file.content_type or not file.content_type.startswith("audio/"):
        raise HTTPException(status_code=400, detail={"code": "invalid_file_type", "message": "Invalid file type. Must be audio."})

    try:
        chunks = []
        total_read = 0
        chunk_size = 1024 * 1024
        while True:
            chunk = await file.read(chunk_size)
            if not chunk:
                break
            total_read += len(chunk)
            if total_read > MAX_PAYLOAD_BYTES:
                raise HTTPException(status_code=413, detail={"code": "file_too_large", "message": f"File too large. Maximum size is {MAX_PAYLOAD_BYTES // (1024*1024)} MB."})
            chunks.append(chunk)
        content = b"".join(chunks)

        metadata = analyze_for_organization(content)
        return DatasetEntryMetadata(**metadata.to_dict())

    except ValueError as e:
        raise HTTPException(status_code=400, detail={"code": "validation_error", "message": str(e)})
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Unexpected error in audio organization: {e}", exc_info=True)
        raise HTTPException(status_code=500, detail={"code": "internal_error", "message": "Internal server error during audio organization"})