"""
Configuration settings for Universal Model Trainer
"""

from pydantic_settings import BaseSettings
from typing import Optional, List
from functools import lru_cache
import os


class Settings(BaseSettings):
    """Application settings loaded from environment variables."""
    
    # Application
    APP_NAME: str = "Universal Model Trainer"
    VERSION: str = "1.0.0"
    DEBUG: bool = False
    SECRET_KEY: str = "change-me-in-production"
    
    # Server
    HOST: str = "0.0.0.0"
    PORT: int = 7860
    WORKERS: int = 1
    
    # HuggingFace
    HF_TOKEN: Optional[str] = None
    HF_USERNAME: Optional[str] = None
    HF_CACHE_DIR: str = "/app/cache"
    
    # Redis / Queue
    REDIS_URL: str = "redis://localhost:6379/0"
    QUEUE_NAME: str = "training_queue"
    MAX_CONCURRENT_JOBS: int = 1  # Single job only - one machine
    
    # Database
    DATABASE_URL: str = "sqlite:///./data/trainer.db"
    
    # Storage Paths
    UPLOAD_DIR: str = "/app/uploads"
    OUTPUT_DIR: str = "/app/outputs"  # Training outputs
    MODELS_DIR: str = "/app/models"
    LOGS_DIR: str = "/app/logs"
    CACHE_DIR: str = "/app/cache"
    
    # Training Defaults
    DEFAULT_BATCH_SIZE: int = 8
    DEFAULT_LEARNING_RATE: float = 5e-5
    DEFAULT_MAX_LENGTH: int = 512
    DEFAULT_EPOCHS: int = 3
    DEFAULT_WARMUP_RATIO: float = 0.1
    
    # Hardware
    DEVICE: str = "auto"  # auto, cpu, cuda, mps
    DTYPE: str = "auto"   # auto, float32, float16, bfloat16
    DEFAULT_HARDWARE: str = "auto"
    AVAILABLE_HARDWARE: List[str] = ["cpu", "cuda", "auto"]
    
    # PEFT / LoRA Defaults
    PEFT_DEFAULTS: dict = {
        "lora_r": 16,
        "lora_alpha": 32,
        "lora_dropout": 0.05,
        "target_modules": ["q_proj", "v_proj"]
    }
    
    # Model Support
    SUPPORTED_TASKS: List[str] = [
        "causal-lm",
        "seq2seq",
        "token-classification",
        "sequence-classification",
        "question-answering",
        "summarization",
        "translation",
        "text-classification",
        "masked-lm",
        "vision-classification",
        "vision-segmentation",
        "audio-classification",
        "audio-transcription"
    ]
    
    # Dataset Sources
    DATASET_SOURCES: List[str] = [
        "huggingface",
        "local_upload",
        "url",
        "s3"
    ]
    
    # Logging
    LOG_LEVEL: str = "INFO"
    LOG_FORMAT: str = "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
    
    # Experiment Tracking
    WANDB_API_KEY: Optional[str] = None
    WANDB_PROJECT: str = "universal-model-trainer"
    
    # Authentication (set via HF Space secrets)
    APP_PASSWORD: str = ""  # Set via APP_PASSWORD env var / HF secret
    SESSION_SECRET_KEY: str = os.environ.get('SESSION_SECRET_KEY','PASIFPSPBE783P7P3R98R392H3')
    SESSION_EXPIRE_HOURS: int = 24
    
    @property
    def is_auth_configured(self) -> bool:
        """Check if authentication is configured"""
        return bool(self.APP_PASSWORD)
    
    # Security
    API_KEY_HEADER: str = "X-API-Key"
    ENABLE_AUTH: bool = False
    
    # Rate Limiting
    RATE_LIMIT_PER_MINUTE: int = 60
    
    # Resource Limits
    MAX_UPLOAD_SIZE_MB: int = 500
    MAX_DATASET_SIZE_MB: int = 10000
    MAX_TRAINING_HOURS: int = 24
    
    class Config:
        env_file = ".env"
        env_file_encoding = "utf-8"
        case_sensitive = True


@lru_cache()
def get_settings() -> Settings:
    """Get cached settings instance."""
    return Settings()


# Export settings instance
settings = get_settings()


# Training Configuration Templates
TRAINING_TEMPLATES = {
    "causal-lm": {
        "task": "causal-lm",
        "model_type": "decoder",
        "default_model": "gpt2",
        "default_args": {
            "per_device_train_batch_size": 4,
            "gradient_accumulation_steps": 4,
            "learning_rate": 5e-5,
            "max_grad_norm": 1.0,
            "warmup_ratio": 0.1,
            "weight_decay": 0.01
        }
    },
    "seq2seq": {
        "task": "seq2seq",
        "model_type": "encoder-decoder",
        "default_model": "t5-small",
        "default_args": {
            "per_device_train_batch_size": 8,
            "learning_rate": 5e-5,
            "warmup_ratio": 0.1,
            "source_lang": "en",
            "target_lang": "en"
        }
    },
    "token-classification": {
        "task": "token-classification",
        "model_type": "encoder",
        "default_model": "bert-base-uncased",
        "default_args": {
            "per_device_train_batch_size": 16,
            "learning_rate": 3e-5,
            "label_column": "ner_tags"
        }
    },
    "sequence-classification": {
        "task": "sequence-classification",
        "model_type": "encoder",
        "default_model": "distilbert-base-uncased",
        "default_args": {
            "per_device_train_batch_size": 16,
            "learning_rate": 2e-5,
            "num_labels": 2,
            "label_column": "label"
        }
    },
    "question-answering": {
        "task": "question-answering",
        "model_type": "encoder",
        "default_model": "distilbert-base-uncased-distilled-squad",
        "default_args": {
            "per_device_train_batch_size": 12,
            "learning_rate": 3e-5,
            "max_answer_length": 30
        }
    },
    "text-classification": {
        "task": "text-classification",
        "model_type": "encoder",
        "default_model": "roberta-base",
        "default_args": {
            "per_device_train_batch_size": 16,
            "learning_rate": 1e-5,
            "num_labels": 2
        }
    },
    "summarization": {
        "task": "summarization",
        "model_type": "encoder-decoder",
        "default_model": "facebook/bart-large-cnn",
        "default_args": {
            "per_device_train_batch_size": 4,
            "learning_rate": 3e-5,
            "max_source_length": 1024,
            "max_target_length": 128
        }
    },
    "translation": {
        "task": "translation",
        "model_type": "encoder-decoder",
        "default_model": "Helsinki-NLP/opus-mt-en-fr",
        "default_args": {
            "per_device_train_batch_size": 8,
            "learning_rate": 5e-5,
            "source_lang": "en",
            "target_lang": "fr"
        }
    },
    "masked-lm": {
        "task": "masked-lm",
        "model_type": "encoder",
        "default_model": "bert-base-uncased",
        "default_args": {
            "per_device_train_batch_size": 16,
            "learning_rate": 5e-5,
            "mlm_probability": 0.15
        }
    },
    "vision-classification": {
        "task": "vision-classification",
        "model_type": "vision",
        "default_model": "google/vit-base-patch16-224",
        "default_args": {
            "per_device_train_batch_size": 32,
            "learning_rate": 2e-5,
            "image_column": "image"
        }
    },
    "audio-transcription": {
        "task": "audio-transcription",
        "model_type": "audio",
        "default_model": "openai/whisper-small",
        "default_args": {
            "per_device_train_batch_size": 8,
            "learning_rate": 1e-5,
            "audio_column": "audio"
        }
    }
}