"""
src/training/config.py — TrainingConfig dataclass

Single source of truth for all training hyperparameters. Import this from
every training script instead of duplicating argparse defaults.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from pathlib import Path
from typing import List


# Generator label index mapping — must match GeneratorLabel enum in src/types.py
# and the classification head in every model file.
GENERATOR_CLASSES: List[str] = [
    "real",               # 0
    "unknown_gan",        # 1
    "stable_diffusion",   # 2
    "midjourney",         # 3
    "dall_e",             # 4
    "flux",               # 5
    "firefly",            # 6
    "imagen",             # 7
]
NUM_GENERATOR_CLASSES: int = len(GENERATOR_CLASSES)  # 8 — never change this


@dataclass
class TrainingConfig:
    """Fingerprint engine training configuration (Phase 1)."""

    # ── Paths ─────────────────────────────────────────────────────────────────
    data_dir:   Path = Path("data/processed/fingerprint")
    output_dir: Path = Path("models/checkpoints/fingerprint")
    log_dir:    Path = Path("training/logs")

    # ── Model ─────────────────────────────────────────────────────────────────
    model_name:             str = "vit_base_patch16_224"  # timm slug
    pretrained:             bool = True
    num_binary_classes:     int = 2
    num_generator_classes:  int = NUM_GENERATOR_CLASSES   # 8

    # ── Training ──────────────────────────────────────────────────────────────
    epochs:            int   = 30
    batch_size:        int   = 64
    learning_rate:     float = 2e-5
    weight_decay:      float = 0.01
    warmup_steps:      int   = 500
    grad_accumulation: int   = 1
    amp:               bool  = True
    generator_loss_weight: float = 0.3  # secondary objective weight

    # ── Optimiser ─────────────────────────────────────────────────────────────
    optimizer:   str = "adamw"
    scheduler:   str = "cosine"

    # ── Early stopping ────────────────────────────────────────────────────────
    patience:    int = 5    # stop if val AUC flat for N epochs

    # ── Reproducibility ───────────────────────────────────────────────────────
    seed:        int = 42

    # ── Kaggle ────────────────────────────────────────────────────────────────
    is_kaggle:   bool = False

    def __post_init__(self) -> None:
        self.data_dir   = Path(self.data_dir)
        self.output_dir = Path(self.output_dir)
        self.log_dir    = Path(self.log_dir)
        self.output_dir.mkdir(parents=True, exist_ok=True)
        self.log_dir.mkdir(parents=True, exist_ok=True)

    def to_dict(self) -> dict:
        return {
            k: str(v) if isinstance(v, Path) else v
            for k, v in self.__dict__.items()
        }


@dataclass
class CoherenceConfig:
    """Coherence engine training configuration (Phase 2)."""

    data_dir:   Path = Path("data/processed/coherence")
    output_dir: Path = Path("models/checkpoints/coherence")
    log_dir:    Path = Path("training/logs")

    epochs:              int   = 25
    batch_size:          int   = 16
    learning_rate:       float = 1e-4
    weight_decay:        float = 1e-4
    contrastive_weight:  float = 0.1
    amp:                 bool  = True
    patience:            int   = 5
    seed:                int   = 42
    is_kaggle:           bool  = False

    def __post_init__(self) -> None:
        self.data_dir   = Path(self.data_dir)
        self.output_dir = Path(self.output_dir)
        self.log_dir    = Path(self.log_dir)
        self.output_dir.mkdir(parents=True, exist_ok=True)
        self.log_dir.mkdir(parents=True, exist_ok=True)

    def to_dict(self) -> dict:
        return {
            k: str(v) if isinstance(v, Path) else v
            for k, v in self.__dict__.items()
        }


@dataclass
class SSTGNNConfig:
    """SSTGNN engine training configuration (Phase 3)."""

    data_dir:   Path = Path("data/processed/sstgnn")
    output_dir: Path = Path("models/checkpoints/sstgnn")
    log_dir:    Path = Path("training/logs")

    # Graph model
    in_channels:   int = 5     # node feature dim: x, y, z, frame_idx/T, lm_idx/L
    hidden_dim:    int = 64
    heads:         int = 4
    num_gat_layers: int = 3

    # Training — note: no AMP by default (NaN risk on GNNs)
    epochs:        int   = 40
    batch_size:    int   = 8
    learning_rate: float = 5e-4
    weight_decay:  float = 5e-4
    grad_clip:     float = 1.0  # always clip for GNNs
    amp:           bool  = False
    patience:      int   = 8    # GNNs need longer to plateau
    seed:          int   = 42
    is_kaggle:     bool  = False

    def __post_init__(self) -> None:
        self.data_dir   = Path(self.data_dir)
        self.output_dir = Path(self.output_dir)
        self.log_dir    = Path(self.log_dir)
        self.output_dir.mkdir(parents=True, exist_ok=True)
        self.log_dir.mkdir(parents=True, exist_ok=True)

    def to_dict(self) -> dict:
        return {
            k: str(v) if isinstance(v, Path) else v
            for k, v in self.__dict__.items()
        }