"""Configuration management using Pydantic Settings."""

import shutil
from enum import Enum
from pathlib import Path

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict


def _find_binary(name: str) -> Path:
    """Return the absolute path to *name* on PATH, falling back to bare name."""
    found = shutil.which(name)
    return Path(found) if found else Path(name)



class CropMode(str, Enum):
    """Crop positioning strategy."""

    SCENE_EQUILIBRIUM = "scene_equilibrium"  # Per-scene equilibrium (resets at cuts)


class DetectionModel(str, Enum):
    """Detection model selection."""

    MEDIAPIPE = "mediapipe"


class Settings(BaseSettings):
    """Application settings loaded from environment variables."""

    # Gemini API Configuration
    # Default is empty string so the library can be imported without a .env file.
    # IntelligenceEngine / CutToMusicIntelligence will raise at call time if unset.
    gemini_api_key: str = ""
    gemini_model: str = "gemini-3-flash-preview"

    # Processing Configuration
    default_output_dir: Path = Path("./output")
    default_num_clips: int = 3
    default_duration_min: float = 12.0
    default_duration_max: float = 17.0

    # Downsampling Configuration (for Gemini API submission only)
    # Gemini samples video at ~1fps internally, so 2fps + 480p is sufficient
    # and dramatically reduces preprocessing time and upload size.
    max_resolution_height: int = 480
    max_fps: int = 2

    # FFmpeg Configuration — auto-discovered via PATH; override with FFMPEG_PATH / FFPROBE_PATH
    ffmpeg_path: Path = Field(default_factory=lambda: _find_binary("ffmpeg"))
    ffprobe_path: Path = Field(default_factory=lambda: _find_binary("ffprobe"))

    # Reframing Configuration
    saliency_keyframe_interval: float = 1.0  # Sample every 1 second for better tracking
    smoothing_window: float = 2.0  # Increased for more aggressive smoothing
    min_transition_duration: float = 0.5
    max_keyframes: int = (
        32  # Maximum keyframes in FFmpeg crop expression (higher = smoother tracking)
    )

    # MediaPipe Face and Pose Detection Configuration
    max_faces: int = 3  # Maximum number of faces to detect
    min_face_confidence: float = 0.5  # Minimum confidence for face detection
    min_tracking_confidence: float = 0.5  # Minimum confidence for tracking
    enable_pose_fallback: bool = True  # Enable pose detection as fallback when faces not detected

    # Scene Change Detection Configuration
    enable_scene_detection: bool = True
    scene_histogram_threshold: float = 0.45
    scene_confidence_drop_threshold: float = 0.35
    scene_pixel_diff_threshold: float = 0.25
    scene_detection_min_interval: float = 0.5  # Debounce interval (seconds)
    scene_detection_debug: bool = False

    # Crop Positioning Mode Selection
    crop_mode: CropMode = CropMode.SCENE_EQUILIBRIUM

    # Equilibrium-Based Crop Positioning
    equilibrium_safety_margin: float = 0.2  # 20% margin on each side (60% safe zone)
    equilibrium_max_movement: float = 80.0  # Slower movement than subject-chasing (150px)
    equilibrium_sample_interval: float = 0.5  # Sample scene every 0.5s for analysis
    equilibrium_rubber_band_strength: float = 0.3  # Pull back toward equilibrium (0.0-1.0)

    # PySceneDetect Configuration (for SCENE_EQUILIBRIUM mode)
    pyscenedetect_detector: str = "adaptive"  # "adaptive" or "content"
    pyscenedetect_adaptive_threshold: float = 3.0  # Lower = more sensitive (default: 3.0)
    pyscenedetect_content_threshold: float = 27.0  # For ContentDetector fallback
    pyscenedetect_min_scene_length: float = 1.0  # Minimum scene duration (seconds)
    pyscenedetect_luma_only: bool = False  # true=brightness only, false=color too

    # Detection Model Configuration
    detection_model: DetectionModel = DetectionModel.MEDIAPIPE

    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=False,
        extra="ignore",
    )


# Global settings instance
settings = Settings()