"""Augmentation settings, stored per project and passed to Ultralytics (REQ-110…113).

Ultralytics augments during training whether or not we ask it to. Before this
module, `training.py` passed no augmentation arguments at all, so every run used
library defaults invisibly. MEDIUM below *is* that default set — a project that
has never been touched trains exactly as it did, only now it is written down.

Validation is never augmented; that is Ultralytics' own behaviour and REQ-112
only requires that we do not defeat it.
"""

import json
from typing import Optional

from backend import db

# name -> (minimum, maximum). Bounds are Ultralytics' own accepted ranges.
FIELDS = {
    "fliplr": (0.0, 1.0),
    "flipud": (0.0, 1.0),
    "degrees": (0.0, 180.0),
    "translate": (0.0, 1.0),
    "scale": (0.0, 1.0),
    "hsv_h": (0.0, 1.0),
    "hsv_s": (0.0, 1.0),
    "hsv_v": (0.0, 1.0),
    "mosaic": (0.0, 1.0),
}

OFF = {name: 0.0 for name in FIELDS}

LIGHT = {"fliplr": 0.5, "flipud": 0.0, "degrees": 0.0, "translate": 0.05,
         "scale": 0.2, "hsv_h": 0.010, "hsv_s": 0.4, "hsv_v": 0.3, "mosaic": 0.0}

# Ultralytics' defaults, spelled out.
MEDIUM = {"fliplr": 0.5, "flipud": 0.0, "degrees": 0.0, "translate": 0.1,
          "scale": 0.5, "hsv_h": 0.015, "hsv_s": 0.7, "hsv_v": 0.4, "mosaic": 1.0}

AGGRESSIVE = {"fliplr": 0.5, "flipud": 0.1, "degrees": 10.0, "translate": 0.2,
              "scale": 0.9, "hsv_h": 0.020, "hsv_s": 0.9, "hsv_v": 0.5, "mosaic": 1.0}

PRESETS = {"off": OFF, "light": LIGHT, "medium": MEDIUM, "aggressive": AGGRESSIVE}


class AugmentError(Exception):
    pass


def normalise(incoming: Optional[dict]) -> dict:
    """Fill in missing keys from MEDIUM and reject out-of-range values."""
    settings = dict(MEDIUM)
    for name, value in (incoming or {}).items():
        if name not in FIELDS:
            raise AugmentError(f"'{name}' is not an augmentation setting")
        if not isinstance(value, (int, float)) or isinstance(value, bool):
            raise AugmentError(f"'{name}' must be a number")
        low, high = FIELDS[name]
        if not low <= value <= high:
            raise AugmentError(f"'{name}' must be between {low} and {high}")
        settings[name] = float(value)
    return settings


def preset_name(settings: dict) -> str:
    """Which preset these settings match, or 'custom'."""
    for name, preset in PRESETS.items():
        if all(abs(settings[field] - preset[field]) < 1e-9 for field in FIELDS):
            return name
    return "custom"


def get(project_id: int) -> dict:
    with db.cursor() as cur:
        cur.execute("SELECT augment FROM projects WHERE id = ?", (project_id,))
        row = cur.fetchone()
    if row is None:
        raise AugmentError("No such project")
    stored = json.loads(row[0]) if row[0] else None
    settings = normalise(stored)
    return {"settings": settings, "preset": preset_name(settings)}


def save(project_id: int, incoming: dict) -> dict:
    settings = normalise(incoming)
    with db.cursor() as cur:
        cur.execute("UPDATE projects SET augment = ? WHERE id = ?",
                    (json.dumps(settings), project_id))
        if cur.rowcount == 0:
            raise AugmentError("No such project")
    return {"settings": settings, "preset": preset_name(settings)}