"""
Constants, field lists, and config loading for the spruce scraper.
"""

import logging
import sys

import yaml

log = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# File-name constants
# ---------------------------------------------------------------------------

DEFAULT_CONFIG = "config.yaml"
PROGRESS_FILENAME = ".progress.json"
SCANS_CSV_FILENAME = "scans.csv"
TILES_CSV_FILENAME = "tiles.csv"

# ---------------------------------------------------------------------------
# CSV field lists
# ---------------------------------------------------------------------------

SCANS_CSV_FIELDS: list[str] = [
    "machine",
    "machine_id",
    "scan_id",
    "name",
    "scan_time",
    "start_x",
    "start_y",
    "end_x",
    "end_y",
    "dx",
    "dy",
    "nx",
    "ny",
    "total_tiles",
    "scan_lines",
    "scan_mode",
    "start_datetime",
    "end_datetime",
    "status",
    "user",
    "disk_space_mb",
    "mosaic_url",
    "mosaic_local_path",
    "mosaic_on_disk",
    "mosaic_download_status",
    "mosaic_error",
    "mosaic_error_code",
    "mosaic_error_class",
]

TILES_CSV_FIELDS: list[str] = [
    "machine",
    "machine_id",
    "scan_id",
    "scan_time",
    "row_index",
    "col_index",
    "x_mm",
    "y_mm",
    "url",
    "local_path",
    "status",
    "error",
    "error_code",
    "error_class",
    "downloaded_at",
    "file_size_bytes",
]

# ---------------------------------------------------------------------------
# Worker safety
# ---------------------------------------------------------------------------

MAX_SAFE_WORKERS = 4  # above this the RootView server starts timing out


def _clamp_workers(n: int) -> int:
    """Return n clamped to MAX_SAFE_WORKERS, logging a warning if clamped."""
    if n > MAX_SAFE_WORKERS:
        log.warning(
            "workers=%d exceeds the safe limit of %d. "
            "The RootView server will time out under this load, causing lost tiles. "
            "Capping at %d.",
            n,
            MAX_SAFE_WORKERS,
            MAX_SAFE_WORKERS,
        )
        return MAX_SAFE_WORKERS
    return n


# ---------------------------------------------------------------------------
# Config loader
# ---------------------------------------------------------------------------


def load_config(path: str) -> dict:
    """Load and validate config.yaml. Exits on missing required fields."""
    with open(path) as fh:
        cfg = yaml.safe_load(fh)
    missing = [k for k in ("username", "password") if not cfg.get(k)]
    if missing:
        sys.exit(f"Config {path} is missing required fields: {missing}")
    cfg.setdefault("base_url", "http://205.149.147.131:8010/")
    cfg.setdefault("image_base_url", "http://205.149.147.131:8011/")
    cfg.setdefault("output_dir", "archives")
    cfg.setdefault("workers", 2)
    cfg.setdefault("timeout", 60)
    cfg.setdefault("request_delay", 0.5)
    cfg.setdefault("tile_scale", 1)
    cfg.setdefault("write_exif", True)
    cfg.setdefault("machine_metadata", {})
    cfg["workers"] = _clamp_workers(cfg["workers"])
    return cfg