# Author: Simon-Pierre Boucher
# Mail: contact@spboucher.ai
"""Central config loading — YAML files + environment overrides.

Env vars (see .env.example):
    EXPLORER_DB      path to the SQLite DB (default ./explorer.db)
                     (PostgreSQL via DATABASE_URL lands in Deliverable 5)
    EXPLORER_CHAINS  comma-separated subset of chains to index (default all)
    EXPLORER_CONFIG  directory holding chains.yaml / tokens.yaml
"""

import os
import pathlib

import yaml

ROOT = pathlib.Path(__file__).parent.parent
CONFIG_DIR = pathlib.Path(os.environ.get("EXPLORER_CONFIG", ROOT / "config"))


def db_path():
    return os.environ.get("EXPLORER_DB", str(ROOT / "explorer.db"))


def load_chains():
    return yaml.safe_load((CONFIG_DIR / "chains.yaml").read_text())["chains"]


def load_tokens():
    return yaml.safe_load((CONFIG_DIR / "tokens.yaml").read_text())["tokens"]


def backfill_blocks(chain_cfg):
    """How many blocks of history to grow backwards. Per-chain
    `backfill_days` wins; else EXPLORER_BACKFILL_DAYS env; else 0 (off)."""
    days = chain_cfg.get("backfill_days")
    if days is None:
        days = float(os.environ.get("EXPLORER_BACKFILL_DAYS", 0) or 0)
    if not days:
        return 0
    return int(days * 86400 / float(chain_cfg.get("block_time", 12)))


def selected_chains(chains, tokens, cli_arg=None, families=("evm",)):
    """Chains to run: CLI arg > EXPLORER_CHAINS env > every chain that has
    both a chain config and a token list. Chains whose family has no
    adapter yet are skipped with a warning."""
    env = os.environ.get("EXPLORER_CHAINS", "").strip()
    if cli_arg:
        wanted = list(cli_arg)
    elif env:
        wanted = [c.strip() for c in env.split(",") if c.strip()]
    else:
        wanted = [c for c in chains if c in tokens]
    unknown = [c for c in wanted if c not in chains or c not in tokens]
    if unknown:
        raise SystemExit(f"unknown chains (need entries in both YAML files): {unknown}")
    skipped = [c for c in wanted if chains[c].get("family", "evm") not in families]
    if skipped:
        import logging
        logging.warning("skipping chains with no adapter yet: %s", skipped)
    return [c for c in wanted if chains[c].get("family", "evm") in families]