"""GitHub PAT configuration for DEPosit collection scripts.

Never commit personal access tokens. Provide credentials via:

  1. Environment variables (recommended for CI)
  2. A local ``.env`` file (copy from ``.env.example``; not committed)
  3. ``--token`` / ``--tokens`` CLI flags where supported

Variables:
  GITHUB_TOKEN_SE4DE  — project-specific name (preferred)
  GITHUB_TOKEN        — standard name
  GITHUB_TOKENS       — comma-separated PATs for rate-limit rotation
"""
from __future__ import annotations

import argparse
import os
import sys
from pathlib import Path

PACKAGE_ROOT = Path(__file__).resolve().parents[1]


def load_dotenv(path: Path | None = None) -> None:
    """Load KEY=VALUE pairs from .env into os.environ (does not override existing)."""
    path = path or PACKAGE_ROOT / ".env"
    if not path.is_file():
        return
    for raw in path.read_text(encoding="utf-8").splitlines():
        line = raw.strip()
        if not line or line.startswith("#") or "=" not in line:
            continue
        key, _, value = line.partition("=")
        key = key.strip()
        value = value.strip().strip("'").strip('"')
        if key and key not in os.environ:
            os.environ[key] = value


def load_tokens() -> list[str]:
    """Return all configured PATs (may be empty)."""
    load_dotenv()
    found: list[str] = []
    for env in ("GITHUB_TOKEN_SE4DE", "GITHUB_TOKEN"):
        value = os.environ.get(env, "").strip()
        if value and value not in found:
            found.append(value)
    for part in os.environ.get("GITHUB_TOKENS", "").split(","):
        part = part.strip()
        if part and part not in found:
            found.append(part)
    return found


def build_authorization_headers(tokens: list[str]) -> list[dict[str, str]]:
    return [
        {"Accept": "application/vnd.github+json", "Authorization": f"Bearer {token}"}
        for token in tokens
    ]


def resolve_token(cli_token: str | None = None, cli_tokens: str | None = None) -> str | None:
    """Single PAT: CLI overrides environment."""
    if cli_token and cli_token.strip():
        return cli_token.strip()
    if cli_tokens:
        parts = [p.strip() for p in cli_tokens.split(",") if p.strip()]
        if parts:
            return parts[0]
    tokens = load_tokens()
    return tokens[0] if tokens else None


def require_github_tokens(
    cli_token: str | None = None,
    cli_tokens: str | None = None,
) -> list[str]:
    """Return PAT list or exit with instructions."""
    if cli_token and cli_token.strip():
        return [cli_token.strip()]
    if cli_tokens:
        parts = [p.strip() for p in cli_tokens.split(",") if p.strip()]
        if parts:
            return parts
    tokens = load_tokens()
    if not tokens:
        _exit_missing_token()
    return tokens


def primary_token(cli_token: str | None = None, cli_tokens: str | None = None) -> str:
    token = resolve_token(cli_token, cli_tokens)
    if not token:
        _exit_missing_token()
    return token


def init_rest_client_auth(
    cli_token: str | None = None,
    cli_tokens: str | None = None,
) -> tuple[list[str], list[dict[str, str]]]:
    """Used by REST collection scripts with token rotation."""
    tokens = require_github_tokens(cli_token, cli_tokens)
    return tokens, build_authorization_headers(tokens)


def add_github_token_args(parser: argparse.ArgumentParser) -> None:
    group = parser.add_argument_group("GitHub authentication")
    group.add_argument(
        "--token",
        metavar="PAT",
        help="GitHub personal access token (overrides environment)",
    )
    group.add_argument(
        "--tokens",
        metavar="PAT1,PAT2",
        help="Comma-separated PATs for rate-limit rotation (overrides environment)",
    )


def _exit_missing_token() -> None:
    print("GitHub token required for API collection.", file=sys.stderr)
    print("  Option A: copy .env.example to .env and set GITHUB_TOKEN_SE4DE", file=sys.stderr)
    print("  Option B: $env:GITHUB_TOKEN_SE4DE = '<your-pat>'  (PowerShell)", file=sys.stderr)
    print("  Option C: pass --token <your-pat> on scripts that support it", file=sys.stderr)
    sys.exit(1)