import os
import re

from .errors import TrackerError  # type: ignore[reportMissingImports]

SUPPORTED_PROVIDERS = ("github", "gitlab", "gitea")


def _validate_provider(value):
    provider = (value or "").strip().lower()
    if provider not in SUPPORTED_PROVIDERS:
        raise TrackerError(
            "invalid_provider",
            f"unsupported provider: {value}",
            details={"supported": list(SUPPORTED_PROVIDERS)},
        )
    return provider


def _providers_from_remote(remote):
    host_match = re.search(r"(?:https?://|ssh://|git@)([^/:]+)", remote or "")
    host = host_match.group(1).lower() if host_match else ""
    found = []
    if host == "github.com" or "github" in host:
        found.append("github")
    if host == "gitlab.com" or "gitlab" in host:
        found.append("gitlab")
    if "gitea" in host:
        found.append("gitea")
    return found


def resolve_provider(explicit=None, *, env=None, remote=None):
    """Resolve provider using CLI, environment, then remote precedence."""
    if explicit is not None:
        return _validate_provider(explicit)
    values = os.environ if env is None else env
    configured = values.get("TRACKER_PROVIDER")
    if configured:
        return _validate_provider(configured)
    matches = _providers_from_remote(remote or "")
    if len(matches) == 1:
        return matches[0]
    if not remote:
        raise TrackerError(
            "provider_detection_failed",
            "provider was not specified and no Git remote was available",
        )
    if len(matches) > 1:
        message = "Git remote matches multiple supported providers"
    else:
        message = f"unsupported or unrecognised Git remote: {remote}"
    raise TrackerError("provider_detection_failed", message, details={"remote": remote})