from __future__ import annotations

import os
from dataclasses import dataclass
from pathlib import Path


def _load_dotenv(path: Path) -> None:
    if not path.exists():
        return
    for raw_line in path.read_text(encoding="utf-8").splitlines():
        line = raw_line.strip()
        if not line or line.startswith("#") or "=" not in line:
            continue
        if line.startswith("export "):
            line = line[len("export ") :].strip()
        key, value = line.split("=", 1)
        key = key.strip()
        value = value.strip().strip("'\"")
        if key:
            os.environ.setdefault(key, value)


def _resolve_path(value: str | None, default: Path, base_dir: Path) -> Path:
    base = Path(value).expanduser() if value else default
    if not base.is_absolute():
        base = base_dir / base
    return base.resolve()


@dataclass(frozen=True)
class Settings:
    project_root: Path
    source_root: Path
    db_path: Path
    log_dir: Path
    weights_root: Path
    task_conda_env: str
    mmseg_conda_env: str
    backend_conda_env: str
    weight_mode: str
    enable_shell_tasks: bool


def get_settings() -> Settings:
    default_project_root = Path(__file__).resolve().parents[2]
    _load_dotenv(default_project_root / ".env")

    project_root = Path(os.getenv("SEG_DATA_SERVER_ROOT", default_project_root)).expanduser()
    if not project_root.is_absolute():
        project_root = (default_project_root / project_root).resolve()
    else:
        project_root = project_root.resolve()
    _load_dotenv(project_root / ".env")

    sibling_source = project_root.parent / "Seg"
    default_source = sibling_source if sibling_source.exists() else project_root.parent
    source_root = _resolve_path(os.getenv("SEG_SOURCE_ROOT"), default_source, project_root)
    db_path = _resolve_path(os.getenv("SEG_BACKEND_DB"), project_root / "var" / "seg_data_server.sqlite3", project_root)
    log_dir = _resolve_path(os.getenv("SEG_BACKEND_LOG_DIR"), project_root / "var" / "job_logs", project_root)
    weights_root = (project_root / "weights").resolve()

    return Settings(
        project_root=project_root,
        source_root=source_root,
        db_path=db_path,
        log_dir=log_dir,
        weights_root=weights_root,
        task_conda_env=os.getenv("SEG_TASK_CONDA_ENV", "seg_smp"),
        mmseg_conda_env=os.getenv("SEG_MMSEG_CONDA_ENV", "seg_mmcv"),
        backend_conda_env=os.getenv("SEG_BACKEND_CONDA_ENV", "seg_smp"),
        weight_mode=os.getenv("SEG_WEIGHT_MODE", "copy"),
        enable_shell_tasks=os.getenv("SEG_ENABLE_SHELL_TASKS", "1") == "1",
    )


settings = get_settings()