"""
Workstation (Docker) build helpers for the Prole installer (root-level).

Compose a deterministic Docker build command and derive the image tag version
from the workstation/Dockerfile. Includes helpers to check if the current
image tag already exists locally to avoid redundant builds.
"""
from __future__ import annotations

from pathlib import Path
import re
import subprocess
from . import config as cfg


def get_workstation_version(project_root: Path) -> str:
    """Parse the workstation Dockerfile for a version.

    Looks for one of the following (first match wins):
      - ARG WORKSTATION_VERSION=1.2.3
      - LABEL org.opencontainers.image.version="1.2.3"
    Falls back to "0.1.0" if none found.
    """
    ws = Path(project_root) / "workstation" / "Dockerfile"
    default_ver = "0.1.0"
    try:
        text = ws.read_text(encoding="utf-8")
    except Exception:
        return default_ver
    # ARG pattern
    m = re.search(r"^\s*ARG\s+WORKSTATION_VERSION\s*=\s*([\w\.-]+)\s*$", text, re.MULTILINE)
    if m:
        return m.group(1)
    # LABEL pattern
    m2 = re.search(r"org\.opencontainers\.image\.version\s*=\s*\"?([\w\.-]+)\"?", text)
    if m2:
        return m2.group(1)
    return default_ver


def get_docker_build_command(project_root: Path) -> str:
    """Return the canonical Docker build command for the workstation image.

    docker build -t prole-workstation:<version> .
    Includes platform flags for Apple Silicon when appropriate.
    """
    ws = Path(project_root) / "workstation"
    version = get_workstation_version(project_root)
    platform_args = cfg.get_docker_build_platform_args()
    plat = (" ".join(platform_args) + " ") if platform_args else ""
    return f"cd \"{ws}\" && docker build {plat}-t prole-workstation:{version} ."


def is_workstation_image_current(project_root: Path) -> bool:
    """Return True if the local Docker image prole-workstation:<version> exists.

    This checks only for the presence of the tag. It does not verify whether
    the image is up-to-date with the Dockerfile. For most installer scenarios,
    skipping a rebuild when the tag exists is sufficient and saves time.
    """
    version = get_workstation_version(project_root)
    try:
        r = subprocess.run(
            ["bash", "-lc", f"docker image inspect prole-workstation:{version} >/dev/null 2>&1"],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )
        return r.returncode == 0
    except Exception:
        return False