"""File generation using Jinja2 templates."""

import sys
from pathlib import Path

from jinja2 import Environment, BaseLoader, TemplateNotFound

from models import HostConfig


class PackageTemplateLoader(BaseLoader):
    """Custom Jinja2 loader that works with both dev and installed packages."""

    def __init__(self):
        # Try to find templates in multiple locations
        self.template_dirs = []

        # Location 1: Development (scripts/create-host/templates)
        dev_dir = Path(__file__).parent / "templates"
        if dev_dir.exists():
            self.template_dirs.append(dev_dir)

        # Location 2: Installed via Nix (../share/create-host/templates from bin dir)
        # When installed via Nix, __file__ is in lib/python3.X/site-packages/
        # and templates are in ../../../share/create-host/templates
        for site_path in sys.path:
            site_dir = Path(site_path)
            # Try to find the Nix store path
            if "site-packages" in str(site_dir):
                # Go up to the package root (e.g., /nix/store/xxx-create-host-0.1.0)
                pkg_root = site_dir.parent.parent.parent
                share_templates = pkg_root / "share" / "create-host" / "templates"
                if share_templates.exists():
                    self.template_dirs.append(share_templates)

        # Location 3: Fallback - sys.path templates
        for site_path in sys.path:
            site_templates = Path(site_path) / "templates"
            if site_templates.exists():
                self.template_dirs.append(site_templates)

    def get_source(self, environment, template):
        for template_dir in self.template_dirs:
            template_path = template_dir / template
            if template_path.exists():
                mtime = template_path.stat().st_mtime
                source = template_path.read_text()
                return source, str(template_path), lambda: mtime == template_path.stat().st_mtime

        raise TemplateNotFound(template)


def generate_host_files(config: HostConfig, repo_root: Path) -> None:
    """
    Generate host configuration files from templates.

    Args:
        config: Host configuration
        repo_root: Path to repository root
    """
    # Setup Jinja2 environment with custom loader
    env = Environment(
        loader=PackageTemplateLoader(),
        trim_blocks=True,
        lstrip_blocks=True,
    )

    # Create host directory
    host_dir = repo_root / "hosts" / config.hostname
    host_dir.mkdir(parents=True, exist_ok=True)

    # Generate default.nix
    default_template = env.get_template("default.nix.j2")
    default_content = default_template.render(hostname=config.hostname)
    (host_dir / "default.nix").write_text(default_content)

    # Generate configuration.nix
    config_template = env.get_template("configuration.nix.j2")
    config_content = config_template.render(
        hostname=config.hostname,
        domain=config.domain,
        nameservers=config.nameservers,
        is_static_ip=config.is_static_ip,
        ip=config.ip,
        gateway=config.gateway,
        state_version=config.state_version,
    )
    (host_dir / "configuration.nix").write_text(config_content)