from __future__ import annotations
from pathlib import Path
import subprocess
import shutil

from jinja2 import Environment, FileSystemLoader, select_autoescape

from .models import Invoice
from .calc import compute_totals, line_net
from .types import RenderResult
from .utils import money_fmt, number_fmt

def render_html(inv: Invoice, template_path: Path) -> str:
    env = Environment(
        loader=FileSystemLoader(str(template_path.parent)),
        autoescape=select_autoescape(["html", "xml", "j2"]),
    )
    env.globals["money"] = lambda x: money_fmt(x, inv.meta.currency)
    env.globals["number"] = number_fmt
    env.filters["de_date"] = lambda d: d.strftime("%d.%m.%Y") if d else ""
    env.globals["unit_label"] = lambda unit: {"HUR": "Std.", "C62": "Stück", "DAY": "Tage"}.get(unit, unit)
    env.globals["price"] = lambda x: f"{number_fmt(x)} {inv.meta.currency}"
    tpl = env.get_template(template_path.name)

    totals = compute_totals(inv)

    items = []
    for it in inv.items:
        d = it.model_dump()
        d["line_total_net"] = line_net(it)
        items.append(type("Obj", (), d))

    ctx = {
        "meta": inv.meta.model_dump(),
        "seller": inv.seller.model_dump(),
        "buyer": inv.buyer.model_dump(),
        "payment": inv.payment.model_dump(),
        "items": items,
        "totals": totals,
    }
    return tpl.render(**ctx)

def _weasyprint_available() -> bool:
    try:
        import weasyprint  # noqa
        return True
    except Exception:
        return False

def render_pdf(html: str, out_pdf: Path, logger, prefer_weasyprint: bool = True, base_url: str | None = None) -> RenderResult:
    out_pdf.parent.mkdir(parents=True, exist_ok=True)

    if prefer_weasyprint and _weasyprint_available():
        logger.info("Rendering PDF using WeasyPrint")
        try:
            from weasyprint import HTML  # type: ignore
            HTML(string=html, base_url=base_url).write_pdf(str(out_pdf), pdf_variant="pdf/a-3b")
            return RenderResult(ok=True, backend="weasyprint", path=out_pdf)
        except Exception as e:
            logger.exception("WeasyPrint rendering failed; trying wkhtmltopdf if available: %s", e)

    wk = shutil.which("wkhtmltopdf")
    if wk:
        logger.info("Rendering PDF using wkhtmltopdf (%s)", wk)
        tmp_html = out_pdf.with_suffix(".tmp.html")
        tmp_html.write_text(html, encoding="utf-8")
        try:
            proc = subprocess.run(
                [wk, "--quiet", "--enable-local-file-access", str(tmp_html), str(out_pdf)],
                capture_output=True,
                text=True,
                check=False,
            )
            if proc.returncode != 0:
                logger.error("wkhtmltopdf failed (rc=%s). stderr=%s", proc.returncode, proc.stderr.strip())
                return RenderResult(ok=False, backend="wkhtmltopdf", path=None, error="wkhtmltopdf failed")
            return RenderResult(ok=True, backend="wkhtmltopdf", path=out_pdf)
        finally:
            try:
                tmp_html.unlink(missing_ok=True)
            except Exception:
                pass

    return RenderResult(ok=False, backend="none", path=None, error="No PDF backend available (install weasyprint or wkhtmltopdf).")