from __future__ import annotations
from pathlib import Path
import shutil
from datetime import date, timedelta

from .presets import load_yaml, deep_merge, load_customer_preset
from .invoice_number import suggest_next_invoice_number
from .folder_naming import default_invoice_folder_name

import yaml

def _dump_yaml(data: dict, path: Path) -> None:
    path.write_text(yaml.safe_dump(data, sort_keys=False, allow_unicode=True), encoding="utf-8")

def init_invoice_folder(
    target_dir: Path,
    repo_root: Path,
    logger,
    force: bool = False,
    customer: str | None = None,
    invoice_number: str | None = None,
    due_days: int = 14,
    invoices_root: Path | None = None,
    project: str | None = None,
) -> Path:
    target_dir = target_dir.resolve()
    target_dir.mkdir(parents=True, exist_ok=True)

    # Create standard subfolders
    (target_dir / "assets").mkdir(parents=True, exist_ok=True)
    for p in [target_dir / "out", target_dir / "out" / "logs", target_dir / "out" / "validation"]:
        p.mkdir(parents=True, exist_ok=True)
        (p / ".gitkeep").write_text("", encoding="utf-8")

    # Copy default logo if not present (or force)
    src_logo = repo_root / "assets" / "logo.svg"
    dst_logo = target_dir / "assets" / "logo.svg"
    if src_logo.exists() and (force or not dst_logo.exists()):
        shutil.copy2(src_logo, dst_logo)
        logger.info("Copied default logo to %s", dst_logo)

    # Base invoice template
    base_tpl = load_yaml(repo_root / "examples" / "invoice.init.yaml")

    # Apply seller defaults
    seller_defaults = load_yaml(repo_root / "presets" / "seller.default.yaml")
    merged = deep_merge(base_tpl, seller_defaults)

    # Apply customer preset
    if customer:
        preset = load_customer_preset(repo_root, customer)
        if preset:
            merged = deep_merge(merged, preset)
            logger.info("Applied customer preset: %s", customer)
        else:
            logger.warning("Customer preset not found for: %s (continuing with generic buyer)", customer)

    # Smart defaults for meta/payment
    today = date.today()
    merged.setdefault("meta", {})
    merged["meta"]["invoice_date"] = str(today)
    merged["meta"]["service_date"] = str(today)

    # invoice number
    if not invoice_number and invoices_root:
        try:
            invoice_number = suggest_next_invoice_number(invoices_root)
            logger.info("Suggested next invoice number: %s (root=%s)", invoice_number, invoices_root)
        except Exception as e:
            logger.warning("Failed to suggest invoice number from %s: %s", invoices_root, e)

    if invoice_number:
        merged["meta"]["invoice_number"] = invoice_number

    # project -> default first item name
    if project:
        merged.setdefault("items", [])
        if len(merged["items"]) == 0:
            merged["items"] = [{
                "name": project,
                "description": "Leistung/Beschreibung",
                "quantity": 1,
                "unit": "C62",
                "unit_price_net": 100.00,
                "tax_rate": 19.0
            }]
        else:
            if merged["items"][0].get("name") in ("Leistung", "Service", None, ""):
                merged["items"][0]["name"] = project
        logger.info("Applied project default: %s", project)

    merged.setdefault("payment", {})
    merged["payment"]["due_date"] = str(today + timedelta(days=due_days))
    inv_no_for_ref = merged["meta"].get("invoice_number", "")
    merged["payment"]["reference"] = f"Rechnung {inv_no_for_ref}".strip()

    dst_yaml = target_dir / "invoice.yaml"
    if dst_yaml.exists() and not force:
        raise FileExistsError(f"{dst_yaml} already exists (use --force to overwrite)")
    _dump_yaml(merged, dst_yaml)

    logger.info("Initialized invoice folder: %s", target_dir)
    return target_dir

def init_invoice_under_root(
    invoices_root: Path,
    repo_root: Path,
    logger,
    customer: str | None,
    project: str | None,
    invoice_number: str | None,
    due_days: int,
    force: bool,
) -> Path:
    invoices_root = invoices_root.expanduser().resolve()
    invoices_root.mkdir(parents=True, exist_ok=True)

    # suggest number if missing
    if not invoice_number:
        invoice_number = suggest_next_invoice_number(invoices_root)
        logger.info("Auto invoice number: %s", invoice_number)

    folder_name = default_invoice_folder_name(invoice_number, customer)
    target_dir = invoices_root / folder_name
    logger.info("Auto folder name: %s", target_dir)

    return init_invoice_folder(
        target_dir=target_dir,
        repo_root=repo_root,
        logger=logger,
        force=force,
        customer=customer,
        invoice_number=invoice_number,
        due_days=due_days,
        invoices_root=invoices_root,
        project=project,
    )