from pathlib import Path
from typing import List

from fastapi import APIRouter, File, HTTPException, UploadFile, status

router = APIRouter(prefix="/settings", tags=["settings"])

TEMPLATES_DIR = Path("data/templates")
ALLOWED_EXCEL = {".xlsx", ".xltx"}
ALLOWED_WORD = {".docx", ".dotx"}
ALLOWED_EXTENSIONS = ALLOWED_EXCEL | ALLOWED_WORD

# Allowed MIME types when client sends Content-Type (validate if present)
ALLOWED_MIME_TYPES = frozenset({
    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",  # .xlsx
    "application/vnd.openxmlformats-officedocument.spreadsheetml.template",  # .xltx
    "application/vnd.openxmlformats-officedocument.wordprocessingml.document",  # .docx
    "application/vnd.openxmlformats-officedocument.wordprocessingml.template",  # .dotx
})


def _ensure_templates_dir() -> Path:
    TEMPLATES_DIR.mkdir(parents=True, exist_ok=True)
    return TEMPLATES_DIR


@router.get("/templates", response_model=List[dict])
async def list_templates():
    """List uploaded template files (name, type, size, mtime)."""
    _ensure_templates_dir()
    out: List[dict] = []
    for f in sorted(TEMPLATES_DIR.iterdir(), key=lambda p: p.stat().st_mtime, reverse=True):
        if not f.is_file():
            continue
        suf = f.suffix.lower()
        if suf not in ALLOWED_EXTENSIONS:
            continue
        st = f.stat()
        out.append({
            "name": f.name,
            "type": "excel" if suf in ALLOWED_EXCEL else "word",
            "size": st.st_size,
            "uploaded_at": st.st_mtime,
        })
    return out


@router.post("/templates/upload", status_code=status.HTTP_201_CREATED)
async def upload_template(file: UploadFile = File(...)):
    """Upload a .xlsx, .xltx, .docx or .dotx template to data/templates/."""
    suf = Path(file.filename or "").suffix.lower()
    if suf not in ALLOWED_EXTENSIONS:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Only .xlsx, .xltx, .docx and .dotx files are allowed.",
        )
    content_type = (file.content_type or "").strip().split(";")[0].strip().lower()
    if content_type and content_type not in ALLOWED_MIME_TYPES:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Invalid content type. Allowed: .xlsx, .xltx, .docx, .dotx Office formats.",
        )
    dir_path = _ensure_templates_dir()
    dest = dir_path / (file.filename or "template" + suf)
    content = await file.read()
    dest.write_bytes(content)
    return {"name": dest.name, "path": str(dest)}


def get_latest_excel_template() -> Path | None:
    """Return path to the most recently modified .xlsx or .xltx in data/templates, or None."""
    if not TEMPLATES_DIR.exists():
        return None
    excel_files = [
        f for f in TEMPLATES_DIR.iterdir()
        if f.is_file() and f.suffix.lower() in ALLOWED_EXCEL
    ]
    if not excel_files:
        return None
    return max(excel_files, key=lambda p: p.stat().st_mtime)


def get_quote_template_path(template_filename: str | None) -> Path:
    """Resolve quote template path: optional filename in data/templates or latest excel template or default."""
    if template_filename:
        candidate = TEMPLATES_DIR / template_filename
        if candidate.is_file() and candidate.suffix.lower() in ALLOWED_EXCEL:
            return candidate
    latest = get_latest_excel_template()
    if latest:
        return latest
    default = Path("templates/quote_template.xlsx")
    return default