"""Spool label printing routes (#809).

Two endpoints, one per inventory backend:

- ``POST /inventory/labels``  — local-DB spools
- ``POST /spoolman/labels``   — Spoolman-backed spools

Both accept ``{spool_ids: [int], template: str, starting_position: int}`` and
return a PDF stream.
The QR code on each label deep-links to ``/inventory?spool=<id>`` so a phone
scan jumps straight back into Bambuddy at that spool's row.
"""

from __future__ import annotations

import io
import logging
from typing import Literal

from fastapi import APIRouter, Depends, HTTPException, Request
from fastapi.responses import StreamingResponse
from pydantic import BaseModel, Field, model_validator
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from backend.app.api.routes._spoolman_helpers import parse_spoolman_multi_colors
from backend.app.api.routes.settings import get_setting
from backend.app.core.auth import RequirePermissionIfAuthEnabled
from backend.app.core.database import get_db
from backend.app.core.permissions import Permission
from backend.app.models.spool import Spool
from backend.app.models.user import User
from backend.app.services.label_renderer import LabelData, TemplateName, get_sheet_capacity, render_labels
from backend.app.services.spoolman import get_spoolman_client
from backend.app.utils.http import build_content_disposition

logger = logging.getLogger(__name__)

router = APIRouter(tags=["labels"])

_VALID_TEMPLATES: tuple[TemplateName, ...] = (
    "ams_holder_74x33",
    "ams_holder_75x55",
    "box_40x30",
    "box_62x29",
    "avery_5160",
    "avery_l7160",
)

# Cap how many labels can be requested in one go. Sane upper bound for the
# largest realistic batch (an Avery sheet at 30/page × ~10 pages).
MAX_LABELS_PER_REQUEST = 500


class LabelRequest(BaseModel):
    spool_ids: list[int] = Field(..., min_length=1, max_length=MAX_LABELS_PER_REQUEST)
    template: Literal[
        "ams_holder_74x33",
        "ams_holder_75x55",
        "box_40x30",
        "box_62x29",
        "avery_5160",
        "avery_l7160",
    ]
    # Black-and-white thermal printers: drop the colour swatch (prints as a
    # muddy grey block) and widen the text column instead (#1870).
    monochrome: bool = False
    starting_position: int = Field(default=1, ge=1)

    @model_validator(mode="after")
    def validate_starting_position(self) -> LabelRequest:
        capacity = get_sheet_capacity(self.template)
        if capacity is None:
            if self.starting_position != 1:
                raise ValueError("starting_position is only supported for sheet label templates")
            return self
        if self.starting_position > capacity:
            raise ValueError(f"starting_position must be between 1 and {capacity} for template {self.template}")
        return self


def _split_extra_colors(raw: str | None) -> list[str] | None:
    """Parse ``Spool.extra_colors`` (comma-separated hex tokens) into a list."""
    if not raw:
        return None
    parts = [p.strip().lstrip("#") for p in raw.split(",") if p.strip()]
    return parts or None


async def _resolve_deeplink_base(request: Request, db: AsyncSession) -> str:
    """Where the QR codes should point. Prefers `external_url` when set so a
    phone scan reaches the user's public Bambuddy URL rather than an internal
    address; falls back to the request's own scheme+host when no setting is
    configured.
    """
    external = (await get_setting(db, "external_url") or "").strip().rstrip("/")
    if external:
        return external
    return f"{request.url.scheme}://{request.url.netloc}"


def _spool_to_label_data(spool: Spool, deeplink_base: str) -> LabelData:
    name = spool.color_name or spool.slicer_filament_name or f"{spool.brand or ''} {spool.material}".strip()
    return LabelData(
        spool_id=spool.id,
        name=name or spool.material,
        material=spool.material,
        brand=spool.brand,
        subtype=spool.subtype,
        rgba=spool.rgba,
        extra_colors=_split_extra_colors(spool.extra_colors),
        storage_location=getattr(spool, "storage_location", None),
        deeplink_url=f"{deeplink_base}/inventory?spool={spool.id}",
    )


def _spoolman_dict_to_label_data(s: dict, deeplink_base: str) -> LabelData:
    """Build LabelData from a raw Spoolman /spool response dict.

    Spoolman models don't have a native 'spool name' — we derive it from the
    embedded filament. Material and brand come from filament/vendor.
    """
    filament = s.get("filament") or {}
    vendor = filament.get("vendor") or {}
    fname = filament.get("name") or ""
    material = filament.get("material") or ""
    brand = vendor.get("name")
    color_hex = filament.get("color_hex")
    rgba = color_hex.lstrip("#") if isinstance(color_hex, str) else None

    # Shared with `_map_spoolman_spool`, so the swatch printed on a label and
    # the swatch drawn on an AMS slot card cannot read the same field two ways.
    extra: list[str] | None = parse_spoolman_multi_colors(filament) or None

    return LabelData(
        spool_id=int(s.get("id", 0)),
        name=fname or material or "Spool",
        material=material or "",
        brand=brand,
        subtype=None,
        rgba=rgba,
        extra_colors=extra,
        storage_location=s.get("location"),
        deeplink_url=f"{deeplink_base}/inventory?spool={int(s.get('id', 0))}",
    )


def _stream_pdf(pdf: bytes, filename: str) -> StreamingResponse:
    return StreamingResponse(
        io.BytesIO(pdf),
        media_type="application/pdf",
        headers={
            "Content-Disposition": build_content_disposition(filename, disposition="inline"),
            "Content-Length": str(len(pdf)),
            # PDFs are deterministic per request; tell the browser not to cache
            # so re-printing after edits picks up the new data.
            "Cache-Control": "no-store",
        },
    )


@router.post("/inventory/labels")
async def render_local_inventory_labels(
    body: LabelRequest,
    request: Request,
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.INVENTORY_READ),
) -> StreamingResponse:
    """Render labels for spools in the local inventory."""
    if body.template not in _VALID_TEMPLATES:
        raise HTTPException(400, f"Unknown template: {body.template}")

    result = await db.execute(select(Spool).where(Spool.id.in_(body.spool_ids)))
    spools = list(result.scalars().all())

    found_ids = {s.id for s in spools}
    missing = [sid for sid in body.spool_ids if sid not in found_ids]
    if missing:
        raise HTTPException(404, f"Spool(s) not found: {missing}")

    # Preserve caller's order so an Avery sheet print matches the on-screen list.
    ordered = sorted(spools, key=lambda s: body.spool_ids.index(s.id))

    deeplink_base = await _resolve_deeplink_base(request, db)
    data_list = [_spool_to_label_data(s, deeplink_base) for s in ordered]

    pdf = render_labels(
        body.template,
        data_list,
        monochrome=body.monochrome,
        starting_position=body.starting_position,
    )
    filename = f"bambuddy-labels-{body.template}.pdf"
    return _stream_pdf(pdf, filename)


@router.post("/spoolman/labels")
async def render_spoolman_labels(
    body: LabelRequest,
    request: Request,
    db: AsyncSession = Depends(get_db),
    _: User | None = RequirePermissionIfAuthEnabled(Permission.INVENTORY_READ),
) -> StreamingResponse:
    """Render labels for spools tracked in Spoolman.

    The Spoolman client doesn't expose a per-id endpoint, so this fetches the
    full spool list and filters in-memory. For typical libraries (~50 spools)
    that's negligible; for very large libraries this is the trade-off until
    Spoolman gains a bulk filter.
    """
    if body.template not in _VALID_TEMPLATES:
        raise HTTPException(400, f"Unknown template: {body.template}")

    spoolman_on = (await get_setting(db, "spoolman_enabled") or "").lower() == "true"
    if not spoolman_on:
        raise HTTPException(400, "Spoolman integration is not enabled")

    client = await get_spoolman_client()
    if client is None or not client.is_connected:
        raise HTTPException(503, "Spoolman not reachable")

    try:
        all_spools = await client.get_spools()
    except Exception as exc:
        logger.warning("Spoolman fetch failed during label render: %s", exc)
        raise HTTPException(502, "Failed to fetch spools from Spoolman") from exc

    by_id = {int(s.get("id", 0)): s for s in all_spools if s.get("id") is not None}
    missing = [sid for sid in body.spool_ids if sid not in by_id]
    if missing:
        raise HTTPException(404, f"Spool(s) not found in Spoolman: {missing}")

    deeplink_base = await _resolve_deeplink_base(request, db)
    data_list = [_spoolman_dict_to_label_data(by_id[sid], deeplink_base) for sid in body.spool_ids]

    pdf = render_labels(
        body.template,
        data_list,
        monochrome=body.monochrome,
        starting_position=body.starting_position,
    )
    filename = f"bambuddy-labels-spoolman-{body.template}.pdf"
    return _stream_pdf(pdf, filename)