# app.py
import asyncio
from functools import lru_cache
from typing import Optional

from barcode import Code128
from barcode.writer import ImageWriter
from brother_ql.backends.helpers import send
from brother_ql.conversion import convert
from brother_ql.raster import BrotherQLRaster
from fastapi import FastAPI, HTTPException
from PIL import Image, ImageDraw, ImageFont
from pydantic import BaseModel, Field
from pylibdmtx.pylibdmtx import encode

TARGET_H = 106
DPI = 300

app = FastAPI(title="QL-1060N Stacked Barcode Printer")


class PrintRequest(BaseModel):
    # from LABEL_PRINTER_PARAMS
    printer_ip: str = Field(..., description="QL-1060N IP on LAN")
    model: str = Field(..., description="Brother model")
    label: str = Field(..., description="12 mm tape")
    # grocy payload:
    grocycode: str = Field(..., description="Raw GrocyCode")
    product: str = Field(..., description="Product name")
    due_date: Optional[str] = Field(None, description="Due date from stock entry")

    class Config:
        # ignore any other fields Grocy might send
        extra = "ignore"


def mm_for_px(px, dpi=DPI):
    return 25.4 * px / dpi


@lru_cache(maxsize=256)
def make_code128_exact(
    grocycode: str,
    xdim_px: int = 4,  # 4–6 px is a good, scannable range
    dpi: int = DPI,
) -> Image.Image:
    code = Code128(grocycode, writer=ImageWriter())
    pil = code.render(
        writer_options={
            "write_text": False,
            "dpi": dpi,
            "module_height": mm_for_px(TARGET_H, dpi),  # exact 106 px tall
            "module_width": mm_for_px(xdim_px, dpi),  # integer px/narrow bar
            "quiet_zone": max(2.5, 10 * mm_for_px(xdim_px, dpi)),  # generous quiet zone
        }
    ).convert(
        "L"
    )  # keep grayscale
    # Height should already be 106 px; if writer adds 1px border, crop vertically.
    if pil.height != TARGET_H:
        pil = pil.resize((pil.width, TARGET_H), Image.NEAREST)
    return pil


@lru_cache(maxsize=256)
def make_datamatrix_scaled(grocycode: str) -> Image.Image:
    dm = encode(grocycode.encode("utf-8"))
    # pylibdmtx returns RGB pixel data; convert to grayscale explicitly
    img = Image.frombytes("RGB", (dm.width, dm.height), dm.pixels).convert("L")
    factor = max(
        1, TARGET_H // img.height
    )  # integer up-scale, never down with fraction
    img_up = img.resize((img.width * factor, img.height * factor), Image.NEAREST)
    # If it doesn’t land exactly at 106 px, don’t fractional-resize it.
    # Just place it on a 106 px tall strip when composing.
    return img_up


def compose_row(parts: list[Image.Image], spacing: int = 18) -> Image.Image:
    h = TARGET_H
    w = sum(p.width for p in parts) + spacing * (len(parts) - 1)
    out = Image.new("L", (w, h), 255)
    x = 0
    for p in parts:
        y = (h - p.height) // 2  # vertical align; still a 106 px output image
        out.paste(p, (x, y))
        x += p.width + spacing
    return out.convert("1")  # binarize once at the very end


def send_to_printer(image: Image.Image, printer_ip: str, model: str, label: str):
    qlr = BrotherQLRaster(model)
    qlr.exception_on_warning = True

    instructions = convert(
        qlr=qlr,
        images=[image],
        label=label,
        rotate="90",  # landscape
        threshold=70.0,
        dither=False,
        compress=True,
        cut=True,
    )

    send(
        instructions=instructions,
        printer_identifier=printer_ip,
        backend_identifier="network",
        blocking=True,
    )


def _try_load_font(size: int) -> ImageFont.ImageFont:
    """Try to load a decent TTF font; fall back to PIL default."""
    candidates = [
        "DejaVuSans.ttf",
        "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
        "/System/Library/Fonts/Supplemental/Arial Unicode.ttf",
        "/System/Library/Fonts/Supplemental/Arial.ttf",
    ]
    for path in candidates:
        try:
            return ImageFont.truetype(path, size)
        except Exception:
            continue
    return ImageFont.load_default()


def _ellipsize(
    text: str, font: ImageFont.ImageFont, max_width: int, draw: ImageDraw.ImageDraw
) -> str:
    if not text:
        return ""
    if draw.textlength(text, font=font) <= max_width:
        return text
    low, high = 0, len(text)
    best = ""
    while low <= high:
        mid = (low + high) // 2
        candidate = (text[:mid] + "…") if mid < len(text) else text
        if draw.textlength(candidate, font=font) <= max_width:
            best = candidate
            low = mid + 1
        else:
            high = mid - 1
    return best or "…"


def make_text_panel(
    product: str, due_date: Optional[str], max_width: int = 360, padding: int = 4
) -> Image.Image:
    """Render up to two lines of text (product, due_date) into a fixed-height strip.

    - Keeps height = TARGET_H.
    - Ellipsizes to ensure the panel width <= max_width.
    - Chooses font sizes that fit vertically.
    """
    # Create a temporary image for measurement
    meas_img = Image.new("L", (max_width, TARGET_H), 255)
    draw = ImageDraw.Draw(meas_img)

    # Try font size pairs, largest first, until both lines fit vertically
    product_sizes = [22, 20, 18, 16, 14, 12, 11, 10, 9, 8]
    due_sizes = [14, 13, 12, 11, 10, 9, 8]
    chosen = None
    have_due = bool(due_date)

    for ps in product_sizes:
        pf = _try_load_font(ps)
        ph = pf.getbbox("Ag")[3] if hasattr(pf, "getbbox") else pf.getsize("Ag")[1]
        if have_due:
            for ds in due_sizes:
                df = _try_load_font(ds)
                dh = (
                    df.getbbox("Ag")[3]
                    if hasattr(df, "getbbox")
                    else df.getsize("Ag")[1]
                )
                total_h = ph + dh + padding  # small gap between lines
                if total_h + 2 * padding <= TARGET_H:
                    chosen = (pf, df)
                    break
            if chosen:
                break
        else:
            if ph + 2 * padding <= TARGET_H:
                chosen = (pf, None)
                break

    if not chosen:
        # Fallback to default tiny font(s)
        chosen = (_try_load_font(8), _try_load_font(8) if have_due else None)

    pf, df = chosen

    # Ellipsize to max_width
    product_text = _ellipsize(product or "", pf, max_width - 2 * padding, draw)
    due_text = (
        _ellipsize(due_date or "", df or pf, max_width - 2 * padding, draw)
        if have_due
        else None
    )

    # Measure final sizes
    p_w = int(draw.textlength(product_text, font=pf))
    p_h = pf.getbbox("Ag")[3] if hasattr(pf, "getbbox") else pf.getsize("Ag")[1]
    d_w = int(draw.textlength(due_text, font=df or pf)) if have_due else 0
    d_h = (
        (df.getbbox("Ag")[3] if hasattr(df, "getbbox") else df.getsize("Ag")[1])
        if have_due
        else 0
    )
    panel_w = min(max(p_w, d_w) + 2 * padding, max_width)

    # Render the panel
    out = Image.new("L", (panel_w, TARGET_H), 255)
    odraw = ImageDraw.Draw(out)
    y = (TARGET_H - (p_h + (d_h + padding if have_due else 0))) // 2
    odraw.text((padding, y), product_text, fill=0, font=pf)
    if have_due and due_text:
        odraw.text((padding, y + p_h + padding), due_text, fill=0, font=df or pf)

    return out


@app.post("/print", summary="Print Code128 + DataMatrix side-by-side")
async def print_from_grocy(req: PrintRequest):
    try:
        loop = asyncio.get_running_loop()
        code_img, dm_img = await asyncio.gather(
            # use default x-dimension and DPI; only pass the payload
            loop.run_in_executor(None, make_code128_exact, req.grocycode),
            loop.run_in_executor(None, make_datamatrix_scaled, req.grocycode),
        )
        # Render a compact text panel; width-capped to keep label length reasonable
        text_panel = make_text_panel(req.product, req.due_date, max_width=360)
        # compose expects a list of images
        label_img = compose_row([code_img, dm_img, text_panel], spacing=12)
        send_to_printer(label_img, req.printer_ip, req.model, req.label)
    except Exception:
        # optionally: log e with traceback and return a generic message
        raise HTTPException(status_code=500, detail="Printing failed.")
    return {
        "status": "printed",
        "model": req.model,
        "label": req.label,
        "layout": "code128 | datamatrix | text",
    }