"""Render DWG/DXF/PDF → PNG image(s) for vision model consumption.

Strategy: multi-floor architectural drawings are split per detected legend.
Each floor renders to its own PNG at a resolution where individual symbols
remain distinguishable for the vision model.
"""
import logging
import subprocess
from pathlib import Path

import io

import ezdxf
from ezdxf.addons.drawing.config import (
    BackgroundPolicy, ColorPolicy, Configuration,
)
from ezdxf.addons.drawing import Frontend, RenderContext, layout
from ezdxf.addons.drawing.svg import SVGBackend
import cairosvg
from PIL import Image

logger = logging.getLogger(__name__)

RENDER_PX = 8000  # target pixel size of the longer edge — Claude vision max


def dwg_to_dxf(dwg_path: Path, out_dir: Path) -> Path:
    dxf_path = out_dir / f"{dwg_path.stem}.dxf"
    r = subprocess.run(
        ["dwgread", "-O", "DXF", "-o", str(dxf_path), str(dwg_path)],
        capture_output=True, text=True, timeout=180,
    )
    if not dxf_path.exists():
        raise RuntimeError(f"DWG→DXF failed (exit {r.returncode}): {r.stderr or r.stdout}")
    return dxf_path


SKIP_LAYER_PATTERNS = (
    "dimens", "kota", "kóta", "koty",  # dimensions
    "sit_konst", "konstrukce", "ckkoty",  # structural / dimensioning
    "ckprofi", "profily", "csprofily",  # steel/concrete profile rezy
    "sanita", "vzt", "ov_kan", "tzb",  # plumbing / HVAC (when not the target)
    "viewport", "defpoints", "0_", "_b_",  # CAD bookkeeping
    "raster", "wipeout",
)


def _clean_doc(doc, drop_layers=False):
    """Strip elements that overwhelm vision rendering."""
    msp = doc.modelspace()
    valid_blocks = {b.name for b in doc.blocks}
    for e in list(msp.query("INSERT")):
        if e.dxf.name not in valid_blocks:
            msp.delete_entity(e)
    for typ in ("HATCH", "SOLID", "MPOLYGON"):
        for e in list(msp.query(typ)):
            msp.delete_entity(e)
    if drop_layers:
        for e in list(msp):
            layer = str(getattr(e.dxf, "layer", "")).lower()
            if any(p in layer for p in SKIP_LAYER_PATTERNS):
                try:
                    msp.delete_entity(e)
                except Exception:
                    pass
    for e in msp:
        try:
            e.dxf.lineweight = 5
        except Exception:
            pass


def find_floors(dxf_path: Path) -> list[dict]:
    """Find legend 'LEGENDA' markers — each represents one floor.

    Returns list of {legend_xy, floor_bbox} dicts ordered top to bottom.
    """
    doc = ezdxf.readfile(str(dxf_path))
    msp = doc.modelspace()

    positions = []
    for e in msp:
        text = ""
        if e.dxftype() == "MTEXT":
            text = e.text
        elif e.dxftype() == "TEXT":
            text = e.dxf.text
        if text and text.strip().upper() == "LEGENDA":
            try:
                positions.append((e.dxf.insert.x, e.dxf.insert.y))
            except Exception:
                pass
    positions.sort(key=lambda p: -p[1])

    if not positions:
        return [{"legend_xy": None, "floor_bbox": None}]

    # Use the same cleanup as render_region so extents reflect what'll be drawn
    _clean_doc(doc)
    from ezdxf.bbox import extents
    try:
        ext = extents(msp, fast=True)
        mxmin, mymin = ext.extmin.x, ext.extmin.y
        mxmax, mymax = ext.extmax.x, ext.extmax.y
    except Exception:
        mxmin, mymin = -1e9, -1e9
        mxmax, mymax = 1e9, 1e9
    logger.info("find_floors: model extents x=(%.0f,%.0f) y=(%.0f,%.0f)",
                mxmin, mxmax, mymin, mymax)

    floors = []
    for i, (lx, ly) in enumerate(positions):
        if i + 1 < len(positions):
            y_height = ly - positions[i + 1][1]
        elif i > 0:
            y_height = positions[i - 1][1] - ly
        else:
            y_height = 60000
        # Legend appears at the TOP of its floor view; plan extends downward
        y_top = min(mymax, ly + 0.10 * y_height)
        y_bot = max(mymin, ly - 0.95 * y_height)
        # X span = whole model width (floor plans typically span the page width)
        x_left = mxmin
        x_right = mxmax
        floors.append({
            "legend_xy": (lx, ly),
            "floor_bbox": (x_left, y_bot, x_right, y_top),
        })
    return floors


def render_region(dxf_path: Path, out_path: Path, bbox: tuple | None) -> Path:
    """Render a DXF (optionally clipped to bbox) to PNG via SVG.

    Pipeline: ezdxf → SVG (vector, faithful linework) → cairosvg → PNG.
    Cropping is done in pixel space after rasterization, using the page
    rectangle ezdxf assigned to the SVG.
    """
    doc = ezdxf.readfile(str(dxf_path))
    auditor = doc.audit()
    if auditor.has_errors:
        logger.info("DXF audit: %d errors", len(auditor.errors))
    _clean_doc(doc)
    msp = doc.modelspace()

    from ezdxf.bbox import extents
    try:
        ext = extents(msp, fast=True)
        model_xmin = ext.extmin.x
        model_ymin = ext.extmin.y
        model_w = ext.size.x or 1
        model_h = ext.size.y or 1
    except Exception:
        model_xmin = model_ymin = 0
        model_w = model_h = 1

    config = Configuration(
        background_policy=BackgroundPolicy.WHITE,
        color_policy=ColorPolicy.BLACK,
        lineweight_scaling=0.5,
        min_lineweight=0.05,
    )

    # ezdxf SVG: target page sized so longest dimension is RENDER_PX pixels.
    # SVG uses mm; pick a scale such that the page fits cleanly.
    aspect = model_w / max(model_h, 1)
    if aspect >= 1:
        page_w_mm = 1000
        page_h_mm = 1000 / aspect
    else:
        page_h_mm = 1000
        page_w_mm = 1000 * aspect

    page = layout.Page(width=page_w_mm, height=page_h_mm,
                       units=layout.Units.mm, margins=layout.Margins.all(0))
    backend = SVGBackend()
    Frontend(RenderContext(doc), backend, config=config).draw_layout(msp, finalize=True)
    svg_str = backend.get_string(page)

    # cairosvg renders SVG → PNG. output_width sets the PNG pixel width.
    longest_px = RENDER_PX
    out_width = longest_px if aspect >= 1 else int(longest_px * aspect)
    png_bytes = cairosvg.svg2png(bytestring=svg_str.encode("utf-8"),
                                  output_width=out_width)
    img = Image.open(io.BytesIO(png_bytes))
    # Ensure white background (cairosvg may produce alpha)
    if img.mode == "RGBA":
        white = Image.new("RGB", img.size, (255, 255, 255))
        white.paste(img, mask=img.split()[3])
        img = white

    if bbox is not None:
        W, H = img.size
        xmin, ymin, xmax, ymax = bbox
        logger.info("Crop input: model_w=%.0f model_h=%.0f W=%d H=%d bbox=%s",
                    model_w, model_h, W, H, bbox)
        px0 = max(0, int((xmin - model_xmin) / model_w * W))
        px1 = min(W, int((xmax - model_xmin) / model_w * W))
        py0 = max(0, int((model_ymin + model_h - ymax) / model_h * H))
        py1 = min(H, int((model_ymin + model_h - ymin) / model_h * H))
        logger.info("Crop pixels: (%d,%d) → (%d,%d)", px0, py0, px1, py1)
        if px1 > px0 and py1 > py0:
            img = img.crop((px0, py0, px1, py1))

    if max(img.size) > RENDER_PX:
        r = RENDER_PX / max(img.size)
        img = img.resize((int(img.size[0] * r), int(img.size[1] * r)), Image.LANCZOS)

    img.save(out_path, "PNG", optimize=True)
    logger.info("Rendered → %s (%dx%d)", out_path.name, img.size[0], img.size[1])
    return out_path


def render(input_path: Path, out_dir: Path) -> dict:
    """Convert input → list of floor images.

    Returns: {"floors": [{"index":0, "png":"floor_0.png", "legend_xy":[x,y]}, ...]}.
    """
    suffix = input_path.suffix.lower()

    if suffix == ".pdf":
        return _render_pdf(input_path, out_dir)

    if suffix == ".dwg":
        dxf_path = dwg_to_dxf(input_path, out_dir)
    elif suffix == ".dxf":
        dxf_path = input_path
    else:
        raise ValueError(f"Unsupported format: {suffix}")

    floors = find_floors(dxf_path)
    logger.info("Detected %d floor(s) via LEGENDA markers", len(floors))
    # MVP: render only the first floor. Multi-floor selection is a follow-up.
    f = floors[0]
    png = out_dir / "floor_0.png"
    render_region(dxf_path, png, f["floor_bbox"])
    return {"floors": [{"index": 0, "png": png.name,
                       "legend_xy": list(f["legend_xy"]) if f["legend_xy"] else None}]}


def _render_pdf(pdf_path: Path, out_dir: Path) -> dict:
    """Render PDF → PNG, auto-rotate so LEGENDA reads horizontally.

    Uses pdfplumber to find 'LEGENDA' text and its rotation, then renders
    via pdf2image and applies image rotation so the legend is upright.
    Returns the same shape as the DXF render path.
    """
    from pdf2image import convert_from_path
    import pdfplumber
    # Allow large rasterizations (architectural PDFs can be 200M+ px at high DPI)
    Image.MAX_IMAGE_PIXELS = None

    # Pick DPI so longest page edge lands near RENDER_PX pixels
    with pdfplumber.open(str(pdf_path)) as pdf:
        first = pdf.pages[0]
        pw_in = max(first.width, first.height) / 72  # PDF points → inches
    target_dpi = max(150, min(600, int(RENDER_PX / max(pw_in, 1))))
    logger.info("PDF page longest edge %.1f in → using dpi=%d", pw_in, target_dpi)

    pages = convert_from_path(str(pdf_path), dpi=target_dpi)
    out_paths = []
    legend_info: list[dict] = []

    with pdfplumber.open(str(pdf_path)) as pdf:
        for i, plumb_page in enumerate(pdf.pages):
            page_img = pages[i] if i < len(pages) else None
            if page_img is None:
                continue
            pw, ph = plumb_page.width, plumb_page.height
            iw, ih = page_img.size
            # Find any text matching legend headings
            words = plumb_page.extract_words(extra_attrs=["upright"]) or []
            legend_word = None
            for w in words:
                text = w["text"].strip().upper()
                if text in ("LEGENDA", "VYSVĚTLIVKY", "LEGENDA:", "POPIS"):
                    legend_word = w
                    break
            rotation = 0
            if legend_word is not None and not legend_word.get("upright", True):
                # Sideways text → rotate the image so text is upright.
                # PIL.rotate uses CCW for positive angles.
                rotation = 90
                page_img = page_img.rotate(90, expand=True)
                iw, ih = page_img.size
                logger.info("PDF page %d: rotated 90° CCW (LEGENDA was sideways)", i)
            if legend_word is not None:
                # Convert PDF coords to NORMALIZED image coords (after rotation)
                x0, y0 = legend_word["x0"], legend_word["top"]
                x1, y1 = legend_word["x1"], legend_word["bottom"]
                if rotation == 90:
                    # CCW 90° rotation: original (x, y) → new (y, W-x).
                    # Rotated image has width=ph, height=pw.
                    nx0 = y0 / ph
                    nx1 = y1 / ph
                    ny0 = 1 - (x1 / pw)
                    ny1 = 1 - (x0 / pw)
                else:
                    nx0, nx1 = x0 / pw, x1 / pw
                    ny0, ny1 = y0 / ph, y1 / ph
                legend_info.append({"page": i, "norm_bbox": (nx0, ny0, nx1, ny1)})
                logger.info("PDF page %d: LEGENDA at norm bbox %s",
                            i, (nx0, ny0, nx1, ny1))

            if max(page_img.size) > RENDER_PX:
                r = RENDER_PX / max(page_img.size)
                page_img = page_img.resize(
                    (int(page_img.size[0] * r), int(page_img.size[1] * r)),
                    Image.LANCZOS,
                )
            p = out_dir / f"floor_{i}.png"
            page_img.save(p, "PNG", optimize=True)
            out_paths.append(p)

    return {
        "floors": [
            {"index": i, "png": p.name, "legend_xy": None,
             "legend_norm_bbox": next((li["norm_bbox"] for li in legend_info
                                        if li["page"] == i), None)}
            for i, p in enumerate(out_paths)
        ]
    }


def crop_region(image_path: Path, bbox: dict, out_path: Path,
                pad: float = 1.5, min_px: int = 120) -> Path:
    """Crop a region with generous padding so symbols are visible.

    pad: multiplier of the bbox half-extent added on each side.
    min_px: ensure the output is at least this many pixels wide/tall by
    expanding the crop region if the requested area is smaller.
    """
    img = Image.open(image_path)
    W, H = img.size
    bx, by, bw, bh = bbox["x"], bbox["y"], bbox["w"], bbox["h"]
    cx, cy = bx + bw / 2, by + bh / 2
    # Padded extents in normalized coords
    half_w = bw / 2 + bw * pad
    half_h = bh / 2 + bh * pad
    # Enforce minimum pixel dimensions
    if (2 * half_w) * W < min_px:
        half_w = (min_px / 2) / W
    if (2 * half_h) * H < min_px:
        half_h = (min_px / 2) / H
    x0 = max(0, int((cx - half_w) * W))
    x1 = min(W, int((cx + half_w) * W))
    y0 = max(0, int((cy - half_h) * H))
    y1 = min(H, int((cy + half_h) * H))
    crop = img.crop((x0, y0, x1, y1))
    crop.save(out_path, "PNG")
    return out_path