"""Export PDF d'une zone : planche d'impression terrain du relief orienté.

Composée directement en Lambert 93 depuis les sources de la pyramide
(tiles.py) — échelle exacte, quadrillage aligné sur les dalles — puis
dessinée avec reportlab (texte, grille et légende vectoriels). Tourne dans
l'image légère : Pillow + pyproj + reportlab, sans numpy.
"""

import logging
import math
from dataclasses import dataclass

logger = logging.getLogger("lidar")

LAYER = "relief_oriente"
PAPERS_MM = {"A4": (210.0, 297.0), "A3": (297.0, 420.0)}
ORIENTS = ("portrait", "paysage")
SCALES = (1000, 2000, 5000, 10000)
DPI = {"A4": 300, "A3": 250}          # borne la mémoire du Pi (~36 Mo en A3)
NATIVE_RES_M = 0.2
MARGIN_MM = 10.0                      # bord non imprimable
ANNOT_MM = 7.0                        # bande des coordonnées autour de la carte
PANEL_SIDE_MM = 64.0                  # bandeau à droite (paysage)
PANEL_BOTTOM_MM = 72.0                # bandeau en bas (portrait)
_GRID_STEPS = {1000: 100, 2000: 100, 5000: 500, 10000: 1000}


@dataclass(frozen=True)
class Layout:
    """Géométrie de la planche, en mm, origine en bas à gauche (reportlab)."""
    paper: str
    orient: str
    scale: int
    dpi: int
    page_w: float
    page_h: float
    map_x: float
    map_y: float
    map_w: float
    map_h: float
    panel_x: float
    panel_y: float
    panel_w: float
    panel_h: float


def layout(paper, orient, scale):
    """Géométrie d'une planche ; ValueError si un réglage est invalide."""
    if paper not in PAPERS_MM:
        raise ValueError(f"format inconnu : {paper} (A4 ou A3)")
    if orient not in ORIENTS:
        raise ValueError(f"orientation inconnue : {orient} (portrait ou paysage)")
    try:
        scale = int(scale)
    except (TypeError, ValueError):
        raise ValueError(f"échelle invalide : {scale}") from None
    if scale not in SCALES:
        raise ValueError("échelle non proposée : 1:" + str(scale)
                         + " (1:1000, 1:2000, 1:5000 ou 1:10000)")
    w, h = PAPERS_MM[paper]
    if orient == "paysage":
        w, h = h, w
    inner = MARGIN_MM + ANNOT_MM
    if orient == "paysage":
        map_w = w - 2 * inner - PANEL_SIDE_MM
        map_h = h - 2 * inner
        return Layout(paper, orient, scale, DPI[paper], w, h, inner, inner, map_w, map_h,
                      w - MARGIN_MM - PANEL_SIDE_MM, MARGIN_MM, PANEL_SIDE_MM, h - 2 * MARGIN_MM)
    map_w = w - 2 * inner
    map_h = h - 2 * inner - PANEL_BOTTOM_MM
    return Layout(paper, orient, scale, DPI[paper], w, h, inner, MARGIN_MM + PANEL_BOTTOM_MM + ANNOT_MM,
                  map_w, map_h, MARGIN_MM, MARGIN_MM, w - 2 * MARGIN_MM, PANEL_BOTTOM_MM)


def center_l93(lat, lon):
    """Centre WGS84 → Lambert 93 ; ValueError si non fini."""
    from .tiles import wgs84_to_l93
    lat, lon = float(lat), float(lon)
    if not (math.isfinite(lat) and math.isfinite(lon)):
        raise ValueError("coordonnées du centre invalides")
    cx, cy = wgs84_to_l93(lon, lat)
    if not (math.isfinite(cx) and math.isfinite(cy)):
        raise ValueError("centre hors du domaine Lambert 93")
    return cx, cy


def map_bbox(cx, cy, lay):
    """Emprise terrain L93 de la zone carte (papier × échelle)."""
    half_w = lay.map_w / 1000.0 * lay.scale / 2
    half_h = lay.map_h / 1000.0 * lay.scale / 2
    return (cx - half_w, cy - half_h, cx + half_w, cy + half_h)


def pixel_size(lay):
    """Taille terrain d'un pixel imprimé (m), jamais plus fine que le natif."""
    return max(NATIVE_RES_M, lay.scale * 0.0254 / lay.dpi)


def grid_step(scale):
    """Pas du quadrillage L93 (m) selon l'échelle."""
    return _GRID_STEPS[int(scale)]


def _to_wgs84(x, y):
    from .tiles import _transformer
    lon, lat = _transformer("EPSG:2154", "EPSG:4326").transform(x, y)
    return lat, lon


def frame(lat, lon, paper, orient, scale):
    """Cadre imprimable pour la carte : emprise L93 et coins WGS84 (NO, NE, SE, SO)."""
    lay = layout(paper, orient, scale)
    cx, cy = center_l93(lat, lon)
    b = map_bbox(cx, cy, lay)
    corners = [_to_wgs84(b[0], b[3]), _to_wgs84(b[2], b[3]),
               _to_wgs84(b[2], b[1]), _to_wgs84(b[0], b[1])]
    return {"cx": cx, "cy": cy, "bbox_l93": list(b),
            "corners": [[round(a, 7), round(o, 7)] for a, o in corners],
            "width_m": round(b[2] - b[0]), "height_m": round(b[3] - b[1])}