"""
EM Embedded - Geometry Module

Contains geometry preview builders and hole computation functions.
"""
import numpy as np
import plotly.graph_objects as go

from .state import state, ctrl
from .globals import DEFAULT_AXIS_TICKS, EXCITATION_SURFACE_COLORSCALE

__all__ = [
    "nearest_gridline",
    "compute_hole_edges",
    "build_geometry_placeholder",
    "build_square_domain_plot",
    "push_geometry_plot",
    "update_geometry_preview",
    "update_geometry_hole_preview",
]


def nearest_gridline(val: float, nx: int) -> float:
    """Snap a value to the nearest gridline."""
    denom = float(max(int(nx) - 1, 1))
    return round(float(val) * denom) / denom


def compute_hole_edges(nx: int, cx: float, cy: float, a: float, snap: bool = True):
    """
    Compute square hole edges (xL, xR, yB, yT) in [0,1].

    Args:
        nx: points per direction; grid lines at k/(nx-1).
        cx, cy: center in (0,1).
        a: edge length in (0,1].
        snap: if True, snap edges to nearest grid lines; else require exact alignment.

    Returns:
        tuple (xL, xR, yB, yT) or None when invalid/out-of-bounds/misaligned.
    """
    try:
        nx = int(nx)
        cx = float(cx)
        cy = float(cy)
        a = float(a)
    except Exception:
        return None

    if not (a > 0.0):
        return None

    half = a / 2.0
    xL, xR = cx - half, cx + half
    yB, yT = cy - half, cy + half

    # Must be strictly inside domain to allow removing interior cells safely
    if not (0.0 < xL < xR < 1.0 and 0.0 < yB < yT < 1.0):
        return None

    if snap:
        xL_s = nearest_gridline(xL, nx)
        xR_s = nearest_gridline(xR, nx)
        yB_s = nearest_gridline(yB, nx)
        yT_s = nearest_gridline(yT, nx)
        # Ensure non-degenerate after snapping; attempt a minimal adjustment if equal
        if xL_s >= xR_s or yB_s >= yT_s:
            step = 1.0 / float(max(nx - 1, 1))
            if xL_s >= xR_s:
                if xL_s - step > 0.0:
                    xL_s -= step
                elif xR_s + step < 1.0:
                    xR_s += step
            if yB_s >= yT_s:
                if yB_s - step > 0.0:
                    yB_s -= step
                elif yT_s + step < 1.0:
                    yT_s += step
            if xL_s >= xR_s or yB_s >= yT_s:
                return None
        return (xL_s, xR_s, yB_s, yT_s)
    else:
        # Require edges to already lie on grid lines
        denom = float(max(nx - 1, 1))
        tol = 1e-9
        def _aligned(v: float) -> bool:
            return abs(v * denom - round(v * denom)) < tol
        if all(_aligned(v) for v in (xL, xR, yB, yT)):
            return (xL, xR, yB, yT)
        return None


def build_geometry_placeholder(message: str) -> go.Figure:
    """Build a placeholder figure with a message."""
    fig = go.Figure()
    fig.add_annotation(
        text=message,
        x=0.5,
        y=0.5,
        showarrow=False,
        font=dict(size=18, color="#5F259F"),
    )
    fig.update_xaxes(visible=False)
    fig.update_yaxes(visible=False)
    fig.update_layout(
        template="plotly_white",
        margin=dict(l=20, r=20, t=40, b=20),
        paper_bgcolor="#ffffff",
        plot_bgcolor="#ffffff",
        height=460,
        showlegend=False,
    )
    return fig


def build_square_domain_plot(
    nx: int,
    title: str,
    hole_edges=None,
    *,
    show_edges: bool = True,
    dense_grid: bool = False,
) -> go.Figure:
    """Build a 3D square domain plot with optional hole."""
    nx = max(int(nx), 3)
    grid = np.linspace(0.0, 1.0, nx)
    X, Y = np.meshgrid(grid, grid, indexing="xy")
    Z = np.zeros_like(X, dtype=float)
    color_field = np.full_like(Z, 0.85)

    if hole_edges is not None:
        xL, xR, yB, yT = hole_edges
        mask = (X >= xL) & (X <= xR) & (Y >= yB) & (Y <= yT)
        Z = np.where(mask, np.nan, Z)
        color_field = np.where(mask, np.nan, color_field)

    fig = go.Figure()
    fig.add_trace(
        go.Surface(
            x=X,
            y=Y,
            z=Z,
            surfacecolor=np.where(np.isnan(color_field), 0.15, color_field),
            colorscale=EXCITATION_SURFACE_COLORSCALE,
            cmin=0.0,
            cmax=1.0,
            showscale=False,
            opacity=0.98,
            lighting=dict(ambient=0.85, diffuse=0.55, specular=0.1),
            hovertemplate="x=%{x:.3f}<br>y=%{y:.3f}<extra></extra>",
        )
    )

    if show_edges:
        base_z = -0.012
        grid_vals = (
            np.linspace(0.0, 1.0, max(int(nx), 2))
            if dense_grid
            else np.asarray(DEFAULT_AXIS_TICKS)
        )
        line_x, line_y, line_z = [], [], []
        x_min_val, x_max_val = float(grid[0]), float(grid[-1])
        for val in grid_vals:
            val_f = float(val)
            line_x.extend([val_f, val_f, np.nan])
            line_y.extend([x_min_val, x_max_val, np.nan])
            line_z.extend([base_z, base_z, np.nan])
        for val in grid_vals:
            val_f = float(val)
            line_x.extend([x_min_val, x_max_val, np.nan])
            line_y.extend([val_f, val_f, np.nan])
            line_z.extend([base_z, base_z, np.nan])
        fig.add_trace(
            go.Scatter3d(
                x=line_x,
                y=line_y,
                z=line_z,
                mode="lines",
                line=dict(color="rgba(174,139,216,0.65)", width=1.6),
                showlegend=False,
                hoverinfo="skip",
            )
        )

    scale_ticks = list(DEFAULT_AXIS_TICKS)
    tick_text = [f"{t:.2f}" for t in scale_ticks]
    tick_plane = -0.02
    fig.add_trace(
        go.Scatter3d(
            x=scale_ticks,
            y=[-0.018] * len(scale_ticks),
            z=[tick_plane] * len(scale_ticks),
            mode="text",
            text=tick_text,
            textfont=dict(color="#5F259F", size=12),
            showlegend=False,
            hoverinfo="skip",
        )
    )
    fig.add_trace(
        go.Scatter3d(
            x=[-0.018] * len(scale_ticks),
            y=scale_ticks,
            z=[tick_plane] * len(scale_ticks),
            mode="text",
            text=tick_text,
            textfont=dict(color="#5F259F", size=12),
            showlegend=False,
            hoverinfo="skip",
        )
    )

    if hole_edges is not None:
        xL, xR, yB, yT = hole_edges
        fig.add_trace(
            go.Scatter3d(
                x=[xL, xR, xR, xL, xL],
                y=[yB, yB, yT, yT, yB],
                z=[0.0] * 5,
                mode="lines",
                line=dict(color="#FFFFFF", width=5),
                hoverinfo="skip",
                showlegend=False,
            )
        )

    fig.update_layout(
        title=title,
        margin=dict(l=8, r=8, t=44, b=8),
        height=620,
        template="plotly_white",
        scene=dict(
            xaxis=dict(range=[-0.05, 1.05], visible=False, backgroundcolor="#f7f3ff"),
            yaxis=dict(range=[-0.05, 1.05], visible=False, backgroundcolor="#f7f3ff"),
            zaxis=dict(range=[0.1, 0.1], visible=False, backgroundcolor="#f7f3ff"),
            aspectmode="cube",
            camera=dict(eye=dict(x=1.25, y=1.25, z=0.85)),
        ),
        dragmode="orbit",
        uirevision="geometry_surface",
    )
    return fig


def push_geometry_plot(fig: go.Figure):
    """Push a geometry plot to the UI."""
    try:
        if hasattr(ctrl, "geometry_preview_update"):
            ctrl.geometry_preview_update(fig)
    except Exception:
        pass


def update_geometry_preview():
    """Update the geometry preview based on current state."""
    if not state.bound:
        return
    
    geo = state.geometry_selection
    if geo in (None, "None"):
        fig = build_geometry_placeholder("Select a geometry to preview.")
    elif geo == "Square Domain":
        nx = int(state.nx or 16)
        fig = build_square_domain_plot(nx, "Square Domain Preview", None, show_edges=True)
    elif geo == "Square Metallic Body":
        nx = int(state.nx or 16)
        # Use hole parameters from state
        edges = compute_hole_edges(
            nx,
            float(state.hole_center_x or 0.5),
            float(state.hole_center_y or 0.5),
            float(state.hole_size_edge or 0.2),
            snap=getattr(state, "hole_snap", True),
        )
        fig = build_square_domain_plot(nx, "Square Metallic Body Preview", edges, show_edges=True)
    else:
        fig = build_geometry_placeholder(f"Geometry: {geo}")
    
    push_geometry_plot(fig)


def update_geometry_hole_preview():
    """Update geometry preview with current hole settings."""
    if not state.bound:
        return
    
    geo = state.geometry_selection
    if geo != "Square Metallic Body":
        return
    
    nx = int(state.nx or 16)
    edges = compute_hole_edges(
        nx,
        float(state.hole_center_x or 0.5),
        float(state.hole_center_y or 0.5),
        float(state.hole_size_edge or 0.2),
        snap=getattr(state, "hole_snap", True),
    )
    
    if edges is None:
        state.hole_error_message = "Invalid hole configuration (edges out of bounds or degenerate)"
    else:
        state.hole_error_message = ""
    
    fig = build_square_domain_plot(nx, "Square Metallic Body Preview", edges, show_edges=True)
    push_geometry_plot(fig)