"""Geometry schema normalization (v1.0 and v2.0 typed-segment support)."""

from __future__ import annotations

import math
from copy import deepcopy
from typing import Any, Dict, List

import numpy as np
from shapely.geometry import Polygon

from src.shared.arc_utils import arc_to_polyline


def _as_xy(pt: Any) -> List[float]:
    return [float(pt[0]), float(pt[1])]


def _arc_span(seg: Dict[str, Any]) -> float:
    cx, cy = _as_xy(seg["center"])
    sx, sy = _as_xy(seg["start"])
    ex, ey = _as_xy(seg["end"])

    a0 = math.atan2(sy - cy, sx - cx)
    a1 = math.atan2(ey - cy, ex - cx)
    cw = bool(seg.get("clockwise", False))

    if abs(sx - ex) < 1e-9 and abs(sy - ey) < 1e-9:
        return 2.0 * math.pi

    if cw:
        if a1 > a0:
            a1 -= 2.0 * math.pi
    else:
        if a1 < a0:
            a1 += 2.0 * math.pi
    return abs(a1 - a0)


def _typed_segments_to_polyline_v2(segments: List[Dict[str, Any]], full_circle_segments: int = 32) -> List[List[float]]:
    out: List[List[float]] = []

    for seg in segments or []:
        stype = seg.get("type", "line")
        if stype == "arc":
            span = _arc_span(seg)
            n_seg = max(2, int(round(full_circle_segments * span / (2.0 * math.pi))))
            pts = arc_to_polyline(seg, n_pts=n_seg + 1)
        else:
            pts = [_as_xy(seg["start"]), _as_xy(seg["end"])]

        if out and pts:
            if abs(out[-1][0] - pts[0][0]) < 1e-9 and abs(out[-1][1] - pts[0][1]) < 1e-9:
                out.extend(pts[1:])
            else:
                out.extend(pts)
        else:
            out.extend(pts)

    if len(out) >= 2 and abs(out[0][0] - out[-1][0]) < 1e-9 and abs(out[0][1] - out[-1][1]) < 1e-9:
        out = out[:-1]

    return out


def _inner_boundary_to_hole(inner: Dict[str, Any], default_weight: float = 0.5) -> Dict[str, Any]:
    segments = inner.get("segments", [])
    boundary = _typed_segments_to_polyline_v2(segments)

    # Circular hole detection: single full-circle arc
    is_circular = False
    center = None
    diameter = None
    if len(segments) == 1 and segments[0].get("type") == "arc":
        seg = segments[0]
        s = _as_xy(seg["start"])
        e = _as_xy(seg["end"])
        if abs(s[0] - e[0]) < 1e-8 and abs(s[1] - e[1]) < 1e-8:
            is_circular = True
            center = _as_xy(seg["center"])
            diameter = 2.0 * float(seg["radius"])

    if center is None or diameter is None:
        if len(boundary) >= 3:
            poly = Polygon(boundary)
            if poly.is_valid and not poly.is_empty:
                c = poly.centroid
                center = [float(c.x), float(c.y)]
                minx, miny, maxx, maxy = poly.bounds
                diameter = float(max(maxx - minx, maxy - miny))
            else:
                arr = np.asarray(boundary, dtype=float)
                center = [float(np.mean(arr[:, 0])), float(np.mean(arr[:, 1]))]
                diameter = float(max(np.ptp(arr[:, 0]), np.ptp(arr[:, 1])))
        else:
            center = [0.0, 0.0]
            diameter = 1.0

    return {
        "index": int(inner.get("index", 0)),
        "center": center,
        "diameter": float(diameter),
        "boundary": boundary,
        "is_circular": bool(is_circular),
        "weight": float(inner.get("weight", default_weight)),
    }


def _detect_fillet_arcs(boundary: List[List[float]], arc_pts: int = 16) -> List[Dict[str, Any]]:
    """
    Detect fillet arcs in a v1 flat polyline and return v2-style typed segments.

    Pattern: a filleted 90° corner produces TWO consecutive vertices at ~135° angles.
    These are the arc start and arc end points. The arc tangent at each point aligns
    with the adjacent straight edge.

    For fillet pair (vertices i, i+1 both at ~135°):
    - Arc start = vertex i, tangent = direction of edge before i
    - Arc end = vertex i+1, tangent = direction of edge after i+1
    - Center = intersection of perpendiculars to tangents at start and end
    """
    pts = [_as_xy(p) for p in boundary]
    n = len(pts)

    if n < 3:
        segments = []
        for i in range(n - 1):
            segments.append({"type": "line", "start": pts[i], "end": pts[i + 1]})
        return segments if segments else []

    # Remove closing duplicate if present
    if n >= 2 and abs(pts[0][0] - pts[-1][0]) < 1e-6 and abs(pts[0][1] - pts[-1][1]) < 1e-6:
        pts = pts[:-1]
        n = len(pts)

    # Compute interior angle at each vertex
    angles = np.zeros(n)
    for i in range(n):
        A = np.array(pts[(i - 1) % n])
        M = np.array(pts[i])
        B = np.array(pts[(i + 1) % n])
        vMA = A - M
        vMB = B - M
        lMA = np.linalg.norm(vMA)
        lMB = np.linalg.norm(vMB)
        if lMA < 1e-9 or lMB < 1e-9:
            angles[i] = 180.0
            continue
        cos_a = np.clip(np.dot(vMA, vMB) / (lMA * lMB), -1.0, 1.0)
        angles[i] = math.degrees(math.acos(cos_a))

    # Find fillet PAIRS: two consecutive vertices both at ~135°
    is_fillet_start = [False] * n  # first vertex of a fillet pair

    for i in range(n):
        j = (i + 1) % n
        if 120 < angles[i] < 150 and 120 < angles[j] < 150:
            is_fillet_start[i] = True

    # Build typed segments
    segments = []
    i = 0

    while i < n:
        j = (i + 1) % n

        if is_fillet_start[i]:
            # Fillet pair at (i, j)
            # Arc start = point i, arc end = point j
            arc_start = np.array(pts[i])
            arc_end = np.array(pts[j])

            # Tangent at arc start = direction of incoming edge (from previous vertex)
            prev_i = (i - 1) % n
            edge_in = np.array(pts[i]) - np.array(pts[prev_i])
            edge_in_len = np.linalg.norm(edge_in)
            if edge_in_len > 1e-9:
                tangent_start = edge_in / edge_in_len
            else:
                tangent_start = np.array([1.0, 0.0])

            # Tangent at arc end = direction of outgoing edge (to next vertex)
            next_j = (j + 1) % n
            edge_out = np.array(pts[next_j]) - np.array(pts[j])
            edge_out_len = np.linalg.norm(edge_out)
            if edge_out_len > 1e-9:
                tangent_end = edge_out / edge_out_len
            else:
                tangent_end = np.array([1.0, 0.0])

            # Normal to tangent at start (perpendicular, pointing toward center)
            # Try both directions, pick the one that creates a valid arc
            n_start_a = np.array([-tangent_start[1], tangent_start[0]])
            n_start_b = np.array([tangent_start[1], -tangent_start[0]])
            n_end_a = np.array([-tangent_end[1], tangent_end[0]])
            n_end_b = np.array([tangent_end[1], -tangent_end[0]])

            # Find center: intersection of line (arc_start + t*n_start) and (arc_end + s*n_end)
            best_center = None
            best_radius = None
            for ns in [n_start_a, n_start_b]:
                for ne in [n_end_a, n_end_b]:
                    # Solve: arc_start + t*ns = arc_end + s*ne
                    # [ns_x, -ne_x] [t]   [end_x - start_x]
                    # [ns_y, -ne_y] [s] = [end_y - start_y]
                    A_mat = np.array([[ns[0], -ne[0]], [ns[1], -ne[1]]])
                    b_vec = arc_end - arc_start
                    det = A_mat[0, 0] * A_mat[1, 1] - A_mat[0, 1] * A_mat[1, 0]
                    if abs(det) < 1e-12:
                        continue
                    t = (b_vec[0] * A_mat[1, 1] - b_vec[1] * A_mat[0, 1]) / det
                    center = arc_start + t * ns
                    r_start = np.linalg.norm(center - arc_start)
                    r_end = np.linalg.norm(center - arc_end)
                    if abs(r_start - r_end) / max(r_start, r_end, 1e-9) < 0.05 and t > 0:
                        if best_center is None or r_start < best_radius:
                            best_center = center
                            best_radius = (r_start + r_end) / 2

            if best_center is not None:
                # Determine clockwise
                vCA = arc_start - best_center
                vCB = arc_end - best_center
                cross = vCA[0] * vCB[1] - vCA[1] * vCB[0]

                segments.append({
                    "type": "arc",
                    "start": pts[i],
                    "end": pts[j],
                    "center": [round(float(best_center[0]), 6), round(float(best_center[1]), 6)],
                    "radius": round(float(best_radius), 6),
                    "clockwise": bool(cross < 0),
                })
                i = j  # continue from arc end (j), next iteration creates line from j to j+1
                continue
            # Fallback: couldn't reconstruct arc, keep as line
            segments.append({"type": "line", "start": pts[i], "end": pts[j]})
            i += 1
        else:
            # Regular line segment
            segments.append({"type": "line", "start": pts[i], "end": pts[j]})
            i += 1

    return segments


def normalize_geometry_schema(geometry: Dict[str, Any]) -> Dict[str, Any]:
    """Return geometry in legacy Brain format (outer_boundary + holes), preserving typed data."""
    schema_version = str(geometry.get("schema_version", "1.0"))

    if schema_version.startswith("1"):
        out = deepcopy(geometry)
        out.setdefault("holes", [])

        # Auto-detect fillet arcs in v1 polyline boundaries
        if 'outer_boundary' in out and 'outer_boundary_typed' not in out:
            typed_segs = _detect_fillet_arcs(out['outer_boundary'])
            n_arcs = sum(1 for s in typed_segs if s['type'] == 'arc')
            if n_arcs > 0:
                out['outer_boundary_typed'] = typed_segs
                # Re-generate polyline from typed segments with proper arc densification
                out['outer_boundary'] = _typed_segments_to_polyline_v2(typed_segs)

        return out

    if not schema_version.startswith("2"):
        # Unknown schema: best effort fallback (assume legacy fields are present)
        out = deepcopy(geometry)
        out.setdefault("holes", [])
        return out

    out = deepcopy(geometry)

    # v2: outer_boundary contains typed segment dicts, or outer_boundary_typed exists
    raw_outer = out.get("outer_boundary", [])
    typed_outer = out.get("outer_boundary_typed", [])

    # Detect if outer_boundary itself contains typed segments (v2 extraction output)
    if raw_outer and isinstance(raw_outer[0], dict) and "type" in raw_outer[0]:
        typed_outer = raw_outer  # outer_boundary IS the typed segments

    if typed_outer:
        out["outer_boundary_typed"] = typed_outer
        out["outer_boundary"] = _typed_segments_to_polyline_v2(typed_outer)

    inner_boundaries = out.get("inner_boundaries", [])
    out["holes"] = [_inner_boundary_to_hole(inner) for inner in inner_boundaries]

    return out