from __future__ import annotations

import argparse
import json
import math
import random
from pathlib import Path
from typing import Dict, List, Tuple

import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
import numpy as np


Cell = Tuple[int, int]


# ---------------------------------------------------------------------------
# Geometry helpers
# ---------------------------------------------------------------------------


def _cross(ox: float, oy: float, px: float, py: float, qx: float, qy: float) -> float:
    return (px - ox) * (qy - oy) - (py - oy) * (qx - ox)


def segments_intersect_properly(
    ax: float, ay: float, bx: float, by: float,
    cx: float, cy: float, dx: float, dy: float,
) -> bool:
    """True if segment AB *properly* crosses segment CD (shared endpoints don't count)."""
    d1 = _cross(cx, cy, dx, dy, ax, ay)
    d2 = _cross(cx, cy, dx, dy, bx, by)
    d3 = _cross(ax, ay, bx, by, cx, cy)
    d4 = _cross(ax, ay, bx, by, dx, dy)
    if ((d1 > 0 and d2 < 0) or (d1 < 0 and d2 > 0)) and \
       ((d3 > 0 and d4 < 0) or (d3 < 0 and d4 > 0)):
        return True
    return False


def point_seg_dist(px: float, py: float, ax: float, ay: float, bx: float, by: float) -> float:
    dx = bx - ax
    dy = by - ay
    len_sq = dx * dx + dy * dy
    if len_sq < 1e-12:
        return math.hypot(px - ax, py - ay)
    t = max(0.0, min(1.0, ((px - ax) * dx + (py - ay) * dy) / len_sq))
    return math.hypot(px - (ax + t * dx), py - (ay + t * dy))


# ---------------------------------------------------------------------------
# Union-Find
# ---------------------------------------------------------------------------


class UnionFind:
    def __init__(self, n: int) -> None:
        self.parent = list(range(n))
        self.rank = [0] * n
        self.size = [1] * n
        self.num_sets = n

    def find(self, x: int) -> int:
        while self.parent[x] != x:
            self.parent[x] = self.parent[self.parent[x]]
            x = self.parent[x]
        return x

    def set_size(self, x: int) -> int:
        return self.size[self.find(x)]

    def union(self, a: int, b: int) -> bool:
        ra, rb = self.find(a), self.find(b)
        if ra == rb:
            return False
        if self.rank[ra] < self.rank[rb]:
            ra, rb = rb, ra
        self.parent[rb] = ra
        self.size[ra] += self.size[rb]
        if self.rank[ra] == self.rank[rb]:
            self.rank[ra] += 1
        self.num_sets -= 1
        return True


# ---------------------------------------------------------------------------
# Graph construction — planar, no-dot-crossing edge set
# ---------------------------------------------------------------------------


def place_dots(
    rng: random.Random,
    grid_rows: int,
    grid_cols: int,
    num_dots: int,
    min_gap: float,
    border_margin: int = 5,
    max_attempts: int = 8000,
) -> List[Cell]:
    cells: List[Cell] = []
    lo_r, hi_r = border_margin, grid_rows - border_margin
    lo_c, hi_c = border_margin, grid_cols - border_margin
    for _ in range(max_attempts):
        if len(cells) == num_dots:
            break
        r = rng.randint(lo_r, hi_r - 1)
        c = rng.randint(lo_c, hi_c - 1)
        if all(math.hypot(r - er, c - ec) >= min_gap for er, ec in cells):
            cells.append((r, c))
    return cells


def build_planar_edge_set(
    dots: List[Cell],
    dot_radius: float,
    max_edge_len: float,
) -> List[Tuple[int, int, float]]:
    """
    Build a set of edges that:
      1. Are shorter than max_edge_len
      2. Don't pass within dot_radius of any other dot
      3. Don't cross each other (planar)
    Returns list of (i, j, dist) sorted by dist, with the planar filter applied.
    """
    n = len(dots)

    # Step 1: candidate edges sorted by length, filtered by dot clearance
    candidates: List[Tuple[float, int, int]] = []
    for i in range(n):
        ri, ci = dots[i]
        for j in range(i + 1, n):
            rj, cj = dots[j]
            d = math.hypot(ri - rj, ci - cj)
            if d > max_edge_len:
                continue
            # Check this edge doesn't pass near any other dot
            clear = True
            for k in range(n):
                if k == i or k == j:
                    continue
                if point_seg_dist(dots[k][0], dots[k][1], ri, ci, rj, cj) < dot_radius + 0.8:
                    clear = False
                    break
            if clear:
                candidates.append((d, i, j))
    candidates.sort()

    # Step 2: greedily add edges, skip if they cross an already-added edge
    accepted: List[Tuple[int, int, float]] = []
    # For fast crossing checks, store segment coords
    seg_coords: List[Tuple[float, float, float, float]] = []

    for dist, i, j in candidates:
        ri, ci = dots[i]
        rj, cj = dots[j]
        crosses = False
        for ax, ay, bx, by in seg_coords:
            # Skip if shared endpoint
            if (ri == ax and ci == ay) or (ri == bx and ci == by) or \
               (rj == ax and cj == ay) or (rj == bx and cj == by):
                continue
            if segments_intersect_properly(ri, ci, rj, cj, ax, ay, bx, by):
                crosses = True
                break
        if not crosses:
            accepted.append((i, j, dist))
            seg_coords.append((float(ri), float(ci), float(rj), float(cj)))

    return accepted


def build_spanning_forest(
    rng: random.Random,
    n: int,
    planar_edges: List[Tuple[int, int, float]],
    num_components: int,
) -> Tuple[List[Tuple[int, int]], List[List[int]]]:
    """
    From the planar edge set, build a spanning forest with exactly
    num_components trees using Union-Find.

    Strategy: shuffle edges, greedily merge until we reach the target
    number of components. Then collect extra intra-component edges.
    """
    uf = UnionFind(n)

    # We need to reduce n sets down to num_components, so we need n - num_components merges.
    target_merges = n - num_components

    # Cap: no single component should exceed ~2x the ideal even share.
    max_component_size = max(4, (n // num_components) * 2)

    # Shuffle edges but bias toward shorter ones: split into short/long halves,
    # shuffle each, concatenate.
    mid = len(planar_edges) // 2
    short = list(planar_edges[:mid])
    long = list(planar_edges[mid:])
    rng.shuffle(short)
    rng.shuffle(long)
    shuffled = short + long

    tree_edges: List[Tuple[int, int]] = []
    deferred: List[Tuple[int, int, float]] = []
    extra_edges: List[Tuple[int, int]] = []

    for i, j, d in shuffled:
        if uf.find(i) != uf.find(j):
            if len(tree_edges) < target_merges:
                merged_size = uf.set_size(i) + uf.set_size(j)
                if merged_size <= max_component_size:
                    uf.union(i, j)
                    tree_edges.append((i, j))
                else:
                    deferred.append((i, j, d))
            else:
                extra_edges.append((i, j))
        else:
            extra_edges.append((i, j))

    # Second pass: use deferred edges if we still need merges
    for i, j, _d in deferred:
        if len(tree_edges) >= target_merges:
            break
        if uf.find(i) != uf.find(j):
            uf.union(i, j)
            tree_edges.append((i, j))

    # Add some extra intra-component edges for visual richness
    # Only pick edges where both endpoints are already in the same component
    intra_edges = [(i, j) for i, j in extra_edges if uf.find(i) == uf.find(j)]
    rng.shuffle(intra_edges)
    bonus = min(len(intra_edges), max(n // 6, 3))
    tree_edges.extend(intra_edges[:bonus])

    # Build component membership
    comp_map: Dict[int, List[int]] = {}
    for node in range(n):
        root = uf.find(node)
        comp_map.setdefault(root, []).append(node)
    components = list(comp_map.values())

    return tree_edges, components


# ---------------------------------------------------------------------------
# Instance sampling
# ---------------------------------------------------------------------------


def sample_instance(
    rng: random.Random,
    width: int,
    height: int,
    grid_rows: int,
    grid_cols: int,
    min_components: int,
    max_components: int,
    num_dots_min: int,
    num_dots_max: int,
    min_gap: float,
    dot_radius: float,
    max_edge_len: float,
    close_strand_tolerance: float = 0.0,
) -> Dict[str, object] | None:
    num_components = rng.randint(min_components, max_components)
    num_dots = rng.randint(max(num_dots_min, num_components * 2), num_dots_max)

    dots = place_dots(rng, grid_rows, grid_cols, num_dots, min_gap)
    if len(dots) < num_components * 2:
        return None

    planar_edges = build_planar_edge_set(dots, dot_radius, max_edge_len)

    # Check we have enough edges to connect dots into num_components trees
    # (need at least len(dots) - num_components edges in a spanning forest)
    if len(planar_edges) < len(dots) - num_components:
        return None

    edges, components = build_spanning_forest(rng, len(dots), planar_edges, num_components)

    # Reject if any component has fewer than 2 dots
    if any(len(c) < 2 for c in components):
        return None

    actual_components = len(components)

    if actual_components < min_components:
        return None

    # Enforce close_strand_tolerance: dots from different components must be
    # at least this many grid units apart (visual separation).
    if close_strand_tolerance > 0:
        node_to_comp = {}
        for ci, comp in enumerate(components):
            for node in comp:
                node_to_comp[node] = ci
        for a in range(len(dots)):
            ra, ca = dots[a]
            for b in range(a + 1, len(dots)):
                if node_to_comp[a] == node_to_comp[b]:
                    continue
                rb, cb = dots[b]
                if math.hypot(ra - rb, ca - cb) < close_strand_tolerance:
                    return None

    margin = int(min(width, height) * 0.10)
    square_size = min(width, height) - 2 * margin
    square_left = (width - square_size) / 2.0
    square_top = (height - square_size) / 2.0

    return {
        "width": width,
        "height": height,
        "grid_rows": grid_rows,
        "grid_cols": grid_cols,
        "square_left": round(square_left, 2),
        "square_top": round(square_top, 2),
        "square_size": round(square_size, 2),
        "num_components": actual_components,
        "num_dots": len(dots),
        "question": (
            "How many connected components are there in the image? "
            "A connected component is a maximal group of dots such that any two dots "
            "in the group are linked by a path of one or more drawn line segments "
            "(directly or through other dots in the same group). "
            "Every component contains at least two dots. "
            "Two dots that are not linked by any chain of line segments "
            "belong to different components, even if they appear visually close. "
            "Count every connected component and report the total. "
            "Provide your final answer enclosed in <answer>...</answer> tags."
        ),
        "answer": actual_components,
        "dots": [[r, c] for r, c in dots],
        "components": components,
        "edges": [[i, j] for i, j in edges],
        "dot_radius": dot_radius,
    }


# ---------------------------------------------------------------------------
# Rendering (matplotlib — smooth anti-aliased output)
# ---------------------------------------------------------------------------

LINE_COLOR = "#2f2f2f"
DOT_COLOR = "#1d1916"


def render_instance(out_path: Path, record: Dict[str, object], noise_seed: int = 0) -> None:
    width = int(record["width"])
    height = int(record["height"])
    grid_rows = int(record["grid_rows"])
    grid_cols = int(record["grid_cols"])
    square_left = float(record["square_left"])
    square_top = float(record["square_top"])
    square_size = float(record["square_size"])
    dots: List[List[int]] = record["dots"]  # type: ignore[assignment]
    edges: List[List[int]] = record["edges"]  # type: ignore[assignment]
    dot_radius_grid = float(record["dot_radius"])

    cell_w = square_size / grid_cols
    cell_h = square_size / grid_rows

    def to_pixel(r: float, c: float) -> Tuple[float, float]:
        px = square_left + (c + 0.5) * cell_w
        py = square_top + (r + 0.5) * cell_h
        return px, py

    pixel_dot_radius = dot_radius_grid * min(cell_w, cell_h) * 0.5
    edge_thickness = max(1.5, pixel_dot_radius * 0.3)

    fig = plt.figure(figsize=(width / 100, height / 100), dpi=100)
    ax = fig.add_axes([0, 0, 1, 1])
    ax.set_xlim(0, width)
    ax.set_ylim(height, 0)
    ax.axis("off")
    ax.set_facecolor("#f8f6f0")

    # Subtle noise background
    nrng = np.random.default_rng(noise_seed)
    noise = nrng.normal(0.0, 1.0, size=(height, width))
    noise = (noise - noise.min()) / max(noise.max() - noise.min(), 1e-6)
    ax.imshow(noise, cmap="Greys", alpha=0.05, extent=(0, width, height, 0),
              interpolation="bilinear")

    # White square background
    ax.fill_between(
        [square_left, square_left + square_size],
        [square_top, square_top],
        [square_top + square_size, square_top + square_size],
        color="#fffdf8", zorder=0.5,
    )

    # Border
    border_lw = 2.0
    bx = [square_left, square_left + square_size, square_left + square_size, square_left, square_left]
    by = [square_top, square_top, square_top + square_size, square_top + square_size, square_top]
    ax.plot(bx, by, color="#2d2720", linewidth=border_lw, solid_capstyle="round", zorder=1.0)

    # Plain (v4_plain): solid edges. No dashed-line anti-shortcut.
    for i, j in edges:
        px1, py1 = to_pixel(dots[i][0], dots[i][1])
        px2, py2 = to_pixel(dots[j][0], dots[j][1])
        ax.plot([px1, px2], [py1, py2],
                color=LINE_COLOR, linewidth=edge_thickness,
                solid_capstyle="round", alpha=0.92, zorder=2.0)

    # Dots on top
    for r, c in dots:
        px, py = to_pixel(r, c)
        circle = plt.Circle((px, py), pixel_dot_radius, color=DOT_COLOR, zorder=3.0)
        ax.add_patch(circle)

    fig.savefig(out_path, dpi=100, bbox_inches="tight", pad_inches=0)
    plt.close(fig)


# ---------------------------------------------------------------------------
# Dataset generation
# ---------------------------------------------------------------------------


def ensure_output_dir(root: Path) -> Tuple[Path, Path]:
    root.mkdir(parents=True, exist_ok=True)
    images_dir = root / "images"
    images_dir.mkdir(exist_ok=True)
    return root, images_dir


def generate_dataset(
    rng: random.Random,
    count: int,
    output_dir: Path,
    images_dir: Path,
    width: int,
    height: int,
    grid_rows: int,
    grid_cols: int,
    min_components: int,
    max_components: int,
    num_dots_min: int,
    num_dots_max: int,
    min_gap: float,
    dot_radius: float,
    max_edge_len: float,
    close_strand_tolerance: float = 0.0,
) -> None:
    records: List[Dict[str, object]] = []
    data_records: List[Dict[str, object]] = []

    # Force evenly-spaced answers across [min_components, max_components].
    if count > 1:
        forced_targets = [
            int(round(min_components + i * (max_components - min_components) / (count - 1)))
            for i in range(count)
        ]
    else:
        forced_targets = [min_components]
    print(f"forced component counts: {forced_targets}")

    for idx in range(count):
        sub_seed = rng.randint(0, 2**31 - 1)
        tgt = forced_targets[idx]
        for _ in range(2000):
            record = sample_instance(
                rng=rng,
                width=width,
                height=height,
                grid_rows=grid_rows,
                grid_cols=grid_cols,
                min_components=tgt,
                max_components=tgt,
                num_dots_min=num_dots_min,
                num_dots_max=num_dots_max,
                min_gap=min_gap,
                dot_radius=dot_radius,
                max_edge_len=max_edge_len,
                close_strand_tolerance=close_strand_tolerance,
            )
            if record is not None and record.get("answer") == tgt:
                break
        else:
            print(f"Warning: could not generate sample {idx}, skipping")
            continue

        image_name = f"counting_connected_components_{idx:05d}.png"
        render_instance(images_dir / image_name, record, noise_seed=sub_seed)
        record["image"] = f"images/{image_name}"
        records.append(record)
        data_records.append({
            "image": record["image"],
            "question": record["question"],
            "answer": record["answer"],
        })
        print(f"  [{idx+1}/{count}] components={record['answer']} dots={record['num_dots']}")

    with (output_dir / "annotations.jsonl").open("w", encoding="utf-8") as fh:
        for record in records:
            fh.write(json.dumps(record) + "\n")

    data_json = {
        "task": "counting_connected_components",
        "category": "distributed_scanning",
        "count": len(data_records),
        "items": data_records,
    }
    with (output_dir / "data.json").open("w", encoding="utf-8") as fh:
        json.dump(data_json, fh, indent=2)


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description="Generate a counting-connected-components dataset.")
    parser.add_argument("--output-root", type=Path, required=True, help="Dataset root directory.")
    parser.add_argument("--count", type=int, default=30)
    parser.add_argument("--width", type=int, default=1024)
    parser.add_argument("--height", type=int, default=1024)
    parser.add_argument("--grid-rows", type=int, default=100)
    parser.add_argument("--grid-cols", type=int, default=100)
    parser.add_argument("--min-components", type=int, default=4)
    parser.add_argument("--max-components", type=int, default=12)
    parser.add_argument("--num-dots-min", type=int, default=60)
    parser.add_argument("--num-dots-max", type=int, default=120)
    parser.add_argument("--min-gap", type=float, default=5.0)
    parser.add_argument("--dot-radius", type=float, default=1.5)
    parser.add_argument("--max-edge-len", type=float, default=25.0)
    parser.add_argument("--seed", type=int, default=42)
    parser.add_argument("--difficulty", type=int, default=5,
                        help="Integer difficulty >=0; scales components and dot count.")
    return parser.parse_args()


def main() -> None:
    args = parse_args()
    rng = random.Random(args.seed)
    output_dir, images_dir = ensure_output_dir(args.output_root)
    d = max(0, int(args.difficulty))
    # Difficulty scaling per spec
    min_components = 10
    max_components = 10 + 2 * d
    num_dots_min = 40
    num_dots_max = 40 + 20 * d
    close_strand_tolerance = float(max(3, 8 - d))

    # Canvas scaling based on num_dots_max growth
    N_d = 20 + 10 * d
    N_0 = 20
    s = math.sqrt(max(1.0, N_d / N_0))
    args.width = int(round(args.width * s))
    args.height = int(round(args.height * s))

    generate_dataset(
        rng=rng,
        count=args.count,
        output_dir=output_dir,
        images_dir=images_dir,
        width=args.width,
        height=args.height,
        grid_rows=args.grid_rows,
        grid_cols=args.grid_cols,
        min_components=min_components,
        max_components=max_components,
        num_dots_min=num_dots_min,
        num_dots_max=num_dots_max,
        min_gap=args.min_gap,
        dot_radius=args.dot_radius,
        max_edge_len=args.max_edge_len,
        close_strand_tolerance=close_strand_tolerance,
    )
    print(f"Saved dataset to {args.output_root}")


if __name__ == "__main__":
    main()