"""
Object Predicate + Action Enumeration Engine
=============================================

For each ARC task, enumerate combinations of:
  (object_abstraction) x (predicate) x (action)

Test each rule against ALL training pairs. If a rule produces
exact output for every pair, use it.

This is the GPAR approach simplified to pure Python — no PDDL,
no planner. Just brute-force enumeration of ~600 rule templates.

Covers:
  - Fill miss (35% of unsolved): enclosed_by, neighbor_count conditions
  - Recolor miss (24%): object attribute conditions (size, color, position)
  - Shape change (25%): extract by predicate
"""

import numpy as np
from collections import Counter, deque
from typing import Dict, List, Tuple, Optional, Set, Callable


# =============================================================================
# Object Extraction (robust, multiple abstractions)
# =============================================================================

def _flood(grid, r, c, visited, color, connectivity=4):
    """BFS flood fill for a single color component."""
    h, w = grid.shape
    cells = set()
    queue = deque([(r, c)])
    visited[r, c] = True
    deltas = [(-1,0),(1,0),(0,-1),(0,1)]
    if connectivity == 8:
        deltas += [(-1,-1),(-1,1),(1,-1),(1,1)]
    while queue:
        cr, cc = queue.popleft()
        cells.add((cr, cc))
        for dr, dc in deltas:
            nr, nc = cr + dr, cc + dc
            if 0 <= nr < h and 0 <= nc < w and not visited[nr, nc] and grid[nr, nc] == color:
                visited[nr, nc] = True
                queue.append((nr, nc))
    return cells


def extract_objects_multi(grid, connectivity=4):
    """Extract all non-background connected components.
    Returns list of dicts with color, cells, mask, bbox, size, touches_border."""
    grid = np.array(grid, dtype=int)
    h, w = grid.shape
    bg = Counter(grid.flatten().tolist()).most_common(1)[0][0]
    visited = np.zeros((h, w), dtype=bool)
    objects = []

    for r in range(h):
        for c in range(w):
            if visited[r, c] or grid[r, c] == bg:
                visited[r, c] = True
                continue
            color = int(grid[r, c])
            cells = _flood(grid, r, c, visited, color, connectivity)
            if not cells:
                continue
            rows = [cr for cr, _ in cells]
            cols = [cc for _, cc in cells]
            rmin, rmax = min(rows), max(rows)
            cmin, cmax = min(cols), max(cols)
            mask = np.zeros((h, w), dtype=bool)
            for cr, cc in cells:
                mask[cr, cc] = True
            touches = any(cr == 0 or cr == h-1 or cc == 0 or cc == w-1 for cr, cc in cells)
            objects.append({
                'color': color,
                'cells': cells,
                'mask': mask,
                'bbox': (rmin, cmin, rmax, cmax),
                'size': len(cells),
                'touches_border': touches,
                'height': rmax - rmin + 1,
                'width': cmax - cmin + 1,
                'center_r': sum(rows) / len(rows),
                'center_c': sum(cols) / len(cols),
            })

    return objects, bg


def get_enclosed_bg_regions(grid, bg):
    """Find background regions NOT reachable from grid border."""
    grid = np.array(grid, dtype=int)
    h, w = grid.shape
    visited = np.zeros((h, w), dtype=bool)
    queue = deque()

    # Flood from all border bg cells
    for r in range(h):
        for c in range(w):
            if (r == 0 or r == h-1 or c == 0 or c == w-1) and grid[r, c] == bg:
                if not visited[r, c]:
                    visited[r, c] = True
                    queue.append((r, c))

    while queue:
        r, c = queue.popleft()
        for dr, dc in [(-1,0),(1,0),(0,-1),(0,1)]:
            nr, nc = r + dr, c + dc
            if 0 <= nr < h and 0 <= nc < w and not visited[nr, nc] and grid[nr, nc] == bg:
                visited[nr, nc] = True
                queue.append((nr, nc))

    # Enclosed = bg cells not visited
    enclosed = (grid == bg) & ~visited
    return enclosed


def get_neighbor_colors(grid, r, c, bg=0):
    """Get non-bg neighbor colors (4-connectivity)."""
    h, w = grid.shape
    colors = []
    for dr, dc in [(-1,0),(1,0),(0,-1),(0,1)]:
        nr, nc = r + dr, c + dc
        if 0 <= nr < h and 0 <= nc < w and grid[nr, nc] != bg:
            colors.append(int(grid[nr, nc]))
    return colors


# =============================================================================
# Object Predicates
# =============================================================================

def _build_predicates(objects, bg):
    """Build predicate functions that test object properties."""
    if not objects:
        return {}

    sizes = [o['size'] for o in objects]
    max_size = max(sizes)
    min_size = min(sizes)
    colors_list = [o['color'] for o in objects]
    color_counts = Counter(colors_list)
    most_common_color = color_counts.most_common(1)[0][0]
    least_common_color = color_counts.most_common()[-1][0]

    predicates = {
        'is_largest': lambda o: o['size'] == max_size,
        'is_smallest': lambda o: o['size'] == min_size,
        'touches_border': lambda o: o['touches_border'],
        'not_touches_border': lambda o: not o['touches_border'],
        'is_most_common_color': lambda o: o['color'] == most_common_color,
        'is_least_common_color': lambda o: o['color'] == least_common_color,
        'always_true': lambda o: True,
    }

    # Add per-color predicates
    for color in set(colors_list):
        predicates[f'color_is_{color}'] = (lambda c: lambda o: o['color'] == c)(color)

    # Size-based
    if len(set(sizes)) > 1:
        median_size = sorted(sizes)[len(sizes) // 2]
        predicates['size_above_median'] = lambda o: o['size'] > median_size
        predicates['size_below_median'] = lambda o: o['size'] < median_size

    return predicates


# =============================================================================
# Actions
# =============================================================================

def _build_actions(objects, bg, grid_shape):
    """Build action functions that transform a grid based on selected objects."""

    all_colors = set(o['color'] for o in objects) | {bg}

    actions = {}

    # Recolor: change matching objects to a specific color
    for target_color in range(10):
        if target_color == bg:
            continue
        actions[f'recolor_to_{target_color}'] = (
            lambda tc: lambda grid, selected_masks: _apply_recolor(grid, selected_masks, tc)
        )(target_color)

    # Fill enclosed regions of matching objects
    actions['fill_enclosed'] = lambda grid, selected_masks: _apply_fill_enclosed(grid, selected_masks, bg)

    # Fill interior (bbox minus object cells)
    actions['fill_interior'] = lambda grid, selected_masks: _apply_fill_interior(grid, selected_masks, bg)

    # Remove (set to bg)
    actions['remove'] = lambda grid, selected_masks: _apply_remove(grid, selected_masks, bg)

    # Extract (keep only selected, clear rest)
    actions['extract'] = lambda grid, selected_masks: _apply_extract(grid, selected_masks, bg)

    return actions


def _apply_recolor(grid, selected_masks, target_color):
    result = grid.copy()
    for mask in selected_masks:
        result[mask] = target_color
    return result


def _apply_fill_enclosed(grid, selected_masks, bg):
    """Fill enclosed background regions that are bounded by selected objects."""
    result = grid.copy()
    h, w = grid.shape

    for mask in selected_masks:
        color = int(grid[mask][0]) if np.any(mask) else 0
        if color == 0:
            continue
        # Find bbox of this object
        rows, cols = np.where(mask)
        if len(rows) == 0:
            continue
        rmin, rmax = rows.min(), rows.max()
        cmin, cmax = cols.min(), cols.max()

        # Within bbox, find bg cells enclosed by this object
        for r in range(rmin, rmax + 1):
            for c in range(cmin, cmax + 1):
                if result[r, c] == bg:
                    # Check if this bg cell is "inside" the object
                    # Simple test: surrounded on all 4 cardinal directions by object cells
                    inside = True
                    for dr, dc in [(-1,0),(1,0),(0,-1),(0,1)]:
                        found = False
                        nr, nc = r + dr, c + dc
                        while 0 <= nr < h and 0 <= nc < w:
                            if mask[nr, nc]:
                                found = True
                                break
                            nr += dr
                            nc += dc
                        if not found:
                            inside = False
                            break
                    if inside:
                        result[r, c] = color
    return result


def _apply_fill_interior(grid, selected_masks, bg):
    """Fill the bounding box interior of selected objects with the object's color."""
    result = grid.copy()
    for mask in selected_masks:
        color = int(grid[mask][0]) if np.any(mask) else 0
        if color == 0:
            continue
        rows, cols = np.where(mask)
        if len(rows) == 0:
            continue
        rmin, rmax = rows.min(), rows.max()
        cmin, cmax = cols.min(), cols.max()
        for r in range(rmin, rmax + 1):
            for c in range(cmin, cmax + 1):
                if result[r, c] == bg:
                    result[r, c] = color
    return result


def _apply_remove(grid, selected_masks, bg):
    result = grid.copy()
    for mask in selected_masks:
        result[mask] = bg
    return result


def _apply_extract(grid, selected_masks, bg):
    result = np.full_like(grid, bg)
    for mask in selected_masks:
        result[mask] = grid[mask]
    return result


# =============================================================================
# Neighborhood Rule Table (CA-style)
# =============================================================================

def learn_neighborhood_rule(train_pairs):
    """
    For same-shape tasks: build a lookup table
      (center_color, sorted_neighbor_colors) -> output_color
    If consistent across all training pairs, return the rule.
    """
    # Check all same shape
    for pair in train_pairs:
        inp = np.array(pair['input'])
        out = np.array(pair['output'])
        if inp.shape != out.shape:
            return None

    rule_table = {}  # (center, neighbor_sig) -> output_color
    conflicts = False

    for pair in train_pairs:
        inp = np.array(pair['input'], dtype=int)
        out = np.array(pair['output'], dtype=int)
        h, w = inp.shape

        for r in range(h):
            for c in range(w):
                center = int(inp[r, c])
                out_val = int(out[r, c])

                # Get 4-neighbor colors
                neighbors = []
                for dr, dc in [(-1,0),(1,0),(0,-1),(0,1)]:
                    nr, nc = r + dr, c + dc
                    if 0 <= nr < h and 0 <= nc < w:
                        neighbors.append(int(inp[nr, nc]))
                    else:
                        neighbors.append(-1)  # border sentinel

                key = (center, tuple(sorted(neighbors)))

                if key in rule_table:
                    if rule_table[key] != out_val:
                        conflicts = True
                        break
                else:
                    rule_table[key] = out_val

            if conflicts:
                break
        if conflicts:
            break

    if conflicts:
        return None

    return rule_table


def apply_neighborhood_rule(grid, rule_table):
    """Apply a learned neighborhood rule table to a grid."""
    grid = np.array(grid, dtype=int)
    h, w = grid.shape
    result = grid.copy()

    for r in range(h):
        for c in range(w):
            center = int(grid[r, c])
            neighbors = []
            for dr, dc in [(-1,0),(1,0),(0,-1),(0,1)]:
                nr, nc = r + dr, c + dc
                if 0 <= nr < h and 0 <= nc < w:
                    neighbors.append(int(grid[nr, nc]))
                else:
                    neighbors.append(-1)

            key = (center, tuple(sorted(neighbors)))
            if key in rule_table:
                result[r, c] = rule_table[key]

    return result


# =============================================================================
# Global Fill Rules (not object-specific)
# =============================================================================

def try_global_enclosed_fill(train_pairs):
    """
    Try: fill all enclosed bg regions with a consistent color.
    Learn the fill color from training pairs.
    """
    fill_colors = []

    for pair in train_pairs:
        inp = np.array(pair['input'], dtype=int)
        out = np.array(pair['output'], dtype=int)
        if inp.shape != out.shape:
            return None

        bg = Counter(inp.flatten().tolist()).most_common(1)[0][0]
        enclosed = get_enclosed_bg_regions(inp, bg)

        if not np.any(enclosed):
            continue

        # What color fills the enclosed region in output?
        fill_vals = out[enclosed]
        unique = np.unique(fill_vals)
        non_bg = unique[unique != bg]
        if len(non_bg) == 1:
            fill_colors.append(int(non_bg[0]))
        elif len(non_bg) > 1:
            return None  # multiple colors fill enclosed — too complex

    if not fill_colors:
        return None

    # Check consistency
    if len(set(fill_colors)) != 1:
        return None

    fill_color = fill_colors[0]

    # Validate on all pairs
    for pair in train_pairs:
        inp = np.array(pair['input'], dtype=int)
        out = np.array(pair['output'], dtype=int)
        bg = Counter(inp.flatten().tolist()).most_common(1)[0][0]

        result = inp.copy()
        enclosed = get_enclosed_bg_regions(inp, bg)
        result[enclosed] = fill_color

        if not np.array_equal(result, out):
            return None

    return fill_color


def try_per_object_enclosed_fill(train_pairs):
    """
    Try: for each object, fill its enclosed interior with its own color.
    """
    for pair in train_pairs:
        inp = np.array(pair['input'], dtype=int)
        out = np.array(pair['output'], dtype=int)
        if inp.shape != out.shape:
            return False

        objects, bg = extract_objects_multi(inp, connectivity=4)
        result = inp.copy()

        for obj in objects:
            mask = obj['mask']
            color = obj['color']
            rmin, cmin, rmax, cmax = obj['bbox']
            h, w = inp.shape

            for r in range(rmin, rmax + 1):
                for c in range(cmin, cmax + 1):
                    if result[r, c] == bg:
                        # Ray-cast: is this cell inside the object?
                        inside = True
                        for dr, dc in [(-1,0),(1,0),(0,-1),(0,1)]:
                            found = False
                            nr, nc = r + dr, c + dc
                            while 0 <= nr < h and 0 <= nc < w:
                                if mask[nr, nc]:
                                    found = True
                                    break
                                nr += dr
                                nc += dc
                            if not found:
                                inside = False
                                break
                        if inside:
                            result[r, c] = color

        if not np.array_equal(result, out):
            return False

    return True


def apply_per_object_enclosed_fill(grid):
    """Apply per-object enclosed fill."""
    grid = np.array(grid, dtype=int)
    objects, bg = extract_objects_multi(grid, connectivity=4)
    result = grid.copy()
    h, w = grid.shape

    for obj in objects:
        mask = obj['mask']
        color = obj['color']
        rmin, cmin, rmax, cmax = obj['bbox']

        for r in range(rmin, rmax + 1):
            for c in range(cmin, cmax + 1):
                if result[r, c] == bg:
                    inside = True
                    for dr, dc in [(-1,0),(1,0),(0,-1),(0,1)]:
                        found = False
                        nr, nc = r + dr, c + dc
                        while 0 <= nr < h and 0 <= nc < w:
                            if mask[nr, nc]:
                                found = True
                                break
                            nr += dr
                            nc += dc
                        if not found:
                            inside = False
                            break
                    if inside:
                        result[r, c] = color
    return result


# =============================================================================
# Main Enumeration Engine
# =============================================================================

def enumerate_rules(train_pairs, max_time_ms=5000):
    """
    Try all rule strategies on a task. Return the first that passes
    all training pairs, or None.

    Strategies (in order):
    1. Global enclosed fill (single color)
    2. Per-object enclosed fill
    3. Neighborhood rule table (CA-style)
    4. Object predicate × action enumeration
    """
    import time
    start = time.time()

    # Check same shape
    all_same_shape = all(
        np.array(p['input']).shape == np.array(p['output']).shape
        for p in train_pairs
    )

    # === Strategy 1: Global enclosed fill ===
    fill_color = try_global_enclosed_fill(train_pairs)
    if fill_color is not None:
        def rule_fn(grid, _fc=fill_color):
            g = np.array(grid, dtype=int)
            bg = Counter(g.flatten().tolist()).most_common(1)[0][0]
            enclosed = get_enclosed_bg_regions(g, bg)
            result = g.copy()
            result[enclosed] = _fc
            return result
        return ('global_enclosed_fill', rule_fn)

    # === Strategy 2: Per-object enclosed fill ===
    if all_same_shape and try_per_object_enclosed_fill(train_pairs):
        return ('per_object_enclosed_fill', apply_per_object_enclosed_fill)

    # === Strategy 3: Neighborhood rule table ===
    if all_same_shape:
        rule_table = learn_neighborhood_rule(train_pairs)
        if rule_table is not None:
            # Validate
            valid = True
            for pair in train_pairs:
                pred = apply_neighborhood_rule(pair['input'], rule_table)
                if not np.array_equal(pred, np.array(pair['output'], dtype=int)):
                    valid = False
                    break
            if valid:
                def rule_fn(grid, _rt=rule_table):
                    return apply_neighborhood_rule(grid, _rt)
                return ('neighborhood_rule', rule_fn)

    # === Strategy 4: Object predicate × action enumeration ===
    if all_same_shape and (time.time() - start) * 1000 < max_time_ms:
        result = _enumerate_predicate_actions(train_pairs)
        if result is not None:
            return result

    return None


def _enumerate_predicate_actions(train_pairs):
    """Enumerate (connectivity × predicate × action) combinations."""
    for connectivity in [4, 8]:
        # Extract objects for all pairs
        pair_data = []
        for pair in train_pairs:
            inp = np.array(pair['input'], dtype=int)
            out = np.array(pair['output'], dtype=int)
            objects, bg = extract_objects_multi(inp, connectivity)
            pair_data.append((inp, out, objects, bg))

        if not pair_data or not pair_data[0][2]:
            continue

        # Build predicates from first pair
        first_objects = pair_data[0][2]
        first_bg = pair_data[0][3]
        predicates = _build_predicates(first_objects, first_bg)
        actions = _build_actions(first_objects, first_bg, pair_data[0][0].shape)

        # Enumerate
        for pred_name, pred_fn in predicates.items():
            for act_name, act_fn in actions.items():
                # Test on all pairs
                all_pass = True
                for inp, out, objects, bg in pair_data:
                    if not objects:
                        all_pass = False
                        break

                    # Rebuild predicates for this pair's objects
                    local_preds = _build_predicates(objects, bg)
                    local_pred = local_preds.get(pred_name)
                    if local_pred is None:
                        all_pass = False
                        break

                    # Select objects matching predicate
                    selected = [o for o in objects if local_pred(o)]
                    if not selected and pred_name != 'always_true':
                        all_pass = False
                        break

                    selected_masks = [o['mask'] for o in selected]

                    try:
                        result = act_fn(inp, selected_masks)
                        if not np.array_equal(result, out):
                            all_pass = False
                            break
                    except Exception:
                        all_pass = False
                        break

                if all_pass:
                    # Build a reusable rule function
                    def make_rule(pn, an, conn):
                        def rule_fn(grid):
                            g = np.array(grid, dtype=int)
                            objs, bg = extract_objects_multi(g, conn)
                            if not objs:
                                return g
                            preds = _build_predicates(objs, bg)
                            pred = preds.get(pn, lambda o: False)
                            acts = _build_actions(objs, bg, g.shape)
                            act = acts.get(an)
                            if act is None:
                                return g
                            selected = [o for o in objs if pred(o)]
                            masks = [o['mask'] for o in selected]
                            return act(g, masks)
                        return rule_fn

                    return (f'predicate_{pred_name}_action_{act_name}_conn{connectivity}',
                            make_rule(pred_name, act_name, connectivity))

    return None