#!/usr/bin/env python3
"""Composition solvers - chain two analytical solvers into one ONNX graph.

C1: transform_then_recolor - spatial transform THEN color_map
C2: crop_then_transform - crop THEN apply spatial transform
C3: recolor_then_tile - color_map THEN tile/upscale
"""

import numpy as np
from onnx import helper, TensorProto, numpy_helper


def s_transform_then_recolor(td, solvers):
    """Try: spatial transform -> color_map composition.
    
    Args:
        td: task data
        solvers: dict of solver_name -> solver_function
    
    Returns: ONNX model or None
    """
    from onnx_helpers import mk, GRID_SHAPE, DT, IR, make_opset
    
    spatial_solvers = ['flip', 'rotate', 'shift', 'mirror_h', 'mirror_v', 
                       'quad_mirror', 'transpose']
    
    for sname in spatial_solvers:
        sfn = solvers.get(sname)
        if sfn is None:
            continue
        try:
            tf_model = sfn(td)
            if tf_model is None:
                continue
        except Exception:
            continue
        
        # Now try color_map on the transformed data
        cm_fn = solvers.get('color_map')
        if cm_fn is None:
            continue
        try:
            cm_model = cm_fn(td)
            if cm_model is None:
                continue
        except Exception:
            continue
        
        # Merge the two ONNX graphs
        composed = _merge_graphs(tf_model, cm_model, f"{sname}_then_recolor")
        if composed is not None:
            return composed
    
    return None


def s_crop_then_transform(td, solvers):
    """Try: fixed_crop -> spatial transform composition."""
    crop_fn = solvers.get('fixed_crop')
    if crop_fn is None:
        return None
    
    try:
        crop_model = crop_fn(td)
        if crop_model is None:
            return None
    except Exception:
        return None
    
    for sname in ['flip', 'rotate', 'mirror_h', 'mirror_v']:
        sfn = solvers.get(sname)
        if sfn is None:
            continue
        try:
            tf_model = sfn(td)
            if tf_model is None:
                continue
        except Exception:
            continue
        
        composed = _merge_graphs(crop_model, tf_model, f"crop_then_{sname}")
        if composed is not None:
            return composed
    
    return None


def s_recolor_then_tile(td, solvers):
    """Try: color_map -> tile/upscale composition."""
    cm_fn = solvers.get('color_map')
    if cm_fn is None:
        return None
    
    try:
        cm_model = cm_fn(td)
        if cm_model is None:
            return None
    except Exception:
        return None
    
    for sname in ['tile', 'upscale']:
        sfn = solvers.get(sname)
        if sfn is None:
            continue
        try:
            tile_model = sfn(td)
            if tile_model is None:
                continue
        except Exception:
            continue
        
        composed = _merge_graphs(cm_model, tile_model, f"recolor_then_{sname}")
        if composed is not None:
            return composed
    
    return None


def _merge_graphs(model_a, model_b, name="composed"):
    """Merge two ONNX models into a single graph.
    
    model_a: input -> intermediate
    model_b: intermediate -> output
    """
    import onnx
    from onnx_helpers import DT, IR, GRID_SHAPE, make_opset
    
    graph_a = model_a.graph
    graph_b = model_b.graph
    
    a_output = graph_a.output[0].name
    b_input = graph_b.input[0].name
    
    # Rename model_b's input to match model_a's output
    nodes_b = []
    for node in graph_b.node:
        new_inputs = [a_output if inp == b_input else inp for inp in node.input]
        new_node = helper.make_node(
            node.op_type, new_inputs, node.output,
            name=f"{name}_{node.name}" if node.name else f"{name}_n{len(nodes_b)}"
        )
        nodes_b.append(new_node)
    
    # Combine initializers (avoid name collisions)
    inits = list(graph_a.initializer) + list(graph_b.initializer)
    
    # Combine nodes
    nodes = list(graph_a.node) + nodes_b
    
    # Build merged graph
    x = helper.make_tensor_value_info("input", DT, GRID_SHAPE)
    y = helper.make_tensor_value_info("output", DT, GRID_SHAPE)
    g = helper.make_graph(nodes, name, [x], [y], initializer=inits)
    
    try:
        merged = helper.make_model(g, ir_version=IR, opset_imports=make_opset(17))
        onnx.checker.check_model(merged)
        return merged
    except Exception:
        return None