"""
code_parser.py
---------------
Turns raw Python source into a NETVIS "graph" dict.

IMPORTANT: this module only calls `ast.parse`. It never calls `exec`,
`eval`, or imports the user's module. Static analysis only — uploaded
code is data, never executed.
"""
import ast

from .detectors import (
    LAYER_CATEGORY,
    SKLEARN_ESTIMATORS,
    PLOT_SIGNALS,
    THREE_D_MARKERS,
)

FRAMEWORK_IMPORT_MAP = {
    "torch": "pytorch",
    "tensorflow": "keras",
    "keras": "keras",
    "sklearn": "sklearn",
    "xgboost": "xgboost",
    "lightgbm": "lightgbm",
    "catboost": "catboost",
}
PLOT_IMPORT_MAP = {"matplotlib": "matplotlib", "seaborn": "seaborn", "plotly": "plotly"}


def _dotted(node):
    if isinstance(node, ast.Name):
        return node.id
    if isinstance(node, ast.Attribute):
        base = _dotted(node.value)
        return f"{base}.{node.attr}" if base else node.attr
    return ""


def _leaf(node):
    if isinstance(node, ast.Name):
        return node.id
    if isinstance(node, ast.Attribute):
        return node.attr
    return None


def _call_leaf(call):
    return _leaf(call.func) if isinstance(call, ast.Call) else None


def _args_repr(call, max_items=4):
    parts = []
    try:
        for a in call.args[:max_items]:
            parts.append(ast.unparse(a))
        for kw in call.keywords[:max_items]:
            if kw.arg is None:
                continue
            parts.append(f"{kw.arg}={ast.unparse(kw.value)}")
    except Exception:
        pass
    return ", ".join(parts) if parts else "—"


def _collect_imports(tree):
    roots = set()
    for node in ast.walk(tree):
        if isinstance(node, ast.Import):
            for alias in node.names:
                roots.add(alias.name.split(".")[0])
        elif isinstance(node, ast.ImportFrom) and node.module:
            roots.add(node.module.split(".")[0])
    return roots


def _layers_from_init(class_node):
    """Find self.x = Layer(...) assignments inside a class's __init__."""
    init_fn = next(
        (n for n in class_node.body if isinstance(n, ast.FunctionDef) and n.name == "__init__"),
        None,
    )
    if init_fn is None:
        return []
    layers = []
    for node in ast.walk(init_fn):
        if not isinstance(node, ast.Assign) or not isinstance(node.value, ast.Call):
            continue
        target = node.targets[0]
        if not (isinstance(target, ast.Attribute) and isinstance(target.value, ast.Name) and target.value.id == "self"):
            continue
        leaf = _call_leaf(node.value)
        if leaf is None:
            continue
        layers.append({
            "attr": target.attr,
            "leaf": leaf,
            "full": _dotted(node.value.func),
            "params": _args_repr(node.value),
            "lineno": node.lineno,
        })
    return layers


def _sequential_blocks(tree):
    """Find nn.Sequential([...]) / keras.Sequential([...]) list literals anywhere."""
    blocks = []
    for node in ast.walk(tree):
        if isinstance(node, ast.Call) and _call_leaf(node) == "Sequential":
            container = node.args[0] if node.args else None
            if isinstance(container, (ast.List, ast.Tuple)):
                layers = []
                for el in container.elts:
                    if isinstance(el, ast.Call):
                        layers.append({
                            "attr": None,
                            "leaf": _call_leaf(el),
                            "full": _dotted(el.func),
                            "params": _args_repr(el),
                            "lineno": el.lineno,
                        })
                if layers:
                    blocks.append(layers)
    return blocks


def _pipeline_blocks(tree):
    """Find sklearn Pipeline([('name', Estimator(...)), ...]) literals."""
    blocks = []
    for node in ast.walk(tree):
        if isinstance(node, ast.Call) and _call_leaf(node) == "Pipeline":
            container = node.args[0] if node.args else None
            if isinstance(container, (ast.List, ast.Tuple)):
                steps = []
                for el in container.elts:
                    if isinstance(el, ast.Tuple) and len(el.elts) == 2 and isinstance(el.elts[1], ast.Call):
                        call = el.elts[1]
                        steps.append({
                            "attr": None,
                            "leaf": _call_leaf(call),
                            "full": _dotted(call.func),
                            "params": _args_repr(call),
                            "lineno": call.lineno,
                        })
                if steps:
                    blocks.append(steps)
    return blocks


def _top_level_estimators(tree):
    found = []
    seen_lines = set()
    for node in ast.walk(tree):
        if isinstance(node, ast.Call):
            leaf = _call_leaf(node)
            if leaf in SKLEARN_ESTIMATORS and node.lineno not in seen_lines:
                seen_lines.add(node.lineno)
                found.append({
                    "attr": None, "leaf": leaf, "full": _dotted(node.func),
                    "params": _args_repr(node), "lineno": node.lineno,
                })
    return found


def _plot_calls(tree, source):
    calls = []
    is_3d = any(marker in source for marker in THREE_D_MARKERS)
    for node in ast.walk(tree):
        if isinstance(node, ast.Call):
            leaf = _call_leaf(node)
            if leaf in PLOT_SIGNALS:
                calls.append({"call": _dotted(node.func) or leaf, "tag": PLOT_SIGNALS[leaf], "lineno": node.lineno})
    return calls, is_3d


def _best_class(tree):
    """Pick the class definition that looks most like a model (most layers found)."""
    best, best_len = None, -1
    for node in ast.walk(tree):
        if isinstance(node, ast.ClassDef):
            bases = [_dotted(b) for b in node.bases]
            layers = _layers_from_init(node)
            is_model_like = any("Module" in b or "Model" in b or "Layer" in b for b in bases) or len(layers) > 0
            if is_model_like and len(layers) > best_len:
                best, best_len = {"name": node.name, "bases": bases, "layers": layers}, len(layers)
    return best


def _normalize_nodes(raw_layers):
    nodes, edges = [], []
    for i, l in enumerate(raw_layers):
        category = LAYER_CATEGORY.get(l["leaf"], "other")
        nodes.append({
            "id": f"L{i+1:02d}",
            "label": l["leaf"] or "Layer",
            "attr": l.get("attr"),
            "category": category,
            "params": l["params"],
            "order": i,
        })
        if i > 0:
            edges.append([f"L{i:02d}", f"L{i+1:02d}"])
    return nodes, edges


def analyze_python_source(source, filename="uploaded.py"):
    try:
        tree = ast.parse(source)
    except SyntaxError as e:
        return {"error": f"Syntax error at line {e.lineno}: {e.msg}", "filename": filename}

    imports = _collect_imports(tree)
    framework = next((FRAMEWORK_IMPORT_MAP[r] for r in imports if r in FRAMEWORK_IMPORT_MAP), None)

    raw_layers = None
    source_kind = None  # 'class' | 'sequential' | 'pipeline' | 'estimator' | 'plot'

    cls = _best_class(tree)
    if cls and cls["layers"]:
        raw_layers = cls["layers"]
        source_kind = "class"

    seq_blocks = _sequential_blocks(tree)
    if raw_layers is None and seq_blocks:
        raw_layers = max(seq_blocks, key=len)
        source_kind = "sequential"

    pipe_blocks = _pipeline_blocks(tree)
    estimators = _top_level_estimators(tree)
    plot_calls, is_3d = _plot_calls(tree, source)

    nodes, edges, kind = [], [], "unknown"

    if raw_layers:
        nodes, edges = _normalize_nodes(raw_layers)
        kind = "neural_network"
        if framework is None:
            framework = "pytorch" if "torch" in imports else ("keras" if ({"tensorflow", "keras"} & imports) else None)
    elif pipe_blocks:
        nodes, edges = _normalize_nodes(max(pipe_blocks, key=len))
        kind = "sklearn_pipeline"
        framework = framework or "sklearn"
    elif estimators:
        nodes, edges = _normalize_nodes(estimators[:1])
        kind = "sklearn_model"
        framework = framework or "sklearn"
    elif plot_calls:
        kind = "plot_3d" if is_3d else "plot"
        framework = framework or next((PLOT_IMPORT_MAP[r] for r in imports if r in PLOT_IMPORT_MAP), "matplotlib")

    plot_tally = {}
    for p in plot_calls:
        plot_tally[p["tag"]] = plot_tally.get(p["tag"], 0) + 1

    class_names = [n.name for n in ast.walk(tree) if isinstance(n, ast.ClassDef)]
    fn_names = [n.name for n in tree.body if isinstance(n, ast.FunctionDef)]

    return {
        "filename": filename,
        "kind": kind,
        "framework": framework,
        "source_kind": source_kind,
        "nodes": nodes,
        "edges": edges,
        "plot_signals": [{"tag": k, "count": v} for k, v in plot_tally.items()],
        "is_3d": is_3d,
        "summary": {
            "lines": source.count("\n") + 1,
            "classes": class_names,
            "functions": fn_names,
            "imports": sorted(imports),
        },
    }