from __future__ import annotations

import re
from typing import Any


MAX_SWITCH_INPUTS = 64
INDEX_SWITCH_MODES = ["pick_input", "route_output"]
INDEX_SWITCH_BASES = ["one_based", "zero_based"]
INDEX_SWITCH_MISSING_BEHAVIORS = ["fallback", "none", "clamp", "wrap"]


def normalize_index_base(value: Any) -> str:
    return value if value in INDEX_SWITCH_BASES else "one_based"


def normalize_missing_behavior(value: Any) -> str:
    return value if value in INDEX_SWITCH_MISSING_BEHAVIORS else "fallback"


def normalize_mode(value: Any) -> str:
    return value if value in INDEX_SWITCH_MODES else "pick_input"


def available_input_indices(kwargs: dict[str, Any]) -> list[int]:
    indices = []
    for key in kwargs:
        match = re.match(r"^input_(\d+)$", str(key))
        if match:
            indices.append(int(match.group(1)))
    return sorted(set(indices))


def requested_index(index: Any, index_base: str) -> int:
    requested = int(index)
    return requested + 1 if normalize_index_base(index_base) == "zero_based" else requested


def resolved_input_index(requested: int, available: list[int], missing_behavior: str) -> int | None:
    missing_behavior = normalize_missing_behavior(missing_behavior)
    if requested in available:
        return requested
    if missing_behavior in ("fallback", "none") or not available:
        return None
    if missing_behavior == "wrap":
        return available[(requested - 1) % len(available)]
    if requested <= available[0]:
        return available[0]
    if requested >= available[-1]:
        return available[-1]
    lower = [value for value in available if value <= requested]
    return lower[-1] if lower else available[0]


def input_selection(index: Any, index_base: str, missing_behavior: str, kwargs: dict[str, Any]) -> tuple[int, int | None, list[int]]:
    requested = requested_index(index, index_base)
    available = available_input_indices(kwargs)
    selected = resolved_input_index(requested, available, missing_behavior)
    return requested, selected, available


def route_selection(index: Any, index_base: str, missing_behavior: str, max_outputs: int = MAX_SWITCH_INPUTS) -> tuple[int, int | None]:
    requested = requested_index(index, index_base)
    max_outputs = max(1, int(max_outputs))
    missing_behavior = normalize_missing_behavior(missing_behavior)
    if 1 <= requested <= max_outputs:
        return requested, requested
    if missing_behavior == "wrap":
        return requested, ((requested - 1) % max_outputs) + 1
    if missing_behavior == "clamp":
        return requested, min(max(requested, 1), max_outputs)
    return requested, None


def input_status(requested: int, selected: int | None, used_fallback: bool, available: list[int]) -> str:
    available_text = ",".join(str(index) for index in available) or "none"
    if used_fallback:
        return f"requested=input_{requested}; selected=fallback; available={available_text}"
    if selected is None:
        return f"requested=input_{requested}; selected=none; available={available_text}"
    return f"requested=input_{requested}; selected=input_{selected}; available={available_text}"


def route_status(requested: int, selected: int | None, max_outputs: int = MAX_SWITCH_INPUTS) -> str:
    selected_text = "none" if selected is None else f"output_{selected}"
    return f"requested=output_{requested}; selected={selected_text}; range=1-{max_outputs}"


def lazy_inputs(index: Any, mode: str, index_base: str, missing_behavior: str, kwargs: dict[str, Any]) -> list[str]:
    mode = normalize_mode(mode)
    missing_behavior = normalize_missing_behavior(missing_behavior)
    if mode == "route_output":
        return ["route_value"] if "route_value" in kwargs else []
    requested, selected, _available = input_selection(index, index_base, missing_behavior, kwargs)
    selected_name = f"input_{selected}" if selected is not None else f"input_{requested}"
    if selected_name in kwargs:
        return [selected_name]
    if missing_behavior == "fallback" and "fallback" in kwargs:
        return ["fallback"]
    return []