"""工作流节点规格 + 图校验(对齐 dograh 的 node-spec / GraphConstraints 思路)。

当前实现 3 个核心节点:开始(startCall)/智能体(agentNode)/结束(endCall)。
本模块是「节点类型」的唯一事实源:
  - /api/node-types 接口直接吐这里的规格;
  - 助手保存时用这里的约束校验 workflow 图。

新增节点类型只需在 NODE_SPECS 里加一条并补充约束。前端 specs.ts 与此保持一致。
"""

from __future__ import annotations

from typing import Any

# 规格版本号:节点定义有破坏性变更时 +1,前端可据此判断是否需要刷新缓存。
SPEC_VERSION = "1"

# 每个节点的图约束。None 表示不限制。
#   min_incoming / max_incoming:入边数量
#   min_outgoing / max_outgoing:出边数量
NODE_SPECS: list[dict[str, Any]] = [
    {
        "name": "startCall",
        "displayName": "开始",
        "category": "call_node",
        "description": "工作流入口,每个流程有且仅有一个。播放开场白并进入首个节点。",
        "icon": "Play",
        "accent": "mint",
        "addable": False,
        "constraints": {"minIncoming": 0, "maxIncoming": 0},
        "fields": [
            {"key": "name", "label": "节点名称", "type": "text"},
            {"key": "greeting", "label": "开场白", "type": "textarea"},
            {"key": "prompt", "label": "全局提示词", "type": "textarea"},
        ],
    },
    {
        "name": "agentNode",
        "displayName": "智能体节点",
        "category": "call_node",
        "description": "对话处理单元。按提示词与用户多轮交互,可有多个并通过条件边流转。",
        "icon": "Bot",
        "accent": "sky",
        "addable": True,
        "constraints": {"minIncoming": 1},
        "fields": [
            {"key": "name", "label": "节点名称", "type": "text"},
            {"key": "prompt", "label": "节点提示词", "type": "textarea", "required": True},
            {"key": "allowInterrupt", "label": "允许用户打断", "type": "switch"},
        ],
    },
    {
        "name": "endCall",
        "displayName": "结束",
        "category": "call_node",
        "description": "终止节点,礼貌结束对话。可有多个,均无出边。",
        "icon": "Flag",
        "accent": "rose",
        "addable": False,
        "constraints": {"minIncoming": 1, "minOutgoing": 0, "maxOutgoing": 0},
        "fields": [
            {"key": "name", "label": "节点名称", "type": "text"},
            {"key": "prompt", "label": "结束语提示词", "type": "textarea"},
        ],
    },
]

_SPEC_BY_NAME = {spec["name"]: spec for spec in NODE_SPECS}


def node_types_response() -> dict[str, Any]:
    """/api/node-types 的响应体(camelCase,直接喂前端)。"""
    return {"specVersion": SPEC_VERSION, "nodeTypes": NODE_SPECS}


def validate_graph(graph: dict[str, Any]) -> list[str]:
    """校验 workflow 图,返回错误信息列表(空列表 = 通过)。

    基础规则(对齐 dograh 的核心不变量):
      1. 节点类型必须是已注册类型;
      2. 有且仅有一个 startCall;
      3. 至少有一个 endCall;
      4. 边的 source/target 必须指向存在的节点;
      5. 入边/出边数量满足各节点类型的约束。

    空图(无节点)视为草稿,直接放行,方便先存后编排。
    """
    errors: list[str] = []
    nodes = graph.get("nodes") or []
    edges = graph.get("edges") or []

    if not nodes:
        return errors  # 草稿:放行

    node_ids: set[str] = set()
    type_counts: dict[str, int] = {}
    node_type_by_id: dict[str, str] = {}

    for node in nodes:
        node_id = node.get("id")
        node_type = node.get("type")
        if not node_id:
            errors.append("存在缺少 id 的节点")
            continue
        if node_id in node_ids:
            errors.append(f"节点 id 重复:{node_id}")
        node_ids.add(node_id)
        if node_type not in _SPEC_BY_NAME:
            errors.append(f"未知节点类型:{node_type}(节点 {node_id})")
            continue
        node_type_by_id[node_id] = node_type
        type_counts[node_type] = type_counts.get(node_type, 0) + 1

    start_count = type_counts.get("startCall", 0)
    if start_count == 0:
        errors.append("工作流必须有一个「开始」节点")
    elif start_count > 1:
        errors.append("工作流只能有一个「开始」节点")

    if type_counts.get("endCall", 0) == 0:
        errors.append("工作流至少需要一个「结束」节点")

    # 统计入边/出边
    incoming: dict[str, int] = {nid: 0 for nid in node_ids}
    outgoing: dict[str, int] = {nid: 0 for nid in node_ids}
    for edge in edges:
        source = edge.get("source")
        target = edge.get("target")
        if source not in node_ids:
            errors.append(f"连线指向了不存在的源节点:{source}")
            continue
        if target not in node_ids:
            errors.append(f"连线指向了不存在的目标节点:{target}")
            continue
        outgoing[source] += 1
        incoming[target] += 1

    for node_id, node_type in node_type_by_id.items():
        constraints = _SPEC_BY_NAME[node_type]["constraints"]
        name = node_type
        _check_count(errors, incoming[node_id], constraints, "Incoming", name, "入边")
        _check_count(errors, outgoing[node_id], constraints, "Outgoing", name, "出边")

    return errors


def _check_count(
    errors: list[str],
    actual: int,
    constraints: dict[str, int],
    suffix: str,
    node_type: str,
    label: str,
) -> None:
    lo = constraints.get(f"min{suffix}")
    hi = constraints.get(f"max{suffix}")
    display = _SPEC_BY_NAME[node_type]["displayName"]
    if lo is not None and actual < lo:
        errors.append(f"「{display}」节点{label}数量不能少于 {lo}(当前 {actual})")
    if hi is not None and actual > hi:
        errors.append(f"「{display}」节点{label}数量不能多于 {hi}(当前 {actual})")