ai-video-fullstack/backend/services/workflow_engine.py

"""Pure Workflow v3 graph queries and deterministic edge evaluation."""

from __future__ import annotations

import re
from typing import Any

from services.node_specs import normalize_graph
from services.runtime_variables import DynamicVariableStore


class WorkflowEngine:
    def __init__(self, graph: dict[str, Any]):
        self.graph = normalize_graph(graph)
        self.settings = self.graph.get("settings") or {}
        self.nodes: dict[str, dict] = {
            str(node["id"]): node
            for node in self.graph.get("nodes") or []
            if node.get("id")
        }
        self.edges: list[dict] = list(self.graph.get("edges") or [])
        self.start_id = next(
            (node_id for node_id, node in self.nodes.items() if node.get("type") == "start"),
            None,
        )

    def has_graph(self) -> bool:
        return bool(self.start_id)

    def node_type(self, node_id: str | None) -> str | None:
        return self.nodes.get(node_id or "", {}).get("type")

    def data(self, node_id: str | None) -> dict:
        return self.nodes.get(node_id or "", {}).get("data") or {}

    def name(self, node_id: str | None) -> str:
        return str(self.data(node_id).get("name") or self.node_type(node_id) or "")

    def outgoing(self, node_id: str | None) -> list[dict]:
        result = [edge for edge in self.edges if edge.get("source") == node_id]
        return sorted(result, key=lambda edge: int((edge.get("data") or {}).get("priority", 10)))

    def edge_mode(self, edge: dict) -> str:
        return str((edge.get("data") or {}).get("mode") or "always")

    def edge_fn_name(self, edge: dict) -> str:
        raw = edge.get("id") or f"{edge.get('source')}_{edge.get('target')}"
        slug = re.sub(r"[^a-z0-9]+", "_", str(raw).lower()).strip("_")
        return f"goto_{slug or 'next'}"

    def edge_description(self, edge: dict) -> str:
        data = edge.get("data") or {}
        target = self.name(str(edge.get("target") or ""))
        condition = str(data.get("condition") or "").strip()
        if condition:
            return f"当满足以下条件时转到「{target}」：{condition}"
        return f"当当前阶段任务完成时转到「{target}」。"

    def edge_transition_speech(self, edge: dict | None) -> str:
        if not edge:
            return ""
        data = edge.get("data") or {}
        return str(data.get("transitionSpeech") or data.get("transition_speech") or "")

    def global_prompt(self) -> str:
        return str(self.settings.get("globalPrompt") or "").strip()

    def prompt_for(self, node_id: str, store: DynamicVariableStore) -> str:
        prompt = store.render(str(self.data(node_id).get("prompt") or "").strip())
        sections = [f"[当前阶段：{self.name(node_id)}]"]
        if self.global_prompt():
            sections.append(f"[全局规则]\n{store.render(self.global_prompt())}")
        if prompt:
            sections.append(f"[当前阶段任务]\n{prompt}")
        return "\n\n".join(sections)

    def greeting(self, store: DynamicVariableStore) -> str:
        return store.render(str(self.data(self.start_id).get("greeting") or ""))

    def expression_matches(self, expression: dict, values: dict[str, Any]) -> bool:
        results = []
        for rule in expression.get("rules") or []:
            name = str(rule.get("variable") or "")
            operator = str(rule.get("operator") or "")
            expected = rule.get("value")
            exists = name in values
            actual = values.get(name)
            try:
                if operator == "exists":
                    matched = exists if expected is not False else not exists
                elif operator == "eq":
                    matched = actual == expected
                elif operator == "neq":
                    matched = actual != expected
                elif operator == "gt":
                    matched = actual > expected
                elif operator == "gte":
                    matched = actual >= expected
                elif operator == "lt":
                    matched = actual < expected
                elif operator == "lte":
                    matched = actual <= expected
                elif operator == "contains":
                    matched = expected in actual
                elif operator == "in":
                    matched = actual in expected
                else:
                    matched = False
            except (TypeError, ValueError):
                matched = False
            results.append(matched)
        if not results:
            return False
        return all(results) if expression.get("combinator", "and") == "and" else any(results)

    def deterministic_edge(
        self,
        node_id: str,
        store: DynamicVariableStore,
        *,
        include_default: bool,
    ) -> dict | None:
        default = None
        for edge in self.outgoing(node_id):
            data = edge.get("data") or {}
            mode = data.get("mode")
            if mode == "expression" and self.expression_matches(
                data.get("expression") or {}, store.values
            ):
                return edge
            if mode == "always":
                default = edge
        return default if include_default else None

    def llm_edges(self, node_id: str) -> list[dict]:
        return [
            edge
            for edge in self.outgoing(node_id)
            if self.edge_mode(edge) in {"llm", "always"}
        ]