from typing import List, Dict, Any


class PolicyEngine:
    def __init__(self):
        # Separate allow and deny policies for straightforward evaluation order
        self._policies: List[Dict[str, Any]] = []  # allowed rules
        self._denies: List[Dict[str, Any]] = []    # denied rules

    def load_policies(self, dsl: str) -> None:
        # Very small DSL parser for a single-line policy per call.
        # Supports two forms:
        # allow ...
        # deny ...
        # Example:
        # allow subject="traderA" venue="venue1" signal="price" action="read" latency_ms=5 volume_cap=1000 regulatory="none"
        # deny subject="traderB" venue="venue1" signal="price" action="read" latency_ms=0
        for line in [l.strip() for l in dsl.splitlines() if l.strip()]:
            if not line:
                continue
            # Determine policy type
            if line.startswith("allow"):
                rest = line[len("allow"):].strip()
                policy: Dict[str, Any] = {}
                parts = rest.split()
                for part in parts:
                    if "=" not in part:
                        continue
                    k, v = part.split("=", 1)
                    v = v.strip().strip('"')
                    if v.isdigit():
                        policy[k] = int(v)
                    else:
                        policy[k] = v
                policy.setdefault("latency_ms", 0)
                policy.setdefault("volume_cap", None)
                self._policies.append(policy)
            elif line.startswith("deny"):
                rest = line[len("deny"):].strip()
                policy: Dict[str, Any] = {}
                parts = rest.split()
                for part in parts:
                    if "=" not in part:
                        continue
                    k, v = part.split("=", 1)
                    v = v.strip().strip('"')
                    if v.isdigit():
                        policy[k] = int(v)
                    else:
                        policy[k] = v
                policy.setdefault("latency_ms", 0)
                policy.setdefault("volume_cap", None)
                self._denies.append(policy)

    def check_access(self, subject: str, venue: str, signal: str, action: str) -> bool:
        # Deny policies take precedence: if any deny matches, deny access
        for p in self._denies:
            if (
                p.get("subject") in (subject, "any")
                and p.get("venue") in (venue, "any")
                and p.get("signal") == signal
                and p.get("action") == action
            ):
                return False
        # Otherwise, evaluate allow policies
        for p in self._policies:
            if (
                p.get("subject") in (subject, "any")
                and p.get("venue") in (venue, "any")
                and p.get("signal") == signal
                and p.get("action") == action
            ):
                return True
        return False