# analysis/timeline_store.py

class TimelineStore:

    def __init__(self):
        self.events = []

    # -----------------------------
    # APPEND EVENT (IMMUTABLE LOG)
    # -----------------------------
    def record(self, event):
        """
        Every state transition in the system must go here.
        """
        self.events.append(event)

    # -----------------------------
    # GET EVENTS FOR NODE
    # -----------------------------
    def get_node_events(self, node_name):

        return [
            e for e in self.events
            if e.get("data", {}).get("node") == node_name
        ]

    # -----------------------------
    # GET TIMELINE SNAPSHOT
    # -----------------------------
    def snapshot_at(self, index):

        if index < 0 or index >= len(self.events):
            return None

        return self.events[index]

    # -----------------------------
    # FIND LAST STATE BEFORE EVENT
    # -----------------------------
    def rewind_to_event(self, node_name, event_index):

        history = []

        for i in range(event_index + 1):
            e = self.events[i]

            if e.get("data", {}).get("node") == node_name:
                history.append(e)

        return history

    # -----------------------------
    # FIND LAST SCHEDULER DECISION
    # -----------------------------
    def last_scheduler_state(self, node_name, event_index):

        for i in range(event_index, -1, -1):
            e = self.events[i]

            if e["type"] == "schedule_decision":
                if e.get("data", {}).get("node") == node_name:
                    return e["data"]

        return None