import fs from "fs";
import path from "path";
import { PollState, VoteEntry } from "@src/types";
import { Store } from "@systems/store";
import { Paths } from "@helpers/paths";

const PERSIST_PATH = Paths.data("poll-state.json");

// ─── Serialized shape ─────────────────────────────────────────────────────────
// Maps → arrays of [key, value] tuples, Sets → arrays of values

interface SerializedPollState {
  messageId?:      string | null;
  slot:            number;
  yes:             [string, VoteEntry][];
  no:              [string, VoteEntry][];
  locked:          boolean;
  confirmed?:      "yes" | "no" | null;
  lockMessage?:    string;
  confirmMessage?: string;
  lockedYesKeys?:  string[];
}

// ─── Serialize / deserialize ──────────────────────────────────────────────────

function serialize(polls: Map<number, PollState>): SerializedPollState[] {
  return [...polls.values()].map((s) => ({
    messageId:      s.messageId,
    slot:           s.slot,
    yes:            [...s.yes.entries()],
    no:             [...s.no.entries()],
    locked:         s.locked,
    confirmed:      s.confirmed,
    lockMessage:    s.lockMessage,
    confirmMessage: s.confirmMessage,
    lockedYesKeys:  s.lockedYesKeys ? [...s.lockedYesKeys] : undefined,
  }));
}

function deserialize(data: SerializedPollState[]): Map<number, PollState> {
  const polls = new Map<number, PollState>();
  for (const s of data) {
    polls.set(s.slot, {
      messageId:      s.messageId,
      slot:           s.slot,
      yes:            new Map(s.yes),
      no:             new Map(s.no),
      locked:         s.locked,
      confirmed:      s.confirmed,
      lockMessage:    s.lockMessage,
      confirmMessage: s.confirmMessage,
      lockedYesKeys:  s.lockedYesKeys ? new Set(s.lockedYesKeys) : undefined,
    });
  }
  return polls;
}

// ─── Public API ───────────────────────────────────────────────────────────────

export namespace persist {
  export function save(polls: Map<number, PollState>): void {
    try {
      Store.write(PERSIST_PATH, serialize(polls));
    } catch (err) {
      console.error("[pollPersistence] Failed to save poll state:", err);
    }
  }

  export function load(): Map<number, PollState> | null {
    try {
      const data = Store.read<SerializedPollState[]>(PERSIST_PATH);
      if (!data) return null;

      const polls = deserialize(data);
      console.log(`[pollPersistence] Restored ${polls.size} poll(s) from disk.`);
      return polls;
    } catch (err) {
      console.error("[pollPersistence] Failed to load poll state:", err);
      return null;
    }
  }

  export function clear(): void {
    try {
      Store.delete(PERSIST_PATH);
    } catch (err) {
      console.error("[pollPersistence] Failed to clear poll state:", err);
    }
  }
}