import fs from "node:fs";
import path from "node:path";

export type IdentityEntry = {
  discordUserId: string;
  agentId: string;
  agentName: string;
};

export class IdentityRegistry {
  private filePath: string;
  private entries: IdentityEntry[] = [];
  private loaded = false;

  constructor(filePath: string) {
    this.filePath = filePath;
  }

  private load(): void {
    if (this.loaded) return;
    this.loaded = true;
    if (!fs.existsSync(this.filePath)) {
      this.entries = [];
      return;
    }
    try {
      const raw = fs.readFileSync(this.filePath, "utf8");
      const parsed = JSON.parse(raw);
      this.entries = Array.isArray(parsed) ? parsed : [];
    } catch {
      this.entries = [];
    }
  }

  private save(): void {
    const dir = path.dirname(this.filePath);
    if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
    fs.writeFileSync(this.filePath, JSON.stringify(this.entries, null, 2), "utf8");
  }

  upsert(entry: IdentityEntry): void {
    this.load();
    const idx = this.entries.findIndex((e) => e.agentId === entry.agentId);
    if (idx >= 0) {
      this.entries[idx] = entry;
    } else {
      this.entries.push(entry);
    }
    this.save();
  }

  remove(agentId: string): boolean {
    this.load();
    const before = this.entries.length;
    this.entries = this.entries.filter((e) => e.agentId !== agentId);
    if (this.entries.length !== before) {
      this.save();
      return true;
    }
    return false;
  }

  findByAgentId(agentId: string): IdentityEntry | undefined {
    this.load();
    return this.entries.find((e) => e.agentId === agentId);
  }

  findByDiscordUserId(discordUserId: string): IdentityEntry | undefined {
    this.load();
    return this.entries.find((e) => e.discordUserId === discordUserId);
  }

  list(): IdentityEntry[] {
    this.load();
    return [...this.entries];
  }

  /** Build a map from discordUserId → agentId for fast lookup. */
  buildDiscordToAgentMap(): Map<string, string> {
    this.load();
    const map = new Map<string, string>();
    for (const e of this.entries) map.set(e.discordUserId, e.agentId);
    return map;
  }

  /** Build a map from agentId → discordUserId for fast lookup. */
  buildAgentToDiscordMap(): Map<string, string> {
    this.load();
    const map = new Map<string, string>();
    for (const e of this.entries) map.set(e.agentId, e.discordUserId);
    return map;
  }
}