import {
  BUILTIN_RULE,
  CodecError,
  parseRewrittenRuleMessage
} from "../../../Yonexus.Protocol/src/index.js";

export type ServerRuleProcessor = (message: string) => unknown;

export class ServerRuleRegistryError extends Error {
  constructor(message: string) {
    super(message);
    this.name = "ServerRuleRegistryError";
  }
}

export interface ServerRuleRegistry {
  readonly size: number;
  registerRule(rule: string, processor: ServerRuleProcessor): void;
  hasRule(rule: string): boolean;
  dispatch(raw: string): boolean;
  getRules(): readonly string[];
}

export class YonexusServerRuleRegistry implements ServerRuleRegistry {
  private readonly rules = new Map<string, ServerRuleProcessor>();

  get size(): number {
    return this.rules.size;
  }

  registerRule(rule: string, processor: ServerRuleProcessor): void {
    const normalizedRule = this.normalizeRule(rule);
    if (this.rules.has(normalizedRule)) {
      throw new ServerRuleRegistryError(
        `Rule '${normalizedRule}' is already registered`
      );
    }

    this.rules.set(normalizedRule, processor);
  }

  hasRule(rule: string): boolean {
    return this.rules.has(rule.trim());
  }

  dispatch(raw: string): boolean {
    const parsed = parseRewrittenRuleMessage(raw);
    const processor = this.rules.get(parsed.ruleIdentifier);
    if (!processor) {
      return false;
    }

    processor(raw);
    return true;
  }

  getRules(): readonly string[] {
    return [...this.rules.keys()];
  }

  private normalizeRule(rule: string): string {
    const normalizedRule = rule.trim();
    if (!normalizedRule) {
      throw new ServerRuleRegistryError("Rule identifier must be a non-empty string");
    }

    if (normalizedRule === BUILTIN_RULE) {
      throw new ServerRuleRegistryError(
        `Rule identifier '${BUILTIN_RULE}' is reserved`
      );
    }

    try {
      parseRewrittenRuleMessage(`${normalizedRule}::sender::probe`);
    } catch (error) {
      if (error instanceof CodecError) {
        throw new ServerRuleRegistryError(error.message);
      }

      throw error;
    }

    return normalizedRule;
  }
}

export function createServerRuleRegistry(): ServerRuleRegistry {
  return new YonexusServerRuleRegistry();
}