import type { SkillCommandSpec } from "../agents/skills.js";
import {
  normalizeLowercaseStringOrEmpty,
  normalizeOptionalLowercaseString,
} from "../shared/string-coerce.js";
import { getChatCommands } from "./commands-registry.data.js";

export function listReservedChatSlashCommandNames(extraNames: string[] = []): Set<string> {
  const reserved = new Set<string>();
  for (const command of getChatCommands()) {
    if (command.nativeName) {
      reserved.add(normalizeOptionalLowercaseString(command.nativeName) ?? "");
    }
    for (const alias of command.textAliases) {
      const trimmed = alias.trim();
      if (!trimmed.startsWith("/")) {
        continue;
      }
      reserved.add(normalizeLowercaseStringOrEmpty(trimmed.slice(1)));
    }
  }
  for (const name of extraNames) {
    const trimmed = normalizeOptionalLowercaseString(name);
    if (trimmed) {
      reserved.add(trimmed);
    }
  }
  return reserved;
}

function normalizeSkillCommandLookup(value: string): string {
  return (normalizeOptionalLowercaseString(value) ?? "").replace(/[\s_]+/g, "-");
}

function findSkillCommand(
  skillCommands: SkillCommandSpec[],
  rawName: string,
): SkillCommandSpec | undefined {
  const trimmed = rawName.trim();
  if (!trimmed) {
    return undefined;
  }
  const lowered = normalizeOptionalLowercaseString(trimmed) ?? "";
  const normalized = normalizeSkillCommandLookup(trimmed);
  return skillCommands.find((entry) => {
    if (normalizeOptionalLowercaseString(entry.name) === lowered) {
      return true;
    }
    if (normalizeOptionalLowercaseString(entry.skillName) === lowered) {
      return true;
    }
    return (
      normalizeSkillCommandLookup(entry.name) === normalized ||
      normalizeSkillCommandLookup(entry.skillName) === normalized
    );
  });
}

export function resolveSkillCommandInvocation(params: {
  commandBodyNormalized: string;
  skillCommands: SkillCommandSpec[];
}): { command: SkillCommandSpec; args?: string } | null {
  const trimmed = params.commandBodyNormalized.trim();
  if (!trimmed.startsWith("/")) {
    return null;
  }
  const match = trimmed.match(/^\/([^\s]+)(?:\s+([\s\S]+))?$/);
  if (!match) {
    return null;
  }
  const commandName = normalizeOptionalLowercaseString(match[1]);
  if (!commandName) {
    return null;
  }
  if (commandName === "skill") {
    const remainder = match[2]?.trim();
    if (!remainder) {
      return null;
    }
    const skillMatch = remainder.match(/^([^\s]+)(?:\s+([\s\S]+))?$/);
    if (!skillMatch) {
      return null;
    }
    const skillCommand = findSkillCommand(params.skillCommands, skillMatch[1] ?? "");
    if (!skillCommand) {
      return null;
    }
    const args = skillMatch[2]?.trim();
    return { command: skillCommand, args: args || undefined };
  }
  const command = params.skillCommands.find(
    (entry) => normalizeOptionalLowercaseString(entry.name) === commandName,
  );
  if (!command) {
    return null;
  }
  const args = match[2]?.trim();
  return { command, args: args || undefined };
}