/** Tool names that must never appear as pasted JSON in user-visible bot text. */
export const UNSPEAKABLE_DELEGATION_TOOLS = new Set([
  "handoff_to_bot",
  "message_bot",
  "message_agent",
  "message_user",
  "ask_user",
  "run_subagent",
  "spawn_bot",
]);

export type ProseToolCall = {
  name: string;
  parameters: Record<string, unknown>;
};

export type SanitizedBotReply = {
  text: string;
  proseToolCalls: ProseToolCall[];
  strippedRolePrefix: boolean;
};

const ASSISTANT_ROLE_PREFIX = /^assistant:\s*/i;

/** Strip a leaked chat-template role prefix from model output. */
export function stripAssistantRolePrefix(text: string): string {
  return text.replace(ASSISTANT_ROLE_PREFIX, "");
}

const TOOL_META_PREAMBLE =
  /^(?:[^\n]*\b(?:json response|tool[- ]call|handoff_to_bot|provide the json|i'll provide the json|handoff is given|since the handoff)[^\n]*\n?)+/gim;

const TRAILING_TOOL_META_LINE =
  /^(?:since the handoff is given|i(?:'|’)ll provide the json|here(?:'|’)s the json|the json response).*?:?\s*$/i;

/** Remove narration that only exists to introduce a pasted tool-call blob. */
export function stripToolMetaPreamble(text: string): string {
  let next = text.trim();
  for (let pass = 0; pass < 3; pass += 1) {
    const stripped = next.replace(TOOL_META_PREAMBLE, "").trim();
    if (stripped === next) break;
    next = stripped;
  }
  if (TRAILING_TOOL_META_LINE.test(next)) return "";
  return next;
}

function parseProseToolObject(raw: string): ProseToolCall | null {
  try {
    const parsed = JSON.parse(raw) as {
      name?: unknown;
      parameters?: unknown;
      arguments?: unknown;
    };
    if (typeof parsed.name !== "string" || !parsed.name.trim()) return null;
    const params = parsed.parameters ?? parsed.arguments;
    if (!params || typeof params !== "object" || Array.isArray(params)) return null;
    return { name: parsed.name.trim(), parameters: params as Record<string, unknown> };
  } catch {
    return null;
  }
}

/** Find `{ "name": "tool", "parameters": … }` blobs the model typed as prose. */
export function findProseToolCalls(
  text: string,
): Array<{ start: number; end: number; call: ProseToolCall }> {
  const found: Array<{ start: number; end: number; call: ProseToolCall }> = [];
  const marker = /"name"\s*:\s*"([a-z_][a-z0-9_]*)"/gi;
  for (let match = marker.exec(text); match; match = marker.exec(text)) {
    let start = match.index;
    while (start > 0 && text[start] !== "{") start -= 1;
    if (text[start] !== "{") continue;

    let depth = 0;
    let end = start;
    for (; end < text.length; end += 1) {
      const char = text[end];
      if (char === "{") depth += 1;
      else if (char === "}") {
        depth -= 1;
        if (depth === 0) {
          end += 1;
          break;
        }
      }
    }
    if (depth !== 0) continue;

    const call = parseProseToolObject(text.slice(start, end));
    if (!call) continue;
    if (found.some((item) => item.start === start)) continue;
    found.push({ start, end, call });
  }
  return found.sort((a, b) => a.start - b.start);
}

export function stripProseToolCalls(text: string): {
  text: string;
  proseToolCalls: ProseToolCall[];
} {
  const matches = findProseToolCalls(text);
  if (matches.length === 0) return { text, proseToolCalls: [] };

  let cleaned = text;
  for (const match of [...matches].reverse()) {
    cleaned = `${cleaned.slice(0, match.start)}${cleaned.slice(match.end)}`;
  }
  cleaned = stripToolMetaPreamble(cleaned.replace(/\n{3,}/g, "\n\n").trim());
  return { text: cleaned, proseToolCalls: matches.map((item) => item.call) };
}

/** Prepare bot text for transcript, notifications, and TTS. */
export function sanitizeBotReplyText(text: string): SanitizedBotReply {
  const strippedRolePrefix = ASSISTANT_ROLE_PREFIX.test(text);
  const withoutRole = stripAssistantRolePrefix(text);
  const { text: withoutTools, proseToolCalls } = stripProseToolCalls(withoutRole);
  return { text: withoutTools.trim(), proseToolCalls, strippedRolePrefix };
}

export function isUnspeakableDelegationTool(name: string): boolean {
  return UNSPEAKABLE_DELEGATION_TOOLS.has(name);
}

/** True when the whole message is only unspeakable tool prose. */
export function isOnlyUnspeakableToolProse(text: string): boolean {
  const { text: cleaned, proseToolCalls } = sanitizeBotReplyText(text);
  return cleaned.length === 0 && proseToolCalls.length > 0;
}