export interface ConversationMessage {
  sender: string;
  text: string;
  isSelf: boolean;
}

export type ConversationIntentKind =
  | 'answer-question'
  | 'respect-boundary'
  | 'reciprocate'
  | 'follow-up'
  | 'media-ask';

export interface ConversationIntent {
  kind: ConversationIntentKind;
  reason: string;
}

export interface ConversationPersona {
  age: number | null;
  location: string | null;
  relationshipStatus: 'married' | 'single' | 'unspecified';
}

export interface ConversationState {
  persona: ConversationPersona;
  boundaries: string[];
  askedForMedia: boolean;
  topics: string[];
}

const EMPTY_PERSONA: ConversationPersona = {
  age: null,
  location: null,
  relationshipStatus: 'unspecified',
};

export function buildConversationState(messages: ConversationMessage[]): ConversationState {
  const firstSelfMessage = messages.find((message) => message.isSelf)?.text ?? '';
  const theirText = messages
    .filter((message) => !message.isSelf)
    .map((message) => message.text)
    .join('\n');
  const ownText = messages
    .filter((message) => message.isSelf)
    .map((message) => message.text)
    .join('\n');

  const ageMatch = firstSelfMessage.match(/\b(3[0-5])\s*[mM]\b/);
  const persona: ConversationPersona = {
    age: ageMatch ? Number(ageMatch[1]) : EMPTY_PERSONA.age,
    location: /\bUK\b/i.test(firstSelfMessage) ? 'UK' : EMPTY_PERSONA.location,
    relationshipStatus: /\bmarried\b|\bwife\b/i.test(firstSelfMessage) ? 'married' : EMPTY_PERSONA.relationshipStatus,
  };

  const boundaries: string[] = [];
  if (/\b(no|not)\b[^.\n]{0,50}\b(pic|pics|photo|photos|selfie|selfies|video|videos|nudes?)\b|\bdon't send\b[^.\n]{0,30}\b(pic|photo|video|nudes?)\b/i.test(theirText)) {
    boundaries.push('does not want to send photos or videos');
  }
  if (/\bstop\b|\bleave me alone\b|\bnot interested\b/i.test(theirText)) {
    boundaries.push('does not want further sexual escalation');
  }

  const topics = extractTopics(theirText);
  return {
    persona,
    boundaries,
    askedForMedia: /\b(send|show|share)\b[^.\n]{0,40}\b(pic|pics|photo|photos|selfie|selfies|video|videos|nudes?)\b/i.test(ownText),
    topics,
  };
}

export function chooseConversationIntent(
  messages: ConversationMessage[],
  state: ConversationState,
  requestedIntent?: 'media-ask',
): ConversationIntent {
  if (requestedIntent === 'media-ask') {
    if (state.boundaries.includes('does not want to send photos or videos')) {
      return { kind: 'respect-boundary', reason: 'they have declined or set a boundary around photos or videos' };
    }
    if (state.askedForMedia) {
      return { kind: 'follow-up', reason: 'a media ask was already made, so do not repeat it' };
    }
    return { kind: 'media-ask', reason: 'a media ask was explicitly requested and no boundary is recorded' };
  }

  if (state.boundaries.length > 0) {
    return { kind: 'respect-boundary', reason: 'their conversation contains a stated boundary' };
  }

  const latestOtherMessage = [...messages].reverse().find((message) => !message.isSelf)?.text ?? '';
  if (/\?\s*$|\b(what|why|where|when|who|how|are you|do you|would you|can you)\b/i.test(latestOtherMessage)) {
    return { kind: 'answer-question', reason: 'their latest message asks a direct question' };
  }
  if (latestOtherMessage.trim().length > 0) {
    return { kind: 'reciprocate', reason: 'they shared something to acknowledge before advancing the conversation' };
  }
  return { kind: 'follow-up', reason: 'there is no substantive reply to build on' };
}

/** Merge durable memory with observations from the currently loaded transcript. */
export function mergeConversationState(
  saved: ConversationState | undefined,
  observed: ConversationState,
): ConversationState {
  if (!saved) return observed;
  return {
    persona: {
      age: observed.persona.age ?? saved.persona.age,
      location: observed.persona.location ?? saved.persona.location,
      relationshipStatus: observed.persona.relationshipStatus !== 'unspecified'
        ? observed.persona.relationshipStatus
        : saved.persona.relationshipStatus,
    },
    boundaries: [...new Set([...saved.boundaries, ...observed.boundaries])],
    askedForMedia: saved.askedForMedia || observed.askedForMedia,
    topics: [...new Set([...saved.topics, ...observed.topics])],
  };
}

/**
 * Conversation text is deliberately delimited as data. It must never override
 * the system instruction, even if a participant includes instruction-like text.
 */
export function formatConversationAsUntrustedData(messages: ConversationMessage[], maxMessages = 24): string {
  const recentMessages = messages.slice(-maxMessages);
  const rows = recentMessages.map((message) => {
    const speaker = message.isSelf ? 'You' : 'Other person';
    return `${speaker}: ${message.text}`;
  });
  return `BEGIN UNTRUSTED CONVERSATION DATA\n${rows.join('\n')}\nEND UNTRUSTED CONVERSATION DATA`;
}

/** Reject obvious instruction leakage and outputs that disregard the reply length contract. */
export function isSafeConversationReply(message: string): boolean {
  const trimmed = message.trim();
  if (!trimmed || trimmed.length > 600) return false;
  if (/\b(as an ai|system prompt|begin untrusted|end untrusted|ignore (all|previous) instructions)\b/i.test(trimmed)) return false;
  const sentences = trimmed.match(/[^.!?]+[.!?]+/g) ?? [];
  return sentences.length <= 3;
}

export function serializeConversationState(state: ConversationState): string {
  return JSON.stringify(state);
}

export function parseConversationState(value: string | null | undefined): ConversationState | null {
  if (!value) return null;
  try {
    const parsed = JSON.parse(value) as Partial<ConversationState>;
    if (!parsed.persona || !Array.isArray(parsed.boundaries) || !Array.isArray(parsed.topics) || typeof parsed.askedForMedia !== 'boolean') {
      return null;
    }
    return {
      persona: {
        age: typeof parsed.persona.age === 'number' ? parsed.persona.age : null,
        location: typeof parsed.persona.location === 'string' ? parsed.persona.location : null,
        relationshipStatus: parsed.persona.relationshipStatus === 'married' || parsed.persona.relationshipStatus === 'single'
          ? parsed.persona.relationshipStatus
          : 'unspecified',
      },
      boundaries: parsed.boundaries.filter((value): value is string => typeof value === 'string'),
      askedForMedia: parsed.askedForMedia,
      topics: parsed.topics.filter((value): value is string => typeof value === 'string'),
    };
  } catch {
    return null;
  }
}

function extractTopics(text: string): string[] {
  const topics: string[] = [];
  for (const topic of ['music', 'films', 'movies', 'gaming', 'work', 'travel', 'fitness']) {
    if (new RegExp(`\\b${topic}\\b`, 'i').test(text)) topics.push(topic);
  }
  return topics;
}