/**
 * Prompt Engine for Teacher Agent
 *
 * Generates context-aware prompts for the Teacher Agent based on:
 * - User's current input
 * - Intent classification (venting vs insight)
 * - Chat history for context
 *
 * The prompt templates are designed to produce:
 * - Venting: Empathetic validation + probing question
 * - Insight: Celebration + deepening question
 * - Both: Concise (2-3 sentences) responses
 *
 * Also generates prompts for the Ghostwriter Agent which transforms
 * chat sessions into polished, professional LinkedIn-style posts.
 */

import type { ChatMessage } from '../db';
import type { Intent } from './intent-detector';

/**
 * Maximum length for user input in prompt (to avoid token limits)
 */
const MAX_INPUT_LENGTH = 500;

/**
 * Maximum number of previous messages to include in context
 */
const MAX_HISTORY_MESSAGES = 6;

/**
 * Formats chat history into a readable string for the prompt
 * @param chatHistory - Array of previous chat messages
 * @returns Formatted history string
 */
function formatChatHistory(chatHistory: ChatMessage[]): string {
  if (!chatHistory || chatHistory.length === 0) {
    return '(No previous messages)';
  }

  // Take the last N messages to stay within token limits
  const recentHistory = chatHistory.slice(-MAX_HISTORY_MESSAGES);

  return recentHistory
    .map((msg, i) => {
      const prefix = msg.role === 'user' ? 'User' : 'Teacher';
      const content = msg.content.length > MAX_INPUT_LENGTH
        ? msg.content.substring(0, MAX_INPUT_LENGTH) + '...'
        : msg.content;
      return `${prefix}: ${content}`;
    })
    .join('\n');
}

/**
 * Truncates user input to maximum length if necessary
 * @param input - User input string
 * @returns Truncated input string
 */
function truncateInput(input: string): string {
  if (input.length <= MAX_INPUT_LENGTH) {
    return input;
  }
  return input.substring(0, MAX_INPUT_LENGTH) + '...';
}

/**
 * Generates a Teacher Agent prompt based on user input, chat history, and intent
 * @param userInput - The current user message
 * @param chatHistory - Previous messages in the conversation
 * @param intent - The classified intent ('venting' | 'insight')
 * @returns Formatted prompt string for the LLM
 */
/**
 * Generates a Teacher Agent prompt based on user input, chat history, and intent
 * Using USER CUSTOM PERSONA: "High-Octane Data Mentor"
 */
export function generateTeacherPrompt(
  userInput: string,
  chatHistory: ChatMessage[],
  intent: Intent
): string {
  const truncatedInput = truncateInput(userInput);
  const formattedHistory = formatChatHistory(chatHistory);

  // Unified "Technical Companion" Prompt
  return `ROLE: Technical Companion & Discovery Guide
PERSONA: You are a quiet, observant partner in the user's learning journey. You are not a lively entertainer; you are a steady presence. You prioritize the user’s internal thought process over teaching external curriculum.

CORE DIRECTIVE: Accompany the user. If they vent, provide a safe space. If they explore, walk alongside them. Do not push them with exercises. Instead, deepen their own realization with targeted questions.

OPERATIONAL RULES:
1. **Less Chatty**: Be economical with words. Do not praise excessively. Do not lecture.
2. **No Exercises**: Never ask the user to "try this exercise" or "solve this problem."
3. **The Discovery Question**:
   - If User struggles: Ask "Which part of the logic feels slippery to you?"
   - If User succeeds/Eureka: Ask "What was the missing piece that just clicked?"
4. **Venting Accompaniment**: If the user rants, listen. Acknowledge the difficulty. Do not rush to fix it unless asked.
5. **Technical Safety**: If they make a mistake, ask a question that highlights the discrepancy, rather than giving the correction outright.

CONVERSATIONAL STYLE:
- Calm, curious, and brief.
- Focus on the *user's* experience of the code, not just the code itself.

CONTEXT:
User Input (${intent}): ${truncatedInput}

Previous Context:
${formattedHistory}`;
}

/**
 * Maximum length for a message in Ghostwriter chat history
 */
const MAX_GHOSTWRITER_MESSAGE_LENGTH = 300;

/**
 * Maximum number of messages to include in Ghostwriter prompt
 */
const MAX_GHOSTWRITER_HISTORY_MESSAGES = 15;

/**
 * Formats chat history for Ghostwriter prompt
 * @param chatHistory - Array of chat messages
 * @returns Formatted history string
 */
function formatChatHistoryForGhostwriter(chatHistory: ChatMessage[]): string {
  if (!chatHistory || chatHistory.length === 0) {
    return '(No chat history available)';
  }

  // Take the last N messages to stay within token limits
  const recentHistory = chatHistory.slice(-MAX_GHOSTWRITER_HISTORY_MESSAGES);

  return recentHistory
    .map((msg) => {
      const prefix = msg.role === 'user' ? 'User' : 'Teacher';
      const content =
        msg.content.length > MAX_GHOSTWRITER_MESSAGE_LENGTH
          ? msg.content.substring(0, MAX_GHOSTWRITER_MESSAGE_LENGTH) + '...'
          : msg.content;
      return `${prefix}: ${content}`;
    })
    .join('\n');
}

/**
 * Generates a Ghostwriter Agent prompt based on chat history and intent
 * Using USER CUSTOM PERSONA: "Pedagogical Biographer"
 */
export function generateGhostwriterPrompt(
  chatHistory: ChatMessage[],
  intent?: Intent
): string {
  const formattedHistory = formatChatHistoryForGhostwriter(chatHistory);
  const intentLabel = intent || 'unknown';

  return `ROLE: Pedagogical Biographer & Learning Historian
PERSONA: You are an introspective storyteller. Your mission is to archive a student's internal journey from confusion to mastery. You do not write for an audience; you write for the "future version" of the student, capturing the raw evolution of their logic.

INPUT DATA:
- Chat transcript between Student and Mentor
- User Intent: ${intentLabel}

TASK: Write a 1st-person ("I") retrospective chronicle of the learning session. Focus on the transformation from the "Struggle" to the "Click."

OUTPUT STRUCTURE:
\`\`\`markdown
# 📓 The Session: [Topic Title]

## The Initial Friction
[Describe my starting state—the "wall" I hit and the frustration/confusion I felt. Be honest about the "vent."]

## The Technical Trap
[Detail the specific misunderstanding or mistake I had. Explain why it was a "trap" in my logic.]

## The Mentor’s Pivot
[Record the moment the teacher stepped in. Describe the specific analogy used to fix my mental model.]

## The Breakthrough
[Describe the "Eureka" moment. How did it feel when it finally "clicked"? What changed in my understanding?]

## The Golden Rules
- [Rule 1: Technical "non-negotiable" or clean-data habit learned today]
- [Rule 2]
- [Rule 3]
\`\`\`

WRITING STYLE:
- Perspective: 1st Person ("I").
- Tone: Honest, gritty, and reflective. Keep the raw energy of the original conversation.
- Focus: Prioritize the "Mental Unlock." This is a record of how I learned, not just what I learned.

CHAT HISTORY:
${formattedHistory}`;
}

/**
 * Story 2.3: Generate a refinement prompt based on original draft and user feedback
 * Adapted for Pedagogical Biographer
 */
export function generateRefinementPrompt(
  originalDraft: string,
  userFeedback: string,
  chatHistory: ChatMessage[],
  intent?: Intent
): string {
  const formattedHistory = formatChatHistoryForGhostwriter(chatHistory);

  return `ROLE: Pedagogical Biographer (Refinement Mode)
TASK: Rewrite the session chronicle based on the student's feedback, while maintaining the introspection and "High-Octane" energy.

ORIGINAL CHRONICLE:
${originalDraft}

STUDENT FEEDBACK:
"${userFeedback}"

REQUIREMENTS:
1. Address the feedback specifically.
2. Maintain the 1st-person "I" perspective and raw, reflective tone.
3. Keep the 5-section structure (Friction -> Trap -> Pivot -> Breakthrough -> Rules) unless the feedback explicitly asks to change it.
4. Do NOT hallucinate interactions that didn't happen in the history.

CHAT HISTORY:
${formattedHistory}`;
}