/**
 * Session Storage & Export Service
 * 
 * Manages persistent storage of completed CBT roleplay sessions,
 * enabling history review, markdown report exports, and JSON backups.
 */

import { SavedSession, Scenario, SessionMode, Message, AnalysisResult } from '../types';

const SESSIONS_STORAGE_KEY = 'cognitive-clarity-saved-sessions';

/**
 * Retrieves all saved sessions from LocalStorage.
 */
export function getSavedSessions(): SavedSession[] {
  try {
    const raw = localStorage.getItem(SESSIONS_STORAGE_KEY);
    return raw ? JSON.parse(raw) : [];
  } catch (e) {
    console.error("Failed to load saved sessions", e);
    return [];
  }
}

/**
 * Saves a completed session to LocalStorage.
 */
export function saveSession(
  scenario: Scenario,
  mode: SessionMode,
  messages: Message[],
  finalReport?: AnalysisResult
): SavedSession {
  const newSession: SavedSession = {
    id: `session-${Date.now()}-${Math.random().toString(36).substring(2, 7)}`,
    scenarioId: scenario.id,
    scenarioTitle: scenario.title,
    category: scenario.category,
    difficulty: scenario.difficulty,
    timestamp: new Date().toISOString(),
    mode,
    messages,
    finalReport
  };

  try {
    const existing = getSavedSessions();
    const updated = [newSession, ...existing].slice(0, 50); // Keep last 50 sessions
    localStorage.setItem(SESSIONS_STORAGE_KEY, JSON.stringify(updated));
  } catch (e) {
    console.error("Failed to save session", e);
  }

  return newSession;
}

/**
 * Deletes a session by ID.
 */
export function deleteSession(sessionId: string): void {
  try {
    const existing = getSavedSessions();
    const filtered = existing.filter(s => s.id !== sessionId);
    localStorage.setItem(SESSIONS_STORAGE_KEY, JSON.stringify(filtered));
  } catch (e) {
    console.error("Failed to delete session", e);
  }
}

/**
 * Generates an Apple HIG-styled Markdown summary of a CBT session report.
 */
export function formatSessionAsMarkdown(
  scenarioTitle: string,
  analysis: AnalysisResult,
  messages?: Message[]
): string {
  const dateStr = new Date().toLocaleDateString(undefined, {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
    hour: '2-digit',
    minute: '2-digit'
  });

  let md = `# Cognitive Clarity — Clinical CBT Session Report\n\n`;
  md += `**Scenario:** ${scenarioTitle}\n`;
  md += `**Date:** ${dateStr}\n`;
  md += `**Clinical Evaluation:** ${analysis.analysis.isAdaptive ? '✅ Adaptive Growth Observed' : '⚠️ Clinical Patterns / Distortions Detected'}\n`;
  md += `**Mastery Rating:** ${analysis.rating.score} / 5\n\n`;
  md += `---\n\n`;

  md += `## 1. Clinical Analysis\n\n`;
  if (analysis.analysis.distortions.length > 0) {
    md += `**Cognitive Distortions Identified:**\n`;
    analysis.analysis.distortions.forEach(d => {
      md += `- ${d}\n`;
    });
    md += `\n`;
  }
  md += `**Behavioral Evidence:**\n> "${analysis.analysis.evidence}"\n\n`;
  md += `**Clinical Justification:**\n${analysis.rating.reason}\n\n`;

  md += `## 2. Cognitive Reframing & Tactical Steps\n\n`;
  md += `**Master Reframe:**\n> "${analysis.suggestions.alternativeThought}"\n\n`;
  md += `**Homework & Behavioral Step:**\n${analysis.suggestions.behavioralStep}\n\n`;

  if (messages && messages.length > 0) {
    md += `---\n\n## 3. Session Transcript\n\n`;
    messages.forEach(m => {
      const sender = m.role === 'user' ? 'You' : 'AI Partner';
      md += `**[${sender}]**: ${m.text}\n\n`;
    });
  }

  return md;
}

/**
 * Triggers a client-side file download of text content.
 */
export function downloadFile(content: string, fileName: string, contentType: string): void {
  const blob = new Blob([content], { type: contentType });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = fileName;
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  URL.revokeObjectURL(url);
}