// Transcript parsing utility for converting raw transcript content into structured messages
import { prisma } from './prisma.js';

export interface ParsedMessage {
  sessionId: string;
  timestamp: Date;
  role: string;
  content: string;
  order: number;
}

export interface TranscriptParseResult {
  success: boolean;
  messages?: ParsedMessage[];
  error?: string;
}

/**
 * Parse European date format (DD.MM.YYYY HH:mm:ss) to Date object
 */
function parseEuropeanDate(dateStr: string): Date {
  const match = dateStr.match(/(\d{2})\.(\d{2})\.(\d{4}) (\d{2}):(\d{2}):(\d{2})/);
  if (!match) {
    throw new Error(`Invalid date format: ${dateStr}`);
  }

  const [, day, month, year, hour, minute, second] = match;
  return new Date(
    parseInt(year, 10),
    parseInt(month, 10) - 1, // JavaScript months are 0-indexed
    parseInt(day, 10),
    parseInt(hour, 10),
    parseInt(minute, 10),
    parseInt(second, 10)
  );
}

/**
 * Parse raw transcript content into structured messages
 * @param content Raw transcript content
 * @param startTime Session start time
 * @param endTime Session end time
 * @returns Parsed messages with timestamps
 */
export function parseTranscriptToMessages(
  content: string,
  startTime: Date,
  endTime: Date
): TranscriptParseResult {
  try {
    if (!content || !content.trim()) {
      return {
        success: false,
        error: 'Empty transcript content'
      };
    }

    const messages: ParsedMessage[] = [];
    const lines = content.split('\n');
    let currentMessage: { role: string; content: string; timestamp?: string } | null = null;
    let order = 0;

    for (const line of lines) {
      const trimmedLine = line.trim();

      // Skip empty lines
      if (!trimmedLine) {
        continue;
      }

      // Check if line starts with a timestamp and role [DD.MM.YYYY HH:MM:SS] Role: content
      const timestampRoleMatch = trimmedLine.match(/^\[(\d{2}\.\d{2}\.\d{4} \d{2}:\d{2}:\d{2})\]\s+(User|Assistant|System|user|assistant|system):\s*(.*)$/i);

      // Check if line starts with just a role (User:, Assistant:, System:, etc.)
      const roleMatch = trimmedLine.match(/^(User|Assistant|System|user|assistant|system):\s*(.*)$/i);

      if (timestampRoleMatch) {
        // Save previous message if exists
        if (currentMessage) {
          messages.push({
            sessionId: '', // Will be set by caller
            timestamp: new Date(), // Will be calculated below
            role: currentMessage.role,
            content: currentMessage.content.trim(),
            order: order++
          });
        }

        // Start new message with timestamp
        const timestamp = timestampRoleMatch[1];
        const role = timestampRoleMatch[2].charAt(0).toUpperCase() + timestampRoleMatch[2].slice(1).toLowerCase();
        const content = timestampRoleMatch[3] || '';

        currentMessage = {
          role,
          content,
          timestamp // Store the timestamp for later parsing
        };
      } else if (roleMatch) {
        // Save previous message if exists
        if (currentMessage) {
          messages.push({
            sessionId: '', // Will be set by caller
            timestamp: new Date(), // Will be calculated below
            role: currentMessage.role,
            content: currentMessage.content.trim(),
            order: order++
          });
        }

        // Start new message without timestamp
        const role = roleMatch[1].charAt(0).toUpperCase() + roleMatch[1].slice(1).toLowerCase();
        const content = roleMatch[2] || '';

        currentMessage = {
          role,
          content
        };
      } else if (currentMessage) {
        // Continue previous message (multi-line)
        currentMessage.content += '\n' + trimmedLine;
      }
      // If no current message and no role match, skip the line (orphaned content)
    }

    // Save the last message
    if (currentMessage) {
      messages.push({
        sessionId: '', // Will be set by caller
        timestamp: new Date(), // Will be calculated below
        role: currentMessage.role,
        content: currentMessage.content.trim(),
        order: order++
      });
    }

    if (messages.length === 0) {
      return {
        success: false,
        error: 'No messages found in transcript'
      };
    }

    // Calculate timestamps - use parsed timestamps if available, otherwise distribute across session duration
    const hasTimestamps = messages.some(msg => (msg as any).timestamp);

    if (hasTimestamps) {
      // Use parsed timestamps from the transcript
      messages.forEach((message, index) => {
        const msgWithTimestamp = message as any;
        if (msgWithTimestamp.timestamp) {
          try {
            message.timestamp = parseEuropeanDate(msgWithTimestamp.timestamp);
          } catch (error) {
            // Fallback to distributed timestamp if parsing fails
            const sessionDurationMs = endTime.getTime() - startTime.getTime();
            const messageInterval = messages.length > 1 ? sessionDurationMs / (messages.length - 1) : 0;
            message.timestamp = new Date(startTime.getTime() + (index * messageInterval));
          }
        } else {
          // Fallback to distributed timestamp
          const sessionDurationMs = endTime.getTime() - startTime.getTime();
          const messageInterval = messages.length > 1 ? sessionDurationMs / (messages.length - 1) : 0;
          message.timestamp = new Date(startTime.getTime() + (index * messageInterval));
        }
      });
    } else {
      // Distribute messages across session duration
      const sessionDurationMs = endTime.getTime() - startTime.getTime();
      const messageInterval = messages.length > 1 ? sessionDurationMs / (messages.length - 1) : 0;

      messages.forEach((message, index) => {
        message.timestamp = new Date(startTime.getTime() + (index * messageInterval));
      });
    }

    return {
      success: true,
      messages
    };

  } catch (error) {
    return {
      success: false,
      error: error instanceof Error ? error.message : String(error)
    };
  }
}

/**
 * Store parsed messages in the database for a session
 * @param sessionId The session ID
 * @param messages Array of parsed messages
 */
export async function storeMessagesForSession(
  sessionId: string,
  messages: ParsedMessage[]
): Promise<void> {
  // Delete existing messages for this session (in case of re-processing)
  await prisma.message.deleteMany({
    where: { sessionId }
  });

  // Create new messages
  const messagesWithSessionId = messages.map(msg => ({
    ...msg,
    sessionId
  }));

  await prisma.message.createMany({
    data: messagesWithSessionId
  });
}

/**
 * Process transcript for a single session
 * @param sessionId The session ID to process
 */
export async function processSessionTranscript(sessionId: string): Promise<void> {
  // Get the session and its import data
  const session = await prisma.session.findUnique({
    where: { id: sessionId },
    include: {
      import: true
    }
  });

  if (!session) {
    throw new Error(`Session not found: ${sessionId}`);
  }

  if (!session.import) {
    throw new Error(`No import data found for session: ${sessionId}`);
  }

  if (!session.import.rawTranscriptContent) {
    throw new Error(`No transcript content found for session: ${sessionId}`);
  }

  // Parse the start and end times
  const startTime = parseEuropeanDate(session.import.startTimeRaw);
  const endTime = parseEuropeanDate(session.import.endTimeRaw);

  // Parse the transcript
  const parseResult = parseTranscriptToMessages(
    session.import.rawTranscriptContent,
    startTime,
    endTime
  );

  if (!parseResult.success) {
    throw new Error(`Failed to parse transcript: ${parseResult.error}`);
  }

  // Store the messages
  await storeMessagesForSession(sessionId, parseResult.messages!);

  console.log(`✅ Processed ${parseResult.messages!.length} messages for session ${sessionId}`);
}

/**
 * Process all sessions that have transcript content but no messages
 */
export async function processAllUnparsedTranscripts(): Promise<void> {
  console.log('🔍 Finding sessions with unparsed transcripts...');

  // Find sessions that have transcript content but no messages
  const sessionsToProcess = await prisma.session.findMany({
    where: {
      import: {
        rawTranscriptContent: {
          not: null
        }
      },
      messages: {
        none: {}
      }
    },
    include: {
      import: true,
      _count: {
        select: {
          messages: true
        }
      }
    }
  });

  console.log(`📋 Found ${sessionsToProcess.length} sessions to process`);

  let processed = 0;
  let errors = 0;

  for (const session of sessionsToProcess) {
    try {
      await processSessionTranscript(session.id);
      processed++;
    } catch (error) {
      console.error(`❌ Error processing session ${session.id}:`, error);
      errors++;
    }
  }

  console.log(`\n📊 Processing complete:`);
  console.log(`  ✅ Successfully processed: ${processed} sessions`);
  console.log(`  ❌ Errors: ${errors} sessions`);
  console.log(`  📝 Total messages created: ${await getTotalMessageCount()}`);
}

/**
 * Get total count of messages in the database
 */
export async function getTotalMessageCount(): Promise<number> {
  const result = await prisma.message.count();
  return result;
}

/**
 * Get messages for a specific session
 * @param sessionId The session ID
 * @returns Array of messages ordered by order field
 */
export async function getMessagesForSession(sessionId: string) {
  return await prisma.message.findMany({
    where: { sessionId },
    orderBy: { order: 'asc' }
  });
}

/**
 * Get parsing statistics
 */
export async function getParsingStats() {
  const totalSessions = await prisma.session.count();
  const sessionsWithTranscripts = await prisma.session.count({
    where: {
      import: {
        rawTranscriptContent: {
          not: null
        }
      }
    }
  });
  const sessionsWithMessages = await prisma.session.count({
    where: {
      messages: {
        some: {}
      }
    }
  });
  const totalMessages = await getTotalMessageCount();

  return {
    totalSessions,
    sessionsWithTranscripts,
    sessionsWithMessages,
    unparsedSessions: sessionsWithTranscripts - sessionsWithMessages,
    totalMessages
  };
}