import { verifyToken, getUserById, hasAnyRole } from '../../utils/auth.js'
import { readMembers, writeMembers, normalizeDate } from '../../utils/members.js'
import { randomUUID } from 'crypto'

// Helper function to check for duplicates in a list (with optional exclude)
function findDuplicateMemberInList(members, firstName, lastName, geburtsdatum, excludeId = null) {
  const normalizedFirstName = (firstName || '').trim().toLowerCase()
  const normalizedLastName = (lastName || '').trim().toLowerCase()
  const normalizedDate = normalizeDate(geburtsdatum)
  
  return members.find(m => {
    if (excludeId && m.id === excludeId) return false
    const mFirstName = (m.firstName || '').trim().toLowerCase()
    const mLastName = (m.lastName || '').trim().toLowerCase()
    const mDate = normalizeDate(m.geburtsdatum)
    
    return mFirstName === normalizedFirstName &&
           mLastName === normalizedLastName &&
           mDate === normalizedDate &&
           mDate !== ''
  })
}

export default defineEventHandler(async (event) => {
  try {
    // Support both Cookie and Authorization Header
    let token = getCookie(event, 'auth_token')
    
    if (!token) {
      const authHeader = getHeader(event, 'authorization')
      if (authHeader && authHeader.startsWith('Bearer ')) {
        token = authHeader.substring(7)
      }
    }

    if (!token) {
      throw createError({
        statusCode: 401,
        message: 'Nicht authentifiziert. Bitte Token im Cookie oder Authorization-Header bereitstellen.'
      })
    }

    const decoded = verifyToken(token)

    if (!decoded) {
      throw createError({
        statusCode: 401,
        message: 'Ungültiges Token.'
      })
    }

    const user = await getUserById(decoded.id)

    if (!user) {
      throw createError({
        statusCode: 401,
        message: 'Benutzer nicht gefunden.'
      })
    }

    // Only admin and vorstand can add members in bulk
    if (!hasAnyRole(user, 'admin', 'vorstand')) {
      throw createError({
        statusCode: 403,
        message: 'Keine Berechtigung zum Bulk-Import von Mitgliedern. Erforderlich: admin oder vorstand Rolle.'
      })
    }

    const body = await readBody(event)
    const { members: membersToImport } = body

    if (!Array.isArray(membersToImport) || membersToImport.length === 0) {
      throw createError({
        statusCode: 400,
        message: 'Bitte senden Sie ein Array von Mitgliedern im Feld "members".'
      })
    }

    // Validate all members before processing
    const validationErrors = []
    membersToImport.forEach((member, index) => {
      if (!member.firstName || !member.lastName) {
        validationErrors.push(`Zeile ${index + 1}: Vorname und Nachname sind erforderlich.`)
      }
      if (!member.geburtsdatum) {
        validationErrors.push(`Zeile ${index + 1}: Geburtsdatum ist erforderlich.`)
      }
    })

    if (validationErrors.length > 0) {
      throw createError({
        statusCode: 400,
        message: `Validierungsfehler:\n${validationErrors.join('\n')}`
      })
    }

    // Read existing members
    const existingMembers = await readMembers()
    
    const results = {
      success: [],
      duplicates: [],
      errors: []
    }

    // Process each member
    for (let i = 0; i < membersToImport.length; i++) {
      const memberData = membersToImport[i]
      
      try {
        // Check for duplicates in existing members
        const duplicateInExisting = findDuplicateMemberInList(
          existingMembers,
          memberData.firstName,
          memberData.lastName,
          memberData.geburtsdatum
        )

        if (duplicateInExisting) {
          results.duplicates.push({
            index: i + 1,
            member: memberData,
            reason: `Existiert bereits (ID: ${duplicateInExisting.id})`
          })
          continue
        }

        // Check for duplicates within the import batch
        const duplicateInBatch = findDuplicateMemberInList(
          membersToImport.slice(0, i),
          memberData.firstName,
          memberData.lastName,
          memberData.geburtsdatum
        )

        if (duplicateInBatch) {
          results.duplicates.push({
            index: i + 1,
            member: memberData,
            reason: 'Duplikat innerhalb des Imports'
          })
          continue
        }

        // Add new member
        const newMember = {
          ...memberData,
          id: memberData.id || randomUUID()
        }
        
        existingMembers.push(newMember)
        results.success.push({
          index: i + 1,
          member: newMember
        })

      } catch (error) {
        results.errors.push({
          index: i + 1,
          member: memberData,
          error: error.message || 'Unbekannter Fehler'
        })
      }
    }

    // Save all successfully imported members
    if (results.success.length > 0) {
      await writeMembers(existingMembers)
    }

    return {
      success: results.success.length > 0,
      summary: {
        total: membersToImport.length,
        imported: results.success.length,
        duplicates: results.duplicates.length,
        errors: results.errors.length
      },
      results: results
    }
  } catch (error) {
    console.error('Fehler beim Bulk-Import von Mitgliedern:', error)
    if (error.statusCode) {
      throw error
    }
    throw createError({
      statusCode: error.statusCode || 500,
      message: error.message || 'Fehler beim Bulk-Import von Mitgliedern.'
    })
  }
})