/**
 * DSR API Client
 *
 * API client for Data Subject Request management
 * Connects to the Go Consent Service backend
 */

import {
  DSRRequest,
  DSRListResponse,
  DSRFilters,
  DSRCreateRequest,
  DSRUpdateRequest,
  DSRVerifyIdentityRequest,
  DSRCompleteRequest,
  DSRRejectRequest,
  DSRExtendDeadlineRequest,
  DSRSendCommunicationRequest,
  DSRCommunication,
  DSRAuditEntry,
  DSRStatistics,
  DSRDataExport,
  DSRErasureChecklist
} from './types'

// =============================================================================
// CONFIGURATION
// =============================================================================

const DSR_API_BASE = process.env.NEXT_PUBLIC_CONSENT_SERVICE_URL || 'http://localhost:8081'
const API_TIMEOUT = 30000 // 30 seconds

// =============================================================================
// HELPER FUNCTIONS
// =============================================================================

function getTenantId(): string {
  // In a real app, this would come from auth context or localStorage
  if (typeof window !== 'undefined') {
    return localStorage.getItem('tenantId') || 'default-tenant'
  }
  return 'default-tenant'
}

function getAuthHeaders(): HeadersInit {
  const headers: HeadersInit = {
    'Content-Type': 'application/json',
    'X-Tenant-ID': getTenantId()
  }

  // Add auth token if available
  if (typeof window !== 'undefined') {
    const token = localStorage.getItem('authToken')
    if (token) {
      headers['Authorization'] = `Bearer ${token}`
    }
  }

  return headers
}

async function fetchWithTimeout<T>(
  url: string,
  options: RequestInit = {},
  timeout: number = API_TIMEOUT
): Promise<T> {
  const controller = new AbortController()
  const timeoutId = setTimeout(() => controller.abort(), timeout)

  try {
    const response = await fetch(url, {
      ...options,
      signal: controller.signal,
      headers: {
        ...getAuthHeaders(),
        ...options.headers
      }
    })

    if (!response.ok) {
      const errorBody = await response.text()
      let errorMessage = `HTTP ${response.status}: ${response.statusText}`
      try {
        const errorJson = JSON.parse(errorBody)
        errorMessage = errorJson.error || errorJson.message || errorMessage
      } catch {
        // Keep the HTTP status message
      }
      throw new Error(errorMessage)
    }

    // Handle empty responses
    const contentType = response.headers.get('content-type')
    if (contentType && contentType.includes('application/json')) {
      return response.json()
    }

    return {} as T
  } finally {
    clearTimeout(timeoutId)
  }
}

// =============================================================================
// DSR LIST & CRUD
// =============================================================================

/**
 * Fetch all DSR requests with optional filters
 */
export async function fetchDSRList(filters?: DSRFilters): Promise<DSRListResponse> {
  const params = new URLSearchParams()

  if (filters) {
    if (filters.status) {
      const statuses = Array.isArray(filters.status) ? filters.status : [filters.status]
      statuses.forEach(s => params.append('status', s))
    }
    if (filters.type) {
      const types = Array.isArray(filters.type) ? filters.type : [filters.type]
      types.forEach(t => params.append('type', t))
    }
    if (filters.priority) params.set('priority', filters.priority)
    if (filters.assignedTo) params.set('assignedTo', filters.assignedTo)
    if (filters.overdue !== undefined) params.set('overdue', String(filters.overdue))
    if (filters.search) params.set('search', filters.search)
    if (filters.dateFrom) params.set('dateFrom', filters.dateFrom)
    if (filters.dateTo) params.set('dateTo', filters.dateTo)
  }

  const queryString = params.toString()
  const url = `${DSR_API_BASE}/api/v1/admin/dsr${queryString ? `?${queryString}` : ''}`

  return fetchWithTimeout<DSRListResponse>(url)
}

/**
 * Fetch a single DSR request by ID
 */
export async function fetchDSR(id: string): Promise<DSRRequest> {
  return fetchWithTimeout<DSRRequest>(`${DSR_API_BASE}/api/v1/admin/dsr/${id}`)
}

/**
 * Create a new DSR request
 */
export async function createDSR(request: DSRCreateRequest): Promise<DSRRequest> {
  return fetchWithTimeout<DSRRequest>(`${DSR_API_BASE}/api/v1/admin/dsr`, {
    method: 'POST',
    body: JSON.stringify(request)
  })
}

/**
 * Update a DSR request
 */
export async function updateDSR(id: string, update: DSRUpdateRequest): Promise<DSRRequest> {
  return fetchWithTimeout<DSRRequest>(`${DSR_API_BASE}/api/v1/admin/dsr/${id}`, {
    method: 'PUT',
    body: JSON.stringify(update)
  })
}

/**
 * Delete a DSR request (soft delete - marks as cancelled)
 */
export async function deleteDSR(id: string): Promise<void> {
  await fetchWithTimeout<void>(`${DSR_API_BASE}/api/v1/admin/dsr/${id}`, {
    method: 'DELETE'
  })
}

// =============================================================================
// DSR WORKFLOW ACTIONS
// =============================================================================

/**
 * Verify the identity of the requester
 */
export async function verifyIdentity(
  dsrId: string,
  verification: DSRVerifyIdentityRequest
): Promise<DSRRequest> {
  return fetchWithTimeout<DSRRequest>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/verify-identity`,
    {
      method: 'POST',
      body: JSON.stringify(verification)
    }
  )
}

/**
 * Complete a DSR request
 */
export async function completeDSR(
  dsrId: string,
  completion?: DSRCompleteRequest
): Promise<DSRRequest> {
  return fetchWithTimeout<DSRRequest>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/complete`,
    {
      method: 'POST',
      body: JSON.stringify(completion || {})
    }
  )
}

/**
 * Reject a DSR request
 */
export async function rejectDSR(
  dsrId: string,
  rejection: DSRRejectRequest
): Promise<DSRRequest> {
  return fetchWithTimeout<DSRRequest>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/reject`,
    {
      method: 'POST',
      body: JSON.stringify(rejection)
    }
  )
}

/**
 * Extend the deadline for a DSR request
 */
export async function extendDeadline(
  dsrId: string,
  extension: DSRExtendDeadlineRequest
): Promise<DSRRequest> {
  return fetchWithTimeout<DSRRequest>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/extend`,
    {
      method: 'POST',
      body: JSON.stringify(extension)
    }
  )
}

/**
 * Assign a DSR request to a user
 */
export async function assignDSR(
  dsrId: string,
  assignedTo: string
): Promise<DSRRequest> {
  return fetchWithTimeout<DSRRequest>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/assign`,
    {
      method: 'POST',
      body: JSON.stringify({ assignedTo })
    }
  )
}

// =============================================================================
// COMMUNICATION
// =============================================================================

/**
 * Get all communications for a DSR request
 */
export async function getCommunications(dsrId: string): Promise<DSRCommunication[]> {
  return fetchWithTimeout<DSRCommunication[]>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/communications`
  )
}

/**
 * Send a communication (email, letter, internal note)
 */
export async function sendCommunication(
  dsrId: string,
  communication: DSRSendCommunicationRequest
): Promise<DSRCommunication> {
  return fetchWithTimeout<DSRCommunication>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/send-communication`,
    {
      method: 'POST',
      body: JSON.stringify(communication)
    }
  )
}

// =============================================================================
// AUDIT LOG
// =============================================================================

/**
 * Get audit log entries for a DSR request
 */
export async function getAuditLog(dsrId: string): Promise<DSRAuditEntry[]> {
  return fetchWithTimeout<DSRAuditEntry[]>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/audit`
  )
}

// =============================================================================
// STATISTICS
// =============================================================================

/**
 * Get DSR statistics
 */
export async function getDSRStatistics(): Promise<DSRStatistics> {
  return fetchWithTimeout<DSRStatistics>(
    `${DSR_API_BASE}/api/v1/admin/dsr/statistics`
  )
}

// =============================================================================
// DATA EXPORT (Art. 15, 20)
// =============================================================================

/**
 * Generate data export for Art. 15 (access) or Art. 20 (portability)
 */
export async function generateDataExport(
  dsrId: string,
  format: 'json' | 'csv' | 'xml' | 'pdf' = 'json'
): Promise<DSRDataExport> {
  return fetchWithTimeout<DSRDataExport>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/export`,
    {
      method: 'POST',
      body: JSON.stringify({ format })
    }
  )
}

/**
 * Download generated data export
 */
export async function downloadDataExport(dsrId: string): Promise<Blob> {
  const response = await fetch(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/export/download`,
    {
      headers: getAuthHeaders()
    }
  )

  if (!response.ok) {
    throw new Error(`Download failed: ${response.statusText}`)
  }

  return response.blob()
}

// =============================================================================
// ERASURE CHECKLIST (Art. 17)
// =============================================================================

/**
 * Get the erasure checklist for an Art. 17 request
 */
export async function getErasureChecklist(dsrId: string): Promise<DSRErasureChecklist> {
  return fetchWithTimeout<DSRErasureChecklist>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/erasure-checklist`
  )
}

/**
 * Update the erasure checklist
 */
export async function updateErasureChecklist(
  dsrId: string,
  checklist: DSRErasureChecklist
): Promise<DSRErasureChecklist> {
  return fetchWithTimeout<DSRErasureChecklist>(
    `${DSR_API_BASE}/api/v1/admin/dsr/${dsrId}/erasure-checklist`,
    {
      method: 'PUT',
      body: JSON.stringify(checklist)
    }
  )
}

// =============================================================================
// EMAIL TEMPLATES
// =============================================================================

/**
 * Get available email templates
 */
export async function getEmailTemplates(): Promise<{ id: string; name: string; stage: string }[]> {
  return fetchWithTimeout<{ id: string; name: string; stage: string }[]>(
    `${DSR_API_BASE}/api/v1/admin/dsr/email-templates`
  )
}

/**
 * Preview an email with variables filled in
 */
export async function previewEmail(
  templateId: string,
  dsrId: string
): Promise<{ subject: string; body: string }> {
  return fetchWithTimeout<{ subject: string; body: string }>(
    `${DSR_API_BASE}/api/v1/admin/dsr/email-templates/${templateId}/preview`,
    {
      method: 'POST',
      body: JSON.stringify({ dsrId })
    }
  )
}

// =============================================================================
// MOCK DATA FUNCTIONS (for development without backend)
// =============================================================================

export function createMockDSRList(): DSRRequest[] {
  const now = new Date()

  return [
    {
      id: 'dsr-001',
      referenceNumber: 'DSR-2025-000001',
      type: 'access',
      status: 'intake',
      priority: 'high',
      requester: {
        name: 'Max Mustermann',
        email: 'max.mustermann@example.de'
      },
      source: 'web_form',
      sourceDetails: 'Kontaktformular auf breakpilot.de',
      receivedAt: new Date(now.getTime() - 2 * 24 * 60 * 60 * 1000).toISOString(),
      deadline: {
        originalDeadline: new Date(now.getTime() + 28 * 24 * 60 * 60 * 1000).toISOString(),
        currentDeadline: new Date(now.getTime() + 28 * 24 * 60 * 60 * 1000).toISOString(),
        extended: false
      },
      identityVerification: {
        verified: false
      },
      assignment: {
        assignedTo: null
      },
      createdAt: new Date(now.getTime() - 2 * 24 * 60 * 60 * 1000).toISOString(),
      createdBy: 'system',
      updatedAt: new Date(now.getTime() - 2 * 24 * 60 * 60 * 1000).toISOString(),
      tenantId: 'default-tenant'
    },
    {
      id: 'dsr-002',
      referenceNumber: 'DSR-2025-000002',
      type: 'erasure',
      status: 'identity_verification',
      priority: 'high',
      requester: {
        name: 'Anna Schmidt',
        email: 'anna.schmidt@example.de',
        phone: '+49 170 1234567'
      },
      source: 'email',
      requestText: 'Ich moechte, dass alle meine Daten geloescht werden.',
      receivedAt: new Date(now.getTime() - 5 * 24 * 60 * 60 * 1000).toISOString(),
      deadline: {
        originalDeadline: new Date(now.getTime() + 9 * 24 * 60 * 60 * 1000).toISOString(),
        currentDeadline: new Date(now.getTime() + 9 * 24 * 60 * 60 * 1000).toISOString(),
        extended: false
      },
      identityVerification: {
        verified: false
      },
      assignment: {
        assignedTo: 'DSB Mueller',
        assignedAt: new Date(now.getTime() - 4 * 24 * 60 * 60 * 1000).toISOString()
      },
      createdAt: new Date(now.getTime() - 5 * 24 * 60 * 60 * 1000).toISOString(),
      createdBy: 'system',
      updatedAt: new Date(now.getTime() - 4 * 24 * 60 * 60 * 1000).toISOString(),
      tenantId: 'default-tenant'
    },
    {
      id: 'dsr-003',
      referenceNumber: 'DSR-2025-000003',
      type: 'rectification',
      status: 'processing',
      priority: 'normal',
      requester: {
        name: 'Peter Meier',
        email: 'peter.meier@example.de'
      },
      source: 'email',
      requestText: 'Meine Adresse ist falsch gespeichert.',
      receivedAt: new Date(now.getTime() - 7 * 24 * 60 * 60 * 1000).toISOString(),
      deadline: {
        originalDeadline: new Date(now.getTime() + 7 * 24 * 60 * 60 * 1000).toISOString(),
        currentDeadline: new Date(now.getTime() + 7 * 24 * 60 * 60 * 1000).toISOString(),
        extended: false
      },
      identityVerification: {
        verified: true,
        method: 'existing_account',
        verifiedAt: new Date(now.getTime() - 6 * 24 * 60 * 60 * 1000).toISOString(),
        verifiedBy: 'DSB Mueller'
      },
      assignment: {
        assignedTo: 'DSB Mueller',
        assignedAt: new Date(now.getTime() - 6 * 24 * 60 * 60 * 1000).toISOString()
      },
      rectificationDetails: {
        fieldsToCorrect: [
          {
            field: 'Adresse',
            currentValue: 'Musterstr. 1, 12345 Berlin',
            requestedValue: 'Musterstr. 10, 12345 Berlin',
            corrected: false
          }
        ]
      },
      createdAt: new Date(now.getTime() - 7 * 24 * 60 * 60 * 1000).toISOString(),
      createdBy: 'system',
      updatedAt: new Date(now.getTime() - 1 * 24 * 60 * 60 * 1000).toISOString(),
      tenantId: 'default-tenant'
    },
    {
      id: 'dsr-004',
      referenceNumber: 'DSR-2025-000004',
      type: 'portability',
      status: 'processing',
      priority: 'normal',
      requester: {
        name: 'Lisa Weber',
        email: 'lisa.weber@example.de'
      },
      source: 'web_form',
      receivedAt: new Date(now.getTime() - 10 * 24 * 60 * 60 * 1000).toISOString(),
      deadline: {
        originalDeadline: new Date(now.getTime() + 20 * 24 * 60 * 60 * 1000).toISOString(),
        currentDeadline: new Date(now.getTime() + 20 * 24 * 60 * 60 * 1000).toISOString(),
        extended: false
      },
      identityVerification: {
        verified: true,
        method: 'id_document',
        verifiedAt: new Date(now.getTime() - 8 * 24 * 60 * 60 * 1000).toISOString(),
        verifiedBy: 'DSB Mueller'
      },
      assignment: {
        assignedTo: 'IT Team',
        assignedAt: new Date(now.getTime() - 8 * 24 * 60 * 60 * 1000).toISOString()
      },
      notes: 'JSON-Export wird vorbereitet',
      createdAt: new Date(now.getTime() - 10 * 24 * 60 * 60 * 1000).toISOString(),
      createdBy: 'system',
      updatedAt: new Date(now.getTime() - 2 * 24 * 60 * 60 * 1000).toISOString(),
      tenantId: 'default-tenant'
    },
    {
      id: 'dsr-005',
      referenceNumber: 'DSR-2025-000005',
      type: 'objection',
      status: 'rejected',
      priority: 'low',
      requester: {
        name: 'Thomas Klein',
        email: 'thomas.klein@example.de'
      },
      source: 'letter',
      requestText: 'Ich widerspreche der Verarbeitung meiner Daten fuer Marketingzwecke.',
      receivedAt: new Date(now.getTime() - 35 * 24 * 60 * 60 * 1000).toISOString(),
      deadline: {
        originalDeadline: new Date(now.getTime() - 5 * 24 * 60 * 60 * 1000).toISOString(),
        currentDeadline: new Date(now.getTime() - 5 * 24 * 60 * 60 * 1000).toISOString(),
        extended: false
      },
      completedAt: new Date(now.getTime() - 7 * 24 * 60 * 60 * 1000).toISOString(),
      identityVerification: {
        verified: true,
        method: 'postal',
        verifiedAt: new Date(now.getTime() - 30 * 24 * 60 * 60 * 1000).toISOString(),
        verifiedBy: 'DSB Mueller'
      },
      assignment: {
        assignedTo: 'Rechtsabteilung',
        assignedAt: new Date(now.getTime() - 28 * 24 * 60 * 60 * 1000).toISOString()
      },
      objectionDetails: {
        processingPurpose: 'Marketing',
        legalBasis: 'Berechtigtes Interesse (Art. 6(1)(f))',
        objectionGrounds: 'Keine konkreten Gruende genannt',
        decision: 'rejected',
        decisionReason: 'Zwingende schutzwuerdige Gruende fuer die Verarbeitung ueberwiegen',
        decisionBy: 'Rechtsabteilung',
        decisionAt: new Date(now.getTime() - 7 * 24 * 60 * 60 * 1000).toISOString()
      },
      notes: 'Widerspruch unberechtigt - zwingende schutzwuerdige Gruende',
      createdAt: new Date(now.getTime() - 35 * 24 * 60 * 60 * 1000).toISOString(),
      createdBy: 'system',
      updatedAt: new Date(now.getTime() - 7 * 24 * 60 * 60 * 1000).toISOString(),
      tenantId: 'default-tenant'
    },
    {
      id: 'dsr-006',
      referenceNumber: 'DSR-2025-000006',
      type: 'access',
      status: 'completed',
      priority: 'normal',
      requester: {
        name: 'Sarah Braun',
        email: 'sarah.braun@example.de'
      },
      source: 'email',
      receivedAt: new Date(now.getTime() - 45 * 24 * 60 * 60 * 1000).toISOString(),
      deadline: {
        originalDeadline: new Date(now.getTime() - 15 * 24 * 60 * 60 * 1000).toISOString(),
        currentDeadline: new Date(now.getTime() - 15 * 24 * 60 * 60 * 1000).toISOString(),
        extended: false
      },
      completedAt: new Date(now.getTime() - 20 * 24 * 60 * 60 * 1000).toISOString(),
      identityVerification: {
        verified: true,
        method: 'id_document',
        verifiedAt: new Date(now.getTime() - 42 * 24 * 60 * 60 * 1000).toISOString(),
        verifiedBy: 'DSB Mueller'
      },
      assignment: {
        assignedTo: 'DSB Mueller',
        assignedAt: new Date(now.getTime() - 42 * 24 * 60 * 60 * 1000).toISOString()
      },
      dataExport: {
        format: 'pdf',
        generatedAt: new Date(now.getTime() - 20 * 24 * 60 * 60 * 1000).toISOString(),
        generatedBy: 'DSB Mueller',
        fileName: 'datenauskunft_sarah_braun.pdf',
        fileSize: 245000,
        includesThirdPartyData: false
      },
      createdAt: new Date(now.getTime() - 45 * 24 * 60 * 60 * 1000).toISOString(),
      createdBy: 'system',
      updatedAt: new Date(now.getTime() - 20 * 24 * 60 * 60 * 1000).toISOString(),
      tenantId: 'default-tenant'
    }
  ]
}

export function createMockStatistics(): DSRStatistics {
  return {
    total: 6,
    byStatus: {
      intake: 1,
      identity_verification: 1,
      processing: 2,
      completed: 1,
      rejected: 1,
      cancelled: 0
    },
    byType: {
      access: 2,
      rectification: 1,
      erasure: 1,
      restriction: 0,
      portability: 1,
      objection: 1
    },
    overdue: 0,
    dueThisWeek: 2,
    averageProcessingDays: 18,
    completedThisMonth: 1
  }
}