/**
 * DSFA API Client
 *
 * API client functions for DSFA (Data Protection Impact Assessment) endpoints.
 */

import type {
  DSFA,
  DSFAListResponse,
  DSFAStatsResponse,
  CreateDSFARequest,
  CreateDSFAFromAssessmentRequest,
  CreateDSFAFromAssessmentResponse,
  UpdateDSFASectionRequest,
  SubmitForReviewResponse,
  ApproveDSFARequest,
  DSFATriggerInfo,
} from './types'
import type { AIUseCaseModule } from './ai-use-case-types'

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

const getBaseUrl = () => {
  if (typeof window !== 'undefined') {
    // Browser environment
    return process.env.NEXT_PUBLIC_SDK_API_URL || '/api/sdk/v1'
  }
  // Server environment
  return process.env.SDK_API_URL || 'http://localhost:8080/api/sdk/v1'
}

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

async function handleResponse<T>(response: Response): Promise<T> {
  if (!response.ok) {
    const errorBody = await response.text()
    let errorMessage = `HTTP ${response.status}`
    try {
      const errorJson = JSON.parse(errorBody)
      errorMessage = errorJson.error || errorJson.message || errorMessage
    } catch {
      // Keep HTTP status message
    }
    throw new Error(errorMessage)
  }
  return response.json()
}

function getHeaders(): HeadersInit {
  return {
    'Content-Type': 'application/json',
  }
}

// =============================================================================
// DSFA CRUD OPERATIONS
// =============================================================================

/**
 * List all DSFAs for the current tenant
 */
export async function listDSFAs(status?: string): Promise<DSFA[]> {
  const url = new URL(`${getBaseUrl()}/dsfa`, window.location.origin)
  if (status) {
    url.searchParams.set('status', status)
  }

  const response = await fetch(url.toString(), {
    method: 'GET',
    headers: getHeaders(),
    credentials: 'include',
  })

  const data = await handleResponse<DSFAListResponse>(response)
  return data.dsfas || []
}

/**
 * Get a single DSFA by ID
 */
export async function getDSFA(id: string): Promise<DSFA> {
  const response = await fetch(`${getBaseUrl()}/dsfa/${id}`, {
    method: 'GET',
    headers: getHeaders(),
    credentials: 'include',
  })

  return handleResponse<DSFA>(response)
}

/**
 * Create a new DSFA
 */
export async function createDSFA(data: CreateDSFARequest): Promise<DSFA> {
  const response = await fetch(`${getBaseUrl()}/dsfa`, {
    method: 'POST',
    headers: getHeaders(),
    credentials: 'include',
    body: JSON.stringify(data),
  })

  return handleResponse<DSFA>(response)
}

/**
 * Update an existing DSFA
 */
export async function updateDSFA(id: string, data: Partial<DSFA>): Promise<DSFA> {
  const response = await fetch(`${getBaseUrl()}/dsfa/${id}`, {
    method: 'PUT',
    headers: getHeaders(),
    credentials: 'include',
    body: JSON.stringify(data),
  })

  return handleResponse<DSFA>(response)
}

/**
 * Delete a DSFA
 */
export async function deleteDSFA(id: string): Promise<void> {
  const response = await fetch(`${getBaseUrl()}/dsfa/${id}`, {
    method: 'DELETE',
    headers: getHeaders(),
    credentials: 'include',
  })

  if (!response.ok) {
    throw new Error(`Failed to delete DSFA: ${response.statusText}`)
  }
}

// =============================================================================
// DSFA SECTION OPERATIONS
// =============================================================================

/**
 * Update a specific section of a DSFA
 */
export async function updateDSFASection(
  id: string,
  sectionNumber: number,
  data: UpdateDSFASectionRequest
): Promise<DSFA> {
  const response = await fetch(`${getBaseUrl()}/dsfa/${id}/sections/${sectionNumber}`, {
    method: 'PUT',
    headers: getHeaders(),
    credentials: 'include',
    body: JSON.stringify(data),
  })

  return handleResponse<DSFA>(response)
}

// =============================================================================
// DSFA WORKFLOW OPERATIONS
// =============================================================================

/**
 * Submit a DSFA for DPO review
 */
export async function submitDSFAForReview(id: string): Promise<SubmitForReviewResponse> {
  const response = await fetch(`${getBaseUrl()}/dsfa/${id}/submit-for-review`, {
    method: 'POST',
    headers: getHeaders(),
    credentials: 'include',
  })

  return handleResponse<SubmitForReviewResponse>(response)
}

/**
 * Approve or reject a DSFA (DPO/CISO/GF action)
 */
export async function approveDSFA(id: string, data: ApproveDSFARequest): Promise<{ message: string }> {
  const response = await fetch(`${getBaseUrl()}/dsfa/${id}/approve`, {
    method: 'POST',
    headers: getHeaders(),
    credentials: 'include',
    body: JSON.stringify(data),
  })

  return handleResponse<{ message: string }>(response)
}

// =============================================================================
// DSFA STATISTICS
// =============================================================================

/**
 * Get DSFA statistics for the dashboard
 */
export async function getDSFAStats(): Promise<DSFAStatsResponse> {
  const response = await fetch(`${getBaseUrl()}/dsfa/stats`, {
    method: 'GET',
    headers: getHeaders(),
    credentials: 'include',
  })

  return handleResponse<DSFAStatsResponse>(response)
}

// =============================================================================
// UCCA INTEGRATION
// =============================================================================

/**
 * Create a DSFA from a UCCA assessment (pre-filled)
 */
export async function createDSFAFromAssessment(
  assessmentId: string,
  data?: CreateDSFAFromAssessmentRequest
): Promise<CreateDSFAFromAssessmentResponse> {
  const response = await fetch(`${getBaseUrl()}/dsfa/from-assessment/${assessmentId}`, {
    method: 'POST',
    headers: getHeaders(),
    credentials: 'include',
    body: JSON.stringify(data || {}),
  })

  return handleResponse<CreateDSFAFromAssessmentResponse>(response)
}

/**
 * Get a DSFA by its linked UCCA assessment ID
 */
export async function getDSFAByAssessment(assessmentId: string): Promise<DSFA | null> {
  try {
    const response = await fetch(`${getBaseUrl()}/dsfa/by-assessment/${assessmentId}`, {
      method: 'GET',
      headers: getHeaders(),
      credentials: 'include',
    })

    if (response.status === 404) {
      return null
    }

    return handleResponse<DSFA>(response)
  } catch (error) {
    // Return null if DSFA not found
    return null
  }
}

/**
 * Check if a DSFA is required for a UCCA assessment
 */
export async function checkDSFARequired(assessmentId: string): Promise<DSFATriggerInfo> {
  const response = await fetch(`${getBaseUrl()}/ucca/assessments/${assessmentId}/dsfa-required`, {
    method: 'GET',
    headers: getHeaders(),
    credentials: 'include',
  })

  return handleResponse<DSFATriggerInfo>(response)
}

// =============================================================================
// EXPORT
// =============================================================================

/**
 * Export a DSFA as JSON
 */
export async function exportDSFAAsJSON(id: string): Promise<Blob> {
  const response = await fetch(`${getBaseUrl()}/dsfa/${id}/export?format=json`, {
    method: 'GET',
    headers: {
      'Accept': 'application/json',
    },
    credentials: 'include',
  })

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

  return response.blob()
}

/**
 * Export a DSFA as PDF
 */
export async function exportDSFAAsPDF(id: string): Promise<Blob> {
  const response = await fetch(`${getBaseUrl()}/dsfa/${id}/export/pdf`, {
    method: 'GET',
    headers: {
      'Accept': 'application/pdf',
    },
    credentials: 'include',
  })

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

  return response.blob()
}

// =============================================================================
// RISK & MITIGATION OPERATIONS
// =============================================================================

/**
 * Add a risk to a DSFA
 */
export async function addDSFARisk(dsfaId: string, risk: {
  category: string
  description: string
  likelihood: 'low' | 'medium' | 'high'
  impact: 'low' | 'medium' | 'high'
  affected_data?: string[]
}): Promise<DSFA> {
  const dsfa = await getDSFA(dsfaId)
  const newRisk = {
    id: crypto.randomUUID(),
    ...risk,
    risk_level: calculateRiskLevelString(risk.likelihood, risk.impact),
    affected_data: risk.affected_data || [],
  }

  const updatedRisks = [...(dsfa.risks || []), newRisk]
  return updateDSFA(dsfaId, { risks: updatedRisks } as Partial<DSFA>)
}

/**
 * Remove a risk from a DSFA
 */
export async function removeDSFARisk(dsfaId: string, riskId: string): Promise<DSFA> {
  const dsfa = await getDSFA(dsfaId)
  const updatedRisks = (dsfa.risks || []).filter(r => r.id !== riskId)
  return updateDSFA(dsfaId, { risks: updatedRisks } as Partial<DSFA>)
}

/**
 * Add a mitigation to a DSFA
 */
export async function addDSFAMitigation(dsfaId: string, mitigation: {
  risk_id: string
  description: string
  type: 'technical' | 'organizational' | 'legal'
  responsible_party: string
}): Promise<DSFA> {
  const dsfa = await getDSFA(dsfaId)
  const newMitigation = {
    id: crypto.randomUUID(),
    ...mitigation,
    status: 'planned' as const,
    residual_risk: 'medium' as const,
  }

  const updatedMitigations = [...(dsfa.mitigations || []), newMitigation]
  return updateDSFA(dsfaId, { mitigations: updatedMitigations } as Partial<DSFA>)
}

/**
 * Update mitigation status
 */
export async function updateDSFAMitigationStatus(
  dsfaId: string,
  mitigationId: string,
  status: 'planned' | 'in_progress' | 'implemented' | 'verified'
): Promise<DSFA> {
  const dsfa = await getDSFA(dsfaId)
  const updatedMitigations = (dsfa.mitigations || []).map(m => {
    if (m.id === mitigationId) {
      return {
        ...m,
        status,
        ...(status === 'implemented' && { implemented_at: new Date().toISOString() }),
        ...(status === 'verified' && { verified_at: new Date().toISOString() }),
      }
    }
    return m
  })

  return updateDSFA(dsfaId, { mitigations: updatedMitigations } as Partial<DSFA>)
}

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

// =============================================================================
// AI USE CASE MODULE OPERATIONS
// =============================================================================

/**
 * Add a new AI use case module to a DSFA (Section 8)
 */
export async function addAIUseCaseModule(dsfaId: string, module: AIUseCaseModule): Promise<DSFA> {
  const dsfa = await getDSFA(dsfaId)
  const existing = dsfa.ai_use_case_modules || []
  return updateDSFA(dsfaId, { ai_use_case_modules: [...existing, module] } as Partial<DSFA>)
}

/**
 * Update an existing AI use case module in a DSFA
 */
export async function updateAIUseCaseModule(
  dsfaId: string,
  moduleId: string,
  updates: Partial<AIUseCaseModule>
): Promise<DSFA> {
  const dsfa = await getDSFA(dsfaId)
  const existing = dsfa.ai_use_case_modules || []
  const updated = existing.map(m =>
    m.id === moduleId ? { ...m, ...updates, updated_at: new Date().toISOString() } : m
  )
  return updateDSFA(dsfaId, { ai_use_case_modules: updated } as Partial<DSFA>)
}

/**
 * Remove an AI use case module from a DSFA
 */
export async function removeAIUseCaseModule(dsfaId: string, moduleId: string): Promise<DSFA> {
  const dsfa = await getDSFA(dsfaId)
  const updated = (dsfa.ai_use_case_modules || []).filter(m => m.id !== moduleId)
  return updateDSFA(dsfaId, { ai_use_case_modules: updated } as Partial<DSFA>)
}

function calculateRiskLevelString(
  likelihood: 'low' | 'medium' | 'high',
  impact: 'low' | 'medium' | 'high'
): string {
  const matrix: Record<string, Record<string, string>> = {
    low: { low: 'low', medium: 'low', high: 'medium' },
    medium: { low: 'low', medium: 'medium', high: 'high' },
    high: { low: 'medium', medium: 'high', high: 'very_high' },
  }
  return matrix[likelihood]?.[impact] || 'medium'
}