/**
 * Predictive Analytics API client for the admin dashboard.
 * Churn prediction, health scoring, and retention campaigns.
 */

import { createApiClient } from '@bytelyst/api-client';

const predictiveApi = createApiClient({
  baseUrl: `${process.env.PLATFORM_SERVICE_URL || 'http://localhost:4003'}/api`,
  defaultHeaders: {
    'x-product-id': process.env.PRODUCT_ID || 'lysnrai',
  },
});

// ── Health Scoring ────────────────────────────────────────────

export interface HealthDimension {
  score: number;
  metrics: Record<string, number>;
  trend: 'improving' | 'stable' | 'declining';
}

export interface ProductHealth {
  id: string;
  productId: string;
  date: string;
  overallHealthScore: number;
  healthStatus: 'critical' | 'warning' | 'healthy';
  dimensions: {
    acquisition: HealthDimension;
    activation: HealthDimension;
    retention: HealthDimension;
    engagement: HealthDimension;
    revenue: HealthDimension;
    stability: HealthDimension;
  };
  anomalies: Array<{
    metric: string;
    expectedValue: number;
    actualValue: number;
    deviationPercent: number;
    severity: 'critical' | 'warning';
    suggestedCause?: string;
  }>;
  forecasts: {
    next7Days: { expectedHealthScore: number; confidenceInterval: [number, number] };
    next30Days: { expectedHealthScore: number; confidenceInterval: [number, number] };
  };
  vsBaseline7Day: number;
  vsBaseline30Day: number;
}

export async function getProductHealth(productId?: string): Promise<ProductHealth[]> {
  const url = productId ? `/predictive/health?productId=${productId}` : '/predictive/health';
  return predictiveApi.fetch<ProductHealth[]>(url);
}

export async function getProductHealthDetail(productId: string): Promise<ProductHealth> {
  return predictiveApi.fetch<ProductHealth>(`/predictive/health/${productId}`);
}

export async function getHealthTrends(productId: string, days = 30): Promise<ProductHealth[]> {
  return predictiveApi.fetch<ProductHealth[]>(`/predictive/health/${productId}/trends?days=${days}`);
}

// ── Churn Prediction ─────────────────────────────────────────

export type RiskSegment = 'critical' | 'high' | 'medium' | 'low';

export interface RiskFactor {
  feature: string;
  contribution: number;
  direction: 'positive' | 'negative';
  description: string;
}

export interface ChurnPrediction {
  userId: string;
  productId: string;
  churnProbability: number;
  riskSegment: RiskSegment;
  confidenceScore: number;
  modelVersion: string;
  predictionTimestamp: string;
  explanation: {
    topRiskFactors: RiskFactor[];
    nlExplanation: string;
    suggestedActions: string[];
  };
}

export async function getChurnScore(userId: string, productId: string, horizon = 30): Promise<ChurnPrediction> {
  return predictiveApi.fetch<ChurnPrediction>('/predictive/churn-score', {
    method: 'POST',
    body: JSON.stringify({ userId, productId, horizon: String(horizon) }),
  });
}

export interface AtRiskUser {
  userId: string;
  productId: string;
  churnProbability: number;
  riskSegment: RiskSegment;
  confidenceScore: number;
  daysSinceLastSession: number;
  predictionTimestamp: string;
}

export async function getAtRiskUsers(options: {
  productId?: string;
  segment?: RiskSegment;
  limit?: number;
  offset?: number;
} = {}): Promise<{ users: AtRiskUser[]; total: number }> {
  const params = new URLSearchParams();
  if (options.productId) params.set('productId', options.productId);
  if (options.segment) params.set('segment', options.segment);
  if (options.limit) params.set('limit', String(options.limit));
  if (options.offset) params.set('offset', String(options.offset));
  return predictiveApi.fetch<{ users: AtRiskUser[]; total: number }>(`/predictive/at-risk-users?${params}`);
}

export interface UserRiskProfile extends ChurnPrediction {
  interventionHistory: Array<{
    action: string;
    timestamp: string;
    outcome?: 'responded' | 'ignored' | 'churned' | 'retained';
  }>;
}

export async function getUserRiskProfile(userId: string): Promise<UserRiskProfile> {
  return predictiveApi.fetch<UserRiskProfile>(`/predictive/users/${userId}/risk-profile`);
}

// ── Model Performance ─────────────────────────────────────────

export interface ModelPerformance {
  modelVersion: string;
  modelType: string;
  trainedAt: string;
  auc: number;
  precisionAt10: number;
  recallAt10: number;
  calibrationSlope: number;
  featureImportance: Array<{ feature: string; importance: number }>;
}

export async function getModelPerformance(): Promise<ModelPerformance> {
  return predictiveApi.fetch<ModelPerformance>('/predictive/model/performance');
}

export async function getFeatureImportance(): Promise<Array<{ feature: string; importance: number }>> {
  const res = await predictiveApi.fetch<{ features: Array<{ feature: string; importance: number }> }>('/predictive/model/features');
  return res.features;
}

// ── Retention Campaigns ──────────────────────────────────────

export type CampaignStatus = 'draft' | 'active' | 'paused' | 'completed';
export type CampaignTriggerType = 'churn_risk' | 'health_score_drop' | 'behavioral' | 'scheduled';
export type CampaignChannel = 'email' | 'push' | 'in_app' | 'slack_cs';

export interface Campaign {
  id: string;
  productId: string;
  name: string;
  description: string;
  status: CampaignStatus;
  trigger: {
    type: CampaignTriggerType;
    conditions: Array<{ field: string; operator: string; value: unknown }>;
  };
  audience: {
    riskSegments?: string[];
    products?: string[];
    userSegments?: string[];
    excludeRecentContact?: number;
  };
  messages: Array<{
    channel: CampaignChannel;
    templateId: string;
    variant?: string;
    delayHours?: number;
  }>;
  stats: {
    triggered: number;
    sent: number;
    opened: number;
    clicked: number;
    converted: number;
    controlChurnRate: number;
    treatmentChurnRate: number;
  };
  createdAt: string;
  updatedAt: string;
}

export async function listCampaigns(productId?: string): Promise<Campaign[]> {
  const url = productId ? `/predictive/campaigns?productId=${productId}` : '/predictive/campaigns';
  return predictiveApi.fetch<Campaign[]>(url);
}

export async function getCampaign(id: string): Promise<Campaign> {
  return predictiveApi.fetch<Campaign>(`/predictive/campaigns/${id}`);
}

export async function createCampaign(input: {
  name: string;
  description: string;
  productId: string;
  trigger: {
    type: CampaignTriggerType;
    conditions: Array<{ field: string; operator: string; value: unknown }>;
  };
  audience: {
    riskSegments?: string[];
    products?: string[];
    userSegments?: string[];
    excludeRecentContact?: number;
  };
  messages: Array<{
    channel: CampaignChannel;
    templateId: string;
    variant?: string;
    delayHours?: number;
  }>;
}): Promise<Campaign> {
  return predictiveApi.fetch<Campaign>('/predictive/campaigns', {
    method: 'POST',
    body: JSON.stringify(input),
  });
}

export async function updateCampaign(id: string, updates: Partial<Campaign>): Promise<Campaign> {
  return predictiveApi.fetch<Campaign>(`/predictive/campaigns/${id}`, {
    method: 'PATCH',
    body: JSON.stringify(updates),
  });
}

export async function getCampaignStats(id: string): Promise<Campaign['stats']> {
  return predictiveApi.fetch<Campaign['stats']>(`/predictive/campaigns/${id}/stats`);
}

export async function triggerCampaign(id: string, testUserId?: string): Promise<{ triggered: number }> {
  return predictiveApi.fetch<{ triggered: number }>(`/predictive/campaigns/${id}/trigger`, {
    method: 'POST',
    body: JSON.stringify(testUserId ? { testUserId } : {}),
  });
}