import {
  Experiment,
  ExperimentCreateInput,
  ExperimentListItem,
  ActiveExperiment,
  ExperimentType,
  ExperimentStatus,
} from '../types';
import { CombinedKPIs } from '../types';

const API_BASE = '/api/experiments';

// ============ Helper Functions ============

export const getExperimentAsins = (experimentAsins: string[], salesData: CombinedKPIs[]): Set<string> => {
  const explicitAsins = new Set<string>();
  const lines = new Set<string>();

  (experimentAsins || []).forEach(a => {
    const val = (a || '').trim().toUpperCase();
    if (val.startsWith('LINE:')) {
      lines.add(val.substring(5).trim());
    } else if (val) {
      explicitAsins.add(val);
    }
  });

  const asinSet = new Set<string>(explicitAsins);
  if (lines.size > 0 && salesData) {
    salesData.forEach(r => {
      const line = (r.line || '').trim().toUpperCase();
      if (line && lines.has(line)) {
        if (r.asin) asinSet.add(r.asin.toUpperCase());
      }
    });
  }

  return asinSet;
};

// ============ CRUD Operations ============

export const createExperiment = async (input: ExperimentCreateInput): Promise<Experiment> => {
  const response = await fetch(API_BASE, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(input),
  });

  if (!response.ok) {
    const error = await response.json();
    throw new Error(error.error || 'Failed to create experiment');
  }

  return response.json();
};

export const updateExperiment = async (
  id: string,
  updates: Partial<Experiment>
): Promise<Experiment> => {
  const response = await fetch(`${API_BASE}?id=${id}`, {
    method: 'PUT',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(updates),
  });

  if (!response.ok) {
    const error = await response.json();
    throw new Error(error.error || 'Failed to update experiment');
  }

  return response.json();
};

export const deleteExperiment = async (id: string): Promise<void> => {
  const response = await fetch(`${API_BASE}?id=${id}`, {
    method: 'DELETE',
  });

  if (!response.ok) {
    const error = await response.json();
    throw new Error(error.error || 'Failed to delete experiment');
  }
};

export const getExperiment = async (id: string): Promise<Experiment | null> => {
  const response = await fetch(`${API_BASE}?id=${id}`);

  if (!response.ok) return null;

  return response.json();
};

export const listExperiments = async (
  filters?: {
    status?: ExperimentStatus[];
    type?: ExperimentType[];
    marketplace?: string[];
    asin?: string;
    dateFrom?: string;
    dateTo?: string;
  }
): Promise<ExperimentListItem[]> => {
  const params = new URLSearchParams();

  if (filters?.status?.length) {
    filters.status.forEach(s => params.append('status', s));
  }
  if (filters?.type?.length) {
    filters.type.forEach(t => params.append('type', t));
  }
  if (filters?.marketplace?.length) {
    filters.marketplace.forEach(m => params.append('marketplace', m));
  }
  if (filters?.asin) {
    params.append('asin', filters.asin);
  }
  if (filters?.dateFrom) {
    params.append('dateFrom', filters.dateFrom);
  }
  if (filters?.dateTo) {
    params.append('dateTo', filters.dateTo);
  }

  const response = await fetch(`${API_BASE}?${params.toString()}`);

  if (!response.ok) {
    const error = await response.json();
    throw new Error(error.error || 'Failed to list experiments');
  }

  const data = await response.json();

  // Transform to ExperimentListItem
  return data.map((exp: any) => {
    const today = new Date();
    const startDate = new Date(exp.start_date);
    const endDate = exp.end_date ? new Date(exp.end_date) : null;

    let progressPercent = 0;
    if (endDate) {
      const totalDays = endDate.getTime() - startDate.getTime();
      const elapsedDays = today.getTime() - startDate.getTime();
      progressPercent = Math.min(100, Math.max(0, (elapsedDays / totalDays) * 100));
    }

    return {
      id: exp.id,
      name: exp.name,
      type: exp.type,
      status: exp.status,
      asin_count: exp.asins?.length || 0,
      asins: exp.asins || [],
      marketplace: exp.marketplace,
      start_date: exp.start_date,
      end_date: exp.end_date,
      progress_percent: Math.round(progressPercent),
      primary_metric: exp.primary_metric,
      actual_lift_percent: exp.actual_lift_percent,
      owner: exp.owner,
    };
  });
};

export const getActiveExperiments = async (
  salesData: CombinedKPIs[]
): Promise<Map<string, ActiveExperiment[]>> => {
  const response = await fetch(`${API_BASE}?status=active`);

  if (!response.ok) {
    const error = await response.json();
    throw new Error(error.error || 'Failed to fetch active experiments');
  }

  const data = await response.json();
  const today = new Date().toISOString().split('T')[0];

  // Filter experiments that are currently active
  const activeExperiments = data.filter((exp: any) =>
    exp.status === 'active' &&
    exp.start_date <= today &&
    (!exp.end_date || exp.end_date >= today)
  );

  const map = new Map<string, ActiveExperiment[]>();

  for (const exp of activeExperiments) {
    const expAsins = getExperimentAsins(exp.asins || [], salesData);

    const endDate = exp.end_date ? new Date(exp.end_date) : null;
    const daysRemaining = endDate
      ? Math.ceil((endDate.getTime() - new Date().getTime()) / (1000 * 60 * 60 * 24))
      : undefined;

    const activeExp: ActiveExperiment = {
      asin: '', // placeholder
      experiment_id: exp.id,
      experiment_name: exp.name,
      type: exp.type,
      status: exp.status,
      start_date: exp.start_date,
      end_date: exp.end_date,
      days_remaining: daysRemaining,
    };

    expAsins.forEach(asin => {
      const asinList = map.get(asin) || [];
      asinList.push({ ...activeExp, asin });
      map.set(asin, asinList);
    });
  }

  return map;
};

// ============ Performance Calculations ============

export const calculateExperimentPerformance = async (
  experiment: Experiment,
  salesData: CombinedKPIs[]
): Promise<{
  baseline_units: number;
  baseline_revenue: number;
  baseline_gv: number;
  baseline_cvr: number;
  baseline_acos: number;
  experiment_units: number;
  experiment_revenue: number;
  experiment_gv: number;
  experiment_cvr: number;
  experiment_acos: number;
  actual_lift_percent: number;
}> => {
  const parseLocalDate = (dateStr: string) => {
    const [y, m, d] = dateStr.split('T')[0].split('-');
    return new Date(Number(y), Number(m) - 1, Number(d));
  };

  const startDate = parseLocalDate(experiment.start_date);
  const endDate = experiment.end_date ? parseLocalDate(experiment.end_date) : new Date();

  // Calculate baseline period (same duration before experiment)
  const durationMs = endDate.getTime() - startDate.getTime();
  const baselineStart = new Date(startDate.getTime() - durationMs);
  const baselineEnd = startDate;

  // Filter sales data for experiment ASINs
  const asinSet = getExperimentAsins(experiment.asins, salesData);

  const baselineData = salesData.filter(r => {
    const recordDate = new Date(r.year, 0, 1 + (r.week - 1) * 7);
    return asinSet.has(r.asin.toUpperCase()) &&
      recordDate >= baselineStart && recordDate < baselineEnd;
  });

  const experimentData = salesData.filter(r => {
    const recordDate = new Date(r.year, 0, 1 + (r.week - 1) * 7);
    return asinSet.has(r.asin.toUpperCase()) &&
      recordDate >= startDate && recordDate <= endDate;
  });

  const baseline_units = baselineData.reduce((sum, r) => sum + r.unitsTotal, 0);
  const baseline_revenue = baselineData.reduce((sum, r) => sum + r.salesTotal, 0);
  const baseline_gv = baselineData.reduce((sum, r) => sum + (r.glanceViews || 0), 0);
  const baseline_cvr = baseline_gv > 0 ? (baseline_units / baseline_gv) * 100 : 0;
  const baseline_spend = baselineData.reduce((sum, r) => sum + (r.cost || 0), 0);
  const baseline_acos = baseline_revenue > 0 ? (baseline_spend / baseline_revenue) * 100 : 0;

  const experiment_units = experimentData.reduce((sum, r) => sum + r.unitsTotal, 0);
  const experiment_revenue = experimentData.reduce((sum, r) => sum + r.salesTotal, 0);
  const experiment_gv = experimentData.reduce((sum, r) => sum + (r.glanceViews || 0), 0);
  const experiment_cvr = experiment_gv > 0 ? (experiment_units / experiment_gv) * 100 : 0;
  const experiment_spend = experimentData.reduce((sum, r) => sum + (r.cost || 0), 0);
  const experiment_acos = experiment_revenue > 0 ? (experiment_spend / experiment_revenue) * 100 : 0;

  let actual_lift_percent = 0;
  if (experiment.primary_metric === 'cvr' && baseline_cvr > 0) {
    actual_lift_percent = ((experiment_cvr - baseline_cvr) / baseline_cvr) * 100;
  } else if (experiment.primary_metric === 'revenue' && baseline_revenue > 0) {
    actual_lift_percent = ((experiment_revenue - baseline_revenue) / baseline_revenue) * 100;
  } else if (experiment.primary_metric === 'acos' && baseline_acos > 0) {
    actual_lift_percent = ((baseline_acos - experiment_acos) / Math.max(0.1, baseline_acos)) * 100; // inverted, lower is better
  } else if (baseline_units > 0) {
    actual_lift_percent = ((experiment_units - baseline_units) / baseline_units) * 100;
  }

  return {
    baseline_units,
    baseline_revenue,
    baseline_gv,
    baseline_cvr: Math.round(baseline_cvr * 10) / 10,
    baseline_acos: Math.round(baseline_acos * 10) / 10,
    experiment_units,
    experiment_revenue,
    experiment_gv,
    experiment_cvr: Math.round(experiment_cvr * 10) / 10,
    experiment_acos: Math.round(experiment_acos * 10) / 10,
    actual_lift_percent: Math.round(actual_lift_percent * 10) / 10,
  };
};

export const updateExperimentResults = async (
  experimentId: string,
  salesData: CombinedKPIs[]
): Promise<Experiment> => {
  const experiment = await getExperiment(experimentId);
  if (!experiment) throw new Error('Experiment not found');

  const performance = await calculateExperimentPerformance(experiment, salesData);

  return updateExperiment(experimentId, {
    ...performance,
  });
};

// ============ Helper Functions ============

function getMonthNumber(monthStr: string): number {
  const months: Record<string, number> = {
    'Jan': 1, 'Feb': 2, 'Mar': 3, 'Apr': 4, 'May': 5, 'Jun': 6,
    'Jul': 7, 'Aug': 8, 'Sep': 9, 'Oct': 10, 'Nov': 11, 'Dec': 12
  };
  return months[monthStr.split('-')[0]] || 1;
}

export const getExperimentStatusColor = (status: ExperimentStatus): string => {
  switch (status) {
    case 'active': return 'bg-emerald-500/20 text-emerald-400 border-emerald-500/30';
    case 'planned': return 'bg-amber-500/20 text-amber-400 border-amber-500/30';
    case 'completed': return 'bg-slate-500/20 text-slate-400 border-slate-500/30';
    case 'paused': return 'bg-red-500/20 text-red-400 border-red-500/30';
    default: return 'bg-slate-500/20 text-slate-400';
  }
};

export const getExperimentTypeColor = (type: ExperimentType): string => {
  switch (type) {
    case 'pricing': return 'bg-blue-500/20 text-blue-400 border-blue-500/30';
    case 'advertising': return 'bg-purple-500/20 text-purple-400 border-purple-500/30';
    case 'content': return 'bg-pink-500/20 text-pink-400 border-pink-500/30';
    case 'promotion': return 'bg-orange-500/20 text-orange-400 border-orange-500/30';
    default: return 'bg-slate-500/20 text-slate-400';
  }
};

export const getExperimentIcon = (type: ExperimentType): string => {
  switch (type) {
    case 'pricing': return '💰';
    case 'advertising': return '📢';
    case 'content': return '📝';
    case 'promotion': return '🏷️';
    default: return '🧪';
  }
};