import React, { useState, useMemo } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { useForm } from 'react-hook-form';
import { zodResolver } from '@hookform/resolvers/zod';
import { z } from 'zod';
import {
  Target,
  Plus,
  TrendingUp,
  X,
  RotateCcw,
  AlertTriangle,
  Briefcase,
  Filter,
  Info,
  ShieldCheck,
  Coins,
} from 'lucide-react';
import { Modal } from '../ui/Modal';
import { HelpTooltip } from '../ui/HelpTooltip';
import { useToast } from '../ui/Toast';
import {
  getProjectIndicators,
  createIndicator,
  getActivities,
} from '../../services/api';
import { Project, Indicator, UnitOfMeasure, Activity } from '../../types';
import { getUnitOfMeasureLabel, UNIT_OF_MEASURE_OPTIONS, formatZAR } from '../../lib/formatters';

const indicatorSchema = z.object({
  name: z.string().min(4, 'Indicator delivery specification required (min 4 chars)'),
  activityId: z.string().optional().nullable(),
  unitOfMeasure: z.coerce.number().min(1),
  baselineAmount: z.coerce.number().min(0, 'Baseline must be >= 0'),
  targetAmount: z.coerce.number().min(1, 'Target must be > 0'),
  targetCost: z.coerce.number().min(0, 'Target cost must be >= 0').optional(),
});

type IndicatorFormValues = z.infer<typeof indicatorSchema>;

interface ProjectIndicatorsModalProps {
  isOpen: boolean;
  onClose: () => void;
  project: Project | null;
  initialActivityId?: string | number | null;
}

export const ProjectIndicatorsModal: React.FC<ProjectIndicatorsModalProps> = ({
  isOpen,
  onClose,
  project,
  initialActivityId = null,
}) => {
  const queryClient = useQueryClient();
  const { success, error: toastError } = useToast();

  const [isFormOpen, setIsFormOpen] = useState(false);
  const [selectedActivityFilter, setSelectedActivityFilter] = useState<string>('all');

  const projectId = project?.id;

  const {
    data: indicators = [],
    isLoading: isLoadingIndicators,
    refetch,
  } = useQuery({
    queryKey: ['indicators', projectId],
    queryFn: () => (projectId ? getProjectIndicators(projectId) : Promise.resolve([])),
    enabled: isOpen && !!projectId,
  });

  const {
    data: activities = [],
    isLoading: isLoadingActivities,
  } = useQuery({
    queryKey: ['activities', projectId],
    queryFn: () => (projectId ? getActivities(projectId) : Promise.resolve([])),
    enabled: isOpen && !!projectId,
  });

  const form = useForm<IndicatorFormValues>({
    resolver: zodResolver(indicatorSchema),
    defaultValues: {
      name: '',
      activityId: initialActivityId ? String(initialActivityId) : '',
      unitOfMeasure: UnitOfMeasure.Count,
      baselineAmount: 0,
      targetAmount: 100,
      targetCost: 0,
    },
  });

  const createMutation = useMutation({
    mutationFn: async (data: IndicatorFormValues) => {
      if (!projectId) return;
      const parsedActivityId = data.activityId && String(data.activityId).trim() !== ''
        ? data.activityId
        : null;

      return createIndicator({
        projectId: projectId,
        activityId: parsedActivityId,
        name: data.name,
        unitOfMeasure: Number(data.unitOfMeasure),
        baselineAmount: Number(data.baselineAmount),
        targetAmount: Number(data.targetAmount),
        targetCost: Number(data.targetCost) || 0,
      });
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['indicators', projectId] });
      queryClient.invalidateQueries({ queryKey: ['indicators'] });
      queryClient.invalidateQueries({ queryKey: ['activities', projectId] });
      success('Delivery Indicator Created', 'Indicator specification linked to work activity');
      setIsFormOpen(false);
      form.reset();
    },
    onError: (err: unknown) => {
      toastError('Failed to create indicator', err);
    },
  });

  // Filter indicators by activity
  const filteredIndicators = useMemo(() => {
    if (selectedActivityFilter === 'all') return indicators;
    if (selectedActivityFilter === 'unlinked') return indicators.filter((i) => !i.activityId);
    return indicators.filter((i) => String(i.activityId) === String(selectedActivityFilter));
  }, [indicators, selectedActivityFilter]);

  // Aggregate totals
  const totalTargetCost = useMemo(
    () => indicators.reduce((sum, i) => sum + (Number(i.targetCost) || 0), 0),
    [indicators]
  );
  const totalActualCost = useMemo(
    () => indicators.reduce((sum, i) => sum + (Number(i.actualCost) || 0), 0),
    [indicators]
  );

  if (!project) return null;

  return (
    <Modal
      isOpen={isOpen}
      onClose={() => {
        setIsFormOpen(false);
        onClose();
      }}
      title={`M&E Delivery Indicators: ${project.name}`}
      subtitle={`Project #${project.id} • Activity Delivery Specifications & Evidence Requirements`}
      helpText="Each indicator specifies an expected delivery output linked to an operational activity. Quantities and material costs are captured as actuals by the partner in the Partner Portal."
      maxWidth="xl"
    >
      <div className="space-y-5">
        {/* KPI Summary Cards */}
        <div className="grid grid-cols-1 sm:grid-cols-3 gap-3">
          <div className="bg-[#0b101c] p-3.5 rounded-xl border border-slate-800">
            <span className="text-[10px] uppercase font-bold text-slate-400 flex items-center gap-1.5">
              <Target className="w-3.5 h-3.5 text-indigo-400" />
              Delivery Indicators
            </span>
            <div className="flex items-baseline gap-2 mt-1">
              <span className="text-xl font-bold text-white font-mono">{indicators.length}</span>
              <span className="text-[11px] text-slate-400">specifications</span>
            </div>
          </div>

          <div className="bg-[#0b101c] p-3.5 rounded-xl border border-slate-800">
            <span className="text-[10px] uppercase font-bold text-slate-400 flex items-center gap-1.5">
              <Coins className="w-3.5 h-3.5 text-cyan-400" />
              Target Delivery Cost
            </span>
            <div className="flex items-baseline gap-2 mt-1">
              <span className="text-xl font-bold font-mono text-cyan-400">{formatZAR(totalTargetCost)}</span>
            </div>
          </div>

          <div className="bg-[#0b101c] p-3.5 rounded-xl border border-slate-800">
            <span className="text-[10px] uppercase font-bold text-slate-400 flex items-center gap-1.5">
              <TrendingUp className="w-3.5 h-3.5 text-emerald-400" />
              Partner Actuals Incurred
            </span>
            <div className="flex items-baseline gap-2 mt-1">
              <span className={`text-xl font-bold font-mono ${totalActualCost > totalTargetCost && totalTargetCost > 0 ? 'text-amber-400' : 'text-emerald-400'}`}>
                {formatZAR(totalActualCost)}
              </span>
            </div>
          </div>
        </div>

        {/* Action Header & Activity Filter Bar */}
        <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-3 bg-[#0d121f] p-3 rounded-xl border border-slate-800">
          <div className="flex items-center gap-2 flex-1">
            <Filter className="w-3.5 h-3.5 text-slate-400 shrink-0" />
            <span className="text-xs text-slate-400 shrink-0">Filter by Activity:</span>
            <select
              value={selectedActivityFilter}
              onChange={(e) => setSelectedActivityFilter(e.target.value)}
              className="px-2.5 py-1 text-xs border border-slate-700/80 rounded-lg focus:outline-none focus:ring-1 focus:ring-indigo-500 bg-[#090d16] text-white max-w-xs truncate"
            >
              <option value="all">All Activities ({indicators.length})</option>
              {activities.map((act) => {
                const count = indicators.filter((i) => String(i.activityId) === String(act.id)).length;
                return (
                  <option key={act.id} value={String(act.id)}>
                    {act.title} ({count} indicators)
                  </option>
                );
              })}
              <option value="unlinked">Unlinked General Indicators</option>
            </select>
          </div>

          <div className="flex items-center gap-2">
            {!isFormOpen && (
              <button
                type="button"
                onClick={() => {
                  form.reset({
                    name: '',
                    activityId: selectedActivityFilter !== 'all' && selectedActivityFilter !== 'unlinked' ? selectedActivityFilter : '',
                    unitOfMeasure: UnitOfMeasure.Count,
                    baselineAmount: 0,
                    targetAmount: 100,
                    targetCost: 0,
                  });
                  setIsFormOpen(true);
                }}
                className="inline-flex items-center gap-1.5 px-3.5 py-2 text-xs font-semibold text-white bg-gradient-to-r from-indigo-600 to-blue-600 hover:from-indigo-500 hover:to-blue-500 rounded-xl shadow-md shadow-indigo-600/20 transition cursor-pointer"
              >
                <Plus className="w-3.5 h-3.5" />
                Add Indicator
              </button>
            )}
          </div>
        </div>

        {/* Indicator Create Form */}
        {isFormOpen && (
          <div className="bg-[#0d121f] p-4 rounded-xl border border-indigo-500/30 space-y-4 animate-in fade-in">
            <div className="flex items-center justify-between border-b border-slate-800 pb-2.5">
              <span className="text-xs font-bold text-indigo-400 flex items-center gap-1.5">
                <Target className="w-3.5 h-3.5" />
                Define Activity Delivery Indicator & Evidence Expectation
              </span>
              <button
                type="button"
                onClick={() => setIsFormOpen(false)}
                className="text-slate-400 hover:text-slate-200 text-xs p-1"
              >
                <X className="w-4 h-4" />
              </button>
            </div>

            <form onSubmit={form.handleSubmit((data) => createMutation.mutate(data))} className="space-y-3">
              <div>
                <label className="block text-xs font-semibold text-slate-300 mb-1">
                  Indicator Name / Delivery Output Specification *
                </label>
                <input
                  type="text"
                  {...form.register('name')}
                  className="w-full px-3 py-2 text-xs border border-slate-700/80 rounded-xl focus:outline-none focus:ring-1 focus:ring-indigo-500 text-white bg-[#090d16]"
                  placeholder="e.g. Number of solar microgrids commissioned and tested"
                />
                {form.formState.errors.name && (
                  <p className="text-[10px] text-rose-500 mt-1">{form.formState.errors.name.message}</p>
                )}
              </div>

              <div>
                <label className="block text-xs font-semibold text-slate-300 mb-1">
                  Parent Activity (Required Delivery Link) *
                </label>
                <select
                  {...form.register('activityId')}
                  className="w-full px-3 py-2 text-xs border border-slate-700/80 rounded-xl focus:outline-none focus:ring-1 focus:ring-indigo-500 bg-[#090d16] text-white font-medium"
                >
                  <option value="">-- Select Parent Activity --</option>
                  {activities.map((act) => (
                    <option key={act.id} value={String(act.id)}>
                      {act.title} (Budget: {formatZAR(act.amount)})
                    </option>
                  ))}
                </select>
                <p className="text-[10px] text-slate-500 mt-1">
                  Linking to an activity establishes the causal delivery chain from planned task to substantiated output.
                </p>
              </div>

              <div className="grid grid-cols-1 sm:grid-cols-2 gap-3">
                <div>
                  <label className="block text-xs font-semibold text-slate-300 mb-1">Unit of Measure *</label>
                  <select
                    {...form.register('unitOfMeasure')}
                    className="w-full px-3 py-2 text-xs border border-slate-700/80 rounded-xl focus:outline-none focus:ring-1 focus:ring-indigo-500 bg-[#090d16] text-white font-medium"
                  >
                    {UNIT_OF_MEASURE_OPTIONS.map((opt) => (
                      <option key={opt.value} value={opt.value}>
                        {opt.label}
                      </option>
                    ))}
                  </select>
                </div>

                <div>
                  <label className="block text-xs font-semibold text-slate-300 mb-1">
                    Expected Delivery Cost (Target Cost ZAR)
                  </label>
                  <input
                    type="number"
                    step="0.01"
                    {...form.register('targetCost')}
                    className="w-full px-3 py-2 text-xs border border-slate-700/80 rounded-xl focus:outline-none focus:ring-1 focus:ring-indigo-500 text-white font-mono bg-[#090d16]"
                    placeholder="0.00"
                  />
                  <p className="text-[10px] text-slate-500 mt-1">Estimated monetary cost for delivering this indicator.</p>
                </div>
              </div>

              <div className="grid grid-cols-1 sm:grid-cols-2 gap-3">
                <div>
                  <label className="block text-xs font-semibold text-slate-300 mb-1">Baseline Metric *</label>
                  <input
                    type="number"
                    step="any"
                    {...form.register('baselineAmount')}
                    className="w-full px-3 py-2 text-xs border border-slate-700/80 rounded-xl focus:outline-none focus:ring-1 focus:ring-indigo-500 text-white font-mono bg-[#090d16]"
                  />
                </div>

                <div>
                  <label className="block text-xs font-semibold text-slate-300 mb-1">Target Metric *</label>
                  <input
                    type="number"
                    step="any"
                    {...form.register('targetAmount')}
                    className="w-full px-3 py-2 text-xs border border-slate-700/80 rounded-xl focus:outline-none focus:ring-1 focus:ring-indigo-500 text-white font-mono bg-[#090d16]"
                  />
                </div>
              </div>

              <div className="flex items-center justify-end gap-2 pt-2 border-t border-slate-800">
                <button
                  type="button"
                  onClick={() => setIsFormOpen(false)}
                  className="px-3 py-1.5 text-xs font-semibold text-slate-300 bg-slate-800 hover:bg-slate-700 rounded-xl cursor-pointer"
                >
                  Cancel
                </button>
                <button
                  type="submit"
                  disabled={createMutation.isPending}
                  className="px-4 py-1.5 text-xs font-semibold text-white bg-gradient-to-r from-indigo-600 to-blue-600 hover:from-indigo-500 hover:to-blue-500 rounded-xl shadow-md shadow-indigo-500/20 cursor-pointer"
                >
                  {createMutation.isPending ? 'Saving...' : 'Define Indicator'}
                </button>
              </div>
            </form>
          </div>
        )}

        {/* Notice Card Explaining Partner Action */}
        <div className="bg-slate-900/60 p-3 rounded-xl border border-slate-800 flex items-start gap-2.5 text-slate-400 text-[11px] leading-relaxed">
          <Info className="w-4 h-4 text-cyan-400 shrink-0 mt-0.5" />
          <div>
            <strong className="text-slate-200">Maker-Checker Operational Notice:</strong> ConsoleUI enables Project Managers to establish output specifications and expected delivery costs. Actual item quantities, material expenditures, and verification evidence documents are recorded by the Grantee/Partner via the <strong className="text-cyan-400 font-mono">PartnerUI Portal</strong>.
          </div>
        </div>

        {/* Indicators List */}
        <div className="space-y-2.5">
          <div className="flex items-center justify-between text-xs font-semibold text-slate-400 px-1">
            <span>
              Defined Delivery Specifications ({filteredIndicators.length} of {indicators.length})
            </span>
            <button
              type="button"
              onClick={() => refetch()}
              className="text-[11px] text-slate-400 hover:text-white flex items-center gap-1 cursor-pointer"
            >
              <RotateCcw className="w-3 h-3" /> Refresh
            </button>
          </div>

          {isLoadingIndicators || isLoadingActivities ? (
            <div className="p-8 text-center text-xs text-slate-400 bg-[#0b101c] rounded-xl border border-slate-800">
              Loading indicators...
            </div>
          ) : filteredIndicators.length === 0 ? (
            <div className="p-8 text-center bg-[#0b101c] rounded-xl border border-dashed border-slate-800 text-slate-400 space-y-2">
              <Target className="w-8 h-8 text-slate-600 mx-auto" />
              <p className="text-xs font-semibold text-slate-300">No indicators matching selection</p>
              <p className="text-[11px] text-slate-500">
                Define delivery output specifications and link them to operational activities.
              </p>
              <button
                type="button"
                onClick={() => setIsFormOpen(true)}
                className="mt-2 inline-flex items-center gap-1 text-xs font-semibold text-indigo-400 hover:underline"
              >
                <Plus className="w-3.5 h-3.5" /> Define first indicator
              </button>
            </div>
          ) : (
            <div className="space-y-3 max-h-[420px] overflow-y-auto pr-1">
              {filteredIndicators.map((ind) => {
                const target = Number(ind.targetAmount) || 1;
                const actual = Number(ind.actualAmount) || 0;
                const baseline = Number(ind.baselineAmount) || 0;
                const targetCost = Number(ind.targetCost) || 0;
                const actualCost = Number(ind.actualCost) || 0;
                const pct = Math.round((actual / target) * 100);

                const parentActivity = activities.find((a) => String(a.id) === String(ind.activityId));
                const isOverrun = (actualCost > targetCost && targetCost > 0) || (parentActivity && actualCost > parentActivity.amount);

                return (
                  <div
                    key={ind.id}
                    className={`p-4 rounded-xl border bg-[#0d121f] transition space-y-3 ${
                      isOverrun ? 'border-amber-500/40 bg-amber-950/10' : 'border-slate-800 hover:border-slate-700'
                    }`}
                  >
                    <div className="flex flex-col sm:flex-row sm:items-start justify-between gap-2">
                      <div className="space-y-1">
                        <div className="flex items-center gap-2 flex-wrap">
                          <span className="text-xs font-bold text-white">{ind.name}</span>
                          <span className="bg-slate-900 border border-slate-700 text-slate-300 px-2 py-0.5 rounded-md text-[10px]">
                            {getUnitOfMeasureLabel(ind.unitOfMeasure)}
                          </span>
                          {parentActivity ? (
                            <span className="bg-cyan-500/10 border border-cyan-500/30 text-cyan-300 px-2 py-0.5 rounded-md text-[10px] flex items-center gap-1">
                              <Briefcase className="w-2.5 h-2.5" />
                              {parentActivity.title}
                            </span>
                          ) : (
                            <span className="bg-slate-800 text-slate-400 px-2 py-0.5 rounded-md text-[10px]">
                              General Project Indicator
                            </span>
                          )}
                        </div>
                        <div className="text-[10px] text-slate-500 font-mono">
                          Indicator ID #{ind.id}
                          {ind.activityId && ` • Activity #${ind.activityId}`}
                        </div>
                      </div>

                      <div className="flex items-center gap-2 shrink-0">
                        {isOverrun && (
                          <span className="inline-flex items-center gap-1 px-2 py-0.5 rounded-md bg-rose-500/10 text-rose-400 border border-rose-500/30 text-[10px] font-bold">
                            <AlertTriangle className="w-3 h-3 text-rose-400" />
                            Cost Overrun
                          </span>
                        )}

                        <span
                          className={`text-xs font-bold px-2 py-0.5 rounded-md border ${
                            pct >= 100
                              ? 'bg-emerald-500/10 text-emerald-400 border-emerald-500/30'
                              : pct >= 50
                              ? 'bg-blue-500/10 text-blue-400 border-blue-500/30'
                              : 'bg-amber-500/10 text-amber-400 border-amber-500/30'
                          }`}
                        >
                          {pct}% Delivered
                        </span>

                        <span
                          className="inline-flex items-center gap-1 text-[10px] text-slate-400 bg-slate-900/90 border border-slate-700/80 px-2 py-0.5 rounded-md"
                          title="Actuals are recorded by the partner in PartnerUI"
                        >
                          <ShieldCheck className="w-3 h-3 text-cyan-400" />
                          Partner Verified
                        </span>
                      </div>
                    </div>

                    {/* Deliverable Units Progress Bar */}
                    <div className="space-y-1">
                      <div className="w-full h-2 bg-slate-900 rounded-full overflow-hidden border border-slate-800">
                        <div
                          className={`h-full rounded-full transition-all duration-300 ${
                            pct >= 100
                              ? 'bg-emerald-500'
                              : pct >= 50
                              ? 'bg-gradient-to-r from-blue-500 to-indigo-500'
                              : 'bg-amber-500'
                          }`}
                          style={{ width: `${Math.min(100, Math.max(0, pct))}%` }}
                        />
                      </div>
                      <div className="flex justify-between text-[11px] text-slate-400">
                        <span>
                          Baseline: <strong className="text-slate-300 font-mono">{baseline}</strong>
                        </span>
                        <span>
                          Partner Actuals Reported:{' '}
                          <strong className="text-white font-mono font-bold">{actual}</strong>
                        </span>
                        <span>
                          Target: <strong className="text-indigo-400 font-mono">{target}</strong>
                        </span>
                      </div>
                    </div>

                    {/* Financial Cost Specification & Actuals Row */}
                    <div className="pt-2 border-t border-slate-800/80 flex flex-col sm:flex-row sm:items-center justify-between gap-2 text-xs">
                      <div className="flex items-center gap-4 text-slate-400 text-[11px]">
                        <span>
                          Target Cost: <strong className="text-cyan-400 font-mono">{formatZAR(targetCost)}</strong>
                        </span>
                        <span>
                          Actual Material Cost:{' '}
                          <strong className={`font-mono font-bold ${actualCost > targetCost && targetCost > 0 ? 'text-amber-400' : 'text-white'}`}>
                            {formatZAR(actualCost)}
                          </strong>
                        </span>
                        {targetCost > 0 && (
                          <span className="text-slate-500">
                            Variance: {formatZAR(targetCost - actualCost)}
                          </span>
                        )}
                      </div>

                      {isOverrun && (
                        <div className="text-[10px] text-amber-300 bg-amber-500/10 px-2 py-0.5 rounded border border-amber-500/20">
                          Cost exceeds delivery allocation; subject to project variation approval (M15).
                        </div>
                      )}
                    </div>
                  </div>
                );
              })}
            </div>
          )}
        </div>
      </div>
    </Modal>
  );
};