import { useEffect, useState } from 'react'
import { useParams, useNavigate } from 'react-router-dom'
import { Wrench, Calendar, Play, Settings, Clock, CheckCircle, AlertCircle } from 'lucide-react'
import { treesApi } from '@/api/trees'
import { sessionsApi } from '@/api/sessions'
import { maintenanceSchedulesApi } from '@/api/maintenanceSchedules'
import { BatchLaunchModal } from '@/components/maintenance/BatchLaunchModal'
import { ActiveBatchBanner } from '@/components/maintenance/ActiveBatchBanner'
import { Spinner } from '@/components/common/Spinner'
import { EmptyState } from '@/components/common/EmptyState'
import { PageHeader } from '@/components/common/PageHeader'
import { toast } from '@/lib/toast'
import { cn } from '@/lib/utils'
import type { Tree, MaintenanceSchedule, Session } from '@/types'

const OUTCOME_LABELS: Record<string, string> = {
  resolved: 'resolved',
  escalated: 'escalated',
  workaround: 'workaround',
  unresolved: 'unresolved',
}

export default function MaintenanceFlowDetailPage() {
  const { id } = useParams<{ id: string }>()
  const navigate = useNavigate()
  const [tree, setTree] = useState<Tree | null>(null)
  const [schedule, setSchedule] = useState<MaintenanceSchedule | null>(null)
  const [recentSessions, setRecentSessions] = useState<Session[]>([])
  const [showBatchModal, setShowBatchModal] = useState(false)
  const [isLoading, setIsLoading] = useState(true)
  const [isRunning, setIsRunning] = useState(false)
  const [bannerDismissed, setBannerDismissed] = useState(false)

  useEffect(() => {
    if (!id) return
    const load = async () => {
      try {
        const treeData = await treesApi.get(id)
        if (treeData.tree_type !== 'maintenance') {
          toast.error('This page is only for maintenance flows')
          navigate('/trees?type=maintenance')
          return
        }
        setTree(treeData)

        try {
          const sessionData = await sessionsApi.list({ tree_id: id, size: 30 })
          setRecentSessions(Array.isArray(sessionData) ? sessionData : [])
        } catch {
          // Sessions load is optional
        }

        try {
          const sched = await maintenanceSchedulesApi.getForTree(id)
          setSchedule(sched)
        } catch {
          // No schedule yet is fine
        }
      } catch {
        toast.error('Failed to load maintenance flow')
        navigate('/trees?type=maintenance')
      } finally {
        setIsLoading(false)
      }
    }
    load()
  }, [id, navigate])

  const handleLaunched = (batchId: string, _count: number) => {
    setShowBatchModal(false)
    setBannerDismissed(false)
    // Reload sessions so banner picks up the new batch
    if (id) {
      sessionsApi.list({ tree_id: id, size: 30 })
        .then(data => setRecentSessions(Array.isArray(data) ? data : []))
        .catch(() => {})
    }
    navigate(`/flows/${id}/batches/${batchId}`)
  }

  const handleRun = () => {
    setIsRunning(true)
    navigate(`/flows/${id}/navigate`)
  }

  if (isLoading) {
    return (
      <div className="flex h-64 items-center justify-center">
        <Spinner size="sm" className="h-6 w-6 border-primary border-t-transparent" />
      </div>
    )
  }

  if (!tree) {
    return (
      <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
        <EmptyState
          title="Maintenance flow not found"
          description="This flow is unavailable or you do not have access."
          action={(
            <button
              onClick={() => navigate('/trees?type=maintenance')}
              className="rounded-md border border-border px-4 py-2 text-sm text-muted-foreground hover:bg-accent hover:text-foreground"
            >
              Back to Maintenance Flows
            </button>
          )}
        />
      </div>
    )
  }

  // Group sessions by batch_id for run history
  const batchMap = new Map<string, Session[]>()
  for (const s of recentSessions) {
    const key = s.batch_id ?? s.id
    const existing = batchMap.get(key) ?? []
    batchMap.set(key, [...existing, s])
  }
  const batches = Array.from(batchMap.entries()).slice(0, 10)

  // Show banner only if there are in-progress batch sessions and it hasn't been dismissed
  const hasActiveBatch = recentSessions.some(s => s.started_at && !s.completed_at && s.batch_id)

  return (
    <div className="container mx-auto max-w-4xl space-y-6 px-4 py-6 sm:px-6 sm:py-8">
      {/* Active batch banner */}
      {hasActiveBatch && !bannerDismissed && (
        <ActiveBatchBanner
          treeId={id!}
          sessions={recentSessions}
          onDismiss={() => setBannerDismissed(true)}
        />
      )}

      {/* Header */}
      <PageHeader
        title={tree.name}
        description={tree.description || undefined}
        icon={(
          <div className="flex h-10 w-10 items-center justify-center rounded-lg bg-amber-500/10 text-amber-400">
            <Wrench className="h-5 w-5" />
          </div>
        )}
        titleClassName="text-xl font-semibold"
        action={(
          <div className="flex gap-2">
            <button
              onClick={() => navigate(`/flows/${id}/edit`)}
              className="flex items-center gap-1.5 rounded-lg border border-border px-3 py-2 text-[0.875rem] text-muted-foreground hover:bg-accent hover:text-foreground"
            >
              <Settings className="h-3.5 w-3.5" />
              Edit Flow
            </button>
            <button
              onClick={handleRun}
              disabled={isRunning}
              className="flex items-center gap-1.5 rounded-lg bg-gradient-brand px-4 py-2 text-[0.875rem] font-medium text-white shadow-lg shadow-primary/20 hover:opacity-90 disabled:opacity-70"
            >
              {isRunning
                ? <Spinner size="sm" className="h-3.5 w-3.5 border-white border-t-transparent" />
                : <Play className="h-3.5 w-3.5" />}
              Run
            </button>
            <button
              onClick={() => setShowBatchModal(true)}
              className="flex items-center gap-1.5 rounded-lg border border-border px-3 py-2 text-[0.875rem] text-muted-foreground hover:bg-accent hover:text-foreground"
            >
              Batch Launch
            </button>
          </div>
        )}
      />

      {/* Schedule Panel */}
      <div className="rounded-xl border border-border bg-card p-5">
        <div className="flex items-center gap-2 mb-3">
          <Calendar className="h-4 w-4 text-muted-foreground" />
          <h2 className="font-semibold text-foreground">Schedule</h2>
        </div>
        {schedule ? (
          <div className="space-y-2 text-[0.875rem]">
            <div className="flex flex-wrap items-center gap-2">
              <span className={cn(
                "inline-flex items-center gap-1 rounded-full px-2 py-0.5 font-label text-[0.625rem] uppercase tracking-wide",
                schedule.is_active
                  ? "bg-emerald-500/10 text-emerald-400"
                  : "bg-muted text-muted-foreground"
              )}>
                {schedule.is_active
                  ? <CheckCircle className="h-3 w-3" />
                  : <AlertCircle className="h-3 w-3" />}
                {schedule.is_active ? 'Active' : 'Paused'}
              </span>
              <code className="rounded bg-accent px-1.5 py-0.5 text-[0.8125rem] text-foreground">
                {schedule.cron_expression}
              </code>
              <span className="text-muted-foreground">({schedule.timezone})</span>
            </div>
            {schedule.next_run_at && (
              <p className="text-muted-foreground">
                Next run: {new Date(schedule.next_run_at).toLocaleString()}
              </p>
            )}
          </div>
        ) : (
          <p className="text-[0.875rem] text-muted-foreground">
            No schedule configured. Sessions can still be launched manually via Batch Launch.
          </p>
        )}
      </div>

      {/* Run History */}
      <div className="rounded-xl border border-border bg-card p-5">
        <div className="flex items-center gap-2 mb-4">
          <Clock className="h-4 w-4 text-muted-foreground" />
          <h2 className="font-semibold text-foreground">Run History</h2>
        </div>
        {batches.length === 0 ? (
          <p className="text-[0.875rem] text-muted-foreground">No runs yet. Launch a batch to get started.</p>
        ) : (
          <div className="space-y-2">
            {batches.map(([batchKey, batchSessions]) => {
              const completed = batchSessions.filter(s => s.completed_at).length
              const total = batchSessions.length
              const isActive = batchSessions.some(s => s.started_at && !s.completed_at)
              const date = batchSessions[0]?.started_at
              const isSingleRun = !batchSessions[0]?.batch_id

              // Outcome summary
              const outcomeCounts = batchSessions.reduce<Record<string, number>>((acc, s) => {
                if (s.outcome) acc[s.outcome] = (acc[s.outcome] ?? 0) + 1
                return acc
              }, {})
              const outcomeParts = Object.entries(outcomeCounts)
                .map(([k, v]) => `${v} ${OUTCOME_LABELS[k] ?? k}`)

              // Mini progress dots (up to 8 shown)
              const dotsToShow = Math.min(total, 8)
              const dots = Array.from({ length: dotsToShow }, (_, i) => i < completed)
              const extraDots = total > 8 ? total - 8 : 0

              const handleRowClick = () => {
                if (isSingleRun && batchSessions[0]) {
                  navigate(`/sessions/${batchSessions[0].id}`)
                } else {
                  navigate(`/flows/${id}/batches/${batchKey}`)
                }
              }

              return (
                <button
                  key={batchKey}
                  onClick={handleRowClick}
                  className="w-full flex items-center justify-between rounded-lg border border-border px-4 py-3 hover:bg-accent transition-colors text-left"
                >
                  <div>
                    <div className="flex items-center gap-2">
                      {isActive && (
                        <span className="inline-block h-2 w-2 rounded-full bg-amber-400 animate-pulse" />
                      )}
                      <p className="text-[0.875rem] font-medium text-foreground">
                        {isSingleRun ? 'Manual run' : `${total} target${total !== 1 ? 's' : ''}`}
                      </p>
                    </div>
                    <div className="flex items-center gap-2 mt-0.5">
                      {date && (
                        <p className="text-[0.8125rem] text-muted-foreground">
                          {new Date(date).toLocaleDateString()}
                        </p>
                      )}
                      {outcomeParts.length > 0 && (
                        <p className="text-[0.8125rem] text-muted-foreground">
                          · {outcomeParts.join(' · ')}
                        </p>
                      )}
                    </div>
                  </div>
                  <div className="flex items-center gap-2">
                    {!isSingleRun && total > 1 && (
                      <div className="flex items-center gap-0.5">
                        {dots.map((done, i) => (
                          <span
                            key={i}
                            className={cn(
                              'inline-block h-2 w-2 rounded-full',
                              done ? 'bg-emerald-400' : 'bg-muted'
                            )}
                          />
                        ))}
                        {extraDots > 0 && (
                          <span className="ml-1 text-[0.6875rem] text-muted-foreground">+{extraDots}</span>
                        )}
                      </div>
                    )}
                    <span className={cn(
                      "font-label text-[0.75rem] uppercase tracking-wide",
                      isActive ? "text-amber-400" : completed === total ? "text-emerald-400" : "text-muted-foreground"
                    )}>
                      {isActive ? 'In Progress' : `${completed}/${total}`}
                    </span>
                  </div>
                </button>
              )
            })}
          </div>
        )}
      </div>

      {showBatchModal && (
        <BatchLaunchModal
          treeId={id!}
          treeName={tree.name}
          onClose={() => setShowBatchModal(false)}
          onLaunched={handleLaunched}
        />
      )}
    </div>
  )
}