import { useEffect, useState, useCallback } from 'react'
import { useParams, useNavigate, useSearchParams } from 'react-router-dom'
import { Save, ArrowLeft, ListOrdered, Wrench, Settings, FileText, Calendar } from 'lucide-react'
import { treesApi } from '@/api/trees'
import { useProceduralEditorStore } from '@/store/proceduralEditorStore'
import { CollapsibleEditorSection } from '@/components/procedural-editor/CollapsibleEditorSection'
import { IntakeFormBuilder } from '@/components/procedural-editor/IntakeFormBuilder'
import { MaintenanceScheduleSection } from '@/components/procedural-editor/MaintenanceScheduleSection'
import { getScheduleSummary } from '@/components/procedural-editor/scheduleUtils'
import { StepList } from '@/components/procedural-editor/StepList'
import { TagInput } from '@/components/common/TagInput'
import { Spinner } from '@/components/common/Spinner'
import { toast } from '@/lib/toast'
import type { TreeType, MaintenanceSchedule, TargetList } from '@/types'

type SectionKey = 'details' | 'intake' | 'schedule'

export function ProceduralEditorPage() {
  const { id } = useParams<{ id: string }>()
  const [searchParams] = useSearchParams()
  const navigate = useNavigate()
  const isEditMode = !!id

  const {
    treeId,
    treeType,
    name,
    description,
    tags,
    isPublic,
    intakeForm,
    isDirty,
    isSaving,
    isLoading,
    initNew,
    loadTree,
    reset,
    setName,
    setDescription,
    setTags,
    setIsPublic,
    setIsSaving,
    markSaved,
    getTreeForSave,
  } = useProceduralEditorStore()

  const isMaintenance = treeType === 'maintenance'
  const flowLabel = isMaintenance ? 'Maintenance Flow' : 'Procedure'

  // Accordion state: only one section open at a time
  const [expandedSection, setExpandedSection] = useState<SectionKey | null>(
    isEditMode ? null : 'details'
  )

  // Schedule state for collapsed summary
  const [schedule, setSchedule] = useState<MaintenanceSchedule | null>(null)
  const [scheduleTargetList, setScheduleTargetList] = useState<TargetList | null>(null)

  const toggleSection = useCallback((key: SectionKey) => {
    setExpandedSection(prev => prev === key ? null : key)
  }, [])

  const handleScheduleLoaded = useCallback((s: MaintenanceSchedule | null, tl: TargetList | null) => {
    setSchedule(s)
    setScheduleTargetList(tl)
  }, [])

  // Load tree or init new
  useEffect(() => {
    if (isEditMode && id) {
      loadExistingTree(id)
    } else {
      const urlType = searchParams.get('type')
      initNew((urlType === 'maintenance' ? 'maintenance' : 'procedural') as TreeType)
      // New flows: details expanded, or schedule for new maintenance
      setExpandedSection(urlType === 'maintenance' ? 'schedule' : 'details')
    }

    return () => { reset() }
  }, [id])

  const loadExistingTree = async (treeId: string) => {
    try {
      const tree = await treesApi.get(treeId)
      if (tree.tree_type !== 'procedural' && tree.tree_type !== 'maintenance') {
        toast.error('This flow is not a procedural or maintenance flow')
        navigate('/trees')
        return
      }
      loadTree(tree)
    } catch {
      toast.error('Failed to load flow')
      navigate('/trees')
    }
  }

  const handleSave = async (saveStatus?: 'draft' | 'published') => {
    if (!name.trim()) {
      toast.error(`Please enter a name for the ${flowLabel.toLowerCase()}`)
      return
    }

    setIsSaving(true)
    try {
      const payload = getTreeForSave()
      if (saveStatus) {
        payload.status = saveStatus
      }

      if (isEditMode && treeId) {
        await treesApi.update(treeId, payload)
        markSaved()
        toast.success(`${flowLabel} saved`)
      } else {
        const created = await treesApi.create(payload)
        markSaved()
        toast.success(`${flowLabel} created`)
        navigate(`/flows/${created.id}/edit`, { replace: true })
      }
    } catch (err: unknown) {
      const message = err && typeof err === 'object' && 'response' in err
        ? (err as { response?: { data?: { detail?: string | { message?: string } } } }).response?.data?.detail
        : null
      const errorText = typeof message === 'string' ? message : typeof message === 'object' && message?.message ? message.message : `Failed to save ${flowLabel.toLowerCase()}`
      toast.error(errorText)
    } finally {
      setIsSaving(false)
    }
  }

  // Summary strings for collapsed sections
  const detailsSummary = [
    name ? `"${name}"` : '"Untitled"',
    tags.length > 0 ? `${tags.length} tag${tags.length !== 1 ? 's' : ''}` : 'No tags',
    isPublic ? 'Public' : 'Private',
  ].join(' \u00b7 ')

  const scheduleSummary = getScheduleSummary(schedule, scheduleTargetList)

  const intakeSummary = intakeForm.length === 0
    ? 'No fields defined'
    : `${intakeForm.length} field${intakeForm.length !== 1 ? 's' : ''}: ${intakeForm.map(f => f.label || f.variable_name).slice(0, 4).join(', ')}${intakeForm.length > 4 ? ', \u2026' : ''}`

  if (isLoading) {
    return (
      <div className="flex min-h-[50vh] items-center justify-center">
        <Spinner />
      </div>
    )
  }

  return (
    <div className="flex h-full flex-col overflow-hidden">
      {/* Toolbar — sticky */}
      <div className="flex shrink-0 items-center justify-between border-b border-border bg-card px-4 py-2">
        <div className="flex items-center gap-3">
          <button
            onClick={() => navigate('/trees')}
            className="rounded-md p-2 text-muted-foreground hover:bg-accent hover:text-foreground"
          >
            <ArrowLeft className="h-5 w-5" />
          </button>
          <div className="flex items-center gap-2">
            {isMaintenance
              ? <Wrench className="h-5 w-5 text-amber-400" />
              : <ListOrdered className="h-5 w-5 text-muted-foreground" />}
            <h1 className="text-lg font-bold text-foreground">
              {isEditMode ? `Edit ${flowLabel}` : `New ${flowLabel}`}
              {name && <span className="ml-2 font-normal text-muted-foreground">— {name}</span>}
            </h1>
          </div>
        </div>

        <div className="flex items-center gap-2">
          {isDirty && (
            <span className="text-xs text-muted-foreground">Unsaved changes</span>
          )}
          <button
            onClick={() => handleSave('draft')}
            disabled={isSaving}
            className="flex items-center gap-1.5 rounded-md border border-border px-3 py-2 text-sm text-muted-foreground hover:bg-accent hover:text-foreground disabled:opacity-50"
          >
            Save Draft
          </button>
          <button
            onClick={() => handleSave('published')}
            disabled={isSaving}
            className="flex items-center gap-1.5 rounded-md bg-gradient-brand px-4 py-2 text-sm font-medium text-white shadow-lg shadow-primary/20 hover:opacity-90 disabled:opacity-50"
          >
            <Save className="h-4 w-4" />
            {isSaving ? 'Saving...' : 'Publish'}
          </button>
        </div>
      </div>

      {/* Collapsible sections */}
      <div className="shrink-0">
        <CollapsibleEditorSection
          title="Details"
          icon={<Settings className="h-4 w-4" />}
          summary={detailsSummary}
          expanded={expandedSection === 'details'}
          onToggle={() => toggleSection('details')}
        >
          <div className="space-y-4">
            <div>
              <label className="mb-1 block text-sm font-medium text-muted-foreground">Name</label>
              <input
                type="text"
                value={name}
                onChange={(e) => setName(e.target.value)}
                placeholder="e.g. Domain Controller Build"
                className="w-full rounded-lg border border-border bg-card px-3 py-2 text-foreground placeholder:text-muted-foreground focus:border-primary focus:outline-none focus:ring-1 focus:ring-primary/20"
              />
            </div>

            <div>
              <label className="mb-1 block text-sm font-medium text-muted-foreground">Description</label>
              <textarea
                value={description}
                onChange={(e) => setDescription(e.target.value)}
                placeholder="Brief description of this procedure..."
                rows={2}
                className="w-full rounded-lg border border-border bg-card px-3 py-2 text-foreground placeholder:text-muted-foreground focus:border-primary focus:outline-none focus:ring-1 focus:ring-primary/20"
              />
            </div>

            <div className="grid grid-cols-2 gap-4">
              <div>
                <label className="mb-1 block text-sm font-medium text-muted-foreground">Tags</label>
                <TagInput tags={tags} onChange={setTags} />
              </div>

              <div className="flex items-end pb-1">
                <label className="flex items-center gap-2 text-sm text-muted-foreground">
                  <input
                    type="checkbox"
                    checked={isPublic}
                    onChange={(e) => setIsPublic(e.target.checked)}
                    className="rounded border-border"
                  />
                  Public (visible to all users)
                </label>
              </div>
            </div>
          </div>
        </CollapsibleEditorSection>

        <CollapsibleEditorSection
          title="Intake Form"
          icon={<FileText className="h-4 w-4" />}
          summary={intakeSummary}
          expanded={expandedSection === 'intake'}
          onToggle={() => toggleSection('intake')}
        >
          <IntakeFormBuilder />
        </CollapsibleEditorSection>

        {isMaintenance && (
          <CollapsibleEditorSection
            title="Schedule"
            icon={<Calendar className="h-4 w-4" />}
            summary={scheduleSummary}
            expanded={expandedSection === 'schedule'}
            onToggle={() => toggleSection('schedule')}
          >
            <MaintenanceScheduleSection
              treeId={treeId}
              onScheduleLoaded={handleScheduleLoaded}
            />
          </CollapsibleEditorSection>
        )}
      </div>

      {/* Step List — flex-1, scrolls independently */}
      <div className="min-h-0 flex-1 overflow-y-auto px-4 py-4">
        <StepList />
      </div>
    </div>
  )
}

export default ProceduralEditorPage