import { useEffect, useState } from 'react'
import { useNavigate, Link } from 'react-router-dom'
import { Play, Pencil, Share2, Trash2, GitBranch, Clock, TrendingUp, FolderTree, Plus, ListOrdered, ChevronDown, Wrench, Sparkles } from 'lucide-react'
import { treesApi } from '@/api/trees'
import { sessionsApi } from '@/api/sessions'
import type { TreeListItem } from '@/types'
import { TagBadges } from '@/components/common/TagBadges'
import { ConfirmDialog } from '@/components/common/ConfirmDialog'
import { ShareTreeModal } from '@/components/library/ShareTreeModal'
import { Spinner } from '@/components/common/Spinner'
import { cn } from '@/lib/utils'
import { useAuthStore } from '@/store/authStore'
import { usePermissions } from '@/hooks/usePermissions'
import { toast } from '@/lib/toast'
import { AIFlowBuilderModal } from '@/components/ai-builder/AIFlowBuilderModal'
import { aiBuilderApi } from '@/api/aiBuilder'
import { ForkModal } from '@/components/library/ForkModal'

interface TreeWithStats extends TreeListItem {
  lastUsed?: string
  sessionCount?: number
  parent_tree_id?: string | null
  parent_tree_name?: string | null
}

export function MyTreesPage() {
  const navigate = useNavigate()
  const { user } = useAuthStore()
  const { canEditTree, canCreateTrees } = usePermissions()
  const [trees, setTrees] = useState<TreeWithStats[]>([])
  const [isLoading, setIsLoading] = useState(true)
  const [treeToDelete, setTreeToDelete] = useState<TreeWithStats | null>(null)
  const [showDeleteConfirm, setShowDeleteConfirm] = useState(false)
  const [isDeleting, setIsDeleting] = useState(false)
  const [treeToShare, setTreeToShare] = useState<TreeWithStats | null>(null)
  const [showShareModal, setShowShareModal] = useState(false)
  const [showCreateMenu, setShowCreateMenu] = useState(false)
  const [showAIBuilder, setShowAIBuilder] = useState(false)
  const [aiEnabled, setAiEnabled] = useState(false)
  const [forkTarget, setForkTarget] = useState<TreeWithStats | null>(null)

  useEffect(() => {
    loadMyTrees()
  }, [user?.id])

  useEffect(() => {
    aiBuilderApi.getQuota().then((q) => setAiEnabled(q.ai_enabled)).catch(() => {})
  }, [])

  const loadMyTrees = async () => {
    if (!user?.id) return
    setIsLoading(true)
    try {
      // Fetch trees and recent sessions in parallel (2 API calls total, not N+1)
      const [userTrees, recentSessions] = await Promise.all([
        treesApi.list({ author_id: user.id }),
        sessionsApi.list({ size: 100 }),
      ])

      // Build a map of tree_id -> most recent session start time
      const lastUsedMap = new Map<string, string>()
      for (const session of recentSessions) {
        const existing = lastUsedMap.get(session.tree_id)
        if (!existing || new Date(session.started_at) > new Date(existing)) {
          lastUsedMap.set(session.tree_id, session.started_at)
        }
      }

      const treesWithStats: TreeWithStats[] = userTrees.map((tree) => ({
        ...tree,
        lastUsed: lastUsedMap.get(tree.id),
        sessionCount: tree.usage_count ?? 0,
      }))

      setTrees(treesWithStats)
    } catch (err) {
      toast.error('Failed to load your flows')
      console.error(err)
    } finally {
      setIsLoading(false)
    }
  }

  const handleStartSession = (tree: TreeWithStats) => {
    if (tree.tree_type === 'maintenance') {
      navigate(`/flows/${tree.id}/maintenance`)
    } else if (tree.tree_type === 'procedural') {
      navigate(`/flows/${tree.id}/navigate`)
    } else {
      navigate(`/trees/${tree.id}/navigate`)
    }
  }

  const getEditPath = (tree: TreeWithStats) => {
    return tree.tree_type === 'procedural' || tree.tree_type === 'maintenance'
      ? `/flows/${tree.id}/edit` : `/trees/${tree.id}/edit`
  }

  const handleDeleteTree = async () => {
    if (!treeToDelete) return
    setIsDeleting(true)
    try {
      await treesApi.delete(treeToDelete.id)
      setTrees(trees.filter((t) => t.id !== treeToDelete.id))
      toast.success(`"${treeToDelete.name}" deleted successfully`)
    } catch (err) {
      console.error('Failed to delete flow:', err)
      toast.error('Failed to delete flow')
    } finally {
      setIsDeleting(false)
      setShowDeleteConfirm(false)
      setTreeToDelete(null)
    }
  }

  const formatDate = (dateString?: string) => {
    if (!dateString) return 'Never'
    return new Date(dateString).toLocaleDateString('en-US', {
      month: 'short',
      day: 'numeric',
      year: 'numeric',
    })
  }

  return (
    <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
      <div className="mb-6 flex items-center justify-between sm:mb-8">
        <div>
          <h1 className="text-2xl font-bold font-heading text-foreground sm:text-3xl">My Flows</h1>
          <p className="mt-2 text-muted-foreground">
            Your forked and custom flows
          </p>
        </div>
        {canCreateTrees && (
          <div className="relative">
            <button
              onClick={() => setShowCreateMenu(!showCreateMenu)}
              className="flex items-center gap-2 rounded-md bg-gradient-brand text-white shadow-lg shadow-primary/20 px-4 py-2 text-sm font-medium hover:opacity-90"
            >
              <Plus className="h-4 w-4" />
              Create New
              <ChevronDown className="h-3.5 w-3.5" />
            </button>
            {showCreateMenu && (
              <>
                <div className="fixed inset-0 z-10" onClick={() => setShowCreateMenu(false)} />
                <div className="absolute right-0 z-20 mt-1 w-56 rounded-lg border border-border bg-card p-1 shadow-xl backdrop-blur-sm">
                  <Link
                    to="/trees/new"
                    onClick={() => setShowCreateMenu(false)}
                    className="flex items-center gap-3 rounded-md px-3 py-2.5 text-sm text-foreground hover:bg-accent"
                  >
                    <FolderTree className="h-4 w-4 text-muted-foreground" />
                    <div>
                      <div className="font-medium">Troubleshooting Tree</div>
                      <div className="text-xs text-muted-foreground">Branching decision flow</div>
                    </div>
                  </Link>
                  <Link
                    to="/flows/new"
                    onClick={() => setShowCreateMenu(false)}
                    className="flex items-center gap-3 rounded-md px-3 py-2.5 text-sm text-foreground hover:bg-accent"
                  >
                    <ListOrdered className="h-4 w-4 text-muted-foreground" />
                    <div>
                      <div className="font-medium">Procedural Flow</div>
                      <div className="text-xs text-muted-foreground">Step-by-step procedure</div>
                    </div>
                  </Link>
                  <Link
                    to="/flows/new?type=maintenance"
                    onClick={() => setShowCreateMenu(false)}
                    className="flex items-center gap-3 rounded-md px-3 py-2.5 text-sm text-foreground hover:bg-accent"
                  >
                    <Wrench className="h-4 w-4 text-amber-400" />
                    <div>
                      <div className="font-medium">Maintenance Flow</div>
                      <div className="text-xs text-muted-foreground">Scheduled multi-target tasks</div>
                    </div>
                  </Link>
                  {aiEnabled && (
                    <>
                      <div className="my-1 border-t border-border" />
                      <button
                        type="button"
                        onClick={() => {
                          setShowCreateMenu(false)
                          setShowAIBuilder(true)
                        }}
                        className="flex w-full items-center gap-3 rounded-md px-3 py-2.5 text-sm text-foreground hover:bg-accent"
                      >
                        <Sparkles className="h-4 w-4 text-primary" />
                        <div className="text-left">
                          <div className="font-medium">Flow Assist</div>
                          <div className="text-xs text-muted-foreground">AI-powered flow builder</div>
                        </div>
                      </button>
                    </>
                  )}
                </div>
              </>
            )}
          </div>
        )}
      </div>

      {/* Loading State */}
      {isLoading ? (
        <div className="flex justify-center py-12">
          <Spinner />
        </div>
      ) : trees.length === 0 ? (
        <div className="rounded-lg border border-dashed border-border bg-accent px-4 py-12 text-center">
          <FolderTree className="mx-auto mb-4 h-12 w-12 text-muted-foreground" />
          <h2 className="mb-2 text-lg font-semibold text-foreground">No personal flows yet</h2>
          <p className="mb-4 text-sm text-muted-foreground">
            Fork a flow from the library to customize it for your workflow
          </p>
          <div className="flex items-center justify-center gap-3">
            <Link
              to="/trees"
              className={cn(
                'inline-flex items-center gap-2 rounded-md bg-gradient-brand text-white shadow-lg shadow-primary/20 px-4 py-2 text-sm font-medium',
                'hover:opacity-90'
              )}
            >
              Browse Library
            </Link>
            {canCreateTrees && (
              <Link
                to="/trees/new"
                className={cn(
                  'inline-flex items-center gap-2 rounded-md border border-border px-4 py-2 text-sm font-medium text-muted-foreground',
                  'hover:bg-accent hover:text-foreground'
                )}
              >
                <Plus className="h-4 w-4" />
                Create from Scratch
              </Link>
            )}
          </div>
        </div>
      ) : (
        <div className="grid gap-4 sm:grid-cols-2 lg:grid-cols-3">
          {trees.map((tree) => (
            <div
              key={tree.id}
              className="bg-card border border-border rounded-xl p-4 transition-all hover:border-border/80 sm:p-6"
            >
              {/* Header */}
              <div className="mb-3 flex items-start justify-between gap-2">
                <div className="flex items-center gap-2">
                  {tree.tree_type === 'procedural' && (
                    <ListOrdered className="h-4 w-4 shrink-0 text-muted-foreground" />
                  )}
                  {tree.tree_type === 'maintenance' && (
                    <Wrench className="h-4 w-4 shrink-0 text-amber-400" />
                  )}
                  <h3 className="font-semibold text-foreground">{tree.name}</h3>
                  {tree.parent_tree_id && (
                    <span className="shrink-0 rounded-full bg-violet-400/15 px-1.5 py-0.5 text-[9px] font-semibold uppercase tracking-wide text-violet-400">
                      Fork
                    </span>
                  )}
                </div>
                <div className="flex items-center gap-1.5">
                  {tree.tree_type === 'procedural' && (
                    <span className="rounded-full bg-blue-400/10 px-2 py-0.5 text-[10px] font-medium text-blue-400">
                      Procedure
                    </span>
                  )}
                  {tree.tree_type === 'maintenance' && (
                    <span className="rounded-full bg-amber-400/10 px-2 py-0.5 text-[10px] font-medium text-amber-400">
                      Maintenance
                    </span>
                  )}
                  {tree.category_info && (
                    <span className="rounded-full bg-accent px-2 py-0.5 text-xs text-muted-foreground">
                      {tree.category_info.name}
                    </span>
                  )}
                </div>
              </div>

              {/* Description */}
              <p className="mb-3 text-sm text-muted-foreground line-clamp-2">
                {tree.description || 'No description available'}
              </p>

              {/* Fork Badge */}
              {tree.parent_tree_id && (
                <div className="mb-3 flex items-center gap-2 rounded-md bg-accent px-2 py-1.5 text-sm">
                  <GitBranch className="h-4 w-4 text-muted-foreground" />
                  <span className="text-muted-foreground">
                    Forked from{' '}
                    <Link
                      to={`/trees/${tree.parent_tree_id}/navigate`}
                      className="font-medium text-foreground hover:underline"
                    >
                      original
                    </Link>
                  </span>
                </div>
              )}

              {/* Tags */}
              {tree.tags && tree.tags.length > 0 && (
                <div className="mb-3">
                  <TagBadges tags={tree.tags} maxVisible={3} />
                </div>
              )}

              {/* Stats */}
              <div className="mb-4 flex items-center gap-4 text-xs text-muted-foreground">
                <div className="flex items-center gap-1">
                  <Clock className="h-3.5 w-3.5" />
                  <span>{formatDate(tree.lastUsed)}</span>
                </div>
                <div className="flex items-center gap-1">
                  <TrendingUp className="h-3.5 w-3.5" />
                  <span>{tree.sessionCount || 0} uses</span>
                </div>
              </div>

              {/* Actions */}
              <div className="flex items-center gap-2">
                <button
                  type="button"
                  onClick={() => handleStartSession(tree)}
                  className={cn(
                    'flex flex-1 items-center justify-center gap-2 rounded-md bg-gradient-brand text-white shadow-lg shadow-primary/20 px-3 py-2 text-sm font-medium',
                    'hover:opacity-90'
                  )}
                >
                  <Play className="h-4 w-4" />
                  Start
                </button>
                {canEditTree({ author_id: tree.author_id, account_id: tree.account_id }) && (
                  <Link
                    to={getEditPath(tree)}
                    className={cn(
                      'rounded-md border border-border p-2 text-muted-foreground',
                      'hover:bg-accent hover:text-foreground'
                    )}
                    title="Edit tree"
                  >
                    <Pencil className="h-4 w-4" />
                  </Link>
                )}
                <button
                  type="button"
                  onClick={() => {
                    setTreeToShare(tree)
                    setShowShareModal(true)
                  }}
                  className={cn(
                    'rounded-md border border-border p-2 text-muted-foreground',
                    'hover:bg-accent hover:text-foreground'
                  )}
                  title="Share tree"
                >
                  <Share2 className="h-4 w-4" />
                </button>
                <button
                  type="button"
                  onClick={() => setForkTarget(tree)}
                  className="rounded-md border border-border p-2 text-muted-foreground hover:bg-accent hover:text-foreground transition-colors"
                  title="Fork flow"
                >
                  <GitBranch className="h-4 w-4" />
                </button>
                <button
                  type="button"
                  onClick={() => {
                    setTreeToDelete(tree)
                    setShowDeleteConfirm(true)
                  }}
                  className={cn(
                    'rounded-md border border-border p-2 text-muted-foreground',
                    'hover:bg-red-400/10 hover:text-red-400'
                  )}
                  title="Delete tree"
                >
                  <Trash2 className="h-4 w-4" />
                </button>
              </div>
            </div>
          ))}
        </div>
      )}

      {/* Delete Confirmation */}
      <ConfirmDialog
        isOpen={showDeleteConfirm}
        onClose={() => {
          setShowDeleteConfirm(false)
          setTreeToDelete(null)
        }}
        onConfirm={handleDeleteTree}
        title="Delete Flow"
        message={`Are you sure you want to delete "${treeToDelete?.name}"? This action can be undone by an administrator.`}
        confirmLabel="Delete"
        confirmVariant="destructive"
        isLoading={isDeleting}
      />

      {/* Share Tree Modal */}
      {treeToShare && (
        <ShareTreeModal
          tree={treeToShare}
          isOpen={showShareModal}
          onClose={() => {
            setShowShareModal(false)
            setTreeToShare(null)
          }}
        />
      )}

      {/* Fork Modal */}
      {forkTarget && (
        <ForkModal
          treeId={forkTarget.id}
          treeName={forkTarget.name}
          onClose={() => setForkTarget(null)}
        />
      )}

      {/* AI Flow Builder Modal */}
      <AIFlowBuilderModal
        isOpen={showAIBuilder}
        onClose={() => setShowAIBuilder(false)}
      />
    </div>
  )
}

export default MyTreesPage
