import { useEffect, useState } from 'react'
import { Link } from 'react-router-dom'
import { Building2, Users, Mail, Crown, Loader2, AlertCircle, Check, X, Settings, FolderTree, Server, RefreshCw, MessageSquareText, UserCog, AlertTriangle, Clock } from 'lucide-react'
import { accountsApi } from '@/api/accounts'
import type { Account, AccountMember, AccountInvite } from '@/types'
import { TransferOwnershipModal } from '@/components/account/TransferOwnershipModal'
import { LeaveAccountModal } from '@/components/account/LeaveAccountModal'
import { DeleteAccountModal } from '@/components/account/DeleteAccountModal'
import { Spinner } from '@/components/common/Spinner'
import { cn } from '@/lib/utils'
import { usePermissions } from '@/hooks/usePermissions'
import { useSubscription } from '@/hooks/useSubscription'
import { useAuthStore } from '@/store/authStore'
import { useUserPreferencesStore } from '@/store/userPreferencesStore'
import { CheckoutButton } from '@/components/subscription/CheckoutButton'
import { toast } from '@/lib/toast'

export function AccountSettingsPage() {
  const { isAccountOwner } = usePermissions()
  const { plan, limits, usage } = useSubscription()
  const { defaultExportFormat, setDefaultExportFormat } = useUserPreferencesStore()
  const subscription = useAuthStore((s) => s.subscription)

  const [account, setAccount] = useState<Account | null>(null)
  const [members, setMembers] = useState<AccountMember[]>([])
  const [invites, setInvites] = useState<AccountInvite[]>([])
  const [isLoading, setIsLoading] = useState(true)
  const [error, setError] = useState<string | null>(null)

  // Account name editing
  const [isEditingName, setIsEditingName] = useState(false)
  const [editedName, setEditedName] = useState('')
  const [isSavingName, setIsSavingName] = useState(false)

  // Modals
  const [showTransferModal, setShowTransferModal] = useState(false)
  const [showLeaveModal, setShowLeaveModal] = useState(false)
  const [showDeleteModal, setShowDeleteModal] = useState(false)

  // Invite form
  const [inviteEmail, setInviteEmail] = useState('')
  const [inviteRole, setInviteRole] = useState('engineer')
  const [isInviting, setIsInviting] = useState(false)
  const [inviteError, setInviteError] = useState<string | null>(null)
  const [inviteSuccess, setInviteSuccess] = useState<string | null>(null)

  useEffect(() => {
    loadData()
  }, [])

  const loadData = async () => {
    setIsLoading(true)
    setError(null)
    try {
      const accountData = await accountsApi.getMyAccount()
      setAccount(accountData)
      setEditedName(accountData.name)

      if (isAccountOwner) {
        const [membersData, invitesData] = await Promise.all([
          accountsApi.getMembers(),
          accountsApi.getInvites(),
        ])
        setMembers(membersData)
        setInvites(invitesData)
      }
    } catch (err) {
      setError('Failed to load account information')
      console.error(err)
    } finally {
      setIsLoading(false)
    }
  }

  const handleSaveName = async () => {
    if (!editedName.trim() || editedName === account?.name) {
      setIsEditingName(false)
      return
    }
    setIsSavingName(true)
    try {
      const updated = await accountsApi.updateMyAccount({ name: editedName.trim() })
      setAccount(updated)
      setIsEditingName(false)
    } catch (err) {
      console.error('Failed to update account name:', err)
    } finally {
      setIsSavingName(false)
    }
  }

  const handleInvite = async (e: React.FormEvent) => {
    e.preventDefault()
    if (!inviteEmail.trim()) return

    setIsInviting(true)
    setInviteError(null)
    setInviteSuccess(null)
    try {
      await accountsApi.createInvite({ email: inviteEmail.trim(), role: inviteRole })
      setInviteSuccess(`Invitation sent to ${inviteEmail}`)
      setInviteEmail('')
      // Refresh invites list
      const invitesData = await accountsApi.getInvites()
      setInvites(invitesData)
    } catch (err) {
      setInviteError('Failed to send invitation')
      console.error(err)
    } finally {
      setIsInviting(false)
    }
  }

  const [resendingId, setResendingId] = useState<string | null>(null)

  const handleResendInvite = async (inviteId: string) => {
    setResendingId(inviteId)
    try {
      await accountsApi.resendInvite(inviteId)
      toast.success('Invite resent with a new code')
      const invitesData = await accountsApi.getInvites()
      setInvites(invitesData)
    } catch {
      toast.error('Failed to resend invite')
    } finally {
      setResendingId(null)
    }
  }

  const handleRemoveMember = async (userId: string) => {
    try {
      await accountsApi.removeMember(userId)
      setMembers(members.filter((m) => m.id !== userId))
    } catch (err) {
      console.error('Failed to remove member:', err)
    }
  }

  if (isLoading) {
    return (
      <div className="flex justify-center py-12">
        <Spinner />
      </div>
    )
  }

  if (error) {
    return (
      <div className="rounded-md border border-red-400/20 bg-red-400/10 p-4 text-red-400">
        <div className="flex items-center gap-2">
          <AlertCircle className="h-5 w-5" />
          {error}
        </div>
      </div>
    )
  }

  const sub = subscription?.subscription

  return (
    <div>
      <div className="mb-8">
        <div className="flex items-center gap-3">
          <Building2 className="h-8 w-8 text-muted-foreground" />
          <h1 className="text-2xl font-bold font-heading text-foreground sm:text-3xl">Account Settings</h1>
        </div>
        <p className="mt-2 text-muted-foreground">
          Manage your account, subscription, and team
        </p>
      </div>

      <div className="max-w-3xl space-y-6">
        {/* Account Info Section */}
        <div className="bg-card border border-border rounded-xl p-4 sm:p-6">
          <h2 className="text-lg font-semibold text-foreground">Account Information</h2>

          <div className="mt-4 space-y-4">
            {/* Account Name */}
            <div>
              <label className="block text-sm font-medium text-foreground">
                Account Name
              </label>
              {isEditingName ? (
                <div className="mt-1 flex items-center gap-2">
                  <input
                    type="text"
                    value={editedName}
                    onChange={(e) => setEditedName(e.target.value)}
                    className={cn(
                      'flex-1 rounded-md border border-border bg-card px-3 py-2',
                      'text-foreground placeholder:text-muted-foreground',
                      'focus:border-primary focus:outline-hidden focus:ring-1 focus:ring-primary/20'
                    )}
                    autoFocus
                    onKeyDown={(e) => {
                      if (e.key === 'Enter') handleSaveName()
                      if (e.key === 'Escape') {
                        setEditedName(account?.name ?? '')
                        setIsEditingName(false)
                      }
                    }}
                  />
                  <button
                    onClick={handleSaveName}
                    disabled={isSavingName}
                    className={cn(
                      'rounded-md bg-gradient-brand text-white shadow-lg shadow-primary/20 p-2',
                      'hover:opacity-90 disabled:opacity-50'
                    )}
                  >
                    {isSavingName ? (
                      <Loader2 className="h-4 w-4 animate-spin" />
                    ) : (
                      <Check className="h-4 w-4" />
                    )}
                  </button>
                  <button
                    onClick={() => {
                      setEditedName(account?.name ?? '')
                      setIsEditingName(false)
                    }}
                    className="rounded-md border border-border p-2 text-muted-foreground hover:bg-accent"
                  >
                    <X className="h-4 w-4" />
                  </button>
                </div>
              ) : (
                <div className="mt-1 flex items-center gap-2">
                  <span className="text-sm text-foreground">{account?.name}</span>
                  {isAccountOwner && (
                    <button
                      onClick={() => setIsEditingName(true)}
                      className="text-xs text-foreground hover:underline"
                    >
                      Edit
                    </button>
                  )}
                </div>
              )}
            </div>

            {/* Display Code */}
            <div>
              <label className="block text-sm font-medium text-foreground">
                Display Code
              </label>
              <p className="mt-1 text-sm font-mono text-muted-foreground">
                {account?.display_code}
              </p>
            </div>
          </div>
        </div>

        {/* Subscription Section */}
        <div className="bg-card border border-border rounded-xl p-4 sm:p-6">
          <h2 className="text-lg font-semibold text-foreground">Subscription</h2>

          <div className="mt-4 space-y-4">
            {/* Plan & Status */}
            <div className="flex items-center gap-3">
              <span
                className={cn(
                  'inline-flex items-center gap-1.5 rounded-full px-3 py-1 text-sm font-medium',
                  plan === 'free' && 'bg-accent text-muted-foreground',
                  plan === 'pro' && 'bg-accent text-foreground',
                  plan === 'team' && 'bg-accent text-foreground'
                )}
              >
                <Crown className="h-3.5 w-3.5" />
                {plan.charAt(0).toUpperCase() + plan.slice(1)} Plan
              </span>
              {sub && (
                <span
                  className={cn(
                    'inline-flex rounded-full px-2.5 py-0.5 text-xs font-medium',
                    sub.status === 'active' && 'bg-green-500/10 text-emerald-400',
                    sub.status === 'trialing' && 'bg-blue-500/10 text-blue-400',
                    sub.status === 'past_due' && 'bg-yellow-500/10 text-yellow-400',
                    sub.status === 'canceled' && 'bg-red-400/10 text-red-400',
                    sub.status === 'orphaned' && 'bg-accent text-muted-foreground'
                  )}
                >
                  {sub.status.charAt(0).toUpperCase() + sub.status.slice(1).replace('_', ' ')}
                </span>
              )}
            </div>

            {sub?.current_period_end && (
              <p className="text-sm text-muted-foreground">
                Current period ends: {new Date(sub.current_period_end).toLocaleDateString()}
              </p>
            )}

            {/* Usage Stats */}
            {limits && usage && (
              <div className="mt-4 grid gap-3 sm:grid-cols-3">
                <UsageStat
                  label="Trees"
                  current={usage.tree_count}
                  max={limits.max_trees}
                />
                <UsageStat
                  label="Sessions / month"
                  current={usage.session_count_this_month}
                  max={limits.max_sessions_per_month}
                />
                <UsageStat
                  label="Team members"
                  current={usage.user_count}
                  max={limits.max_users}
                />
              </div>
            )}

            {/* Upgrade buttons */}
            {plan === 'free' && (
              <div className="mt-4 flex gap-3">
                <CheckoutButton plan="pro" />
                <CheckoutButton plan="team" />
              </div>
            )}
            {plan === 'pro' && (
              <div className="mt-4">
                <CheckoutButton plan="team" />
              </div>
            )}
          </div>
        </div>

        {/* Team Members Section (owners only) */}
        {isAccountOwner && (
          <div className="bg-card border border-border rounded-xl p-4 sm:p-6">
            <div className="flex items-center gap-2">
              <Users className="h-5 w-5 text-muted-foreground" />
              <h2 className="text-lg font-semibold text-foreground">Team Members</h2>
            </div>

            {members.length === 0 ? (
              <p className="mt-4 text-sm text-muted-foreground">No team members yet.</p>
            ) : (
              <div className="mt-4 divide-y divide-border">
                {members.map((member) => (
                  <div
                    key={member.id}
                    className="flex items-center justify-between py-3 first:pt-0 last:pb-0"
                  >
                    <div>
                      <p className="text-sm font-medium text-foreground">{member.name}</p>
                      <p className="text-xs text-muted-foreground">{member.email}</p>
                    </div>
                    <div className="flex items-center gap-3">
                      {member.account_role === 'owner' ? (
                        <span className="rounded-full px-2.5 py-0.5 text-xs font-medium bg-accent text-foreground">
                          owner
                        </span>
                      ) : (
                        <select
                          value={member.account_role}
                          onChange={async (e) => {
                            try {
                              const updated = await accountsApi.updateMemberRole(member.id, e.target.value)
                              setMembers(members.map((m) => m.id === member.id ? { ...m, account_role: updated.account_role } : m))
                              toast.success(`Role updated to ${updated.account_role}`)
                            } catch {
                              toast.error('Failed to update role')
                            }
                          }}
                          className={cn(
                            'rounded-md border border-border bg-card px-2 py-0.5 text-xs',
                            'text-foreground focus:border-primary focus:outline-hidden'
                          )}
                        >
                          <option value="engineer">engineer</option>
                          <option value="viewer">viewer</option>
                        </select>
                      )}
                      {!member.is_active && (
                        <span className="rounded-full bg-red-400/10 px-2 py-0.5 text-xs text-red-400">
                          Inactive
                        </span>
                      )}
                      {member.account_role !== 'owner' && (
                        <button
                          onClick={() => handleRemoveMember(member.id)}
                          className="text-muted-foreground hover:text-red-400"
                          title="Remove member"
                        >
                          <X className="h-4 w-4" />
                        </button>
                      )}
                    </div>
                  </div>
                ))}
              </div>
            )}
          </div>
        )}

        {/* Invite Member Section (owners only) */}
        {isAccountOwner && (
          <div className="bg-card border border-border rounded-xl p-4 sm:p-6">
            <div className="flex items-center gap-2">
              <Mail className="h-5 w-5 text-muted-foreground" />
              <h2 className="text-lg font-semibold text-foreground">Invite Member</h2>
            </div>

            <form onSubmit={handleInvite} className="mt-4 space-y-3">
              <div className="flex flex-col gap-3 sm:flex-row">
                <input
                  type="email"
                  placeholder="Email address"
                  value={inviteEmail}
                  onChange={(e) => setInviteEmail(e.target.value)}
                  required
                  className={cn(
                    'flex-1 rounded-md border border-border bg-card px-3 py-2',
                    'text-foreground placeholder:text-muted-foreground',
                    'focus:border-primary focus:outline-hidden focus:ring-1 focus:ring-primary/20'
                  )}
                />
                <select
                  value={inviteRole}
                  onChange={(e) => setInviteRole(e.target.value)}
                  className={cn(
                    'rounded-md border border-border bg-card px-3 py-2',
                    'text-foreground focus:border-primary focus:outline-hidden focus:ring-1 focus:ring-primary/20'
                  )}
                >
                  <option value="engineer">Engineer</option>
                  <option value="viewer">Viewer</option>
                </select>
                <button
                  type="submit"
                  disabled={isInviting || !inviteEmail.trim()}
                  className={cn(
                    'rounded-md bg-gradient-brand text-white shadow-lg shadow-primary/20 px-4 py-2 text-sm font-medium',
                    'hover:opacity-90 disabled:opacity-50 disabled:cursor-not-allowed'
                  )}
                >
                  {isInviting ? (
                    <span className="flex items-center gap-2">
                      <Loader2 className="h-4 w-4 animate-spin" />
                      Sending...
                    </span>
                  ) : (
                    'Send Invite'
                  )}
                </button>
              </div>

              {inviteError && (
                <p className="text-sm text-red-400">{inviteError}</p>
              )}
              {inviteSuccess && (
                <p className="text-sm text-emerald-400">{inviteSuccess}</p>
              )}
            </form>

            {/* Pending Invites */}
            {invites.length > 0 && (
              <div className="mt-6">
                <h3 className="text-sm font-medium text-foreground">Pending Invites</h3>
                <div className="mt-2 divide-y divide-border">
                  {invites
                    .filter((inv) => !inv.used_at)
                    .map((invite) => (
                      <div
                        key={invite.id}
                        className="flex items-center justify-between py-2"
                      >
                        <div>
                          <p className="text-sm text-foreground">{invite.email}</p>
                          <p className="text-xs text-muted-foreground">
                            {invite.expires_at
                              ? `Expires ${new Date(invite.expires_at).toLocaleDateString()}`
                              : 'No expiration'}
                          </p>
                        </div>
                        <div className="flex items-center gap-2">
                          <span className="rounded-full bg-accent px-2.5 py-0.5 text-xs text-muted-foreground">
                            {invite.role}
                          </span>
                          <button
                            onClick={() => handleResendInvite(invite.id)}
                            disabled={resendingId === invite.id}
                            className="text-muted-foreground hover:text-foreground disabled:opacity-50"
                            title="Resend invite"
                          >
                            {resendingId === invite.id ? (
                              <Loader2 className="h-4 w-4 animate-spin" />
                            ) : (
                              <RefreshCw className="h-4 w-4" />
                            )}
                          </button>
                        </div>
                      </div>
                    ))}
                </div>
              </div>
            )}
          </div>
        )}

        {/* Profile Settings Link */}
        <Link
          to="/account/profile"
          className="bg-card border border-border rounded-xl p-4 sm:p-6 flex items-center justify-between group hover:border-border transition-all"
        >
          <div className="flex items-center gap-3">
            <UserCog className="h-5 w-5 text-muted-foreground" />
            <div>
              <h2 className="text-lg font-semibold text-foreground">Profile Settings</h2>
              <p className="text-sm text-muted-foreground">Update your name, email, and personal details</p>
            </div>
          </div>
          <span className="text-muted-foreground group-hover:text-foreground transition-colors">&rarr;</span>
        </Link>

        {/* Team Categories Link (owners only) */}
        {isAccountOwner && (
          <Link
            to="/account/categories"
            className="bg-card border border-border rounded-xl p-4 sm:p-6 flex items-center justify-between group hover:border-border transition-all"
          >
            <div className="flex items-center gap-3">
              <FolderTree className="h-5 w-5 text-muted-foreground" />
              <div>
                <h2 className="text-lg font-semibold text-foreground">Team Categories</h2>
                <p className="text-sm text-muted-foreground">Manage tree categories for your team</p>
              </div>
            </div>
            <span className="text-muted-foreground group-hover:text-foreground transition-colors">&rarr;</span>
          </Link>
        )}

        {/* Target Lists Link (owners only) */}
        {isAccountOwner && (
          <Link
            to="/account/target-lists"
            className="bg-card border border-border rounded-xl p-4 sm:p-6 flex items-center justify-between group hover:border-border transition-all"
          >
            <div className="flex items-center gap-3">
              <Server className="h-5 w-5 text-muted-foreground" />
              <div>
                <h2 className="text-lg font-semibold text-foreground">Target Lists</h2>
                <p className="text-sm text-muted-foreground">Saved server lists for maintenance flow batch launching</p>
              </div>
            </div>
            <span className="text-muted-foreground group-hover:text-foreground transition-colors">&rarr;</span>
          </Link>
        )}

        {/* Chat Retention Link (owners only) */}
        {isAccountOwner && (
          <Link
            to="/account/chat-retention"
            className="bg-card border border-border rounded-xl p-4 sm:p-6 flex items-center justify-between group hover:border-border transition-all"
          >
            <div className="flex items-center gap-3">
              <Clock className="h-5 w-5 text-muted-foreground" />
              <div>
                <h2 className="text-lg font-semibold text-foreground">Chat Retention</h2>
                <p className="text-sm text-muted-foreground">Configure AI assistant conversation retention policies</p>
              </div>
            </div>
            <span className="text-muted-foreground group-hover:text-foreground transition-colors">&rarr;</span>
          </Link>
        )}

        {/* Feedback Link (all users) */}
        <Link
          to="/feedback"
          className="bg-card border border-border rounded-xl p-4 sm:p-6 flex items-center justify-between group hover:border-border transition-all"
        >
          <div className="flex items-center gap-3">
            <MessageSquareText className="h-5 w-5 text-muted-foreground" />
            <div>
              <h2 className="text-lg font-semibold text-foreground">Send Feedback</h2>
              <p className="text-sm text-muted-foreground">Report bugs, request features, or share your thoughts</p>
            </div>
          </div>
          <span className="text-muted-foreground group-hover:text-foreground transition-colors">&rarr;</span>
        </Link>

        {/* Preferences Section */}
        <div className="bg-card border border-border rounded-xl p-4 sm:p-6">
          <div className="flex items-center gap-2">
            <Settings className="h-5 w-5 text-muted-foreground" />
            <h2 className="text-lg font-semibold text-foreground">Preferences</h2>
          </div>

          <div className="mt-4">
            <label
              htmlFor="export-format"
              className="block text-sm font-medium text-foreground"
            >
              Default Export Format
            </label>
            <p className="text-sm text-muted-foreground">
              This format will be pre-selected when exporting sessions
            </p>
            <select
              id="export-format"
              value={defaultExportFormat}
              onChange={(e) => {
                setDefaultExportFormat(e.target.value as 'markdown' | 'text' | 'html')
                toast.success('Preference saved')
              }}
              className={cn(
                'mt-2 block w-full max-w-xs rounded-xl border border-border bg-card px-3 py-2',
                'text-sm text-foreground',
                'focus:border-primary focus:outline-hidden focus:ring-1 focus:ring-primary/20'
              )}
            >
              <option value="markdown">Markdown (.md)</option>
              <option value="text">Plain Text (.txt)</option>
              <option value="html">HTML (.html)</option>
            </select>
          </div>
        </div>
        {/* Danger Zone */}
        <div className="rounded-xl border border-rose-500/20 p-4 sm:p-6">
          <div className="flex items-center gap-2 mb-4">
            <AlertTriangle className="h-5 w-5 text-rose-500" />
            <h2 className="text-lg font-semibold text-foreground">Danger Zone</h2>
          </div>

          <div className="space-y-3">
            {isAccountOwner ? (
              <>
                <div className="flex items-center justify-between">
                  <div>
                    <p className="text-sm font-medium text-foreground">Transfer Ownership</p>
                    <p className="text-xs text-muted-foreground">Make another member the account owner</p>
                  </div>
                  <button
                    onClick={() => setShowTransferModal(true)}
                    className={cn(
                      'rounded-[10px] px-3 py-1.5 text-sm font-medium',
                      'border border-amber-500/30 text-amber-400 hover:bg-amber-500/10'
                    )}
                  >
                    Transfer
                  </button>
                </div>
                <div className="flex items-center justify-between border-t border-border pt-3">
                  <div>
                    <p className="text-sm font-medium text-foreground">Delete Account</p>
                    <p className="text-xs text-muted-foreground">Permanently delete your account and all data</p>
                  </div>
                  <button
                    onClick={() => setShowDeleteModal(true)}
                    className={cn(
                      'rounded-[10px] px-3 py-1.5 text-sm font-medium',
                      'border border-rose-500/30 text-rose-400 hover:bg-rose-500/10'
                    )}
                  >
                    Delete
                  </button>
                </div>
              </>
            ) : (
              <div className="flex items-center justify-between">
                <div>
                  <p className="text-sm font-medium text-foreground">Leave Account</p>
                  <p className="text-xs text-muted-foreground">Leave this account and create a personal one</p>
                </div>
                <button
                  onClick={() => setShowLeaveModal(true)}
                  className={cn(
                    'rounded-[10px] px-3 py-1.5 text-sm font-medium',
                    'border border-rose-500/30 text-rose-400 hover:bg-rose-500/10'
                  )}
                >
                  Leave
                </button>
              </div>
            )}
          </div>
        </div>
      </div>

      {/* Modals */}
      {showTransferModal && (
        <TransferOwnershipModal
          members={members}
          onClose={() => setShowTransferModal(false)}
          onTransferred={() => { setShowTransferModal(false); loadData() }}
        />
      )}
      {showLeaveModal && account && (
        <LeaveAccountModal
          accountName={account.name}
          onClose={() => setShowLeaveModal(false)}
        />
      )}
      {showDeleteModal && (
        <DeleteAccountModal onClose={() => setShowDeleteModal(false)} />
      )}
    </div>
  )
}

/** Small helper component for usage stat display */
function UsageStat({
  label,
  current,
  max,
}: {
  label: string
  current: number
  max: number | null
}) {
  const isUnlimited = max === null
  const percentage = isUnlimited ? 0 : Math.min((current / max) * 100, 100)
  const isNearLimit = !isUnlimited && percentage >= 80
  const isAtLimit = !isUnlimited && current >= max

  return (
    <div className="rounded-md border border-border bg-card p-3">
      <p className="text-xs font-medium text-muted-foreground">{label}</p>
      <p
        className={cn(
          'mt-1 text-lg font-semibold',
          isAtLimit ? 'text-red-400' : isNearLimit ? 'text-yellow-400' : 'text-foreground'
        )}
      >
        {current}
        <span className="text-sm font-normal text-muted-foreground">
          {' '}/ {isUnlimited ? 'Unlimited' : max}
        </span>
      </p>
      {!isUnlimited && (
        <div className="mt-2 h-1.5 overflow-hidden rounded-full bg-accent">
          <div
            className={cn(
              'h-full rounded-full transition-all',
              isAtLimit ? 'bg-red-400' : isNearLimit ? 'bg-yellow-500' : 'bg-primary'
            )}
            style={{ width: `${percentage}%` }}
          />
        </div>
      )}
    </div>
  )
}

export default AccountSettingsPage
