import { useState } from "react";
import { Card, CardContent } from "@/components/ui/card";
import { Input } from "@/components/ui/input";
import { Button } from "@/components/ui/button";
import { Badge } from "@/components/ui/badge";
import { Checkbox } from "@/components/ui/checkbox";
import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter, DialogDescription } from "@/components/ui/dialog";
import { Label } from "@/components/ui/label";
import { Search, Plus, Download, Shield, Pencil, UserCog } from "lucide-react";
import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
import { api } from "@/lib/api-client";
import { useToast } from "@/hooks/use-toast";

interface PlatformUser {
  id: number;
  name: string;
  email: string;
  login: string;
  user_type: string;
  active: boolean;
  phone: string;
  role_ids: number[];
  roles: { id: number; name: string }[];
  effective_permission_count: number;
}

interface RoleInfo {
  id: number;
  name: string;
  description: string;
  assigned: boolean;
  permission_count: number;
}

const TYPE_COLORS: Record<string, string> = {
  admin: "bg-red-100 text-red-800 border-red-200",
  teacher: "bg-blue-100 text-blue-800 border-blue-200",
  student: "bg-green-100 text-green-800 border-green-200",
  user: "bg-gray-100 text-gray-800 border-gray-200",
};

export default function UsersPage() {
  const [search, setSearch] = useState("");
  const [typeFilter, setTypeFilter] = useState<string>("all");
  const [createOpen, setCreateOpen] = useState(false);
  const [editUser, setEditUser] = useState<PlatformUser | null>(null);
  const [rolesUser, setRolesUser] = useState<PlatformUser | null>(null);
  const [form, setForm] = useState({ name: "", email: "", password: "", phone: "" });
  const { toast } = useToast();
  const qc = useQueryClient();

  const usersQ = useQuery({
    queryKey: ["platform-users", search],
    queryFn: async () => {
      const params: Record<string, string | number> = { size: 200 };
      if (search) params.search = search;
      const res = await api.get<{ items?: PlatformUser[]; data?: PlatformUser[]; total: number }>("/users/list", params);
      return (res.items ?? res.data ?? []) as PlatformUser[];
    },
  });

  const rolesQ = useQuery({
    queryKey: ["user-roles-detail", rolesUser?.id],
    queryFn: async () => {
      if (!rolesUser) return null;
      return api.get<{ roles: RoleInfo[]; effective_permissions: unknown[] }>(`/users/${rolesUser.id}/roles`);
    },
    enabled: !!rolesUser,
  });

  const createMut = useMutation({
    mutationFn: (data: { name: string; email: string; password: string; phone?: string }) =>
      api.post<{ data: PlatformUser }>("/users/create", data),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ["platform-users"] });
      setCreateOpen(false);
      setForm({ name: "", email: "", password: "", phone: "" });
      toast({ title: "User created" });
    },
    onError: (err: Error) => toast({ title: "Error", description: err.message, variant: "destructive" }),
  });

  const updateMut = useMutation({
    mutationFn: (data: { id: number; name?: string; email?: string; phone?: string }) =>
      api.patch<{ data: PlatformUser }>("/users/update", data),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ["platform-users"] });
      setEditUser(null);
      toast({ title: "User updated" });
    },
    onError: (err: Error) => toast({ title: "Error", description: err.message, variant: "destructive" }),
  });

  const toggleRoleMut = useMutation({
    mutationFn: ({ userId, roleId }: { userId: number; roleId: number }) =>
      api.post<{ assigned: boolean }>(`/users/${userId}/roles/toggle`, { role_id: roleId }),
    onSuccess: (res) => {
      qc.invalidateQueries({ queryKey: ["platform-users"] });
      qc.invalidateQueries({ queryKey: ["user-roles-detail"] });
      const verb = (res as { assigned: boolean }).assigned ? "assigned" : "removed";
      toast({ title: `Role ${verb}` });
    },
    onError: (err: Error) => toast({ title: "Error", description: err.message, variant: "destructive" }),
  });

  const users = usersQ.data ?? [];
  const filtered = users.filter((u) => {
    if (typeFilter !== "all" && u.user_type !== typeFilter) return false;
    return true;
  });

  const typeCounts = {
    all: users.length,
    admin: users.filter((u) => u.user_type === "admin").length,
    teacher: users.filter((u) => u.user_type === "teacher").length,
    student: users.filter((u) => u.user_type === "student").length,
  };

  function exportCsv() {
    const rows = [["Name", "Email", "Type", "Roles", "Permissions"]];
    users.forEach((u) =>
      rows.push([
        u.name,
        u.email,
        u.user_type,
        u.roles.map((r) => r.name).join("; "),
        String(u.effective_permission_count),
      ]),
    );
    const csv = rows.map((r) => r.map((c) => `"${c}"`).join(",")).join("\n");
    const blob = new Blob([csv], { type: "text/csv" });
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download = "platform_users.csv";
    a.click();
    URL.revokeObjectURL(url);
  }

  const rolesData = rolesQ.data as { roles: RoleInfo[]; effective_permissions: unknown[] } | null;

  return (
    <div className="space-y-6">
      <div className="flex items-center justify-between">
        <div>
          <h1 className="text-2xl font-bold tracking-tight">Users</h1>
          <p className="text-muted-foreground">
            Manage all platform accounts — admins, teachers, and students.
          </p>
        </div>
        <div className="flex gap-2">
          <Button variant="outline" size="sm" onClick={exportCsv}>
            <Download className="h-4 w-4 mr-1" /> Export
          </Button>
          <Button size="sm" onClick={() => setCreateOpen(true)}>
            <Plus className="h-4 w-4 mr-1" /> Create User
          </Button>
        </div>
      </div>

      <div className="flex gap-3 items-center flex-wrap">
        <div className="relative flex-1 max-w-sm">
          <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
          <Input placeholder="Search by name..." className="pl-9" value={search} onChange={(e) => setSearch(e.target.value)} />
        </div>
        <Tabs value={typeFilter} onValueChange={setTypeFilter}>
          <TabsList>
            <TabsTrigger value="all">All ({typeCounts.all})</TabsTrigger>
            <TabsTrigger value="admin">Admins ({typeCounts.admin})</TabsTrigger>
            <TabsTrigger value="teacher">Teachers ({typeCounts.teacher})</TabsTrigger>
            <TabsTrigger value="student">Students ({typeCounts.student})</TabsTrigger>
          </TabsList>
        </Tabs>
      </div>

      {usersQ.isLoading ? (
        <div className="flex items-center justify-center min-h-[300px]">
          <div className="animate-spin rounded-full h-8 w-8 border-b-2 border-primary" />
        </div>
      ) : (
        <Card className="border-0 shadow-sm">
          <CardContent className="p-0">
            <Table>
              <TableHeader>
                <TableRow>
                  <TableHead>User</TableHead>
                  <TableHead>Type</TableHead>
                  <TableHead>Roles</TableHead>
                  <TableHead>Permissions</TableHead>
                  <TableHead>Status</TableHead>
                  <TableHead className="w-[120px]" />
                </TableRow>
              </TableHeader>
              <TableBody>
                {filtered.length === 0 && (
                  <TableRow>
                    <TableCell colSpan={6} className="text-center text-muted-foreground py-8">
                      No users found.
                    </TableCell>
                  </TableRow>
                )}
                {filtered.map((u) => {
                  const initials = u.name
                    .split(" ")
                    .map((w) => w[0])
                    .join("")
                    .slice(0, 2)
                    .toUpperCase();
                  return (
                    <TableRow key={u.id}>
                      <TableCell>
                        <div className="flex items-center gap-3">
                          <div className="h-8 w-8 rounded-full bg-primary/10 flex items-center justify-center text-xs font-semibold text-primary">
                            {initials}
                          </div>
                          <div>
                            <p className="text-sm font-medium">{u.name}</p>
                            <p className="text-xs text-muted-foreground">{u.email}</p>
                          </div>
                        </div>
                      </TableCell>
                      <TableCell>
                        <Badge variant="outline" className={`capitalize text-xs ${TYPE_COLORS[u.user_type] || TYPE_COLORS.user}`}>
                          {u.user_type}
                        </Badge>
                      </TableCell>
                      <TableCell>
                        <div className="flex flex-wrap gap-1">
                          {u.roles.length > 0
                            ? u.roles.map((r) => (
                                <Badge key={r.id} variant="secondary" className="text-xs">
                                  {r.name}
                                </Badge>
                              ))
                            : <span className="text-xs text-muted-foreground">No roles</span>}
                        </div>
                      </TableCell>
                      <TableCell>
                        <span className="text-sm">{u.effective_permission_count}</span>
                      </TableCell>
                      <TableCell>
                        <Badge variant={u.active ? "default" : "secondary"}>
                          {u.active ? "Active" : "Inactive"}
                        </Badge>
                      </TableCell>
                      <TableCell>
                        <div className="flex gap-1">
                          <Button variant="ghost" size="icon" className="h-8 w-8" title="Edit user" onClick={() => setEditUser(u)}>
                            <Pencil className="h-4 w-4" />
                          </Button>
                          <Button variant="ghost" size="icon" className="h-8 w-8" title="Manage roles" onClick={() => setRolesUser(u)}>
                            <UserCog className="h-4 w-4" />
                          </Button>
                        </div>
                      </TableCell>
                    </TableRow>
                  );
                })}
              </TableBody>
            </Table>
          </CardContent>
        </Card>
      )}

      {/* Create User Dialog */}
      <Dialog open={createOpen} onOpenChange={setCreateOpen}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle>Create Platform User</DialogTitle>
            <DialogDescription>
              Creates an internal Odoo user (res.users) with login access.
              For students/teachers, use the LMS pages instead.
            </DialogDescription>
          </DialogHeader>
          <div className="space-y-4">
            <div className="space-y-2">
              <Label>Full Name</Label>
              <Input value={form.name} onChange={(e) => setForm((f) => ({ ...f, name: e.target.value }))} placeholder="e.g. John Admin" />
            </div>
            <div className="space-y-2">
              <Label>Email (login)</Label>
              <Input type="email" value={form.email} onChange={(e) => setForm((f) => ({ ...f, email: e.target.value }))} placeholder="admin@encoach.com" />
            </div>
            <div className="space-y-2">
              <Label>Password</Label>
              <Input type="password" value={form.password} onChange={(e) => setForm((f) => ({ ...f, password: e.target.value }))} placeholder="Minimum 6 characters" />
            </div>
            <div className="space-y-2">
              <Label>Phone (optional)</Label>
              <Input value={form.phone} onChange={(e) => setForm((f) => ({ ...f, phone: e.target.value }))} placeholder="+1234567890" />
            </div>
          </div>
          <DialogFooter>
            <Button variant="outline" onClick={() => setCreateOpen(false)}>Cancel</Button>
            <Button
              disabled={createMut.isPending || !form.name.trim() || !form.email.trim()}
              onClick={() => createMut.mutate({ name: form.name.trim(), email: form.email.trim(), password: form.password || "admin123", phone: form.phone.trim() || undefined })}
            >
              {createMut.isPending ? "Creating..." : "Create User"}
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>

      {/* Edit User Dialog */}
      <Dialog open={!!editUser} onOpenChange={(v) => { if (!v) setEditUser(null); }}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle>Edit User</DialogTitle>
            <DialogDescription>Update profile for {editUser?.name}</DialogDescription>
          </DialogHeader>
          {editUser && (
            <div className="space-y-4">
              <div className="space-y-2">
                <Label>Name</Label>
                <Input
                  value={editUser.name}
                  onChange={(e) => setEditUser((u) => u ? { ...u, name: e.target.value } : null)}
                />
              </div>
              <div className="space-y-2">
                <Label>Email</Label>
                <Input
                  type="email"
                  value={editUser.email}
                  onChange={(e) => setEditUser((u) => u ? { ...u, email: e.target.value } : null)}
                />
              </div>
              <div className="space-y-2">
                <Label>Phone</Label>
                <Input
                  value={editUser.phone || ""}
                  onChange={(e) => setEditUser((u) => u ? { ...u, phone: e.target.value } : null)}
                />
              </div>
            </div>
          )}
          <DialogFooter>
            <Button variant="outline" onClick={() => setEditUser(null)}>Cancel</Button>
            <Button
              disabled={updateMut.isPending || !editUser?.name.trim()}
              onClick={() => {
                if (!editUser) return;
                updateMut.mutate({
                  id: editUser.id,
                  name: editUser.name.trim(),
                  email: editUser.email.trim(),
                  phone: editUser.phone?.trim() || undefined,
                });
              }}
            >
              {updateMut.isPending ? "Saving..." : "Save Changes"}
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>

      {/* Manage Roles Dialog */}
      <Dialog open={!!rolesUser} onOpenChange={(v) => { if (!v) setRolesUser(null); }}>
        <DialogContent className="max-w-lg">
          <DialogHeader>
            <DialogTitle>
              <div className="flex items-center gap-2">
                <Shield className="h-5 w-5" />
                Manage Roles — {rolesUser?.name}
              </div>
            </DialogTitle>
            <DialogDescription>Toggle roles on/off for this user.</DialogDescription>
          </DialogHeader>

          {rolesQ.isLoading ? (
            <div className="flex items-center justify-center py-8">
              <div className="animate-spin rounded-full h-6 w-6 border-b-2 border-primary" />
            </div>
          ) : rolesData?.roles ? (
            <div className="space-y-2 max-h-[400px] overflow-y-auto">
              {rolesData.roles.map((r) => (
                <label
                  key={r.id}
                  className={`flex items-center gap-3 p-3 rounded-lg border cursor-pointer transition-colors ${
                    r.assigned ? "border-primary bg-primary/5" : "border-border hover:bg-muted/50"
                  }`}
                >
                  <Checkbox
                    checked={r.assigned}
                    onCheckedChange={() => {
                      if (rolesUser) toggleRoleMut.mutate({ userId: rolesUser.id, roleId: r.id });
                    }}
                  />
                  <div className="flex-1">
                    <p className="text-sm font-medium">{r.name}</p>
                    {r.description && <p className="text-xs text-muted-foreground">{r.description}</p>}
                  </div>
                  <Badge variant="outline" className="text-xs shrink-0">
                    {r.permission_count} perms
                  </Badge>
                </label>
              ))}
            </div>
          ) : (
            <p className="text-sm text-muted-foreground text-center py-4">No roles available.</p>
          )}

          <DialogFooter>
            <Button variant="outline" onClick={() => setRolesUser(null)}>Close</Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
}