import React, { useRef, useState } from "react";
import { Button } from "./ui/button";
import { Input } from "./ui/input";
import { Label } from "./ui/label";
import { Dialog, DialogContent, DialogTitle } from "./ui/dialog";
import type { User as UserType } from "../App";
import { toast } from "sonner";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "./ui/select";
import { ChevronLeft, ChevronRight } from "lucide-react";

interface OnboardingProps {
  user: UserType;
  onComplete: (user: UserType) => void;
  onSkip: () => void;
}

// ✅ Bio step removed. Total steps: 4
const TOTAL_STEPS = 4;

export function Onboarding({ user, onComplete, onSkip }: OnboardingProps) {
  const [currentStep, setCurrentStep] = useState(1);

  // Step 1: Basic
  const [name, setName] = useState(user.name ?? "");
  const [email, setEmail] = useState(user.email ?? "");

  // Step 2: Academic
  const [studentId, setStudentId] = useState(user.studentId ?? "");
  const [department, setDepartment] = useState(user.department ?? "");
  const [yearLevel, setYearLevel] = useState(user.yearLevel ?? "");
  const [major, setMajor] = useState(user.major ?? "");

  // Step 3: Preferences (controlled, not defaultValue-only)
  const [learningStyle, setLearningStyle] = useState(user.learningStyle ?? "visual");
  const [learningPace, setLearningPace] = useState(user.learningPace ?? "moderate");

  // Step 4: Photo
  const [photoPreview, setPhotoPreview] = useState<string | null>(user.avatarUrl ?? null);
  const fileInputRef = useRef<HTMLInputElement>(null);

  const handlePhotoSelect = (e: React.ChangeEvent<HTMLInputElement>) => {
    const file = e.target.files?.[0];
    if (!file) return;

    if (!file.type.startsWith("image/")) {
      toast.error("Please select an image file");
      return;
    }
    if (file.size > 2 * 1024 * 1024) {
      toast.error("File size must be less than 2MB");
      return;
    }

    const reader = new FileReader();
    reader.onload = (ev) => setPhotoPreview(ev.target?.result as string);
    reader.readAsDataURL(file);
  };

  const handleChangePhotoClick = () => fileInputRef.current?.click();

  const handleNext = () => {
    if (currentStep < TOTAL_STEPS) setCurrentStep((s) => s + 1);
    else handleComplete();
  };

  const handlePrevious = () => {
    if (currentStep > 1) setCurrentStep((s) => s - 1);
  };

  const handleSkip = () => onSkip();

  const handleComplete = () => {
    if (!name.trim() || !email.trim()) {
      toast.error("Please fill in all required fields");
      return;
    }

    // ✅ IMPORTANT: Onboarding must NOT overwrite bio.
    // We merge ...user first to preserve any Clare-generated bio.
    const next: UserType = {
      ...user,
      name: name.trim(),
      email: email.trim(),

      studentId: studentId.trim() || undefined,
      department: department.trim() || undefined,
      yearLevel: yearLevel || undefined,
      major: major.trim() || undefined,

      learningStyle: learningStyle || undefined,
      learningPace: learningPace || undefined,

      avatarUrl: photoPreview || undefined,

      onboardingCompleted: true,
      // ❌ do NOT set bio here
    };

    onComplete(next);
    toast.success("Profile setup completed!");
  };

  const renderStepContent = () => {
    switch (currentStep) {
      case 1:
        return (
          <div className="space-y-4">
            <h3 className="text-lg font-medium">Basic Information</h3>
            <p className="text-sm text-muted-foreground">Let's start with your basic information</p>

            <div className="space-y-4">
              <div className="space-y-2">
                <Label htmlFor="onboarding-name">Full Name *</Label>
                <Input
                  id="onboarding-name"
                  value={name}
                  onChange={(e) => setName(e.target.value)}
                  placeholder="Enter your full name"
                />
              </div>

              <div className="space-y-2">
                <Label htmlFor="onboarding-email">Email *</Label>
                <Input
                  id="onboarding-email"
                  type="email"
                  value={email}
                  onChange={(e) => setEmail(e.target.value)}
                  placeholder="Enter your email"
                />
              </div>
            </div>
          </div>
        );

      case 2:
        return (
          <div className="space-y-4">
            <h3 className="text-lg font-medium">Academic Background</h3>
            <p className="text-sm text-muted-foreground">Tell us about your academic information</p>

            <div className="space-y-4">
              <div className="space-y-2">
                <Label htmlFor="onboarding-student-id">Student ID</Label>
                <Input
                  id="onboarding-student-id"
                  value={studentId}
                  onChange={(e) => setStudentId(e.target.value)}
                  placeholder="Enter your student ID"
                />
              </div>

              <div className="space-y-2">
                <Label htmlFor="onboarding-department">Department</Label>
                <Input
                  id="onboarding-department"
                  value={department}
                  onChange={(e) => setDepartment(e.target.value)}
                  placeholder="Enter your department"
                />
              </div>

              <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
                <div className="space-y-2">
                  <Label htmlFor="onboarding-year">Year Level</Label>
                  <Select value={yearLevel} onValueChange={setYearLevel}>
                    <SelectTrigger id="onboarding-year">
                      <SelectValue placeholder="Select year level" />
                    </SelectTrigger>
                    <SelectContent>
                      <SelectItem value="1st Year">1st Year</SelectItem>
                      <SelectItem value="2nd Year">2nd Year</SelectItem>
                      <SelectItem value="3rd Year">3rd Year</SelectItem>
                      <SelectItem value="4th Year">4th Year</SelectItem>
                      <SelectItem value="Graduate">Graduate</SelectItem>
                    </SelectContent>
                  </Select>
                </div>

                <div className="space-y-2">
                  <Label htmlFor="onboarding-major">Major</Label>
                  <Input
                    id="onboarding-major"
                    value={major}
                    onChange={(e) => setMajor(e.target.value)}
                    placeholder="Enter your major"
                  />
                </div>
              </div>
            </div>
          </div>
        );

      case 3:
        return (
          <div className="space-y-4">
            <h3 className="text-lg font-medium">Learning Preferences</h3>
            <p className="text-sm text-muted-foreground">Help us personalize your learning experience</p>

            <div className="space-y-4">
              <div className="space-y-2">
                <Label htmlFor="onboarding-learning-style">Preferred Learning Style</Label>
                <Select value={learningStyle} onValueChange={setLearningStyle}>
                  <SelectTrigger id="onboarding-learning-style">
                    <SelectValue />
                  </SelectTrigger>
                  <SelectContent>
                    <SelectItem value="visual">Visual</SelectItem>
                    <SelectItem value="auditory">Auditory</SelectItem>
                    <SelectItem value="reading">Reading/Writing</SelectItem>
                    <SelectItem value="kinesthetic">Kinesthetic</SelectItem>
                  </SelectContent>
                </Select>
              </div>

              <div className="space-y-2">
                <Label htmlFor="onboarding-pace">Learning Pace</Label>
                <Select value={learningPace} onValueChange={setLearningPace}>
                  <SelectTrigger id="onboarding-pace">
                    <SelectValue />
                  </SelectTrigger>
                  <SelectContent>
                    <SelectItem value="slow">Slow & Steady</SelectItem>
                    <SelectItem value="moderate">Moderate</SelectItem>
                    <SelectItem value="fast">Fast-paced</SelectItem>
                  </SelectContent>
                </Select>
              </div>
            </div>
          </div>
        );

      case 4:
        return (
          <div className="space-y-4">
            <h3 className="text-lg font-medium">Profile Picture</h3>
            <p className="text-sm text-muted-foreground">Upload a photo to personalize your profile (optional)</p>

            <div className="flex items-center gap-4">
              <div className="w-24 h-24 rounded-full bg-gradient-to-br from-red-500 to-orange-500 flex items-center justify-center text-white text-3xl overflow-hidden">
                {photoPreview ? (
                  <img src={photoPreview} alt="Profile" className="w-full h-full object-cover" />
                ) : (
                  (name?.charAt(0) || "U").toUpperCase()
                )}
              </div>

              <div>
                <input
                  ref={fileInputRef}
                  type="file"
                  accept="image/jpeg,image/png,image/gif,image/webp"
                  onChange={handlePhotoSelect}
                  className="hidden"
                />
                <Button variant="outline" size="sm" onClick={handleChangePhotoClick}>
                  Change Photo
                </Button>
                <p className="text-xs text-muted-foreground mt-1">JPG, PNG or GIF. Max size 2MB</p>
              </div>
            </div>
          </div>
        );

      default:
        return null;
    }
  };

  return (
    <Dialog open onOpenChange={(open) => { if (!open) onSkip(); }}>
      <DialogContent
        className="sm:max-w-lg p-0 gap-0 max-h-[90vh] overflow-hidden"
        style={{ zIndex: 1001 }}
        overlayClassName="!inset-0 !z-[99]"
        overlayStyle={{ top: 0, left: 0, right: 0, bottom: 0, zIndex: 99, position: "fixed" }}
      >
        <div className="flex flex-col max-h-[90vh]">
          {/* Header */}
          <div className="border-b border-border p-4 flex items-center justify-between flex-shrink-0">
            <div className="flex-1">
              <DialogTitle className="text-xl font-medium">Welcome! Let's set up your profile</DialogTitle>
              <p className="text-sm text-muted-foreground mt-1">
                Step {currentStep} of {TOTAL_STEPS}
              </p>
            </div>

            {/* Progress indicator */}
            <div className="flex gap-1">
              {Array.from({ length: TOTAL_STEPS }).map((_, index) => (
                <div
                  key={index}
                  className={`h-2 w-2 rounded-full transition-colors ${index + 1 <= currentStep ? "bg-primary" : "bg-muted"}`}
                />
              ))}
            </div>
          </div>

          {/* Content */}
          <div className="p-6 overflow-y-auto flex-1">{renderStepContent()}</div>

          {/* Footer */}
          <div className="border-t border-border p-4 flex justify-between gap-2 flex-shrink-0">
            <div className="flex gap-2">
              {currentStep > 1 && (
                <Button variant="outline" onClick={handlePrevious}>
                  <ChevronLeft className="h-4 w-4 mr-1" />
                  Previous
                </Button>
              )}
            </div>

            <div className="flex gap-2">
              <Button variant="outline" onClick={handleSkip}>
                Skip all
              </Button>
              <Button onClick={handleNext}>
                {currentStep === TOTAL_STEPS ? "Complete" : "Next Step"}
                {currentStep < TOTAL_STEPS && <ChevronRight className="h-4 w-4 ml-1" />}
              </Button>
            </div>
          </div>
        </div>
      </DialogContent>
    </Dialog>
  );
}