import { Component, OnInit, OnDestroy } from '@angular/core';
import { FormBuilder, FormGroup, ReactiveFormsModule, Validators } from '@angular/forms';
import { CommonModule } from '@angular/common';
import { Router, RouterModule } from '@angular/router';
import { ExtractionService } from '../../services/extraction.service';
import { SessionService, User } from '../../services/session.service';
import { ExtractionResponse, ClaimSubmission } from '../../services/extraction';
import { LucideAngularModule, ShieldCheck, AlertCircle, CheckCircle, ArrowLeft, Eye, EyeOff, Wand2 } from 'lucide-angular';
import { Subscription } from 'rxjs';

@Component({
  selector: 'app-claim-form',
  standalone: true,
  imports: [CommonModule, ReactiveFormsModule, LucideAngularModule, RouterModule],
  templateUrl: './claim-form.component.html',
  styleUrls: ['./claim-form.component.css']
})
export class ClaimFormComponent implements OnInit, OnDestroy {
  claimForm: FormGroup;
  currentUser: User | null = null;
  previewUrl: string | null = null;
  selectedFile: File | null = null;
  extractionResponse: ExtractionResponse | null = null;
  isLoading = false;
  isSubmitting = false;
  isDragging = false;
  showRawJson = false;

  private amountSpentSub: Subscription | null = null;

  readonly ShieldCheck = ShieldCheck;
  readonly AlertCircle = AlertCircle;
  readonly CheckCircle = CheckCircle;
  readonly ArrowLeft = ArrowLeft;
  readonly Eye = Eye;
  readonly EyeOff = EyeOff;
  readonly Wand2 = Wand2;
  errorMessage: string | null = null;

  constructor(
    private fb: FormBuilder,
    private extractionService: ExtractionService,
    private sessionService: SessionService,
    private router: Router
  ) {
    this.claimForm = this.fb.group({
      provider_name: ['', Validators.required],
      visit_date: ['', Validators.required],
      amount_spent: ['', [Validators.required, Validators.min(0.01)]],
      amount_claimed: [{ value: 0, disabled: true }],
      currency: ['MYR']
    });
  }

  ngOnInit(): void {
    this.currentUser = this.sessionService.getCurrentUser();
    if (!this.currentUser) {
      this.router.navigate(['/']);
      return;
    }

    this.amountSpentSub = this.claimForm.get('amount_spent')?.valueChanges.subscribe(() => {
      this.calculateClaimable();
    }) || null;
  }

  ngOnDestroy(): void {
    if (this.amountSpentSub) {
      this.amountSpentSub.unsubscribe();
    }
  }

  calculateClaimable(): void {
    if (!this.currentUser) return;
    
    const spent = Number(this.claimForm.get('amount_spent')?.value) || 0;
    const remaining = this.currentUser.medical_allowance;
    const claimable = Math.min(spent, remaining);
    
    this.claimForm.patchValue({ amount_claimed: claimable }, { emitEvent: false });
  }

  onDragOver(event: DragEvent): void {
    event.preventDefault();
    event.stopPropagation();
    this.isDragging = true;
  }

  onDragLeave(event: DragEvent): void {
    event.preventDefault();
    event.stopPropagation();
    this.isDragging = false;
  }

  onDrop(event: DragEvent): void {
    event.preventDefault();
    event.stopPropagation();
    this.isDragging = false;
    
    const files = event.dataTransfer?.files;
    if (files && files.length > 0) {
      this.handleFileSelection(files[0]);
    }
  }

  onFileSelected(event: any): void {
    const file: File = event.target.files[0];
    if (file) {
      this.handleFileSelection(file);
    }
  }

  private handleFileSelection(file: File): void {
    if (!this.currentUser) return;
    this.selectedFile = file;
    this.previewUrl = URL.createObjectURL(file);
    this.extractionResponse = null; // reset if existing
    this.errorMessage = null;
  }

  autoFillWithAI(): void {
    if (!this.currentUser || !this.selectedFile) return;

    this.isLoading = true;
    this.errorMessage = null;
    
    this.extractionService.extractData(this.selectedFile, this.currentUser.name, this.currentUser.department).subscribe({
      next: (response) => {
        this.extractionResponse = response;
        this.claimForm.patchValue({
          provider_name: response.provider_name,
          visit_date: response.visit_date,
          amount_spent: response.total_amount,
          currency: response.currency || 'MYR'
        });
        // The valueChanges subscription will trigger calculateClaimable automatically
        this.isLoading = false;
      },
      error: (err: Error) => {
        console.error('Extraction failed', err);
        this.errorMessage = err.message;
        this.isLoading = false;
      }
    });
  }

  onSubmit(): void {
    if (this.claimForm.invalid || !this.currentUser) return;

    this.isSubmitting = true;
    const formData = this.claimForm.getRawValue();
    
    const submissionData: ClaimSubmission = {
      provider_name: formData.provider_name,
      visit_date: formData.visit_date,
      amount_spent: Number(formData.amount_spent),
      currency: formData.currency,
      extraction_data: this.extractionResponse
    };

    this.extractionService.submitClaim(submissionData, this.currentUser.id).subscribe({
      next: () => {
        this.isSubmitting = false;
        this.router.navigate(['/']);
      },
      error: (err) => {
        console.error('Submission failed', err);
        this.errorMessage = 'Failed to submit claim. Please try again.';
        this.isSubmitting = false;
      }
    });
  }

  get rawJson(): string {
    return JSON.stringify(this.extractionResponse, null, 2);
  }
}