import { Component, OnInit } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { DragDropModule, CdkDragDrop, moveItemInArray, transferArrayItem } from '@angular/cdk/drag-drop';
import { SplitterModule } from 'primeng/splitter';
import { ButtonModule } from 'primeng/button';
import { DialogModule } from 'primeng/dialog';
import { InputTextModule } from 'primeng/inputtext';
import { DropdownModule } from 'primeng/dropdown';
import { TableModule } from 'primeng/table';
import { ToastModule } from 'primeng/toast';
import { MessageService } from 'primeng/api';

import { TemplateService, DocumentLayout, TemplateField } from '../services/template.service';

@Component({
  selector: 'app-templates',
  standalone: true,
  imports: [
    CommonModule,
    FormsModule,
    DragDropModule,
    SplitterModule,
    ButtonModule,
    DialogModule,
    InputTextModule,
    DropdownModule,
    TableModule,
    ToastModule
  ],
  providers: [MessageService],
  templateUrl: './templates.component.html',
  styleUrls: ['./templates.component.scss']
})
export class TemplatesComponent implements OnInit {
  // Document State
  documentId: string | null = null;
  layoutNodes: DocumentLayout[] = [];
  
  // Template State
  templateName: string = '';
  templateFields: TemplateField[] = [];
  mappings: { [fieldId: number]: DocumentLayout[] } = {};
  
  // UI State
  displayAddField: boolean = false;
  newField: TemplateField = { field_label: '', field_type: 'TEXT', display_order: 0, required_flag: false };
  fieldTypes = [
    { label: 'TEXT', value: 'TEXT' },
    { label: 'NUMBER', value: 'NUMBER' },
    { label: 'DATE', value: 'DATE' },
    { label: 'AMOUNT', value: 'AMOUNT' },
    { label: 'ADDRESS', value: 'ADDRESS' },
    { label: 'TABLE_COLUMN', value: 'TABLE_COLUMN' }
  ];

  constructor(
    private templateService: TemplateService,
    private messageService: MessageService
  ) {}

  ngOnInit(): void {}

  onFileUpload(event: any) {
    const file = event.target.files[0];
    if (file) {
      this.templateService.uploadDocument(file).subscribe({
        next: (res) => {
          this.documentId = res.id || res.pk_document_id;
          this.messageService.add({ severity: 'success', summary: 'Uploaded', detail: 'Document uploaded successfully.' });
          this.fetchLayout();
        },
        error: (err) => {
          this.messageService.add({ severity: 'error', summary: 'Error', detail: 'Upload failed.' });
        }
      });
    }
  }

  fetchLayout() {
    if (!this.documentId) return;
    this.templateService.getDocumentLayout(this.documentId).subscribe({
      next: (layouts) => {
        if (layouts.length === 0) {
          // Document might still be processing in the background Celery worker
          // Poll again after 2 seconds
          setTimeout(() => this.fetchLayout(), 2000);
          return;
        }
        this.layoutNodes = layouts;
        // Trigger auto-recognition
        this.autoRecognize();
      }
    });
  }
  
  autoRecognize() {
    if (!this.documentId) return;
    this.templateService.recognizeTemplate(this.documentId).subscribe({
      next: (res) => {
        if (res.templateMatched) {
          this.messageService.add({ severity: 'info', summary: 'Template Recognized', detail: `Confidence: ${res.confidence}%` });
          // In a full implementation, we'd load the template fields and populate the mappings.
        }
      }
    });
  }

  showAddFieldDialog() {
    this.newField = { field_label: '', field_type: 'TEXT', display_order: this.templateFields.length, required_flag: false };
    this.displayAddField = true;
  }

  addField() {
    if (!this.newField.field_label) return;
    this.newField.pk_template_field_id = new Date().getTime(); // mock ID until saved
    this.templateFields.push({ ...this.newField });
    this.mappings[this.newField.pk_template_field_id] = [];
    this.displayAddField = false;
  }

  saveTemplateAndMappings() {
    if (!this.templateName || this.templateName.trim() === '') {
      this.messageService.add({ severity: 'warn', summary: 'Warning', detail: 'Please provide a template name.' });
      return;
    }
    
    if (this.templateFields.length === 0) {
      this.messageService.add({ severity: 'warn', summary: 'Warning', detail: 'Please add at least one template field.' });
      return;
    }
    
    this.templateService.createTemplate({
      template_name: this.templateName,
      fields: this.templateFields
    }).subscribe({
      next: (res) => {
        // In a real scenario, we pass res.templateId and map the layoutNodes
        this.messageService.add({ severity: 'success', summary: 'Success', detail: 'Template & Mappings saved successfully.' });
      }
    });
  }

  // Drag and Drop Logic
  drop(event: CdkDragDrop<DocumentLayout[]>, fieldId?: number) {
    if (event.previousContainer === event.container) {
      moveItemInArray(event.container.data, event.previousIndex, event.currentIndex);
    } else {
      transferArrayItem(
        event.previousContainer.data,
        event.container.data,
        event.previousIndex,
        event.currentIndex,
      );
    }
  }
  
  getConnectedDropLists() {
    // Return all field ID strings as drop lists
    return this.templateFields.map(f => 'field-' + f.pk_template_field_id);
  }
}