import { Component, OnInit } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { Observable } from 'rxjs';
import { GridModule } from '@progress/kendo-angular-grid';
import { InputsModule } from '@progress/kendo-angular-inputs';
import { ButtonsModule } from '@progress/kendo-angular-buttons';
import { DropDownsModule } from '@progress/kendo-angular-dropdowns';
import { DateInputsModule } from '@progress/kendo-angular-dateinputs';
import { OfferingSessionApiService } from '../../services/offering-session-api.service';
import { GivingCategoryApiService } from '../../services/giving-category-api.service';
import { MemberApiService } from '../../../members/services/member-api.service';
import { MemberListItemDto, memberDisplayName } from '../../../members/models/member.model';
import { MemberQuickAddDialogComponent } from '../../components/member-quick-add-dialog/member-quick-add-dialog.component';
import {
  GivingCategoryDto, PaymentMethod, OfferingBufferLine, CreateOfferingSessionRequest,
  OfferingSessionListItemDto, OfferingSessionDto,
} from '../../models/giving.model';

interface MemberOption { id: number; displayName: string; }

@Component({
  selector: 'app-offering-session-page',
  standalone: true,
  imports: [
    CommonModule, FormsModule, GridModule, InputsModule, ButtonsModule,
    DropDownsModule, DateInputsModule, MemberQuickAddDialogComponent,
  ],
  templateUrl: './offering-session-page.component.html',
  styleUrls: ['./offering-session-page.component.scss'],
})
export class OfferingSessionPageComponent implements OnInit {
  sessionDate: Date = new Date();
  dateConflict = false;
  categories: GivingCategoryDto[] = [];
  readonly paymentMethods: PaymentMethod[] = ['Cash', 'Check', 'Zelle', 'PayPal', 'Other'];

  memberResults: MemberOption[] = [];
  selectedMemberId: number | null = null;
  selectedMemberName: string | null = null;
  entry = this.blankEntry();

  buffer: OfferingBufferLine[] = [];
  editingIndex: number | null = null;

  cashTotal = 0;
  checkTotal = 0;
  notes: string | null = null;

  showQuickAdd = false;
  submitting = false;

  sessions: OfferingSessionListItemDto[] = [];
  editingSessionId: number | null = null;

  constructor(
    private api: OfferingSessionApiService,
    private categoryApi: GivingCategoryApiService,
    private memberApi: MemberApiService,
  ) {}

  ngOnInit(): void {
    this.categoryApi.getAll(false).subscribe(c => {
      this.categories = c;
      this.entry.givingCategoryId = c[0]?.id ?? 0;
    });
    this.checkDate();
    this.loadSessions();
  }

  get systemTotal(): number { return this.buffer.reduce((s, l) => s + (l.amount || 0), 0); }
  get difference(): number { return (this.cashTotal + this.checkTotal) - this.systemTotal; }

  checkDate(): void {
    this.api.checkDate(this.toIso(this.sessionDate)).subscribe(r => this.dateConflict = r.exists);
  }

  loadSessions(): void {
    this.api.getPaged(1, 20).subscribe(r => this.sessions = r.items);
  }

  reopenAndEdit(s: OfferingSessionListItemDto): void {
    if (s.status !== 'Submitted') return;
    this.api.reopen(s.id).subscribe({
      next: () => this.api.getById(s.id).subscribe(dto => this.loadIntoBuffer(dto)),
      error: (err: { error?: { message?: string } }) => alert(err?.error?.message ?? 'Reopen failed.'),
    });
  }

  // Already a Draft (e.g. a session reopened then left) — load it straight back in, no reopen.
  continueEditDraft(s: OfferingSessionListItemDto): void {
    if (s.status !== 'Draft') return;
    this.api.getById(s.id).subscribe({
      next: dto => this.loadIntoBuffer(dto),
      error: (err: { error?: { message?: string } }) => alert(err?.error?.message ?? 'Load failed.'),
    });
  }

  private loadIntoBuffer(dto: OfferingSessionDto): void {
    this.editingSessionId = dto.id;
    this.sessionDate = new Date(dto.sessionDate + 'T00:00:00');
    this.dateConflict = false;
    this.cashTotal = dto.cashTotal;
    this.checkTotal = dto.checkTotal;
    this.notes = dto.notes;
    this.buffer = dto.givings.map(g => ({
      memberId: g.memberId, givingCategoryId: g.givingCategoryId, amount: g.amount,
      paymentMethod: g.paymentMethod, checkNumber: g.checkNumber,
      zelleReferenceCode: g.zelleReferenceCode, payPalTransactionId: g.payPalTransactionId,
      isAnonymous: g.isAnonymous, notes: g.notes,
      memberName: g.memberName, categoryName: g.categoryName,
    }));
    this.resetEntry();
  }

  cancelEdit(): void {
    this.editingSessionId = null;
    this.editingIndex = null;
    this.buffer = []; this.cashTotal = 0; this.checkTotal = 0; this.notes = null;
    this.sessionDate = new Date();
    this.checkDate();
    // The reopened session is now a server-side Draft — refresh so its "Continue editing" appears.
    this.loadSessions();
  }

  onMemberFilter(term: string): void {
    if (!term) { this.memberResults = []; return; }
    this.memberApi.getPaged({ search: term, pageSize: 10 }).subscribe(r =>
      this.memberResults = r.items.map((m: MemberListItemDto) => ({ id: m.id, displayName: memberDisplayName(m) })));
  }

  onMemberSelected(id: number | null): void {
    this.selectedMemberId = id ?? null;
    this.entry.memberId = this.selectedMemberId;
    this.selectedMemberName = this.memberResults.find(m => m.id === id)?.displayName ?? null;
    if (id != null) this.entry.isAnonymous = false;
  }

  markAnonymous(): void {
    this.entry.isAnonymous = true; this.entry.memberId = null;
    this.selectedMemberId = null; this.selectedMemberName = null;
  }

  clearAnonymous(): void {
    this.entry.isAnonymous = false;
  }

  addLine(): void {
    if (this.entry.amount <= 0) return;
    if (this.entry.paymentMethod === 'Check' && !this.entry.checkNumber) return;
    const cat = this.categories.find(c => c.id === this.entry.givingCategoryId);
    const line: OfferingBufferLine = {
      ...this.entry,
      memberName: this.entry.isAnonymous ? null : this.selectedMemberName,
      categoryName: cat?.name_en ?? '',
    };
    if (this.editingIndex !== null) { this.buffer[this.editingIndex] = line; this.editingIndex = null; }
    else { this.buffer = [...this.buffer, line]; }
    this.resetEntry();
  }

  editLine(i: number): void {
    const l = this.buffer[i];
    this.entry = { ...l };
    this.selectedMemberId = l.memberId;
    this.selectedMemberName = l.memberName;
    // Seed the dropdown so the giver name stays visible while editing the line.
    this.memberResults = (l.memberId && l.memberName)
      ? [{ id: l.memberId, displayName: l.memberName }]
      : [];
    this.editingIndex = i;
  }

  removeLine(i: number): void { this.buffer = this.buffer.filter((_, idx) => idx !== i); }

  onMemberQuickCreated(m: MemberListItemDto): void {
    this.showQuickAdd = false;
    const opt: MemberOption = { id: m.id, displayName: memberDisplayName(m) };
    this.memberResults = [opt, ...this.memberResults.filter(x => x.id !== m.id)];
    this.onMemberSelected(m.id);
  }

  submit(): void {
    if (this.buffer.length === 0 || (this.editingSessionId == null && this.dateConflict)) return;
    this.submitting = true;
    const req: CreateOfferingSessionRequest = {
      sessionDate: this.toIso(this.sessionDate),
      cashTotal: this.cashTotal,
      checkTotal: this.checkTotal,
      notes: this.notes,
      givings: this.buffer.map(l => ({
        memberId: l.memberId,
        givingCategoryId: l.givingCategoryId,
        amount: l.amount,
        paymentMethod: l.paymentMethod,
        checkNumber: l.checkNumber,
        zelleReferenceCode: l.zelleReferenceCode,
        payPalTransactionId: l.payPalTransactionId,
        isAnonymous: l.isAnonymous,
        notes: l.notes,
      })),
    };
    const obs: Observable<unknown> = this.editingSessionId != null
      ? this.api.replace(this.editingSessionId, req)
      : this.api.create(req);
    obs.subscribe({
      next: () => {
        this.submitting = false;
        alert(this.editingSessionId != null ? 'Offering session updated.' : 'Offering session submitted.');
        this.editingSessionId = null;
        this.editingIndex = null;
        this.buffer = []; this.cashTotal = 0; this.checkTotal = 0; this.notes = null;
        this.sessionDate = new Date();
        this.checkDate();
        this.loadSessions();
      },
      error: (err: { error?: { message?: string } }) => {
        this.submitting = false;
        alert(err?.error?.message ?? 'Submit failed.');
      },
    });
  }

  private resetEntry(): void {
    this.editingIndex = null;
    this.selectedMemberId = null; this.selectedMemberName = null; this.memberResults = [];
    this.entry = this.blankEntry();
    this.entry.givingCategoryId = this.categories[0]?.id ?? 0;
  }

  private blankEntry(): OfferingBufferLine {
    return {
      memberId: null, givingCategoryId: 0, amount: 0, paymentMethod: 'Cash',
      checkNumber: null, zelleReferenceCode: null, payPalTransactionId: null,
      isAnonymous: false, notes: null, memberName: null, categoryName: '',
    };
  }

  // Format using LOCAL date components — NOT toISOString(), which converts to UTC and
  // rolls the date forward a day for behind-UTC users when the Date carries an evening time.
  private toIso(d: Date): string {
    const y = d.getFullYear();
    const m = String(d.getMonth() + 1).padStart(2, '0');
    const day = String(d.getDate()).padStart(2, '0');
    return `${y}-${m}-${day}`;
  }
}