import {
  Component,
  ElementRef,
  computed,
  effect,
  inject,
  input,
  signal,
  viewChild,
} from '@angular/core';
import { NgIcon } from '@ng-icons/core';
import type { FileEntry } from '@shared/types';
import { formatDate, formatSize } from '../format';
import { PanelsService, type Side, type SortKey } from '../panels.service';

@Component({
  selector: 'app-file-panel',
  imports: [NgIcon],
  templateUrl: './file-panel.html',
  host: { class: 'flex min-w-0 flex-1 flex-col overflow-hidden' },
})
export class FilePanel {
  readonly side = input.required<Side>();

  readonly panels = inject(PanelsService);
  readonly panel = computed(() => this.panels.get(this.side()));
  readonly isActive = computed(() => this.panels.activeSide() === this.side());

  readonly pathDraft = signal('');

  private readonly listEl = viewChild.required<ElementRef<HTMLDivElement>>('list');
  private lastClickedIndex = 0;

  readonly formatSize = formatSize;
  readonly formatDate = formatDate;

  constructor() {
    // keep the editable path bar in sync with the actual cwd
    effect(() => this.pathDraft.set(this.panel().cwd()));
    // focus follows the active side (Tab switches panels)
    effect(() => {
      if (this.isActive()) this.listEl().nativeElement.focus();
    });
  }

  activate(): void {
    this.panels.activeSide.set(this.side());
  }

  iconFor(entry: FileEntry): string {
    return entry.type === 'dir' ? 'mynaFolder' : 'mynaFile';
  }

  isSelected(entry: FileEntry): boolean {
    return this.panel().selected().has(entry.name);
  }

  sortIndicator(key: SortKey): string {
    if (this.panel().sortKey() !== key) return '';
    return this.panel().sortAsc() ? '↑' : '↓';
  }

  commitPath(): void {
    const value = this.pathDraft().trim();
    if (value) void this.panel().load(value);
    this.listEl().nativeElement.focus();
  }

  resetPath(): void {
    this.pathDraft.set(this.panel().cwd());
    this.listEl().nativeElement.focus();
  }

  rowClick(event: MouseEvent, index: number): void {
    this.activate();
    const panel = this.panel();
    if (event.shiftKey) {
      panel.selectRange(this.lastClickedIndex, index);
    } else if (event.metaKey || event.ctrlKey) {
      const entry = panel.sorted()[index];
      if (entry) panel.toggleSelect(entry.name);
    } else {
      panel.clearSelection();
    }
    panel.cursor.set(index);
    this.lastClickedIndex = index;
  }

  openAt(index: number): void {
    const entry = this.panel().sorted()[index];
    if (entry) this.panel().open(entry);
  }

  onKeydown(event: KeyboardEvent): void {
    const panel = this.panel();
    const key = event.key;

    if (key === 'Tab') {
      event.preventDefault();
      this.panels.activeSide.set(this.panels.otherSide(this.side()));
      return;
    }
    if ((event.metaKey || event.ctrlKey) && key.toLowerCase() === 'a') {
      event.preventDefault();
      panel.selectAll();
      return;
    }

    switch (key) {
      case 'ArrowDown':
        panel.moveCursor(1);
        break;
      case 'ArrowUp':
        panel.moveCursor(-1);
        break;
      case 'PageDown':
        panel.moveCursor(20);
        break;
      case 'PageUp':
        panel.moveCursor(-20);
        break;
      case 'Home':
        panel.cursor.set(0);
        break;
      case 'End':
        panel.cursor.set(Math.max(0, panel.sorted().length - 1));
        break;
      case ' ':
        {
          const entry = panel.sorted()[panel.cursor()];
          if (entry) panel.toggleSelect(entry.name);
          panel.moveCursor(1);
        }
        break;
      case 'Enter':
        this.openAt(panel.cursor());
        return void event.preventDefault();
      case 'Backspace':
        panel.up();
        break;
      default:
        return; // let unhandled keys through
    }
    event.preventDefault();
    this.scrollCursorIntoView();
  }

  private scrollCursorIntoView(): void {
    const row = this.listEl().nativeElement.querySelector(
      `[data-index="${this.panel().cursor()}"]`,
    );
    row?.scrollIntoView({ block: 'nearest' });
  }
}