import {
  ChangeDetectionStrategy,
  Component,
  ElementRef,
  Injector,
  afterNextRender,
  computed,
  inject,
  input,
  model,
  signal,
} from '@angular/core';
import { formatNumber, parseDecimal } from '../../core/format';
import type { ListRow } from '../list/list.types';
import { ValueHelp } from '../value-help/value-help';
import type { GridColumn, GridLine, GridMultiAdd } from './grid.types';

interface LookupTarget {
  row: number;
  column: GridColumn;
}

/**
 * Grilla editable de líneas de un documento. Las celdas se confirman al salir de ellas o con Enter
 * (que baja a la misma columna de la fila siguiente y crea una línea al llegar a la última).
 * Flechas ↑/↓ cambian de fila; F4 abre la lista de valores de la celda.
 */
@Component({
  selector: 'sbo-lines-grid',
  changeDetection: ChangeDetectionStrategy.OnPush,
  imports: [ValueHelp],
  templateUrl: './lines-grid.html',
  styleUrl: './lines-grid.css',
})
export class LinesGrid {
  readonly columns = input.required<readonly GridColumn[]>();
  readonly lines = model<readonly GridLine[]>([]);
  /** Documento cerrado o cancelado: sin edición ni botones de añadir/quitar. */
  readonly readonly = input(false);
  /** Línea nueva con sus valores por defecto. */
  readonly newLine = input<() => GridLine>(() => ({}));
  /** Recalcula la línea tras un cambio (ej. total = cantidad × precio). */
  readonly recalc = input<((line: GridLine, changedKey: string) => GridLine) | undefined>(undefined);
  readonly multiAdd = input<GridMultiAdd>();
  readonly addLabel = input('Añadir línea');

  private readonly host = inject<ElementRef<HTMLElement>>(ElementRef);
  private readonly injector = inject(Injector);

  protected readonly lookupTarget = signal<LookupTarget | null>(null);
  protected readonly multiOpen = signal(false);
  protected readonly lookup = computed(() => this.lookupTarget()?.column.lookup?.config);

  protected cellText(line: GridLine, column: GridColumn): string {
    if (column.format) return column.format(line);
    const value = line[column.key];
    if (column.type === 'number') return formatNumber(value, column.decimals);
    return value === null || value === undefined ? '' : String(value);
  }

  protected isReadonly(line: GridLine, column: GridColumn): boolean {
    if (this.readonly() || column.format) return true;
    return typeof column.readonly === 'function' ? column.readonly(line) : !!column.readonly;
  }

  protected firstEditable(): number {
    return this.columns().findIndex((c) => !c.format && !c.readonly);
  }

  // --- edición ---------------------------------------------------------------------------

  protected numberFocus(event: FocusEvent, line: GridLine, column: GridColumn): void {
    if (this.isReadonly(line, column)) return;
    const input = event.target as HTMLInputElement;
    const value = line[column.key];
    input.value = value === null || value === undefined ? '' : String(value);
    queueMicrotask(() => input.select());
  }

  /** Confirma el valor de una celda; si no cambió, no hace nada. */
  protected commit(row: number, column: GridColumn, input: HTMLInputElement): void {
    const line = this.lines()[row];
    if (!line || this.isReadonly(line, column)) return;
    const text = input.value;

    if (column.type === 'number') {
      const parsed = text.trim() === '' ? null : parseDecimal(text);
      if (text.trim() !== '' && parsed === null) {
        input.value = this.cellText(line, column); // no es un número: se conserva el anterior
        return;
      }
      const d = column.decimals;
      const value = parsed === null || d === undefined ? parsed : Math.round((parsed + Number.EPSILON) * 10 ** d) / 10 ** d;
      this.update(row, column.key, value);
      input.value = formatNumber(value, column.decimals);
    } else if (text !== String(line[column.key] ?? '')) {
      this.update(row, column.key, text);
    }
  }

  private update(row: number, key: string, value: unknown): void {
    const current = this.lines()[row];
    if (!current || current[key] === value) return;
    this.replace(row, { ...current, [key]: value }, key);
  }

  private replace(row: number, line: GridLine, key: string): void {
    const next = this.recalc()?.(line, key) ?? line;
    this.lines.update((ls) => ls.map((l, i) => (i === row ? next : l)));
  }

  // --- filas -----------------------------------------------------------------------------

  protected add(): void {
    if (this.readonly()) return;
    const row = this.lines().length;
    this.lines.update((ls) => [...ls, this.recalc()?.(this.newLine()(), '') ?? this.newLine()()]);
    this.focusCell(row, this.firstEditable());
  }

  protected remove(row: number): void {
    if (this.readonly()) return;
    this.lines.update((ls) => ls.filter((_, i) => i !== row));
  }

  // --- teclado ---------------------------------------------------------------------------

  protected onKey(event: KeyboardEvent, row: number, col: number): void {
    const column = this.columns()[col];
    const input = event.target as HTMLInputElement;
    switch (event.key) {
      case 'Enter': {
        event.preventDefault();
        this.commit(row, column, input);
        if (row + 1 >= this.lines().length) this.add();
        else this.focusCell(row + 1, col);
        break;
      }
      case 'ArrowDown':
        if (row + 1 < this.lines().length) {
          event.preventDefault();
          this.commit(row, column, input);
          this.focusCell(row + 1, col);
        }
        break;
      case 'ArrowUp':
        if (row > 0) {
          event.preventDefault();
          this.commit(row, column, input);
          this.focusCell(row - 1, col);
        }
        break;
      case 'F4':
        if (column.lookup) {
          event.preventDefault();
          this.openLookup(row, column);
        }
        break;
    }
  }

  /** Enfoca una celda; si la fila aún no está dibujada (línea recién creada), espera al render. */
  protected focusCell(row: number, col: number): void {
    if (col < 0) return;
    const focus = (): boolean => {
      const cell = this.host.nativeElement.querySelector<HTMLInputElement>(`input[data-r="${row}"][data-c="${col}"]`);
      cell?.focus();
      return !!cell;
    };
    if (!focus()) afterNextRender(() => void focus(), { injector: this.injector });
  }

  // --- listas de valores -----------------------------------------------------------------

  protected openLookup(row: number, column: GridColumn): void {
    const line = this.lines()[row];
    if (line && !this.isReadonly(line, column)) this.lookupTarget.set({ row, column });
  }

  protected lookupPicked(rows: ListRow[]): void {
    const target = this.lookupTarget();
    const picked = rows[0];
    const line = target ? this.lines()[target.row] : undefined;
    if (!target || !picked || !line || !target.column.lookup) return;
    this.replace(target.row, target.column.lookup.apply(picked, line), target.column.key);
  }

  protected lookupClosed(): void {
    const target = this.lookupTarget();
    this.lookupTarget.set(null);
    if (target) this.focusCell(target.row, this.columns().indexOf(target.column));
  }

  protected multiPicked(rows: ListRow[]): void {
    const config = this.multiAdd();
    if (!config || rows.length === 0) return;
    this.lines.update((ls) => [
      ...ls,
      ...rows.map((r) => {
        const line = config.toLine(r);
        return this.recalc()?.(line, '') ?? line;
      }),
    ]);
  }
}