import { afterNextRender, ChangeDetectionStrategy, Component, computed, inject, signal } from '@angular/core';
import { TaskStore } from '../../data-access/store/task-store';
import { Task, TaskState } from '../../data-access/models/task.model';
import { TaskDetailSidebar } from '../../ui/task-detail-sidebar/task-detail-sidebar';
import { TaskCreateSidebar } from '../../ui/task-create-sidebar/task-create-sidebar';
import { TaskBoardColumn } from '../../ui/task-board-column/task-board-column';
import { Pagination } from '@shared/ui/pagination/pagination';

export type ViewMode = 'table' | 'board' | 'timeline';

@Component({
  selector: 'emi-task-list-page',
  imports: [TaskDetailSidebar, TaskCreateSidebar, TaskBoardColumn, Pagination],
  templateUrl: './task-list-page.html',
  styleUrl: './task-list-page.css',
  changeDetection: ChangeDetectionStrategy.OnPush,
})
export class TaskListPage {
  private readonly store = inject(TaskStore);

  readonly PAGE_SIZE = 5;

  constructor() {
    afterNextRender(() => {
      this.store.loadTasks();
    });
  }

  readonly tasks = this.store.filteredTasks;
  readonly loading = this.store.loading;
  readonly selectedTask = this.store.selectedTask;
  readonly transitioningState = this.store.transitioningState;
  readonly showCreateSidebar = signal(false);
  readonly activeView = signal<ViewMode>('table');
  readonly currentPage = signal(1);

  private readonly stateProgress: Record<TaskState, number> = {
    new: 0,
    active: 50,
    resolved: 100,
    closed: 100,
  };

  private readonly stateLabels: Record<TaskState, string> = {
    new: 'New',
    active: 'Active',
    resolved: 'Resolved',
    closed: 'Closed',
  };

  readonly totalPages = computed(() => {
    return Math.max(1, Math.ceil(this.tasks().length / this.PAGE_SIZE));
  });

  readonly paginatedTasks = computed(() => {
    const start = (this.currentPage() - 1) * this.PAGE_SIZE;
    return this.tasks().slice(start, start + this.PAGE_SIZE);
  });

  readonly completionPercent = computed(() => {
    const all = this.tasks();
    if (all.length === 0) return 0;
    const totalProgress = all.reduce((sum, t) => sum + this.getStateProgress(t), 0);
    return Math.round(totalProgress / all.length);
  });

  readonly completedCount = computed(() =>
    this.tasks().filter(t => this.isFinalized(t)).length
  );

  readonly activeCount = computed(() =>
    this.tasks().filter(t => this.getState(t) === 'active').length
  );

  readonly newCount = computed(() =>
    this.tasks().filter(t => this.getState(t) === 'new').length
  );

  readonly tasksByState = computed(() => {
    const grouped: Record<TaskState, Task[]> = {
      new: [],
      active: [],
      resolved: [],
      closed: [],
    };
    for (const task of this.tasks()) {
      const state = this.getState(task);
      grouped[state].push(task);
    }
    return grouped;
  });

  readonly tasksByDate = computed(() => {
    const sorted = [...this.tasks()].sort((a, b) =>
      new Date(a.dueDate).getTime() - new Date(b.dueDate).getTime()
    );
    const grouped: Record<string, Task[]> = {};
    for (const task of sorted) {
      const date = task.dueDate;
      if (!grouped[date]) {
        grouped[date] = [];
      }
      grouped[date].push(task);
    }
    return grouped;
  });

  readonly dueDates = computed(() => Object.keys(this.tasksByDate()));

  onPageChange(page: number): void {
    this.currentPage.set(page);
  }

  onViewChange(view: ViewMode): void {
    this.activeView.set(view);
  }

  getState(task: Task): TaskState {
    const history = task.stateHistory;
    return history[history.length - 1]?.state ?? 'new';
  }

  getStateLabel(task: Task): string {
    return this.stateLabels[this.getState(task)];
  }

  getStateProgress(task: Task): number {
    return this.stateProgress[this.getState(task)];
  }

  isFinalized(task: Task): boolean {
    const state = this.getState(task);
    return state === 'resolved' || state === 'closed';
  }

  isSelected(task: Task): boolean {
    return this.selectedTask()?.id === task.id;
  }

  onViewTask(task: Task): void {
    this.showCreateSidebar.set(false);
    this.store.setSelectedTask(task);
  }

  onCloseDetailSidebar(): void {
    this.store.setSelectedTask(null);
  }

  onChangeState(state: TaskState): void {
    const task = this.selectedTask();
    if (task) {
      this.store.transitionTask(task.id, state);
    }
  }

  onDeleteTask(task: Task): void {
    this.store.deleteTask(task.id);
    this.store.setSelectedTask(null);
  }

  onAddNote(content: string): void {
    const task = this.selectedTask();
    if (task) {
      this.store.addNote(task.id, content);
    }
  }

  onDeleteNote(index: number): void {
    const task = this.selectedTask();
    if (task) {
      this.store.deleteNote(task.id, index);
    }
  }

  onOpenCreateSidebar(): void {
    this.store.setSelectedTask(null);
    this.showCreateSidebar.set(true);
  }

  onCloseCreateSidebar(): void {
    this.showCreateSidebar.set(false);
  }

  onTaskCreated(): void {
    this.showCreateSidebar.set(false);
  }

  onBoardViewTask(task: Task): void {
    this.onViewTask(task);
  }

  onBoardEditTask(task: Task): void {
    this.onViewTask(task);
  }

  onBoardDeleteTask(task: Task): void {
    this.onDeleteTask(task);
  }
}