import { prisma } from './database';
import { Task, TaskStatus, TaskPriority, TaskSource, BusinessError } from '@/lib/types';
import { Prisma } from '@prisma/client';

/**
 * Service pour la gestion des tâches (version standalone)
 */
export class TasksService {

  /**
   * Récupère toutes les tâches avec filtres optionnels
   */
  async getTasks(filters?: {
    status?: TaskStatus[];
    search?: string;
    limit?: number;
    offset?: number;
  }): Promise<Task[]> {
    const where: Prisma.TaskWhereInput = {};

    if (filters?.status) {
      where.status = { in: filters.status };
    }

    if (filters?.search) {
      where.OR = [
        { title: { contains: filters.search } },
        { description: { contains: filters.search } }
      ];
    }

    const tasks = await prisma.task.findMany({
      where,
      take: filters?.limit || 100,
      skip: filters?.offset || 0,
      orderBy: [
        { completedAt: 'desc' },
        { dueDate: 'asc' },
        { createdAt: 'desc' }
      ]
    });

    return tasks.map(this.mapPrismaTaskToTask);
  }

  /**
   * Crée une nouvelle tâche
   */
  async createTask(taskData: {
    title: string;
    description?: string;
    status?: TaskStatus;
    priority?: TaskPriority;
    tags?: string[];
    dueDate?: Date;
  }): Promise<Task> {
    const task = await prisma.task.create({
      data: {
        title: taskData.title,
        description: taskData.description,
        status: taskData.status || 'todo',
        priority: taskData.priority || 'medium',
        tagsJson: JSON.stringify(taskData.tags || []),
        dueDate: taskData.dueDate,
        source: 'manual', // Source manuelle
        sourceId: `manual-${Date.now()}` // ID unique
      }
    });

    // Gérer les tags
    if (taskData.tags && taskData.tags.length > 0) {
      await this.processTags(taskData.tags);
    }

    return this.mapPrismaTaskToTask(task);
  }

  /**
   * Met à jour une tâche
   */
  async updateTask(taskId: string, updates: {
    title?: string;
    description?: string;
    status?: TaskStatus;
    priority?: TaskPriority;
    tags?: string[];
    dueDate?: Date;
  }): Promise<Task> {
    const task = await prisma.task.findUnique({
      where: { id: taskId }
    });

    if (!task) {
      throw new BusinessError(`Tâche ${taskId} introuvable`);
    }

    // Logique métier : si on marque comme terminé, on ajoute la date
    const updateData: Prisma.TaskUpdateInput = {
      title: updates.title,
      description: updates.description,
      status: updates.status,
      priority: updates.priority,
      dueDate: updates.dueDate,
      updatedAt: new Date()
    };

    if (updates.tags) {
      updateData.tagsJson = JSON.stringify(updates.tags);
    }

    if (updates.status === 'done' && !task.completedAt) {
      updateData.completedAt = new Date();
    } else if (updates.status && updates.status !== 'done' && task.completedAt) {
      updateData.completedAt = null;
    }

    const updatedTask = await prisma.task.update({
      where: { id: taskId },
      data: updateData
    });

    // Gérer les tags
    if (updates.tags && updates.tags.length > 0) {
      await this.processTags(updates.tags);
    }

    return this.mapPrismaTaskToTask(updatedTask);
  }

  /**
   * Supprime une tâche
   */
  async deleteTask(taskId: string): Promise<void> {
    const task = await prisma.task.findUnique({
      where: { id: taskId }
    });

    if (!task) {
      throw new BusinessError(`Tâche ${taskId} introuvable`);
    }

    await prisma.task.delete({
      where: { id: taskId }
    });
  }

  /**
   * Met à jour le statut d'une tâche
   */
  async updateTaskStatus(taskId: string, newStatus: TaskStatus): Promise<Task> {
    return this.updateTask(taskId, { status: newStatus });
  }

  /**
   * Récupère les statistiques des tâches
   */
  async getTaskStats() {
    const [total, completed, inProgress, todo, cancelled] = await Promise.all([
      prisma.task.count(),
      prisma.task.count({ where: { status: 'done' } }),
      prisma.task.count({ where: { status: 'in_progress' } }),
      prisma.task.count({ where: { status: 'todo' } }),
      prisma.task.count({ where: { status: 'cancelled' } })
    ]);

    return {
      total,
      completed,
      inProgress,
      todo,
      cancelled,
      completionRate: total > 0 ? Math.round((completed / total) * 100) : 0
    };
  }

  /**
   * Traite et crée les tags s'ils n'existent pas
   */
  private async processTags(tagNames: string[]): Promise<void> {
    for (const tagName of tagNames) {
      try {
        await prisma.tag.upsert({
          where: { name: tagName },
          update: {}, // Pas de mise à jour nécessaire
          create: {
            name: tagName,
            color: this.generateTagColor(tagName)
          }
        });
      } catch (error) {
        console.error(`Erreur lors de la création du tag ${tagName}:`, error);
      }
    }
  }

  /**
   * Génère une couleur pour un tag basée sur son nom
   */
  private generateTagColor(tagName: string): string {
    const colors = [
      '#ef4444', '#f97316', '#f59e0b', '#eab308',
      '#84cc16', '#22c55e', '#10b981', '#14b8a6',
      '#06b6d4', '#0ea5e9', '#3b82f6', '#6366f1',
      '#8b5cf6', '#a855f7', '#d946ef', '#ec4899'
    ];
    
    // Hash simple du nom pour choisir une couleur
    let hash = 0;
    for (let i = 0; i < tagName.length; i++) {
      hash = tagName.charCodeAt(i) + ((hash << 5) - hash);
    }
    
    return colors[Math.abs(hash) % colors.length];
  }

  /**
   * Convertit une tâche Prisma en objet Task
   */
  private mapPrismaTaskToTask(prismaTask: Prisma.TaskGetPayload<object>): Task {
    return {
      id: prismaTask.id,
      title: prismaTask.title,
      description: prismaTask.description ?? undefined,
      status: prismaTask.status as TaskStatus,
      priority: prismaTask.priority as TaskPriority,
      source: prismaTask.source as TaskSource,
      sourceId: prismaTask.sourceId?? undefined,
      tags: JSON.parse(prismaTask.tagsJson || '[]'),
      dueDate: prismaTask.dueDate ?? undefined,
      completedAt: prismaTask.completedAt ?? undefined,
      createdAt: prismaTask.createdAt,
      updatedAt: prismaTask.updatedAt,
      jiraProject: prismaTask.jiraProject ?? undefined,
      jiraKey: prismaTask.jiraKey ?? undefined,
      assignee: prismaTask.assignee ?? undefined
    };
  }
}

// Instance singleton
export const tasksService = new TasksService();