import { Task, Subtask } from '../types/index.js';
import { Database, Tables } from '../types/database.types.js';

type TaskRow = Tables<'tasks'>;
type DependencyRow = Tables<'task_dependencies'>;

export class TaskMapper {
	/**
	 * Maps database tasks to internal Task format
	 */
	static mapDatabaseTasksToTasks(
		dbTasks: TaskRow[],
		dbDependencies: DependencyRow[]
	): Task[] {
		if (!dbTasks || dbTasks.length === 0) {
			return [];
		}

		// Group dependencies by task_id
		const dependenciesByTaskId = this.groupDependenciesByTaskId(dbDependencies);

		// Separate parent tasks and subtasks
		const parentTasks = dbTasks.filter((t) => !t.parent_task_id);
		const subtasksByParentId = this.groupSubtasksByParentId(dbTasks);

		// Map parent tasks with their subtasks
		return parentTasks.map((taskRow) =>
			this.mapDatabaseTaskToTask(
				taskRow,
				subtasksByParentId.get(taskRow.id) || [],
				dependenciesByTaskId
			)
		);
	}

	/**
	 * Maps a single database task to internal Task format
	 */
	static mapDatabaseTaskToTask(
		dbTask: TaskRow,
		dbSubtasks: TaskRow[],
		dependenciesByTaskId: Map<string, string[]>
	): Task {
		// Map subtasks
		const subtasks: Subtask[] = dbSubtasks.map((subtask, index) => ({
			id: index + 1, // Use numeric ID for subtasks
			parentId: dbTask.id,
			title: subtask.title,
			description: subtask.description || '',
			status: this.mapStatus(subtask.status),
			priority: this.mapPriority(subtask.priority),
			dependencies: dependenciesByTaskId.get(subtask.id) || [],
			details: (subtask.metadata as any)?.details || '',
			testStrategy: (subtask.metadata as any)?.testStrategy || '',
			createdAt: subtask.created_at,
			updatedAt: subtask.updated_at,
			assignee: subtask.assignee_id || undefined,
			complexity: subtask.complexity
				? this.mapComplexityToInternal(subtask.complexity)
				: undefined
		}));

		return {
			id: dbTask.display_id || dbTask.id, // Use display_id if available
			title: dbTask.title,
			description: dbTask.description || '',
			status: this.mapStatus(dbTask.status),
			priority: this.mapPriority(dbTask.priority),
			dependencies: dependenciesByTaskId.get(dbTask.id) || [],
			details: (dbTask.metadata as any)?.details || '',
			testStrategy: (dbTask.metadata as any)?.testStrategy || '',
			subtasks,
			createdAt: dbTask.created_at,
			updatedAt: dbTask.updated_at,
			assignee: dbTask.assignee_id || undefined,
			complexity: dbTask.complexity
				? this.mapComplexityToInternal(dbTask.complexity)
				: undefined,
			effort: dbTask.estimated_hours || undefined,
			actualEffort: dbTask.actual_hours || undefined
		};
	}

	/**
	 * Groups dependencies by task ID
	 */
	private static groupDependenciesByTaskId(
		dependencies: DependencyRow[]
	): Map<string, string[]> {
		const dependenciesByTaskId = new Map<string, string[]>();

		if (dependencies) {
			for (const dep of dependencies) {
				const deps = dependenciesByTaskId.get(dep.task_id) || [];
				deps.push(dep.depends_on_task_id);
				dependenciesByTaskId.set(dep.task_id, deps);
			}
		}

		return dependenciesByTaskId;
	}

	/**
	 * Groups subtasks by their parent ID
	 */
	private static groupSubtasksByParentId(
		tasks: TaskRow[]
	): Map<string, TaskRow[]> {
		const subtasksByParentId = new Map<string, TaskRow[]>();

		for (const task of tasks) {
			if (task.parent_task_id) {
				const subtasks = subtasksByParentId.get(task.parent_task_id) || [];
				subtasks.push(task);
				subtasksByParentId.set(task.parent_task_id, subtasks);
			}
		}

		// Sort subtasks by subtask_position for each parent
		for (const subtasks of subtasksByParentId.values()) {
			subtasks.sort((a, b) => a.subtask_position - b.subtask_position);
		}

		return subtasksByParentId;
	}

	/**
	 * Maps database status to internal status
	 */
	static mapStatus(
		status: Database['public']['Enums']['task_status']
	): Task['status'] {
		switch (status) {
			case 'todo':
				return 'pending';
			case 'in_progress':
				return 'in-progress';
			case 'done':
				return 'done';
			default:
				return 'pending';
		}
	}

	/**
	 * Maps database priority to internal priority
	 */
	private static mapPriority(
		priority: Database['public']['Enums']['task_priority']
	): Task['priority'] {
		switch (priority) {
			case 'urgent':
				return 'critical';
			default:
				return priority as Task['priority'];
		}
	}

	/**
	 * Maps numeric complexity to descriptive complexity
	 */
	private static mapComplexityToInternal(
		complexity: number
	): Task['complexity'] {
		if (complexity <= 2) return 'simple';
		if (complexity <= 5) return 'moderate';
		if (complexity <= 8) return 'complex';
		return 'very-complex';
	}
}