/**
 * Default Coordination Manager - Adapter Implementation
 *
 * Implements CoordinationManager interface with in-memory merge queue
 * and dependency-ordered merging.
 *
 * This is the ADAPTER for the CoordinationManager PORT.
 */

import type {
  EventBus,
  MergeQueuedEvent,
  MergeStartedEvent,
  MergeCompletedEvent,
  MergeConflictedEvent,
} from '../events/index.js';
import type { WorktreeManager } from '../git/types.js';
import type { TaskRepository } from '../db/repositories/task-repository.js';
import type { AgentRepository } from '../db/repositories/agent-repository.js';
import type { MessageRepository } from '../db/repositories/message-repository.js';
import type { CoordinationManager, MergeQueueItem, MergeResult } from './types.js';
import type { ConflictResolutionService } from './conflict-resolution-service.js';
import { DefaultConflictResolutionService } from './conflict-resolution-service.js';

// =============================================================================
// Internal Types
// =============================================================================

/**
 * Internal representation of a merge queue item with status.
 */
interface InternalMergeQueueItem extends MergeQueueItem {
  status: 'queued' | 'in_progress';
}

// =============================================================================
// DefaultCoordinationManager Implementation
// =============================================================================

/**
 * In-memory implementation of CoordinationManager.
 *
 * Uses Map for queue management and processes merges in dependency order.
 * Handles conflicts by creating resolution tasks.
 */
export class DefaultCoordinationManager implements CoordinationManager {
  /** Internal merge queue */
  private mergeQueue: Map<string, InternalMergeQueueItem> = new Map();

  /** Task IDs that have been successfully merged */
  private mergedTasks: Set<string> = new Set();

  /** Tasks with conflicts awaiting resolution */
  private conflictedTasks: Map<string, string[]> = new Map();

  /** Service for handling merge conflicts */
  private conflictResolutionService?: ConflictResolutionService;

  constructor(
    private worktreeManager?: WorktreeManager,
    private taskRepository?: TaskRepository,
    private agentRepository?: AgentRepository,
    private messageRepository?: MessageRepository,
    private eventBus?: EventBus,
    conflictResolutionService?: ConflictResolutionService
  ) {
    // Create default conflict resolution service if none provided
    if (conflictResolutionService) {
      this.conflictResolutionService = conflictResolutionService;
    } else if (taskRepository && agentRepository) {
      this.conflictResolutionService = new DefaultConflictResolutionService(
        taskRepository,
        agentRepository,
        messageRepository,
        eventBus
      );
    }
  }

  /**
   * Queue a completed task for merge.
   * Extracts agent/worktree information from the task.
   */
  async queueMerge(taskId: string): Promise<void> {
    // Look up task to get dependencies
    if (!this.taskRepository) {
      throw new Error('TaskRepository not configured');
    }

    const task = await this.taskRepository.findById(taskId);
    if (!task) {
      throw new Error(`Task not found: ${taskId}`);
    }

    // Look up agent assigned to task to get worktreeId
    if (!this.agentRepository) {
      throw new Error('AgentRepository not configured');
    }

    const agent = await this.agentRepository.findByTaskId(taskId);
    if (!agent) {
      throw new Error(`No agent found for task: ${taskId}`);
    }

    // For now, dependsOn is empty - would need to query task_dependencies table
    // to get actual dependencies
    const dependsOn: string[] = [];

    const queueItem: InternalMergeQueueItem = {
      taskId,
      agentId: agent.id,
      worktreeId: agent.worktreeId,
      priority: task.priority,
      queuedAt: new Date(),
      dependsOn,
      status: 'queued',
    };

    this.mergeQueue.set(taskId, queueItem);

    // Emit MergeQueuedEvent
    const event: MergeQueuedEvent = {
      type: 'merge:queued',
      timestamp: new Date(),
      payload: {
        taskId,
        agentId: agent.id,
        worktreeId: agent.worktreeId,
        priority: task.priority,
      },
    };
    this.eventBus?.emit(event);
  }

  /**
   * Get next task ready to merge.
   * Returns task with all dependency tasks already merged.
   */
  async getNextMergeable(): Promise<MergeQueueItem | null> {
    const queuedItems = Array.from(this.mergeQueue.values()).filter(
      (item) => item.status === 'queued'
    );

    if (queuedItems.length === 0) {
      return null;
    }

    // Filter to only items where ALL dependsOn tasks are in mergedTasks
    const readyItems = queuedItems.filter((item) =>
      item.dependsOn.every((depTaskId) => this.mergedTasks.has(depTaskId))
    );

    if (readyItems.length === 0) {
      return null;
    }

    // Sort by priority (high > medium > low), then by queuedAt (oldest first)
    const priorityOrder: Record<string, number> = { high: 0, medium: 1, low: 2 };

    readyItems.sort((a, b) => {
      const priorityDiff = priorityOrder[a.priority] - priorityOrder[b.priority];
      if (priorityDiff !== 0) {
        return priorityDiff;
      }
      return a.queuedAt.getTime() - b.queuedAt.getTime();
    });

    // Return as MergeQueueItem (without internal status)
    const item = readyItems[0];
    return {
      taskId: item.taskId,
      agentId: item.agentId,
      worktreeId: item.worktreeId,
      priority: item.priority,
      queuedAt: item.queuedAt,
      dependsOn: item.dependsOn,
    };
  }

  /**
   * Process all ready merges in dependency order.
   * Merges each ready task into the target branch.
   */
  async processMerges(targetBranch: string): Promise<MergeResult[]> {
    if (!this.worktreeManager) {
      throw new Error('WorktreeManager not configured');
    }

    const results: MergeResult[] = [];

    // Loop while there are mergeable items
    let nextItem = await this.getNextMergeable();

    while (nextItem) {
      const queueItem = this.mergeQueue.get(nextItem.taskId)!;

      // Mark as in_progress
      queueItem.status = 'in_progress';

      // Emit MergeStartedEvent
      const startEvent: MergeStartedEvent = {
        type: 'merge:started',
        timestamp: new Date(),
        payload: {
          taskId: nextItem.taskId,
          agentId: nextItem.agentId,
          worktreeId: nextItem.worktreeId,
          targetBranch,
        },
      };
      this.eventBus?.emit(startEvent);

      // Attempt merge via worktreeManager
      const mergeResult = await this.worktreeManager.merge(nextItem.worktreeId, targetBranch);

      if (mergeResult.success) {
        // Success - add to mergedTasks and remove from queue
        this.mergedTasks.add(nextItem.taskId);
        this.mergeQueue.delete(nextItem.taskId);

        // Emit MergeCompletedEvent
        const completedEvent: MergeCompletedEvent = {
          type: 'merge:completed',
          timestamp: new Date(),
          payload: {
            taskId: nextItem.taskId,
            agentId: nextItem.agentId,
            worktreeId: nextItem.worktreeId,
            targetBranch,
          },
        };
        this.eventBus?.emit(completedEvent);

        results.push({
          taskId: nextItem.taskId,
          success: true,
          message: mergeResult.message,
        });
      } else {
        // Conflict - add to conflictedTasks and remove from queue
        const conflicts = mergeResult.conflicts || [];
        this.conflictedTasks.set(nextItem.taskId, conflicts);
        this.mergeQueue.delete(nextItem.taskId);

        // Emit MergeConflictedEvent
        const conflictEvent: MergeConflictedEvent = {
          type: 'merge:conflicted',
          timestamp: new Date(),
          payload: {
            taskId: nextItem.taskId,
            agentId: nextItem.agentId,
            worktreeId: nextItem.worktreeId,
            targetBranch,
            conflictingFiles: conflicts,
          },
        };
        this.eventBus?.emit(conflictEvent);

        // Handle conflict - create resolution task
        await this.handleConflict(nextItem.taskId, conflicts);

        results.push({
          taskId: nextItem.taskId,
          success: false,
          conflicts,
          message: mergeResult.message,
        });
      }

      // Get next item
      nextItem = await this.getNextMergeable();
    }

    return results;
  }

  /**
   * Handle a merge conflict.
   * Delegates to the ConflictResolutionService.
   */
  async handleConflict(taskId: string, conflicts: string[]): Promise<void> {
    if (!this.conflictResolutionService) {
      throw new Error('ConflictResolutionService not configured');
    }

    await this.conflictResolutionService.handleConflict(taskId, conflicts);
  }

  /**
   * Get current state of the merge queue.
   */
  async getQueueState(): Promise<{
    queued: MergeQueueItem[];
    inProgress: MergeQueueItem[];
    merged: string[];
    conflicted: Array<{ taskId: string; conflicts: string[] }>;
  }> {
    const allItems = Array.from(this.mergeQueue.values());

    // Filter by status
    const queued = allItems
      .filter((item) => item.status === 'queued')
      .map((item) => ({
        taskId: item.taskId,
        agentId: item.agentId,
        worktreeId: item.worktreeId,
        priority: item.priority,
        queuedAt: item.queuedAt,
        dependsOn: item.dependsOn,
      }));

    const inProgress = allItems
      .filter((item) => item.status === 'in_progress')
      .map((item) => ({
        taskId: item.taskId,
        agentId: item.agentId,
        worktreeId: item.worktreeId,
        priority: item.priority,
        queuedAt: item.queuedAt,
        dependsOn: item.dependsOn,
      }));

    const merged = Array.from(this.mergedTasks);

    const conflicted = Array.from(this.conflictedTasks.entries()).map(([taskId, conflicts]) => ({
      taskId,
      conflicts,
    }));

    return { queued, inProgress, merged, conflicted };
  }
}