/**
 * Self-Healing System — NEW
 * Detects root cause of workflow failures and applies corrective transformations
 * Stores failure patterns in memory, prevents repeat failures
 * Integrates with validation + simulation pipeline
 */
import { type LLMGateway } from '@wfo/integrations/llm-providers/index';
import type { ValidationReport, SimulationReport, N8nWorkflow, WorkflowGraph } from '../types/workflow';
import { isValidNodeType } from '../knowledge/nodeRegistry';

export interface HealingAction {
  type: 'replace_node' | 'fix_expression' | 'add_parameter' | 'fix_connection' | 'add_retry' | 'remove_node';
  targetNodeId?: string;
  description: string;
  applied: boolean;
  before?: unknown;
  after?: unknown;
}

export interface HealingResult {
  healed: boolean;
  actionsApplied: HealingAction[];
  remainingIssues: string[];
  healedWorkflow?: N8nWorkflow;
  confidence: number; // 0-100
}

export interface FailurePattern {
  id: string;
  pattern: string;
  rootCause: string;
  fixStrategy: string;
  occurrences: number;
  lastSeen: string;
}

// In-memory failure store (persists across requests in a single process)
const failureMemory: Map<string, FailurePattern> = new Map();

export class SelfHealingSystem {
  private llm: LLMGateway;

  constructor(llm: LLMGateway) {
    this.llm = llm;
  }

  /**
   * Attempt to auto-heal a workflow based on validation and simulation reports
   */
  async heal(
    workflow: N8nWorkflow,
    graph: WorkflowGraph,
    validationReport: ValidationReport,
    simulationReport?: SimulationReport,
  ): Promise<HealingResult> {
    const actions: HealingAction[] = [];
    let healedWorkflow = structuredClone(workflow);

    // ─── Phase 1: Rule-based deterministic healing ────────────────────────
    const ruleBasedActions = this.applyRuleBasedFixes(healedWorkflow, validationReport);
    actions.push(...ruleBasedActions.actions);
    healedWorkflow = ruleBasedActions.workflow;

    // ─── Phase 2: AI-assisted healing for complex issues ──────────────────
    const complexIssues = validationReport.issues.filter((i) =>
      i.severity === 'error' &&
      !actions.some((a) => a.targetNodeId === i.nodeId && a.applied),
    );

    if (complexIssues.length > 0) {
      try {
        const aiHealing = await this.applyAIHealing(healedWorkflow, graph, complexIssues, simulationReport);
        actions.push(...aiHealing.actions);
        if (aiHealing.healedWorkflow) {
          healedWorkflow = aiHealing.healedWorkflow;
        }
      } catch (err) {
        console.warn('[SelfHealing] AI healing phase failed:', err);
      }
    }

    // ─── Phase 3: Record failure pattern ─────────────────────────────────
    this.recordFailurePattern(validationReport, simulationReport, actions);

    const appliedCount = actions.filter((a) => a.applied).length;
    const remainingErrors = validationReport.issues.filter((i) =>
      i.severity === 'error' &&
      !actions.some((a) => a.targetNodeId === i.nodeId && a.applied),
    );

    return {
      healed: appliedCount > 0 && remainingErrors.length === 0,
      actionsApplied: actions.filter((a) => a.applied),
      remainingIssues: remainingErrors.map((i) => i.message),
      healedWorkflow: appliedCount > 0 ? healedWorkflow : undefined,
      confidence: Math.round((appliedCount / Math.max(1, actions.length)) * 100),
    };
  }

  // ─── Rule-Based Fixes (deterministic, no LLM needed) ─────────────────────
  private applyRuleBasedFixes(
    workflow: N8nWorkflow,
    report: ValidationReport,
  ): { workflow: N8nWorkflow; actions: HealingAction[] } {
    const actions: HealingAction[] = [];

    // Fix 1: active must be false
    if ((workflow.active as any) === true) {
      workflow.active = false;
      actions.push({
        type: 'fix_expression',
        description: 'Set active: false (safety rule — never auto-activate)',
        applied: true,
        before: true,
        after: false,
      });
    }

    // Fix 2: Missing node IDs → generate UUID-like IDs
    workflow.nodes.forEach((node) => {
      if (!node.id || node.id.trim() === '') {
        const newId = generateId();
        actions.push({
          type: 'add_parameter',
          targetNodeId: node.name,
          description: `Generated missing ID for node "${node.name}"`,
          applied: true,
          before: node.id,
          after: newId,
        });
        node.id = newId;
      }
    });

    // Fix 3: Missing typeVersion → set to 1
    workflow.nodes.forEach((node) => {
      if (!node.typeVersion || node.typeVersion < 1) {
        actions.push({
          type: 'add_parameter',
          targetNodeId: node.id,
          description: `Added missing typeVersion: 1 to node "${node.name}"`,
          applied: true,
          before: node.typeVersion,
          after: 1,
        });
        node.typeVersion = 1;
      }
    });

    // Fix 4: Missing position → assign default grid positions
    workflow.nodes.forEach((node, i) => {
      if (!node.position || !Array.isArray(node.position) || node.position.length !== 2) {
        const newPos: [number, number] = [i * 220, 300];
        actions.push({
          type: 'fix_expression',
          targetNodeId: node.id,
          description: `Set default position for node "${node.name}"`,
          applied: true,
          before: node.position,
          after: newPos,
        });
        node.position = newPos;
      }
    });

    // Fix 5: Add retry to external nodes that support it
    workflow.nodes.forEach((node) => {
      const externalTypes = [
        'n8n-nodes-base.httpRequest',
        'n8n-nodes-base.telegram',
        'n8n-nodes-base.slack',
        'n8n-nodes-base.gmail',
        'n8n-nodes-base.openAi',
        '@n8n/n8n-nodes-langchain.agent',
        'n8n-nodes-base.googleSheets',
        'n8n-nodes-base.airtable',
        'n8n-nodes-base.notion',
        'n8n-nodes-base.postgres',
        'n8n-nodes-base.hubspot',
        'n8n-nodes-base.stripe',
        'n8n-nodes-base.github',
      ];

      if (externalTypes.includes(node.type) && !node.retryOnFail) {
        actions.push({
          type: 'add_retry',
          targetNodeId: node.id,
          description: `Added retry policy to external node "${node.name}"`,
          applied: true,
          before: { retryOnFail: false },
          after: { retryOnFail: true, maxTries: 3, waitBetweenTries: 1000 },
        });
        node.retryOnFail = true;
        node.maxTries = node.maxTries ?? 3;
        node.waitBetweenTries = node.waitBetweenTries ?? 1000;
      }
    });

    // Fix 6: onError field default
    workflow.nodes.forEach((node) => {
      if (!node.onError) {
        node.onError = 'continueErrorOutput';
        actions.push({
          type: 'add_parameter',
          targetNodeId: node.id,
          description: `Set onError: continueErrorOutput for node "${node.name}"`,
          applied: true,
          before: undefined,
          after: 'continueErrorOutput',
        });
      }
    });

    // Fix 7: Remove nodes with unknown types from registry
    const unknownNodes = workflow.nodes.filter((n) => n.type && !isValidNodeType(n.type));
    unknownNodes.forEach((node) => {
      actions.push({
        type: 'remove_node',
        targetNodeId: node.id,
        description: `REJECTED unknown node type "${node.type}" for node "${node.name}" — not in registry`,
        applied: true,
        before: node.type,
        after: null,
      });
    });
    if (unknownNodes.length > 0) {
      const unknownIds = new Set(unknownNodes.map((n) => n.id));
      workflow.nodes = workflow.nodes.filter((n) => !unknownIds.has(n.id));
    }

    // Fix 8: Ensure settings are complete
    if (!workflow.settings) {
      workflow.settings = {};
      actions.push({
        type: 'add_parameter',
        description: 'Added missing workflow settings object',
        applied: true,
        before: undefined,
        after: {},
      });
    }
    if (!workflow.settings.executionOrder) {
      workflow.settings.executionOrder = 'v1';
      actions.push({
        type: 'add_parameter',
        description: 'Set settings.executionOrder: v1',
        applied: true,
      });
    }

    return { workflow, actions };
  }

  // ─── AI-Assisted Healing (for complex expression / logic issues) ──────────
  private async applyAIHealing(
    workflow: N8nWorkflow,
    graph: WorkflowGraph,
    issues: Array<{ message: string; nodeId?: string; suggestion: string; category: string }>,
    simulationReport?: SimulationReport,
  ): Promise<{ actions: HealingAction[]; healedWorkflow?: N8nWorkflow }> {
    // Find the historical fix if available
    const historicalFixes = this.getRelevantHistoricalFixes(issues.map((i) => i.message));

    const result = await this.llm.completeJSON<{
      fixedWorkflow: N8nWorkflow;
      actionsApplied: Array<{ nodeId?: string; description: string; type: string }>;
    }>([
      {
        role: 'system',
        content: `You are an n8n workflow self-healing system. Your job is to fix broken workflows.
Fix ONLY the identified issues. Do not change anything else.
NEVER set active: true.
ALWAYS use real expressions like {{$json?.field ?? ""}}.
Return the complete fixed workflow JSON.`,
      },
      {
        role: 'user',
        content: `Fix these workflow issues:

CURRENT WORKFLOW:
${JSON.stringify(workflow, null, 2)}

ISSUES TO FIX:
${issues.map((i, idx) => `${idx + 1}. [${i.category}] ${i.message}\n   Fix: ${i.suggestion}`).join('\n')}

${simulationReport ? `SIMULATION FAILURES:\n${JSON.stringify(simulationReport.predictedFailurePoints, null, 2)}` : ''}

${historicalFixes.length > 0 ? `HISTORICAL FIX STRATEGIES:\n${historicalFixes.join('\n')}` : ''}

Return JSON:
{
  "fixedWorkflow": { ... complete fixed n8n workflow ... },
  "actionsApplied": [{ "nodeId": "...", "description": "what was fixed", "type": "fix_type" }]
}`,
      },
    ], {
      temperature: 0.0,
      retries: 2,
    });

    const actions: HealingAction[] = (result.actionsApplied ?? []).map((a) => ({
      type: a.type as HealingAction['type'],
      targetNodeId: a.nodeId,
      description: a.description,
      applied: true,
    }));

    return {
      actions,
      healedWorkflow: result.fixedWorkflow ? {
        ...result.fixedWorkflow,
        active: false, // Always enforce safety
      } : undefined,
    };
  }

  // ─── Failure Pattern Memory ───────────────────────────────────────────────
  private recordFailurePattern(
    validation: ValidationReport,
    simulation: SimulationReport | undefined,
    actions: HealingAction[],
  ): void {
    validation.issues.forEach((issue) => {
      const key = `${issue.category}-${issue.id}`;
      const existing = failureMemory.get(key);
      const action = actions.find((a) => a.targetNodeId === issue.nodeId);

      if (existing) {
        failureMemory.set(key, {
          ...existing,
          occurrences: existing.occurrences + 1,
          lastSeen: new Date().toISOString(),
          fixStrategy: action?.description ?? existing.fixStrategy,
        });
      } else {
        failureMemory.set(key, {
          id: key,
          pattern: issue.message,
          rootCause: issue.category,
          fixStrategy: action?.description ?? issue.suggestion,
          occurrences: 1,
          lastSeen: new Date().toISOString(),
        });
      }
    });
  }

  private getRelevantHistoricalFixes(issueMessages: string[]): string[] {
    const fixes: string[] = [];
    failureMemory.forEach((pattern) => {
      const isRelevant = issueMessages.some(
        (msg) => msg.toLowerCase().includes(pattern.rootCause.toLowerCase()),
      );
      if (isRelevant && pattern.occurrences > 1) {
        fixes.push(`Pattern: "${pattern.pattern}" → Fix: "${pattern.fixStrategy}" (seen ${pattern.occurrences}x)`);
      }
    });
    return fixes.slice(0, 5); // Top 5 most relevant
  }

  /**
   * Get current failure memory stats (for reporting)
   */
  getMemoryStats(): { totalPatterns: number; topFailures: FailurePattern[] } {
    const patterns = [...failureMemory.values()];
    const sorted = patterns.sort((a, b) => b.occurrences - a.occurrences);
    return {
      totalPatterns: patterns.length,
      topFailures: sorted.slice(0, 10),
    };
  }
}

function generateId(): string {
  const hex = () => Math.floor(Math.random() * 0x10000).toString(16).padStart(4, '0');
  return `${hex()}${hex()}-${hex()}-${hex()}-${hex()}-${hex()}${hex()}${hex()}`;
}