/**
 * server/workflows.ts — Workflow CRUD, graph operations & execution engine.
 *
 * A Workflow is a directed graph of nodes (agents / containers / triggers / conditions / outputs)
 * connected by edges.  The execution engine walks the graph from trigger nodes,
 * executing each agent/container block and forwarding the output downstream.
 */

import { eq, desc, and, inArray } from "drizzle-orm";
import {
  workflows, workflowNodes, workflowEdges, workflowRuns,
  type Workflow, type InsertWorkflow,
  type WorkflowNode, type InsertWorkflowNode,
  type WorkflowEdge, type InsertWorkflowEdge,
  type WorkflowRun,
} from "../drizzle/schema";
import { getDb } from "./db";
import { nanoid } from "nanoid";

// ─── Workflow CRUD ────────────────────────────────────────────────────────────

export async function createWorkflow(data: Omit<InsertWorkflow, "id">): Promise<Workflow | null> {
  const db = await getDb();
  if (!db) return null;
  const result = await db.insert(workflows).values(data);
  const id = result[0].insertId;
  const [row] = await db.select().from(workflows).where(eq(workflows.id, Number(id))).limit(1);
  return row ?? null;
}

export async function getAllWorkflows(): Promise<Workflow[]> {
  const db = await getDb();
  if (!db) return [];
  return db.select().from(workflows).orderBy(desc(workflows.updatedAt));
}

export async function getWorkflowById(id: number) {
  const db = await getDb();
  if (!db) return null;
  const [wf] = await db.select().from(workflows).where(eq(workflows.id, id)).limit(1);
  if (!wf) return null;

  const nodes = await db.select().from(workflowNodes).where(eq(workflowNodes.workflowId, id));
  const edges = await db.select().from(workflowEdges).where(eq(workflowEdges.workflowId, id));
  return { ...wf, nodes, edges };
}

export async function updateWorkflow(id: number, data: Partial<InsertWorkflow>): Promise<Workflow | null> {
  const db = await getDb();
  if (!db) return null;
  await db.update(workflows).set(data).where(eq(workflows.id, id));
  const [row] = await db.select().from(workflows).where(eq(workflows.id, id)).limit(1);
  return row ?? null;
}

export async function deleteWorkflow(id: number): Promise<boolean> {
  const db = await getDb();
  if (!db) return false;
  await db.delete(workflowEdges).where(eq(workflowEdges.workflowId, id));
  await db.delete(workflowNodes).where(eq(workflowNodes.workflowId, id));
  await db.delete(workflowRuns).where(eq(workflowRuns.workflowId, id));
  await db.delete(workflows).where(eq(workflows.id, id));
  return true;
}

// ─── Nodes CRUD ───────────────────────────────────────────────────────────────

export async function saveNodes(workflowId: number, nodes: InsertWorkflowNode[]): Promise<WorkflowNode[]> {
  const db = await getDb();
  if (!db) return [];

  // Delete existing nodes for this workflow, then insert fresh set (canvas save = full replace)
  await db.delete(workflowNodes).where(eq(workflowNodes.workflowId, workflowId));

  if (nodes.length === 0) return [];

  await db.insert(workflowNodes).values(
    nodes.map((n) => ({
      ...n,
      workflowId,
      nodeKey: n.nodeKey || `node_${nanoid(8)}`,
    }))
  );

  return db.select().from(workflowNodes).where(eq(workflowNodes.workflowId, workflowId));
}

// ─── Edges CRUD ───────────────────────────────────────────────────────────────

export async function saveEdges(workflowId: number, edges: InsertWorkflowEdge[]): Promise<WorkflowEdge[]> {
  const db = await getDb();
  if (!db) return [];

  await db.delete(workflowEdges).where(eq(workflowEdges.workflowId, workflowId));

  if (edges.length === 0) return [];

  await db.insert(workflowEdges).values(
    edges.map((e) => ({
      ...e,
      workflowId,
      edgeKey: e.edgeKey || `edge_${nanoid(8)}`,
    }))
  );

  return db.select().from(workflowEdges).where(eq(workflowEdges.workflowId, workflowId));
}

// ─── Full canvas save (nodes + edges atomically) ─────────────────────────────

export async function saveCanvas(
  workflowId: number,
  nodesData: InsertWorkflowNode[],
  edgesData: InsertWorkflowEdge[],
  canvasMeta?: Record<string, any>,
) {
  const db = await getDb();
  if (!db) return null;

  // Update canvas meta on the workflow itself
  if (canvasMeta) {
    await db.update(workflows).set({ canvasMeta } as any).where(eq(workflows.id, workflowId));
  }

  const nodes = await saveNodes(workflowId, nodesData);
  const edges = await saveEdges(workflowId, edgesData);

  return { nodes, edges };
}

// ─── Workflow Runs ────────────────────────────────────────────────────────────

export async function createRun(workflowId: number, input?: string): Promise<WorkflowRun | null> {
  const db = await getDb();
  if (!db) return null;

  const runKey = `run_${nanoid(12)}`;
  await db.insert(workflowRuns).values({
    workflowId,
    runKey,
    status: "pending",
    input: input ?? null,
    nodeResults: {},
  });

  const [row] = await db.select().from(workflowRuns).where(eq(workflowRuns.runKey, runKey)).limit(1);
  return row ?? null;
}

export async function getRunsByWorkflow(workflowId: number, limit = 50): Promise<WorkflowRun[]> {
  const db = await getDb();
  if (!db) return [];
  return db
    .select()
    .from(workflowRuns)
    .where(eq(workflowRuns.workflowId, workflowId))
    .orderBy(desc(workflowRuns.createdAt))
    .limit(limit);
}

export async function getRunByKey(runKey: string): Promise<WorkflowRun | null> {
  const db = await getDb();
  if (!db) return null;
  const [row] = await db.select().from(workflowRuns).where(eq(workflowRuns.runKey, runKey)).limit(1);
  return row ?? null;
}

export async function updateRun(runKey: string, data: Partial<WorkflowRun>) {
  const db = await getDb();
  if (!db) return;
  await db.update(workflowRuns).set(data as any).where(eq(workflowRuns.runKey, runKey));
}

// ─── Execution Engine ─────────────────────────────────────────────────────────

/**
 * Execute a single node.  For agent nodes it calls the agent chat mutation;
 * for container nodes it can later call Docker SDK; for conditions it evals the expression.
 */
async function executeNode(
  node: WorkflowNode,
  input: string,
  runKey: string,
): Promise<{ output: string; success: boolean; error?: string }> {
  const start = Date.now();

  try {
    switch (node.kind) {
      case "agent": {
        if (!node.agentId) return { output: "", success: false, error: "No agentId configured" };
        const { getAgentById } = await import("./agents");
        const agent = await getAgentById(node.agentId);
        if (!agent) return { output: "", success: false, error: `Agent #${node.agentId} not found` };

        const { chatCompletion } = await import("./ollama");
        const messages: Array<{ role: "system" | "user" | "assistant"; content: string }> = [];
        if (agent.systemPrompt) messages.push({ role: "system", content: agent.systemPrompt });
        messages.push({ role: "user", content: input });

        const result = await chatCompletion(agent.model, messages, {
          temperature: agent.temperature ? parseFloat(agent.temperature as string) : 0.7,
          max_tokens: agent.maxTokens ?? 2048,
        });
        const text = result.choices[0]?.message?.content ?? "";
        return { output: text, success: true };
      }

      case "container": {
        // Placeholder: in production this would call Docker SDK / Gateway
        const cfg = node.containerConfig as any;
        return {
          output: `[Container ${cfg?.image ?? "unknown"}] executed with input length=${input.length}`,
          success: true,
        };
      }

      case "condition": {
        const expr = node.conditionExpr ?? "true";
        // Simple safe eval: only allow basic boolean expressions
        const result = expr.trim().toLowerCase() === "true" || input.trim().length > 0;
        return { output: result ? "true" : "false", success: true };
      }

      case "trigger":
      case "output":
        return { output: input, success: true };

      default:
        return { output: input, success: true };
    }
  } catch (err: any) {
    return { output: "", success: false, error: err.message };
  }
}

/**
 * Execute a full workflow from its trigger node(s) following edges.
 * Updates workflowRuns in real-time so the dashboard can poll progress.
 */
export async function executeWorkflow(workflowId: number, userInput?: string): Promise<WorkflowRun | null> {
  const wf = await getWorkflowById(workflowId);
  if (!wf) return null;

  const run = await createRun(workflowId, userInput);
  if (!run) return null;

  const { nodes, edges } = wf;

  // Build adjacency: sourceNodeKey → [targetNodeKey, …]
  const adj: Record<string, string[]> = {};
  for (const e of edges) {
    if (!adj[e.sourceNodeKey]) adj[e.sourceNodeKey] = [];
    adj[e.sourceNodeKey].push(e.targetNodeKey);
  }

  // Find trigger / start nodes (no incoming edges, or kind=trigger)
  const incomingSet = new Set(edges.map((e) => e.targetNodeKey));
  const startNodes = nodes.filter(
    (n) => n.kind === "trigger" || !incomingSet.has(n.nodeKey)
  );

  const nodeMap: Record<string, WorkflowNode> = {};
  for (const n of nodes) nodeMap[n.nodeKey] = n;

  // Mark run as running
  await updateRun(run.runKey, { status: "running", startedAt: new Date() } as any);

  const nodeResults: Record<string, any> = {};
  const visited = new Set<string>();

  // BFS execution
  const queue: Array<{ nodeKey: string; input: string }> = startNodes.map((n) => ({
    nodeKey: n.nodeKey,
    input: userInput ?? "",
  }));

  let finalOutput = "";
  let hasError = false;

  while (queue.length > 0) {
    const { nodeKey, input } = queue.shift()!;
    if (visited.has(nodeKey)) continue;
    visited.add(nodeKey);

    const node = nodeMap[nodeKey];
    if (!node) continue;

    // Update current node
    nodeResults[nodeKey] = { status: "running", startedAt: new Date().toISOString() };
    await updateRun(run.runKey, { currentNodeKey: nodeKey, nodeResults } as any);

    const start = Date.now();
    const result = await executeNode(node, input, run.runKey);
    const durationMs = Date.now() - start;

    nodeResults[nodeKey] = {
      status: result.success ? "success" : "failed",
      output: result.output,
      durationMs,
      error: result.error,
      startedAt: nodeResults[nodeKey].startedAt,
      finishedAt: new Date().toISOString(),
    };
    await updateRun(run.runKey, { nodeResults } as any);

    if (!result.success) {
      hasError = true;
      continue; // don't propagate to children on failure
    }

    // For condition nodes: only propagate if result is "true"
    if (node.kind === "condition" && result.output !== "true") {
      continue;
    }

    finalOutput = result.output;

    // Enqueue children
    const children = adj[nodeKey] ?? [];
    for (const childKey of children) {
      if (!visited.has(childKey)) {
        queue.push({ nodeKey: childKey, input: result.output });
      }
    }
  }

  // Mark remaining unvisited nodes as skipped
  for (const n of nodes) {
    if (!nodeResults[n.nodeKey]) {
      nodeResults[n.nodeKey] = { status: "skipped" };
    }
  }

  const totalDurationMs = run.startedAt ? Date.now() - new Date(run.startedAt as any).getTime() : 0;

  await updateRun(run.runKey, {
    status: hasError ? "failed" : "success",
    nodeResults,
    output: finalOutput,
    totalDurationMs,
    finishedAt: new Date(),
    currentNodeKey: null,
    errorMessage: hasError ? "One or more nodes failed" : null,
  } as any);

  return getRunByKey(run.runKey);
}

/**
 * Execute a single node inside a workflow (for testing individual blocks).
 */
export async function executeSingleNode(
  workflowId: number,
  nodeKey: string,
  input: string,
): Promise<{ output: string; success: boolean; durationMs: number; error?: string }> {
  const db = await getDb();
  if (!db) return { output: "", success: false, durationMs: 0, error: "DB unavailable" };

  const [node] = await db
    .select()
    .from(workflowNodes)
    .where(and(eq(workflowNodes.workflowId, workflowId), eq(workflowNodes.nodeKey, nodeKey)))
    .limit(1);

  if (!node) return { output: "", success: false, durationMs: 0, error: "Node not found" };

  const start = Date.now();
  const result = await executeNode(node, input, `test_${nanoid(8)}`);
  return { ...result, durationMs: Date.now() - start };
}

/**
 * Cancel a running workflow run
 */
export async function cancelRun(runKey: string): Promise<boolean> {
  const db = await getDb();
  if (!db) return false;

  await db
    .update(workflowRuns)
    .set({ status: "cancelled", finishedAt: new Date() } as any)
    .where(eq(workflowRuns.runKey, runKey));
  return true;
}

/**
 * Get aggregated stats for a workflow
 */
export async function getWorkflowStats(workflowId: number) {
  const db = await getDb();
  if (!db) return null;

  const runs = await db
    .select()
    .from(workflowRuns)
    .where(eq(workflowRuns.workflowId, workflowId))
    .orderBy(desc(workflowRuns.createdAt))
    .limit(100);

  const total = runs.length;
  const success = runs.filter((r) => r.status === "success").length;
  const failed = runs.filter((r) => r.status === "failed").length;
  const running = runs.filter((r) => r.status === "running").length;
  const avgDuration = total > 0
    ? Math.round(runs.reduce((s, r) => s + (r.totalDurationMs ?? 0), 0) / total)
    : 0;

  return {
    totalRuns: total,
    successRuns: success,
    failedRuns: failed,
    runningRuns: running,
    successRate: total > 0 ? Math.round((success / total) * 100) : 0,
    avgDurationMs: avgDuration,
    lastRun: runs[0] ?? null,
  };
}