/**
 * Pipeline execution, save, list, and delete routes.
 *
 * POST   /api/v1/pipeline/execute  -- Execute a pipeline (array of tool steps)
 * POST   /api/v1/pipeline/save     -- Save a pipeline definition
 * GET    /api/v1/pipeline/list     -- List saved pipelines
 * DELETE /api/v1/pipeline/:id      -- Delete a saved pipeline
 * POST   /api/v1/pipeline/batch    -- Batch pipeline execution (ZIP output)
 */
import { randomUUID } from "node:crypto";
import { mkdir } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { ANALYTICS_EVENTS, FEATURE_BUNDLES, MODALITY_POOL, TOOLS } from "@snapotter/shared";
import archiver from "archiver";
import type { FlowJob } from "bullmq";
import { eq } from "drizzle-orm";
import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
import { z } from "zod";
import { env } from "../config.js";
import { db, schema } from "../db/index.js";
import { recordChildOutcome } from "../jobs/batch-progress.js";
import { getFlowProducer, injectTraceContext, waitForJob } from "../jobs/enqueue.js";
import { type Pool, queueName, type ToolJobData } from "../jobs/types.js";
import { trackEvent } from "../lib/analytics.js";
import { autoOrient } from "../lib/auto-orient.js";
import { getSecurityHeaders } from "../lib/csp.js";
import { formatZodErrors } from "../lib/errors.js";
import { getFirstMissingBundleForTool } from "../lib/feature-status.js";
import { validateImageBuffer } from "../lib/file-validation.js";
import { sanitizeFilename } from "../lib/filename.js";
import { decodeToSharpCompat, needsCliDecode } from "../lib/format-decoders.js";
import { decodeHeic } from "../lib/heic-converter.js";
import { getObjectStream, putObject } from "../lib/object-storage.js";
import { resolveToolPool } from "../lib/pool.js";
import { isSvgBuffer, sanitizeSvg } from "../lib/svg-sanitize.js";
import { InputValidationError } from "../modality/contract.js";
import { inputHandlerFor } from "../modality/input-handler.js";
import { hasEffectivePermission } from "../permissions.js";
import { getAuthUser, requireAuth } from "../plugins/auth.js";
import { updateJobProgress, updateSingleFileProgress } from "./progress.js";
import { getRegisteredToolIds, getToolConfig } from "./tool-factory.js";

/** Schema for a single pipeline step. */
const pipelineStepSchema = z.object({
  toolId: z.string(),
  settings: z.record(z.unknown()).default({}),
});

/** Schema for a full pipeline definition. */
const stepsSchema =
  env.MAX_PIPELINE_STEPS > 0
    ? z
        .array(pipelineStepSchema)
        .min(1, "Pipeline must have at least one step")
        .max(env.MAX_PIPELINE_STEPS, "Pipeline exceeds maximum steps")
    : z.array(pipelineStepSchema).min(1, "Pipeline must have at least one step");

const pipelineDefinitionSchema = z.object({
  steps: stepsSchema,
});

/** Schema for saving a pipeline. */
const savePipelineSchema = z.object({
  name: z.string().min(1, "Pipeline name is required").max(100),
  description: z.string().max(500).optional(),
  steps: stepsSchema,
});

// ── Helpers ────────────────────────────────────────────────────

interface ParsedStep {
  toolId: string;
  resolvedToolId: string;
  parsedSettings: unknown;
  pool: Pool;
}

/**
 * Tools whose settings carry passwords. They are blocked from ALL pipeline
 * paths so secrets never persist in step rows (the single-tool route redacts
 * via dbSettings).
 */
const PASSWORD_TOOLS = new Set(["protect-pdf", "unlock-pdf"]);

/** Recursively inject OTel trace context into every node of a FlowJob tree. */
function injectTraceContextIntoFlow(node: FlowJob): void {
  injectTraceContext(node.data as ToolJobData);
  if (node.children) {
    for (const child of node.children) {
      injectTraceContextIntoFlow(child);
    }
  }
}

/**
 * Build a FlowJob tree for a single-file pipeline.
 *
 * BullMQ children run BEFORE parents, so the sequential chain nests
 * with step 0 deepest:
 *
 *   finalize (parent)
 *     step N-1
 *       step N-2
 *         ...
 *           step 0 (deepest leaf, runs first)
 */
function buildPipelineFlowTree(opts: {
  jobId: string;
  userId: string | null;
  parsedSteps: ParsedStep[];
  uploadKey: string;
  filename: string;
  pipelinePool: Pool;
  clientJobId?: string;
  parentId?: string;
  totalFiles?: number;
}): { tree: FlowJob; stepJobIds: string[] } {
  const {
    jobId,
    userId,
    parsedSteps,
    uploadKey,
    filename,
    pipelinePool,
    clientJobId,
    parentId,
    totalFiles,
  } = opts;
  const totalSteps = parsedSteps.length;
  const stepJobIds = parsedSteps.map((_: unknown, i: number) => `${jobId}-s${i}`);

  // Build bottom-up: step 0 is the deepest leaf
  // Steps swallow failures via return markers, so a retry would never
  // run; attempts: 1 makes that explicit.
  let currentNode: FlowJob = {
    name: parsedSteps[0].resolvedToolId,
    queueName: queueName(parsedSteps[0].pool),
    data: {
      kind: "pipeline-step",
      jobId: stepJobIds[0],
      toolId: parsedSteps[0].resolvedToolId,
      userId,
      pool: parsedSteps[0].pool,
      stepIndex: 0,
      totalSteps,
      prevJobId: undefined,
      clientJobId,
      inputRefs: [uploadKey],
      filename,
      settings: parsedSteps[0].parsedSettings,
    } satisfies ToolJobData,
    opts: { jobId: stepJobIds[0], attempts: 1 },
  };

  for (let i = 1; i < totalSteps; i++) {
    currentNode = {
      name: parsedSteps[i].resolvedToolId,
      queueName: queueName(parsedSteps[i].pool),
      data: {
        kind: "pipeline-step",
        jobId: stepJobIds[i],
        toolId: parsedSteps[i].resolvedToolId,
        userId,
        pool: parsedSteps[i].pool,
        stepIndex: i,
        totalSteps,
        prevJobId: stepJobIds[i - 1],
        clientJobId,
        inputRefs: [],
        filename,
        settings: parsedSteps[i].parsedSettings,
      } satisfies ToolJobData,
      opts: { jobId: stepJobIds[i], attempts: 1 },
      children: [currentNode],
    };
  }

  // Finalize parent: runs on the pipeline's modality pool (lightweight DB reads
  // + one object copy; steps already run on their own per-step pools; system
  // pool is reserved for crons + batch manifest assembly)
  const tree: FlowJob = {
    name: "pipeline-finalize",
    queueName: queueName(pipelinePool),
    data: {
      kind: "pipeline-finalize",
      jobId,
      toolId: "pipeline",
      userId,
      pool: pipelinePool,
      totalSteps,
      clientJobId,
      parentId,
      totalFiles,
      inputRefs: [],
      filename,
      settings: {},
    } satisfies ToolJobData,
    opts: { jobId, attempts: 1 },
    children: [currentNode],
  };

  return { tree, stepJobIds };
}

export async function registerPipelineRoutes(app: FastifyInstance): Promise<void> {
  /**
   * POST /api/v1/pipeline/execute
   *
   * Accepts multipart with:
   *   - A file part (the file to process)
   *   - A "pipeline" field containing JSON: { steps: [{ toolId, settings }, ...] }
   *
   * Enqueues a BullMQ FlowProducer tree (nested children for sequential
   * execution) and blocks until the finalize job completes.
   */
  app.post(
    "/api/v1/pipeline/execute",
    { config: { rateLimit: { max: 60, timeWindow: "1 minute" } } },
    async (request: FastifyRequest, reply: FastifyReply) => {
      let fileBuffer: Buffer | null = null;
      let filename = "file";
      let pipelineRaw: string | null = null;
      let clientJobId: string | null = null;

      // Parse multipart
      try {
        const parts = request.parts();
        for await (const part of parts) {
          if (part.type === "file") {
            const chunks: Buffer[] = [];
            for await (const chunk of part.file) {
              chunks.push(chunk);
            }
            fileBuffer = Buffer.concat(chunks);
            filename = sanitizeFilename(part.filename ?? "file");
          } else if (part.fieldname === "pipeline") {
            pipelineRaw = part.value as string;
          } else if (part.fieldname === "clientJobId") {
            const raw = part.value as string;
            if (typeof raw === "string" && raw.length > 0 && raw.length <= 128) {
              clientJobId = raw;
            }
          }
        }
      } catch (err) {
        return reply.status(400).send({
          error: "Failed to parse multipart request",
          details: err instanceof Error ? err.message : String(err),
        });
      }

      if (!fileBuffer || fileBuffer.length === 0) {
        return reply.status(400).send({ error: "No file provided" });
      }

      // The first pipeline step determines the input modality, so non-image
      // inputs (audio/video/document) get validated by the right handler instead
      // of always being forced through image validation/decoding.
      let firstToolId: string | undefined;
      try {
        firstToolId = (JSON.parse(pipelineRaw ?? "{}") as { steps?: Array<{ toolId?: string }> })
          ?.steps?.[0]?.toolId;
      } catch {
        // Malformed pipeline JSON is reported when the definition is parsed below.
      }
      const inputModality = TOOLS.find((t) => t.id === firstToolId)?.modality ?? "image";
      const pipelineScratch = join(tmpdir(), "snapotter-scratch", `pipeline-${randomUUID()}`);
      await mkdir(pipelineScratch, { recursive: true });

      if (inputModality === "image") {
        // Validate the initial image
        const validation = await validateImageBuffer(fileBuffer, filename);
        if (!validation.valid) {
          return reply.status(400).send({
            error: `Invalid image: ${validation.reason}`,
          });
        }

        // Decode HEIC/HEIF input via system heif-dec
        if (validation.format === "heif") {
          try {
            fileBuffer = await decodeHeic(fileBuffer);
            const ext = filename.match(/\.[^.]+$/)?.[0];
            if (ext) filename = `${filename.slice(0, -ext.length)}.png`;
          } catch (err) {
            return reply.status(422).send({
              error: "Failed to decode HEIC file. Ensure libheif-examples is installed.",
              details: err instanceof Error ? err.message : String(err),
            });
          }
        }

        // Decode CLI-decoded formats (RAW, TGA, PSD, EXR, HDR)
        if (needsCliDecode(validation.format)) {
          try {
            const fileExt = filename.split(".").pop()?.toLowerCase();
            fileBuffer = await decodeToSharpCompat(fileBuffer, validation.format, fileExt);
            const ext = filename.match(/\.[^.]+$/)?.[0];
            if (ext) filename = `${filename.slice(0, -ext.length)}.png`;
          } catch (err) {
            return reply.status(422).send({
              error: `Failed to decode ${validation.format} file`,
              details: err instanceof Error ? err.message : String(err),
            });
          }
        }

        // Sanitize SVG input and normalize EXIF orientation
        const isSvg = isSvgBuffer(fileBuffer);
        if (isSvg) {
          fileBuffer = sanitizeSvg(fileBuffer);
        } else {
          fileBuffer = await autoOrient(fileBuffer);
        }
      } else {
        // Non-image input: validate/decode via the tool's modality handler.
        try {
          const prepared = await inputHandlerFor(inputModality).prepare(fileBuffer, filename, {
            scratchDir: pipelineScratch,
            lenient: getToolConfig(firstToolId ?? "")?.skipStructuralValidation,
          });
          fileBuffer = prepared.buffer;
          filename = prepared.filename;
        } catch (err) {
          if (err instanceof InputValidationError) {
            const body: Record<string, string> = { error: err.message };
            if (err.details) body.details = err.details;
            return reply.status(err.statusCode).send(body);
          }
          throw err;
        }
      }

      // Parse and validate the pipeline definition
      if (!pipelineRaw) {
        return reply.status(400).send({ error: "No pipeline definition provided" });
      }

      let pipeline: z.infer<typeof pipelineDefinitionSchema>;
      try {
        const parsed = JSON.parse(pipelineRaw);
        const result = pipelineDefinitionSchema.safeParse(parsed);
        if (!result.success) {
          return reply.status(400).send({
            error: "Invalid pipeline definition",
            details: formatZodErrors(result.error.issues),
          });
        }
        pipeline = result.data;
      } catch {
        return reply.status(400).send({ error: "Pipeline must be valid JSON" });
      }

      // Validate all tool IDs and settings; collect parsed steps
      const parsedSteps: ParsedStep[] = [];

      for (let i = 0; i < pipeline.steps.length; i++) {
        const step = pipeline.steps[i];

        // Route content-aware resize to its dedicated tool
        const resolvedToolId =
          step.toolId === "resize" && step.settings?.contentAware
            ? "content-aware-resize"
            : step.toolId;

        const toolConfig = getToolConfig(resolvedToolId);
        if (!toolConfig) {
          return reply.status(400).send({
            error: `Step ${i + 1} (${step.toolId}): Tool not found or not available`,
          });
        }

        // Guard: check if the tool's AI feature bundle is installed
        const missingBundleId = getFirstMissingBundleForTool(resolvedToolId);
        if (missingBundleId) {
          const bundle = FEATURE_BUNDLES[missingBundleId];
          return reply.status(501).send({
            error: `Step ${i + 1} (${step.toolId}): Feature "${bundle?.name}" is not installed`,
            code: "FEATURE_NOT_INSTALLED",
            feature: missingBundleId,
            featureName: bundle?.name ?? resolvedToolId,
          });
        }

        if (PASSWORD_TOOLS.has(step.toolId)) {
          return reply.status(400).send({
            error: `Step ${i + 1}: This tool cannot be used in pipelines because it requires a password`,
          });
        }

        const settingsResult = toolConfig.settingsSchema.safeParse(step.settings);
        if (!settingsResult.success) {
          return reply.status(400).send({
            error: `Step ${i + 1} (${step.toolId}): Invalid settings`,
            details: settingsResult.error.issues.map(
              (iss: { path: (string | number)[]; message: string }) => ({
                path: iss.path.join("."),
                message: iss.message,
              }),
            ),
          });
        }

        if (env.MAX_PIPELINE_STEP_PIXELS > 0) {
          const s = settingsResult.data as Record<string, unknown>;
          const w = Number(s.width) || 0;
          const h = Number(s.height) || 0;
          if (w > 0 && h > 0 && w * h > env.MAX_PIPELINE_STEP_PIXELS) {
            return reply.status(400).send({
              error: `Step ${i + 1} (${step.toolId}): Output dimensions ${w}x${h} exceed per-step pixel limit`,
            });
          }
        }

        parsedSteps.push({
          toolId: step.toolId,
          resolvedToolId,
          parsedSettings: settingsResult.data,
          pool: resolveToolPool(resolvedToolId),
        });
      }

      // ── Enqueue as a BullMQ flow ────────────────────────────────

      const startTime = Date.now();
      const jobId = randomUUID();
      const userId = getAuthUser(request)?.id ?? null;
      const originalSize = fileBuffer.length;

      // Upload decoded file to object storage
      const uploadKey = `uploads/${jobId}/${filename}`;
      await putObject(uploadKey, fileBuffer);

      // Report initial progress
      if (clientJobId) {
        updateSingleFileProgress({
          jobId: clientJobId,
          phase: "processing",
          percent: 0,
          stage: "Preparing pipeline...",
        });
      }

      // Derive the pipeline's pool from the first step's modality so the
      // finalize job and parent row land on the correct queue.
      const firstModality =
        TOOLS.find((t) => t.id === parsedSteps[0].resolvedToolId)?.modality ?? "image";
      const pipelinePool: Pool = MODALITY_POOL[firstModality];

      // Build the nested FlowJob tree
      const { tree, stepJobIds } = buildPipelineFlowTree({
        jobId,
        userId,
        parsedSteps,
        uploadKey,
        filename,
        pipelinePool,
        clientJobId: clientJobId ?? jobId,
      });

      // Insert all durable rows before adding the flow. enqueueToolJob
      // inserts row-then-add; for flows we insert ALL rows first, then
      // one flow.add.
      for (let i = 0; i < parsedSteps.length; i++) {
        await db.insert(schema.jobs).values({
          id: stepJobIds[i],
          userId,
          toolId: parsedSteps[i].resolvedToolId,
          pool: parsedSteps[i].pool,
          type: "pipeline-step",
          status: "queued",
          inputRefs: i === 0 ? [uploadKey] : [],
          settings: parsedSteps[i].parsedSettings as Record<string, unknown>,
        });
      }

      await db.insert(schema.jobs).values({
        id: jobId,
        userId,
        toolId: "pipeline",
        pool: pipelinePool,
        type: "pipeline",
        status: "queued",
        inputRefs: [],
        settings: {},
      });

      // Inject OTel trace context into every node of the flow tree
      injectTraceContextIntoFlow(tree);

      // Add the flow to BullMQ
      await getFlowProducer().add(tree);

      // Wait for the finalize job (pipelines block to completion)
      try {
        const result = await waitForJob(pipelinePool, jobId, 10 * 60_000);

        if (!result) {
          trackEvent(request, ANALYTICS_EVENTS.PIPELINE_EXECUTED, {
            step_count: pipeline.steps.length,
            tool_ids: pipeline.steps.map((s: { toolId: string }) => s.toolId),
            is_batch: false,
            duration_ms: Date.now() - startTime,
            status: "failed",
          });
          return reply.status(422).send({
            error: "Pipeline processing timed out",
          });
        }

        // Check for step failure reported by the finalize handler
        if (result.resultPayload?.error) {
          trackEvent(request, ANALYTICS_EVENTS.PIPELINE_EXECUTED, {
            step_count: pipeline.steps.length,
            tool_ids: pipeline.steps.map((s: { toolId: string }) => s.toolId),
            is_batch: false,
            duration_ms: Date.now() - startTime,
            status: "failed",
          });
          return reply.status(422).send({
            error: result.resultPayload.error as string,
            completedSteps: result.resultPayload.steps,
          });
        }

        trackEvent(request, ANALYTICS_EVENTS.PIPELINE_EXECUTED, {
          step_count: pipeline.steps.length,
          tool_ids: pipeline.steps.map((s: { toolId: string }) => s.toolId),
          is_batch: false,
          duration_ms: Date.now() - startTime,
          status: "completed",
        });

        return reply.send({
          jobId,
          downloadUrl: `/api/v1/download/${jobId}/${encodeURIComponent(result.filename)}`,
          previewUrl: result.previewRef
            ? `/api/v1/download/${jobId}/${result.previewRef.split("/").pop()}`
            : undefined,
          originalSize,
          processedSize: result.processedSize,
          stepsCompleted: result.resultPayload?.stepsCompleted ?? parsedSteps.length,
          steps: result.resultPayload?.steps ?? [],
        });
      } catch (err) {
        trackEvent(request, ANALYTICS_EVENTS.PIPELINE_EXECUTED, {
          step_count: pipeline.steps.length,
          tool_ids: pipeline.steps.map((s: { toolId: string }) => s.toolId),
          is_batch: false,
          duration_ms: Date.now() - startTime,
          status: "failed",
        });
        return reply.status(422).send({
          error: err instanceof Error ? err.message : "Pipeline processing failed",
        });
      }
    },
  );

  /**
   * POST /api/v1/pipeline/save
   *
   * Save a named pipeline definition for later reuse.
   */
  app.post(
    "/api/v1/pipeline/save",
    { config: { rateLimit: { max: 60, timeWindow: "1 minute" } } },
    async (request: FastifyRequest, reply: FastifyReply) => {
      const user = requireAuth(request, reply);
      if (!user) return;

      const body = request.body as unknown;
      const result = savePipelineSchema.safeParse(body);

      if (!result.success) {
        return reply.status(400).send({
          error: "Invalid pipeline definition",
          details: result.error.issues.map((i) => ({
            path: i.path.join("."),
            message: i.message,
          })),
        });
      }

      const { name, description, steps } = result.data;

      // Validate all tool IDs exist
      for (let i = 0; i < steps.length; i++) {
        if (PASSWORD_TOOLS.has(steps[i].toolId)) {
          return reply.status(400).send({
            error: `This tool cannot be used in saved pipelines because it requires a password`,
          });
        }
        const toolConfig = getToolConfig(steps[i].toolId);
        if (!toolConfig) {
          return reply.status(400).send({
            error: `Step ${i + 1}: Tool "${steps[i].toolId}" not found`,
          });
        }
      }

      const id = randomUUID();

      try {
        await db.insert(schema.pipelines).values({
          id,
          userId: user.id,
          name,
          description: description ?? null,
          steps,
        });
      } catch {
        return reply.status(409).send({ error: "Failed to save pipeline" });
      }

      return reply.status(201).send({
        id,
        name,
        description: description ?? null,
        steps,
        createdAt: new Date().toISOString(),
      });
    },
  );

  /**
   * GET /api/v1/pipeline/list
   *
   * List all saved pipelines.
   */
  app.get(
    "/api/v1/pipeline/list",
    { config: { rateLimit: { max: 300, timeWindow: "1 minute" } } },
    async (request: FastifyRequest, reply: FastifyReply) => {
      const user = requireAuth(request, reply);
      if (!user) return;

      // Admins see all pipelines; regular users see their own + legacy (no owner)
      const allRows = await db.select().from(schema.pipelines);
      const rows = (await hasEffectivePermission(user, "pipelines:all"))
        ? allRows
        : allRows.filter((row) => !row.userId || row.userId === user.id);

      const pipelines = rows.map((row) => ({
        id: row.id,
        name: row.name,
        description: row.description,
        steps: row.steps,
        createdAt: row.createdAt.toISOString(),
      }));

      return reply.send({ pipelines });
    },
  );

  /**
   * DELETE /api/v1/pipeline/:id
   *
   * Delete a saved pipeline by its ID.
   */
  app.delete(
    "/api/v1/pipeline/:id",
    { config: { rateLimit: { max: 60, timeWindow: "1 minute" } } },
    async (request: FastifyRequest<{ Params: { id: string } }>, reply: FastifyReply) => {
      const user = requireAuth(request, reply);
      if (!user) return;

      const { id } = request.params;

      const [existing] = await db
        .select()
        .from(schema.pipelines)
        .where(eq(schema.pipelines.id, id));

      if (!existing) {
        return reply.status(404).send({ error: "Pipeline not found" });
      }

      // Only the owner (or admin) can delete; legacy pipelines (no owner) can be deleted by anyone
      if (
        existing.userId &&
        existing.userId !== user.id &&
        !(await hasEffectivePermission(user, "pipelines:all"))
      ) {
        return reply.status(403).send({ error: "Not authorized to delete this pipeline" });
      }

      await db.delete(schema.pipelines).where(eq(schema.pipelines.id, id));

      return reply.send({ ok: true });
    },
  );

  /**
   * GET /api/v1/pipeline/tools
   *
   * Returns the IDs of tools that can be used as pipeline steps.
   * Only tools registered via createToolRoute() support pipeline execution.
   */
  app.get("/api/v1/pipeline/tools", async (_request: FastifyRequest, reply: FastifyReply) => {
    return reply.send({ toolIds: getRegisteredToolIds() });
  });

  /**
   * POST /api/v1/pipeline/batch
   *
   * Accepts multipart with multiple files + a "pipeline" JSON field.
   * Each file is processed through the full pipeline via a per-file
   * FlowProducer chain. All chains are children of a single
   * batch-finalize parent. Returns a ZIP containing all results.
   */
  app.post(
    "/api/v1/pipeline/batch",
    {
      config: { rateLimit: { max: 20, timeWindow: "1 minute" } },
    },
    async (request: FastifyRequest, reply: FastifyReply) => {
      // ── Parse multipart ──────────────────────────────────────────────
      interface ParsedFile {
        buffer: Buffer;
        filename: string;
      }

      const files: ParsedFile[] = [];
      let pipelineRaw: string | null = null;
      let clientJobId: string | null = null;

      try {
        const parts = request.parts();
        for await (const part of parts) {
          if (part.type === "file") {
            const chunks: Buffer[] = [];
            for await (const chunk of part.file) {
              chunks.push(chunk);
            }
            const buffer = Buffer.concat(chunks);
            if (buffer.length > 0) {
              files.push({
                buffer,
                filename: sanitizeFilename(part.filename ?? "file"),
              });
            }
          } else if (part.fieldname === "pipeline") {
            pipelineRaw = part.value as string;
          } else if (part.fieldname === "clientJobId") {
            const raw = part.value as string;
            if (typeof raw === "string" && raw.length > 0 && raw.length <= 128) {
              clientJobId = raw;
            }
          }
        }
      } catch (err) {
        return reply.status(400).send({
          error: "Failed to parse multipart request",
          details: err instanceof Error ? err.message : String(err),
        });
      }

      if (files.length === 0) {
        return reply.status(400).send({ error: "No files provided" });
      }

      // Enforce batch size limit
      if (env.MAX_BATCH_SIZE > 0 && files.length > env.MAX_BATCH_SIZE) {
        return reply.status(400).send({
          error: `Too many files. Maximum batch size is ${env.MAX_BATCH_SIZE}`,
        });
      }

      // ── Parse and validate pipeline definition ───────────────────────
      if (!pipelineRaw) {
        return reply.status(400).send({ error: "No pipeline definition provided" });
      }

      let pipeline: z.infer<typeof pipelineDefinitionSchema>;
      try {
        const parsed = JSON.parse(pipelineRaw);
        const result = pipelineDefinitionSchema.safeParse(parsed);
        if (!result.success) {
          return reply.status(400).send({
            error: "Invalid pipeline definition",
            details: formatZodErrors(result.error.issues),
          });
        }
        pipeline = result.data;
      } catch {
        return reply.status(400).send({ error: "Pipeline must be valid JSON" });
      }

      // Validate all tool IDs and settings
      const parsedSteps: ParsedStep[] = [];

      for (let i = 0; i < pipeline.steps.length; i++) {
        const step = pipeline.steps[i];

        const resolvedToolId =
          step.toolId === "resize" && step.settings?.contentAware
            ? "content-aware-resize"
            : step.toolId;

        const toolConfig = getToolConfig(resolvedToolId);
        if (!toolConfig) {
          return reply.status(400).send({
            error: `Step ${i + 1}: Tool "${step.toolId}" not found`,
          });
        }

        const missingBundleId = getFirstMissingBundleForTool(resolvedToolId);
        if (missingBundleId) {
          const bundle = FEATURE_BUNDLES[missingBundleId];
          return reply.status(501).send({
            error: `Step ${i + 1} (${step.toolId}): Feature "${bundle?.name}" is not installed`,
            code: "FEATURE_NOT_INSTALLED",
            feature: missingBundleId,
            featureName: bundle?.name ?? resolvedToolId,
          });
        }

        if (PASSWORD_TOOLS.has(step.toolId)) {
          return reply.status(400).send({
            error: `Step ${i + 1}: This tool cannot be used in pipelines because it requires a password`,
          });
        }

        const settingsResult = toolConfig.settingsSchema.safeParse(step.settings);
        if (!settingsResult.success) {
          return reply.status(400).send({
            error: `Step ${i + 1} (${step.toolId}): Invalid settings`,
            details: settingsResult.error.issues.map(
              (iss: { path: (string | number)[]; message: string }) => ({
                path: iss.path.join("."),
                message: iss.message,
              }),
            ),
          });
        }

        if (env.MAX_PIPELINE_STEP_PIXELS > 0) {
          const s = settingsResult.data as Record<string, unknown>;
          const w = Number(s.width) || 0;
          const h = Number(s.height) || 0;
          if (w > 0 && h > 0 && w * h > env.MAX_PIPELINE_STEP_PIXELS) {
            return reply.status(400).send({
              error: `Step ${i + 1} (${step.toolId}): Output dimensions ${w}x${h} exceed per-step pixel limit`,
            });
          }
        }

        parsedSteps.push({
          toolId: step.toolId,
          resolvedToolId,
          parsedSettings: settingsResult.data,
          pool: resolveToolPool(resolvedToolId),
        });
      }

      // ── Prepare files and build flow ─────────────────────────────────
      const batchStartTime = Date.now();
      const parentId = clientJobId || randomUUID();
      const userId = getAuthUser(request)?.id ?? null;

      // Insert batch-finalize row BEFORE updateJobProgress to avoid
      // a duplicate-key race with the progress persist layer.
      await db.insert(schema.jobs).values({
        id: parentId,
        userId,
        toolId: "pipeline-batch",
        pool: "system",
        type: "batch",
        status: "queued",
        inputRefs: [],
        settings: { flowChildCount: 0 },
      });

      // Emit initial batch progress
      updateJobProgress({
        jobId: parentId,
        status: "processing",
        totalFiles: files.length,
        completedFiles: 0,
        failedFiles: 0,
        errors: [],
      });

      // Validate, decode, and upload each file; build per-file pipeline chains
      const perFileChildren: FlowJob[] = [];
      const preFailures: Array<{ originalIndex: number; filename: string; error: string }> = [];
      let flowChildIndex = 0;

      // The first step's modality drives input validation for every file, so
      // audio, video, and document pipelines are not rejected by the image
      // validator.
      const batchModality =
        TOOLS.find((t) => t.id === pipeline.steps[0]?.toolId)?.modality ?? "image";
      const batchPipelinePool: Pool = MODALITY_POOL[batchModality];
      const pipelineBatchScratch = join(
        tmpdir(),
        "snapotter-scratch",
        `pipeline-batch-${parentId}`,
      );
      await mkdir(pipelineBatchScratch, { recursive: true });

      for (let fi = 0; fi < files.length; fi++) {
        const file = files[fi];
        let processBuffer = file.buffer;
        let processFilename = file.filename;

        if (batchModality === "image") {
          const fileValidation = await validateImageBuffer(processBuffer, processFilename);
          if (!fileValidation.valid) {
            preFailures.push({
              originalIndex: fi,
              filename: file.filename,
              error: `Invalid image: ${fileValidation.reason}`,
            });
            continue;
          }

          // Decode chain
          if (fileValidation.format === "heif") {
            try {
              processBuffer = await decodeHeic(processBuffer);
              const ext = processFilename.match(/\.[^.]+$/)?.[0];
              if (ext) processFilename = `${processFilename.slice(0, -ext.length)}.png`;
            } catch {
              preFailures.push({
                originalIndex: fi,
                filename: file.filename,
                error: "Failed to decode HEIC file",
              });
              continue;
            }
          }

          if (needsCliDecode(fileValidation.format)) {
            try {
              const fileExt = processFilename.split(".").pop()?.toLowerCase();
              processBuffer = await decodeToSharpCompat(
                processBuffer,
                fileValidation.format,
                fileExt,
              );
              const ext = processFilename.match(/\.[^.]+$/)?.[0];
              if (ext) processFilename = `${processFilename.slice(0, -ext.length)}.png`;
            } catch {
              // Fall through -- tool might handle it
            }
          }

          if (isSvgBuffer(processBuffer)) {
            processBuffer = sanitizeSvg(processBuffer);
          } else {
            processBuffer = await autoOrient(processBuffer);
          }
        } else {
          // Non-image input: validate/decode via the tool's modality handler.
          try {
            const prepared = await inputHandlerFor(batchModality).prepare(
              processBuffer,
              processFilename,
              {
                scratchDir: pipelineBatchScratch,
                lenient: getToolConfig(pipeline.steps[0]?.toolId ?? "")?.skipStructuralValidation,
              },
            );
            processBuffer = prepared.buffer;
            processFilename = prepared.filename;
          } catch (err) {
            if (err instanceof InputValidationError) {
              preFailures.push({ originalIndex: fi, filename: file.filename, error: err.message });
              continue;
            }
            throw err;
          }
        }

        // Upload decoded file
        const perFileJobId = `${parentId}-f${flowChildIndex}`;
        const uploadKey = `uploads/${perFileJobId}-s0/${processFilename}`;
        await putObject(uploadKey, processBuffer);

        // Build per-file pipeline chain
        const { tree: perFileTree, stepJobIds } = buildPipelineFlowTree({
          jobId: perFileJobId,
          userId,
          parsedSteps,
          uploadKey,
          filename: processFilename,
          pipelinePool: batchPipelinePool,
          parentId,
          totalFiles: files.length,
        });

        // Insert step + finalize rows for this file
        for (let si = 0; si < parsedSteps.length; si++) {
          await db.insert(schema.jobs).values({
            id: stepJobIds[si],
            userId,
            toolId: parsedSteps[si].resolvedToolId,
            pool: parsedSteps[si].pool,
            type: "pipeline-step",
            status: "queued",
            inputRefs: si === 0 ? [uploadKey] : [],
            settings: parsedSteps[si].parsedSettings as Record<string, unknown>,
          });
        }

        await db.insert(schema.jobs).values({
          id: perFileJobId,
          userId,
          toolId: "pipeline",
          pool: batchPipelinePool,
          type: "pipeline-finalize",
          status: "queued",
          inputRefs: [],
          settings: {},
        });

        perFileChildren.push(perFileTree);
        flowChildIndex++;
      }

      // Record pre-failures in batch progress
      for (const pf of preFailures) {
        await recordChildOutcome(parentId, files.length, pf.filename, pf.error);
      }

      if (perFileChildren.length === 0) {
        // All files failed validation
        trackEvent(request, ANALYTICS_EVENTS.PIPELINE_EXECUTED, {
          step_count: pipeline.steps.length,
          tool_ids: pipeline.steps.map((s: { toolId: string }) => s.toolId),
          is_batch: true,
          file_count: files.length,
          duration_ms: Date.now() - batchStartTime,
          status: "failed",
        });
        return reply.status(422).send({
          error: "All files failed processing",
          errors: preFailures.map((f) => ({ filename: f.filename, error: f.error })),
        });
      }

      // Build batch-finalize parent
      const batchTree: FlowJob = {
        name: "batch-finalize",
        queueName: queueName("system"),
        data: {
          kind: "batch-finalize",
          jobId: parentId,
          toolId: "pipeline-batch",
          userId,
          pool: "system" as Pool,
          totalFiles: files.length,
          inputRefs: [],
          filename: "",
          settings: { flowChildCount: perFileChildren.length },
        } satisfies ToolJobData,
        opts: { jobId: parentId, attempts: 1 },
        children: perFileChildren,
      };

      // Update the parent row with the final flow child count
      await db
        .update(schema.jobs)
        .set({ settings: { flowChildCount: perFileChildren.length } })
        .where(eq(schema.jobs.id, parentId));

      // Inject OTel trace context into every node of the batch flow tree
      injectTraceContextIntoFlow(batchTree);

      await getFlowProducer().add(batchTree);

      // Wait for batch completion
      const batchResult = await waitForJob("system", parentId, 30 * 60_000);

      if (!batchResult) {
        trackEvent(request, ANALYTICS_EVENTS.PIPELINE_EXECUTED, {
          step_count: pipeline.steps.length,
          tool_ids: pipeline.steps.map((s: { toolId: string }) => s.toolId),
          is_batch: true,
          file_count: files.length,
          duration_ms: Date.now() - batchStartTime,
          status: "failed",
        });
        return reply.status(422).send({ error: "Pipeline batch processing timed out" });
      }

      const manifest = (batchResult.resultPayload?.manifest ?? []) as Array<{
        index: number;
        filename: string;
        outputRef?: string;
        error?: string;
      }>;

      // Combine manifest with pre-failures
      const allResults: Array<{
        originalIndex: number;
        filename: string;
        outputRef?: string;
        error?: string;
      }> = [];

      // Map flow indices back to original file indices
      let fci = 0;
      for (let fi = 0; fi < files.length; fi++) {
        const pf = preFailures.find((p) => p.originalIndex === fi);
        if (pf) {
          allResults.push({
            originalIndex: fi,
            filename: pf.filename,
            error: pf.error,
          });
        } else {
          const entry = manifest.find((m) => m.index === fci);
          if (entry) {
            allResults.push({
              originalIndex: fi,
              filename: entry.filename,
              outputRef: entry.outputRef,
              error: entry.error,
            });
          }
          fci++;
        }
      }

      // Deduplicate output filenames
      const usedNames = new Set<string>();
      function getUniqueName(name: string): string {
        if (!usedNames.has(name)) {
          usedNames.add(name);
          return name;
        }
        const dotIdx = name.lastIndexOf(".");
        const base = dotIdx > 0 ? name.slice(0, dotIdx) : name;
        const ext = dotIdx > 0 ? name.slice(dotIdx) : "";
        let counter = 1;
        let candidate = `${base}_${counter}${ext}`;
        while (usedNames.has(candidate)) {
          counter++;
          candidate = `${base}_${counter}${ext}`;
        }
        usedNames.add(candidate);
        return candidate;
      }

      const successEntries = allResults.filter((r) => r.outputRef);
      const failedEntries = allResults.filter((r) => !r.outputRef);

      if (successEntries.length === 0) {
        trackEvent(request, ANALYTICS_EVENTS.PIPELINE_EXECUTED, {
          step_count: pipeline.steps.length,
          tool_ids: pipeline.steps.map((s: { toolId: string }) => s.toolId),
          is_batch: true,
          file_count: files.length,
          duration_ms: Date.now() - batchStartTime,
          status: "failed",
        });
        return reply.status(422).send({
          error: "All files failed processing",
          errors: failedEntries.map((f) => ({ filename: f.filename, error: f.error ?? "Failed" })),
        });
      }

      trackEvent(request, ANALYTICS_EVENTS.PIPELINE_EXECUTED, {
        step_count: pipeline.steps.length,
        tool_ids: pipeline.steps.map((s: { toolId: string }) => s.toolId),
        is_batch: true,
        file_count: files.length,
        duration_ms: Date.now() - batchStartTime,
        status: "completed",
      });

      const fileResultsMap: Record<string, string> = {};
      for (const entry of successEntries) {
        const uniqueName = getUniqueName(entry.filename);
        entry.filename = uniqueName;
        fileResultsMap[String(entry.originalIndex)] = uniqueName;
      }

      // ── Stream ZIP response ──────────────────────────────────────────
      reply.hijack();
      reply.raw.writeHead(200, {
        "Content-Type": "application/zip",
        "Content-Disposition": `attachment; filename="pipeline-batch-${parentId.slice(0, 8)}.zip"`,
        "Transfer-Encoding": "chunked",
        "X-Job-Id": parentId,
        "X-File-Results": encodeURIComponent(JSON.stringify(fileResultsMap)),
        ...getSecurityHeaders(),
      });

      const archive = archiver("zip", { zlib: { level: 5 } });

      archive.on("error", (err) => {
        request.log.error({ err }, "Archiver error during pipeline batch processing");
        if (!reply.raw.writableEnded) {
          reply.raw.end();
        }
      });

      archive.pipe(reply.raw);

      // Append results from object storage in original upload order
      try {
        for (const entry of successEntries) {
          if (!entry.outputRef) continue;
          const stream = await getObjectStream(entry.outputRef);
          archive.append(stream, { name: entry.filename });
        }

        await archive.finalize();
      } catch (err) {
        request.log.error({ err }, "Failed to stream ZIP entries during pipeline batch processing");
        archive.abort();
        if (!reply.raw.writableEnded) {
          reply.raw.end();
        }
      }
    },
  );

  app.log.info("Pipeline routes registered");
}