import { execFile } from "node:child_process";
import fs from "node:fs/promises";
import path from "node:path";
import { promisify } from "node:util";
import { artifactUrl, createStepGlbPreview, readArtifact } from "@/lib/preview-artifacts";
import { enginePath } from "@/lib/paths";
import { ensureTask, sanitizeFilename, upsertManifest } from "@/lib/task-store";

const execFileAsync = promisify(execFile);

export type CadGenerationResult = {
  handled: true;
  taskId: string;
  artifactPath: string;
  artifactUrl: string;
  previewPath: string;
  previewUrl: string;
  viewerAssetPath: string;
  viewerAssetUrl: string;
  sourcePath: string;
  summary: string;
};

function ensureRelativeFilename(filename: string, extension: string, fallback: string) {
  const safeName = sanitizeFilename(filename || fallback);
  return safeName.toLowerCase().endsWith(extension) ? safeName : `${safeName}${extension}`;
}

function pythonExecutable() {
  return process.env.CAD_PYTHON
    || enginePath("text-to-cad", ".venv", "bin", "python");
}

function pipelineScript() {
  return enginePath("designir-pipeline", "scripts", "designir_pipeline.py");
}

function routerScript() {
  return enginePath("text-to-cad", "skills", "cad-router", "scripts", "route.py");
}

async function runJson(command: string, args: string[], cwd: string) {
  const { stdout } = await execFileAsync(command, args, {
    cwd,
    timeout: 120_000,
    maxBuffer: 1024 * 1024 * 8,
  });
  return JSON.parse(stdout) as Record<string, unknown>;
}

export async function executeDesignIR({
  prompt,
  summary,
  designir,
  designirFilename,
  stepFilename,
  selectedTaskId,
  assumptions = [],
  teacherTaskId,
  teacherPath,
}: {
  prompt: string;
  summary: string;
  designir: Record<string, unknown>;
  designirFilename?: string;
  stepFilename?: string;
  selectedTaskId?: string;
  assumptions?: string[];
  teacherTaskId?: string;
  teacherPath?: string;
}): Promise<CadGenerationResult> {
  const task = await ensureTask(selectedTaskId || undefined);
  const sourcePath = ensureRelativeFilename(
    designirFilename || "model.designir.json",
    ".designir.json",
    "model.designir.json",
  );
  const artifactPath = ensureRelativeFilename(stepFilename || "model.step", ".step", "model.step");
  const sourceAbsolutePath = path.join(task.dir, sourcePath);
  const artifactAbsolutePath = path.join(task.dir, artifactPath);
  await fs.writeFile(sourceAbsolutePath, `${JSON.stringify(designir, null, 2)}\n`);

  const route = await runJson(
    pythonExecutable(),
    [routerScript(), prompt],
    task.dir,
  );
  const selectedBackend = String(route.selected_backend || "build123d");
  const normalizedDesignIR = {
    ...designir,
    backend_hint: selectedBackend,
  };
  await fs.writeFile(sourceAbsolutePath, `${JSON.stringify(normalizedDesignIR, null, 2)}\n`);

  const antiCheat = await runJson(
    pythonExecutable(),
    [pipelineScript(), "anti-cheat", sourceAbsolutePath],
    task.dir,
  );
  if (antiCheat.valid !== true) {
    throw new Error(`DesignIR anti-cheat validation failed: ${JSON.stringify(antiCheat.violations || [])}`);
  }
  const rebuild = await runJson(
    pythonExecutable(),
    [
      pipelineScript(),
      "isolated-rebuild",
      sourceAbsolutePath,
      "--output",
      artifactAbsolutePath,
      "--backend",
      selectedBackend,
    ],
    task.dir,
  );
  if (rebuild.valid !== true) {
    throw new Error("Isolated DesignIR rebuild failed.");
  }

  const validation: string[] = [
    "CAD Router selected the backend before compilation.",
    "DesignIR anti-cheat validation passed.",
    "STEP rebuilt in an isolated workspace without teacher STEP access.",
  ];
  const artifacts: Array<{ path: string; role: string; kind?: string }> = [
    { path: sourcePath, role: "editable_contract", kind: "designir-2.0" },
    { path: artifactPath, role: "primary", kind: "step" },
  ];
  if (typeof rebuild.model_json === "string" && rebuild.model_json) {
    const simpleCadModelPath = path.basename(rebuild.model_json);
    artifacts.push({
      path: simpleCadModelPath,
      role: "backend_editable_graph",
      kind: "simplecad-model-json",
    });
  }

  if (teacherTaskId && teacherPath) {
    const { absolutePath: teacherAbsolutePath } = await readArtifact(
      teacherTaskId,
      teacherPath,
    );
    const reportPath = "acceptance-report.json";
    const reportAbsolutePath = path.join(task.dir, reportPath);
    const acceptance = await runJson(
      pythonExecutable(),
      [
        pipelineScript(),
        "accept",
        "--teacher",
        teacherAbsolutePath,
        "--designir",
        sourceAbsolutePath,
        "--rebuilt",
        artifactAbsolutePath,
        "--report",
        reportAbsolutePath,
      ],
      task.dir,
    );
    artifacts.push({ path: reportPath, role: "acceptance", kind: "json" });
    validation.push(`Independent acceptance verdict: ${String(acceptance.verdict || "unknown")}.`);
  }

  const viewerAssetPath = await createStepGlbPreview({
    taskId: task.taskId,
    stepPath: artifactPath,
  });
  artifacts.push({ path: viewerAssetPath, role: "viewer", kind: "glb" });
  const artifactVersion = Date.now().toString(36);

  await upsertManifest(task.taskId, {
    request: prompt,
    route: {
      selected_backend: selectedBackend,
      runner_skill: String(route.runner_skill || "cad"),
      project: String(route.project || "text-to-cad"),
      fallback_order: Array.isArray(route.fallback_order) ? route.fallback_order : [],
      workflow_profiles: Array.isArray(route.workflow_profiles) ? route.workflow_profiles : [],
    },
    source: {
      path: sourcePath,
      format: "designir-2.0",
      backend: selectedBackend,
      source_editability: "editable_source",
      generated_by: "llm_designir_tool_call",
    },
    artifacts,
    assumptions,
    validation,
    studio: {
      latestArtifact: artifactPath,
      latestPreview: artifactPath,
      latestViewerAsset: viewerAssetPath,
      latestVersion: artifactVersion,
    },
  });

  const stepUrl = artifactUrl(task.taskId, artifactPath, artifactVersion);
  return {
    handled: true,
    taskId: task.taskId,
    artifactPath,
    artifactUrl: stepUrl,
    previewPath: artifactPath,
    previewUrl: stepUrl,
    viewerAssetPath,
    viewerAssetUrl: artifactUrl(task.taskId, viewerAssetPath, artifactVersion),
    sourcePath,
    summary: summary || "CAD model generated from executable DesignIR 2.0.",
  };
}

export function cadResultDirective(result: CadGenerationResult) {
  return `::cad-result{base64="${Buffer.from(JSON.stringify(result), "utf8").toString("base64")}"}`;
}