import { mkdir, writeFile } from "node:fs/promises";
import { join } from "node:path";
import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { requireBrain } from "./context.ts";
import { collectBlocks } from "./intent-blocks.ts";
import { renderTarget } from "./build-renderers.ts";
import { isValidIdentifier } from "./utils.ts";
import { readEnolaConfig } from "./brain-home.ts";
import { enolaGateCheck, runEnolaBaseline } from "./enola.ts";

export function registerBuild(pi: ExtensionAPI) {
  pi.registerCommand("brain:build", {
    description: "Generate code from approved intent blocks (usage: /brain:build <scope> <target>)",
    handler: async (args, ctx) => {
      const trimmed = args.trim();
      if (!trimmed) {
        ctx.ui.notify("Usage: /brain:build <scope> <target>", "warning");
        return;
      }

      const parts = trimmed.split(/\s+/);
      if (parts.length !== 2) {
        ctx.ui.notify("Usage: /brain:build <scope> <target>", "warning");
        return;
      }

      const [scope, target] = parts;
      if (!isValidIdentifier(scope) || !isValidIdentifier(target)) {
        ctx.ui.notify("Scope and target must be simple identifiers (letters, numbers, -, _).", "warning");
        return;
      }
      const home = await requireBrain(ctx.cwd);
      if (!home) {
        ctx.ui.notify("No pi-brain home found.", "error");
        return;
      }

      const enolaConfig = await readEnolaConfig(home);
      if (enolaConfig.enabled && enolaConfig.gateBuild) {
        const gate = await enolaGateCheck(home, "/brain:build");
        if (!gate.proceed) {
          ctx.ui.notify(gate.message, "warning");
          return;
        }
      }

      const blocks = await collectBlocks(home, scope);
      const rendered = renderTarget(blocks, target);
      if (rendered === null) {
        ctx.ui.notify(`Unknown build target: ${target}`, "error");
        return;
      }

      const header = [
        "// Generated by /brain:build",
        `// Scope: ${scope}`,
        `// Target: ${target}`,
        `// Source blocks: ${blocks.map((b) => `${b.source}#${b.name}`).join(", ")}`,
        "// Review before applying; do not edit this header manually.",
        "",
      ].join("\n");

      const output = header + rendered;
      const outputDir = join(home.path, "wiki", scope, "ai-suggestions", "build", target);
      const outputPath = join(outputDir, "generated.ts");
      await mkdir(outputDir, { recursive: true });
      await writeFile(outputPath, output, "utf-8");

      if (enolaConfig.enabled && enolaConfig.autoBaseline) {
        const baseline = await runEnolaBaseline(home);
        ctx.ui.notify(`Generated ${outputPath}\n\n${baseline.summary ?? "Baseline updated."}\n\n${output.slice(0, 1000)}`, "info");
      } else {
        ctx.ui.notify(`Generated ${outputPath}\n\n${output.slice(0, 1200)}`, "info");
      }
    },
  });
}