// emit.mjs — project the engine's deploy adapter into a target dir.
//
//   node engine/emit.mjs <target> <dir>
//   e.g. node engine/emit.mjs cloudflare site-instruments
//
// Rule (uniform for every generated file): READ the target for its per-target
// values, then REBUILD all adapter files from the plugin templates carrying
// those values. Structural template changes propagate to every target on the
// next run; hand-added values (name/TITLE) survive because they're read back
// out of the target. content/ is AUTHORED — never generated, never touched.

import { readFileSync, writeFileSync, existsSync, mkdirSync, readdirSync } from "node:fs";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";
import { execFileSync } from "node:child_process";

const ENGINE = dirname(fileURLToPath(import.meta.url));   // .../engine
const [target, dir] = process.argv.slice(2);
if (!target || !dir) {
  console.error("usage: node engine/emit.mjs <target> <dir>");
  process.exit(1);
}

const plugin = join(ENGINE, target);
if (!existsSync(plugin)) {
  console.error(`no deploy plugin '${target}' (expected ${plugin}/)`);
  process.exit(1);
}

// --- read per-target values out of the existing target (preserve across rebuild) ---
const tomlPath = join(dir, "wrangler.toml");
const prior = existsSync(tomlPath) ? readFileSync(tomlPath, "utf8") : "";
const NAME  = (prior.match(/^name\s*=\s*"([^"]*)"/m) || [])[1] || "{{NAME}}";
const TITLE = (prior.match(/TITLE\s*=\s*"([^"]*)"/m) || [])[1] || "{{TITLE}}";

// --- regenerate every adapter file from templates, injecting preserved values ---
mkdirSync(join(dir, "content"), { recursive: true });     // ensure authored dir exists (untouched if present)
const fill = s => s.replaceAll("{{NAME}}", NAME).replaceAll("{{TITLE}}", TITLE);
for (const f of readdirSync(plugin)) {
  const out = f === "gitignore" ? ".gitignore" : f;       // stored dotless in the plugin; dotted in the target
  writeFileSync(join(dir, out), fill(readFileSync(join(plugin, f), "utf8")));
}

// --- manifest from authored content (gen owns _manifest.js; content is read-only to us) ---
execFileSync("node", [join(ENGINE, "gen.mjs"), "--src", "content", "--target", "_manifest.js"],
  { cwd: dir, stdio: "inherit" });

// --- first-scaffold notice: values with no prior source stay as placeholders ---
const todo = [];
if (NAME  === "{{NAME}}")  todo.push("name");
if (TITLE === "{{TITLE}}") todo.push("TITLE");
console.log(`emit: ${target} → ${dir}/  (adapter files regenerated)`);
if (todo.length) console.log(`  fill in ${todo.join(" and ")} in ${dir}/wrangler.toml before deploy`);