import { readdirSync, readFileSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import { format, resolveConfig } from "prettier";

const uiRoot = join(import.meta.dirname, "..", "packages", "ui");
const componentsDir = join(uiRoot, "components");
const catalog = JSON.parse(readFileSync(join(uiRoot, "component-catalog.json"), "utf8"));
const metadata = new Map(catalog.components.map((entry) => [entry.name, entry]));

async function writeFormatted(path, source, parser) {
  const config = (await resolveConfig(path)) ?? {};
  const formatted = await format(source, {
    ...config,
    filepath: path,
    parser,
  });
  writeFileSync(path, formatted);
}

function block(source, keyword) {
  const start = source.indexOf(`${keyword} {`);
  if (start < 0) return "";
  const open = source.indexOf("{", start);
  let depth = 0;
  for (let index = open; index < source.length; index++) {
    if (source[index] === "{") depth++;
    if (source[index] === "}" && --depth === 0) return source.slice(open + 1, index);
  }
  return "";
}

function propsOf(source) {
  const props = [];
  for (const line of block(source, "props").split(/\r?\n/)) {
    const match = line
      .trim()
      .match(/^([A-Za-z][A-Za-z0-9_]*)(?:\s*:\s*([^=]+?))?\s*(?:=\s*(.+))?$/);
    if (!match) continue;
    const [, name, annotation, rawDefault] = match;
    const value = rawDefault?.trim();
    const type =
      annotation?.trim() ||
      (value === "true" || value === "false"
        ? "boolean"
        : /^-?\d+(?:\.\d+)?$/.test(value ?? "")
          ? "number"
          : "string");
    props.push({ name, type, required: value === undefined, default: value ?? null });
  }
  return props;
}

function words(name) {
  return name.replace(/([a-z0-9])([A-Z])/g, "$1 $2").toLowerCase();
}

const components = readdirSync(componentsDir)
  .filter((file) => file.endsWith(".wrn"))
  .map((file) => {
    const source = readFileSync(join(componentsDir, file), "utf8");
    const declaration = /^\s*component\s+([A-Za-z][A-Za-z0-9_]*)\b/m.exec(source);
    if (!declaration) {
      throw new Error(`UI component source does not declare a component: ${file}`);
    }
    const name = declaration[1];
    const entry = metadata.get(name);
    const slots = [...source.matchAll(/<slot(?:\s+name="([^"]+)")?/g)].map(
      (match) => match[1] ?? "default",
    );
    const declaredEvents = [
      ...new Set(
        [...source.matchAll(/@event\s+([A-Za-z][A-Za-z0-9_]*)\s*=\s*function/g)].map(
          (match) => match[1],
        ),
      ),
    ];
    // Only `@event` declarations form the public component contract. Native
    // handlers in a component's implementation are private wiring and must not
    // leak into the generated consumer-facing reference.
    const events = declaredEvents;
    return {
      name,
      mount: name,
      category: entry?.category ?? "core",
      purpose: entry?.purpose ?? `Reusable ${words(name)} component.`,
      props: propsOf(source),
      slots: [...new Set(slots)],
      events,
      source: `components/${file}`,
    };
  })
  .sort((left, right) => left.name.localeCompare(right.name));

const referencePath = join(uiRoot, "component-reference.json");
await writeFormatted(
  referencePath,
  JSON.stringify(
    { generatedFrom: "packages/ui/components/*.wrn", count: components.length, components },
    null,
    2,
  ) + "\n",
  "json",
);

const lines = [
  "# WRNexus UI component reference",
  "",
  `This reference is generated from the ${components.length} packaged \`.wrn\` component sources. Props marked required have no default; all others show their runtime default.`,
  "",
];
for (const category of [...new Set(components.map((component) => component.category))].sort()) {
  lines.push(`## ${category[0].toUpperCase()}${category.slice(1)}`, "");
  for (const component of components.filter((item) => item.category === category)) {
    const props = component.props.length
      ? component.props
          .map(
            (prop) =>
              `\`${prop.name}: ${prop.type}${prop.required ? " (required)" : ` = ${prop.default}`}\``,
          )
          .join(", ")
      : "None";
    lines.push(
      `### ${component.name}`,
      "",
      component.purpose,
      "",
      `- Mount: \`data-component="${component.mount}"\``,
      `- Props: ${props}`,
      `- Slots: ${component.slots.length ? component.slots.map((slot) => `\`${slot}\``).join(", ") : "None"}`,
      `- Events: ${component.events.length ? component.events.map((event) => `\`${event}\``).join(", ") : "None"}`,
      "",
    );
  }
}
const componentsPath = join(uiRoot, "COMPONENTS.md");
await writeFormatted(componentsPath, `${lines.join("\n").trimEnd()}\n`, "markdown");