import fs from "fs";
import path from "path";
import yaml from "yaml";
import { SCRIPTS_DIR, WORKFLOWS_DIR } from "./paths.js";

export function assertScriptName(name) {
  if (typeof name !== "string" || !/^[A-Za-z0-9._-]+\.js$/.test(name)) {
    const err = new Error("invalid script name");
    err.statusCode = 400;
    throw err;
  }
  return name;
}

export function assertOwner(name) {
  if (typeof name !== "string" || !/^[A-Za-z0-9_-]+$/.test(name)) {
    const err = new Error("invalid owner");
    err.statusCode = 400;
    throw err;
  }
  return name;
}

export function assertWorkflowFile(name) {
  if (
    typeof name !== "string" ||
    !/^[A-Za-z0-9._-]+\.ya?ml$/.test(name) ||
    name === "registers.yaml"
  ) {
    const err = new Error("invalid workflow file");
    err.statusCode = 400;
    throw err;
  }
  return name;
}

export function listScriptFiles() {
  if (!fs.existsSync(SCRIPTS_DIR)) return [];
  return fs
    .readdirSync(SCRIPTS_DIR)
    .filter((f) => f.endsWith(".js"))
    .sort();
}

export function readScript(name) {
  assertScriptName(name);
  const filePath = path.join(SCRIPTS_DIR, name);
  if (!fs.existsSync(filePath)) return null;
  return fs.readFileSync(filePath, "utf8");
}

/**
 * Icon next to the script: `fetch-html.js` → `fetch-html.png` or `.jpg`.
 * @returns {{ filePath: string, contentType: string } | null}
 */
export function resolveScriptIcon(name) {
  assertScriptName(name);
  const base = name.slice(0, -3);
  for (const { ext, contentType } of [
    { ext: "png", contentType: "image/png" },
    { ext: "jpg", contentType: "image/jpeg" },
  ]) {
    const filePath = path.join(SCRIPTS_DIR, `${base}.${ext}`);
    if (fs.existsSync(filePath) && fs.statSync(filePath).isFile()) {
      return { filePath, contentType };
    }
  }
  return null;
}

export function scriptHasIcon(name) {
  return resolveScriptIcon(name) != null;
}

export function listOwners() {
  if (!fs.existsSync(WORKFLOWS_DIR)) return [];
  return fs
    .readdirSync(WORKFLOWS_DIR, { withFileTypes: true })
    .filter((d) => d.isDirectory())
    .map((d) => d.name)
    .sort();
}

function registersPath(owner) {
  return path.join(WORKFLOWS_DIR, owner, "registers.yaml");
}

export function readRegisters(owner) {
  const filePath = registersPath(owner);
  if (!fs.existsSync(filePath)) return [];
  const parsed = yaml.parse(fs.readFileSync(filePath, "utf8")) ?? {};
  return Array.isArray(parsed.scripts) ? parsed.scripts : [];
}

export function writeRegisters(owner, files) {
  const ownerDir = path.join(WORKFLOWS_DIR, owner);
  fs.mkdirSync(ownerDir, { recursive: true });
  fs.writeFileSync(
    registersPath(owner),
    yaml.stringify({ scripts: files }),
    "utf8",
  );
}

export function readWorkflowYaml(owner, file) {
  assertOwner(owner);
  assertWorkflowFile(file);
  const filePath = path.join(WORKFLOWS_DIR, owner, file);
  if (!fs.existsSync(filePath)) return null;
  return fs.readFileSync(filePath, "utf8");
}

/**
 * Last content change time for a workflow YAML file.
 * Uses birthtime (creation) when the file has not been modified since it was created.
 * @returns {string | null} ISO timestamp
 */
export function workflowLastModifiedAt(owner, file) {
  try {
    assertOwner(owner);
    assertWorkflowFile(file);
  } catch {
    return null;
  }
  const filePath = path.join(WORKFLOWS_DIR, owner, file);
  try {
    const st = fs.statSync(filePath);
    const birthMs = Number.isFinite(st.birthtimeMs) && st.birthtimeMs > 0 ? st.birthtimeMs : null;
    const mtimeMs = Number.isFinite(st.mtimeMs) && st.mtimeMs > 0 ? st.mtimeMs : null;
    const unmodified = birthMs != null && (mtimeMs == null || mtimeMs <= birthMs + 1000);
    const ms = unmodified ? birthMs : (mtimeMs ?? birthMs);
    return ms != null ? new Date(ms).toISOString() : null;
  } catch {
    return null;
  }
}

export function writeWorkflowYaml(owner, file, content) {
  assertOwner(owner);
  assertWorkflowFile(file);
  const ownerDir = path.join(WORKFLOWS_DIR, owner);
  fs.mkdirSync(ownerDir, { recursive: true });
  fs.writeFileSync(path.join(ownerDir, file), content, "utf8");
}

export function listOwnerYamlFiles(owner) {
  const ownerDir = path.join(WORKFLOWS_DIR, owner);
  if (!fs.existsSync(ownerDir)) return [];
  return fs
    .readdirSync(ownerDir)
    .filter((f) => f.endsWith(".yaml") && f !== "registers.yaml")
    .sort();
}