import { randomUUID } from "node:crypto";
import { existsSync, readFileSync, writeFileSync } from "node:fs";
import { homedir } from "node:os";
import { join, resolve } from "node:path";
import { copyToClipboard, type ExtensionContext } from "@earendil-works/pi-coding-agent";
import { CURRENT_VERSION, type StatuslineSettings } from "./schema.ts";
import { parseStatuslineSettings } from "./validation.ts";

type TransferContext = Pick<ExtensionContext, "cwd" | "ui">;

/** Export the saved document, not unsaved edits, matching ce-workflow. */
export async function exportStatuslineSettings(ctx: TransferContext, path: string, copy = copyToClipboard): Promise<void> {
  let status: string;
  try {
    await copy(readFileSync(path, "utf8"));
    status = "Settings JSON copied to clipboard (terminal support required).";
  } catch (error) {
    status = (error as NodeJS.ErrnoException).code === "ENOENT"
      ? "No settings file exists yet; nothing copied."
      : "Could not read or copy settings; use the file path below.";
  }
  ctx.ui.notify(`${status}\n${path}`, "info");
  await ctx.ui.select("Export statusline settings", [`Settings JSON file: ${path} (Enter to return)`]);
}

/** Reject malformed/unrelated documents rather than silently replacing settings with defaults. */
export function parseSettingsImport(content: string): StatuslineSettings {
  let value: Record<string, unknown>;
  try {
    value = JSON.parse(content.replace(/^\uFEFF/, ""), (key, value) => {
      if (["__proto__", "constructor", "prototype"].includes(key)) throw new Error("Unsafe settings key");
      return value;
    });
  } catch {
    // JSON parser errors may contain pasted secrets.
    throw new Error("Settings must be valid JSON without prototype-related keys.");
  }
  if (!value || typeof value !== "object" || Array.isArray(value)) throw new Error("Settings must be a JSON object.");
  if (value.version !== CURRENT_VERSION) throw new Error(`Expected statusline settings version ${CURRENT_VERSION}.`);
  const sections = ["providers", "layout", "separators", "segments", "bars", "thresholds", "timing", "icons", "preview", "extras"];
  if (!["enabled", ...sections].some((key) => Object.hasOwn(value, key))) throw new Error("No statusline settings found.");
  if (Object.hasOwn(value, "enabled") && typeof value.enabled !== "boolean") throw new Error("Enabled must be a boolean.");
  for (const key of sections) {
    if (Object.hasOwn(value, key) && (!value[key] || typeof value[key] !== "object" || Array.isArray(value[key]))) {
      throw new Error(`Statusline ${key} must be a JSON object.`);
    }
  }
  return parseStatuslineSettings(value).settings;
}

/** Confirm and back up before the caller atomically saves and applies the imported settings. */
export async function importStatuslineSettings(
  ctx: TransferContext,
  path: string,
  apply: (settings: StatuslineSettings) => void,
  dirty = false,
): Promise<boolean> {
  const input = await ctx.ui.editor("Import statusline settings: paste a file path or JSON", "");
  if (!input?.trim()) return false;
  let backup: string | undefined;
  try {
    const text = input.trim().replace(/^\uFEFF/, "");
    let content = text;
    if (!/^[{\[]/.test(text) && !/^(?:null|true|false|-?\d+(?:\.\d+)?(?:[eE][+-]?\d+)?)$/.test(text)) {
      let source = text.replace(/^(["'])(.*)\1$/s, "$2");
      if (/^~[/\\]/.test(source)) source = join(homedir(), source.slice(2));
      content = readFileSync(resolve(ctx.cwd, source), "utf8");
    }
    const imported = parseSettingsImport(content);
    if (!await ctx.ui.confirm("Replace statusline settings?", `Only import trusted settings. Back up and replace ${path}.${dirty ? " Unsaved edits will be discarded." : ""}`)) return false;
    if (existsSync(path)) {
      backup = `${path}.${new Date().toISOString().replace(/[:.]/g, "-")}.${randomUUID()}.bak`;
      writeFileSync(backup, readFileSync(path), { flag: "wx", mode: 0o600 });
    }
    apply(imported);
  } catch (error) {
    const code = (error as NodeJS.ErrnoException).code;
    ctx.ui.notify(`Settings import failed; current settings were not replaced. ${code ?? (error as Error).message}${backup ? `\nBackup: ${backup}` : ""}`, "error");
    return false;
  }
  ctx.ui.notify(`Imported statusline settings: ${path}\n${backup ? `Backup: ${backup}` : "No previous file; no backup needed."}\nStatusline settings applied immediately.`, "info");
  return true;
}