import { mkdirSync } from "fs";
import path from "path";
import { workspacePath } from "../../workspace/paths.js";
import { WORKSPACE_FILES } from "../../../src/config/workspacePaths.js";
import { loadJsonFile, writeJsonAtomicSync } from "./json.js";
import { log } from "../../system/logger/index.js";
import { isRecord } from "../types.js";

export interface ScheduleOverride {
  intervalMs?: number;
  // "HH:MM" in UTC for daily schedules.
  time?: string;
}

export type ScheduleOverrides = Record<string, ScheduleOverride>;

// Strict HH:MM — rejects 99:99 etc.
export const UTC_HH_MM_RE = /^([01]\d|2[0-3]):[0-5]\d$/;

function isScheduleOverride(value: unknown): value is ScheduleOverride {
  if (!isRecord(value)) return false;
  const obj = value;
  const hasInterval = "intervalMs" in obj && typeof obj.intervalMs === "number" && obj.intervalMs > 0;
  const hasTime = "time" in obj && typeof obj.time === "string" && UTC_HH_MM_RE.test(obj.time);
  return hasInterval || hasTime;
}

function overridesPath(root?: string): string {
  return path.join(root ?? workspacePath, WORKSPACE_FILES.schedulerOverrides);
}

/** Keep only the entries that parse as an override, warning about the rest.
 *  Shared by the disk read and the PUT route so both accept exactly the same
 *  shapes — a value that survives here is the only thing ever stored. */
export function keepValidOverrides(raw: Record<string, unknown>): ScheduleOverrides {
  const result: ScheduleOverrides = {};
  for (const [key, value] of Object.entries(raw)) {
    if (isScheduleOverride(value)) {
      result[key] = value;
    } else {
      log.warn("scheduler-overrides", "invalid entry, skipping", { key });
    }
  }
  return result;
}

// Filters out invalid entries with a warning.
export function loadSchedulerOverrides(root?: string): ScheduleOverrides {
  const raw = loadJsonFile<unknown>(overridesPath(root), {});
  if (!isRecord(raw)) {
    log.warn("scheduler-overrides", "overrides.json is not an object");
    return {};
  }
  return keepValidOverrides(raw);
}

export function saveSchedulerOverrides(overrides: ScheduleOverrides, root?: string): void {
  const filePath = overridesPath(root);
  mkdirSync(path.dirname(filePath), { recursive: true });
  writeJsonAtomicSync(filePath, overrides);
}