/**
 * Configuration loading for the extension.
 *
 * Reads global/project JSON config files plus environment overrides and exposes
 * a normalized, fully-populated runtime config object.
 */
import { existsSync, readFileSync } from "node:fs";
import { homedir } from "node:os";
import { join } from "node:path";

export type JsonRecord = Record<string, unknown>;

export type ExtensionConfig = {
  enabled?: boolean;
  notify?: boolean;
};

export function isRecord(value: unknown): value is JsonRecord {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

function readJsonFile(path: string): JsonRecord | undefined {
  if (!existsSync(path)) return undefined;
  try {
    const parsed = JSON.parse(readFileSync(path, "utf8"));
    return isRecord(parsed) ? parsed : undefined;
  } catch {
    return undefined;
  }
}

function toBoolean(value: unknown): boolean | undefined {
  if (typeof value === "boolean") return value;
  if (typeof value === "number") return value !== 0;
  if (typeof value !== "string") return undefined;
  const normalized = value.trim().toLowerCase();
  if (["1", "true", "yes", "on"].includes(normalized)) return true;
  if (["0", "false", "no", "off"].includes(normalized)) return false;
  return undefined;
}

export function loadConfig(cwd: string): Required<ExtensionConfig> {
  const globalPath = join(homedir(), ".pi", "agent", "openai-server-compaction.json");
  const projectPath = join(cwd, ".pi", "openai-server-compaction.json");
  const globalCfg = readJsonFile(globalPath) ?? {};
  const projectCfg = readJsonFile(projectPath) ?? {};
  const merged = { ...globalCfg, ...projectCfg };

  return {
    enabled:
      toBoolean(process.env.PI_OPENAI_SERVER_COMPACTION_ENABLED) ??
      toBoolean(merged.enabled) ??
      true,
    notify:
      toBoolean(process.env.PI_OPENAI_SERVER_COMPACTION_NOTIFY) ??
      toBoolean(merged.notify) ??
      false,
  };
}