/**
 * Shared settings.json loading utilities.
 *
 * Reads global (~/.pi/agent/settings.json) and project (.pi/settings.json)
 * settings, merging them so the closest-to-cwd wins.
 */

import { getAgentDir } from "@earendil-works/pi-coding-agent";
import * as fs from "node:fs";
import * as path from "node:path";

type SettingsObject = Record<string, unknown>;

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

function mergeInto(target: SettingsObject, source: SettingsObject): void {
  for (const [key, value] of Object.entries(source)) {
    const existing = target[key];
    if (isSettingsObject(existing) && isSettingsObject(value)) {
      mergeInto(existing, value);
    } else {
      target[key] = value;
    }
  }
}

/**
 * Read and merge settings from global + all project-level settings.json files.
 * Project settings are walked up from `cwd` and applied farthest-first,
 * so the closest `.pi/settings.json` wins over more distant ones.
 */
export function loadSettings(cwd: string): Record<string, unknown> {
  const merged: SettingsObject = {};

  function mergeFrom(raw: string) {
    try {
      const settings = JSON.parse(raw);
      if (isSettingsObject(settings)) {
        mergeInto(merged, settings);
      }
    } catch {
      /* ignore */
    }
  }

  // Global settings
  try {
    mergeFrom(fs.readFileSync(path.join(getAgentDir(), "settings.json"), "utf-8"));
  } catch {
    /* ignore */
  }

  // Project settings (walk up from cwd, collect all, apply farthest-first so closest wins)
  const projectPaths: string[] = [];
  let dir = cwd;
  while (true) {
    projectPaths.push(path.join(dir, ".pi", "settings.json"));
    const parent = path.dirname(dir);
    if (parent === dir) break;
    dir = parent;
  }
  for (let i = projectPaths.length - 1; i >= 0; i--) {
    try {
      mergeFrom(fs.readFileSync(projectPaths[i], "utf-8"));
    } catch {
      /* ignore */
    }
  }

  return merged;
}