import { readFileSync } from "node:fs";
import { join } from "node:path";
import { fileURLToPath } from "node:url";

const TOOL_SEARCH_DIR = join("my-pi", "tool-search");

/**
 * Bundle-level `config/` is the single source of truth: the extension reads
 * `config/tool-search.json` from inside the installed bundle (resolved
 * relative to this source file), never deployed to or migrated from the
 * agent directory.
 */
export function getToolSearchConfigPath(): string {
  return fileURLToPath(new URL("../../config/tool-search.json", import.meta.url));
}

/** Disposable catalog cache under the agent dir's `my-pi/tool-search/` tree. */
export function getToolSearchCatalogPath(agentDir: string): string {
  return join(agentDir, TOOL_SEARCH_DIR, "catalog-v1.json");
}

export const BUNDLE_TOOL_SEARCH_DEFAULTS = {
  alwaysEnabled: [
    "codegraph_explore",
    "lsp_diagnostics",
    "memory_search",
    "session_search",
    "memory_add",
    "memory_replace",
    "memory_remove",
    "skill_manage",
    "context_tree_query",
    "overflow_query",
    "codemode",
  ],
  showToolSearchFooterStatus: false,
  maxActiveGroups: 5,
  maxToolsPerGroup: 8,
  maxDynamicTools: 28,
  groupOverrides: {},
} as const;

export interface ToolSearchConfig {
  alwaysEnabled: string[];
  showToolSearchFooterStatus: boolean;
  maxActiveGroups: number;
  maxToolsPerGroup: number;
  maxDynamicTools: number;
  groupOverrides: Record<string, string[]>;
}

function isObject(value: unknown): value is Record<string, unknown> {
  return value !== null && typeof value === "object" && !Array.isArray(value);
}

function positiveInteger(value: unknown, fallback: number): number {
  return typeof value === "number" && Number.isInteger(value) && value > 0 ? value : fallback;
}

function stringList(value: unknown): string[] {
  if (!Array.isArray(value)) return [];
  return [...new Set(value.filter((item): item is string => typeof item === "string" && item.length > 0))];
}

function readGroupOverrides(value: unknown): Record<string, string[]> {
  if (!isObject(value)) return {};
  const overrides: Record<string, string[]> = {};
  for (const [groupId, names] of Object.entries(value)) {
    const tools = stringList(names);
    if (groupId.trim() && tools.length > 0) overrides[groupId] = tools;
  }
  return overrides;
}

export function bundleFallbackConfig(): ToolSearchConfig {
  return {
    alwaysEnabled: [...BUNDLE_TOOL_SEARCH_DEFAULTS.alwaysEnabled],
    showToolSearchFooterStatus: BUNDLE_TOOL_SEARCH_DEFAULTS.showToolSearchFooterStatus,
    maxActiveGroups: BUNDLE_TOOL_SEARCH_DEFAULTS.maxActiveGroups,
    maxToolsPerGroup: BUNDLE_TOOL_SEARCH_DEFAULTS.maxToolsPerGroup,
    maxDynamicTools: BUNDLE_TOOL_SEARCH_DEFAULTS.maxDynamicTools,
    groupOverrides: {},
  };
}

/**
 * Read the Tool Search config. Defaults to the bundle-level
 * `config/tool-search.json`; tests inject an explicit temp path. A missing,
 * unreadable, or non-object file falls back to the bundle defaults.
 */
export function readToolSearchConfig(
  configPath: string = getToolSearchConfigPath(),
): ToolSearchConfig {
  const fallback = bundleFallbackConfig();
  try {
    const parsed: unknown = JSON.parse(readFileSync(configPath, "utf8"));
    if (!isObject(parsed)) return fallback;
    const config = parsed;
    return {
      alwaysEnabled: Array.isArray(config.alwaysEnabled) ? stringList(config.alwaysEnabled) : fallback.alwaysEnabled,
      showToolSearchFooterStatus:
        typeof config.showToolSearchFooterStatus === "boolean"
          ? config.showToolSearchFooterStatus
          : fallback.showToolSearchFooterStatus,
      maxActiveGroups: positiveInteger(config.maxActiveGroups, fallback.maxActiveGroups),
      maxToolsPerGroup: positiveInteger(config.maxToolsPerGroup, fallback.maxToolsPerGroup),
      maxDynamicTools: positiveInteger(config.maxDynamicTools, fallback.maxDynamicTools),
      groupOverrides: readGroupOverrides(config.groupOverrides),
    };
  } catch {
    return fallback;
  }
}