import * as fs from "fs";
import * as os from "os";
import * as path from "path";
import * as dotenv from "dotenv";
import * as YAML from "yaml";
import { ZodError } from "zod";
import { childLogger } from "../runtime/logger";
import { DisclawConfigSchema } from "./schema";
import type { DisclawConfig } from "./schema";

export type { DisclawConfig } from "./schema";

const log = childLogger("config");

export interface EnvConfig {
  DISCORD_BOT_TOKEN: string;
  DISCORD_GUILD_ID?: string;
  CLAUDE_PATH?: string;
}

/**
 * Expands a leading `~` in a path to the user's home directory and resolves
 * the result to an absolute, normalised path. No shell expansion is used.
 *
 * Exported as a pure function so it can be unit-tested independently.
 */
export function expandWorkspacesRoot(raw: string, repoRoot: string): string {
  let expanded = raw;

  if (expanded.startsWith("~")) {
    expanded = os.homedir() + expanded.slice(1);
  }

  const resolved = path.resolve(repoRoot, expanded);

  const rel = path.relative(repoRoot, resolved);
  const isInsideRepo = !rel.startsWith("..") && !path.isAbsolute(rel);

  if (isInsideRepo) {
    log.warn(
      { workspacesRoot: resolved },
      "workspaces_root lies inside the DisClaw repository. " +
        "Claude Code walks parent directories and concatenates every CLAUDE.md it finds. " +
        "A workspace under the repo root will inherit the project CLAUDE.md, " +
        "leaking DisClaw system instructions into every agent context. " +
        "Set workspaces_root to a path outside the repository (e.g. ~/.disclaw/workspaces)."
    );
  }

  return resolved;
}

export function loadEnv(rootDir: string): EnvConfig {
  dotenv.config({ path: path.join(rootDir, ".env") });

  const token = process.env.DISCORD_BOT_TOKEN;

  if (!token) {
    throw new Error("DISCORD_BOT_TOKEN is not set in .env");
  }

  return {
    DISCORD_BOT_TOKEN: token,
    DISCORD_GUILD_ID: process.env.DISCORD_GUILD_ID,
    CLAUDE_PATH: process.env.CLAUDE_PATH,
  };
}

export function loadDisclawConfig(rootDir: string): DisclawConfig {
  const configPath = path.join(rootDir, "disclaw.yaml");

  if (!fs.existsSync(configPath)) {
    throw new Error(`disclaw.yaml not found at ${configPath}`);
  }

  const raw = fs.readFileSync(configPath, "utf-8");
  const rawParsed = YAML.parse(raw);

  let validated: DisclawConfig;
  try {
    validated = DisclawConfigSchema.parse(rawParsed);
  } catch (err) {
    if (err instanceof ZodError) {
      const first = err.errors[0];
      const fieldPath = first.path.length > 0 ? first.path.join(".") : "(root)";
      throw new Error(
        `Invalid disclaw.yaml: field "${fieldPath}" -- ${first.message}`
      );
    }
    throw err;
  }

  const config: DisclawConfig = {
    ...validated,
    workspaces_root: expandWorkspacesRoot(validated.workspaces_root, rootDir),
  };

  return config;
}