/**
 * @fileoverview Validates plugin instance configuration against its JSON Schema.
 *
 * Uses Ajv to validate `configJson` values against the `instanceConfigSchema`
 * declared in a plugin's manifest. This ensures that invalid configuration is
 * rejected at the API boundary, not discovered later at worker startup.
 *
 * @module server/services/plugin-config-validator
 */

import Ajv, { type ErrorObject } from "ajv";
import addFormats from "ajv-formats";
import { envBindingSecretRefSchema, type JsonSchema } from "@paperclipai/shared";

export interface ConfigValidationResult {
  valid: boolean;
  errors?: { field: string; message: string }[];
}

/**
 * Secret-ref fields are declared `type: "string"`, but the settings form and the
 * plugin secrets API store the `{ type: "secret_ref", secretId, version }` binding
 * object there. Validate the binding's secret id in its place so the schema
 * checks the field without rejecting the only shape the secrets handler accepts.
 * The walk follows object properties, array items and schema combinators, and
 * accepts a binding only when the secrets handler's own parser accepts it.
 */
function secretRefsAsIds(value: unknown, schema: unknown): unknown {
  if (!schema || typeof schema !== "object" || Array.isArray(schema)) return value;
  const node = schema as Record<string, unknown>;

  if (node.format === "secret-ref") {
    const binding = envBindingSecretRefSchema.safeParse(value);
    if (binding.success) return binding.data.secretId;
  }

  let result = value;
  for (const keyword of ["allOf", "anyOf", "oneOf"] as const) {
    const branches = node[keyword];
    if (!Array.isArray(branches)) continue;
    for (const branch of branches) result = secretRefsAsIds(result, branch);
  }

  if (Array.isArray(result)) {
    const items = node.items;
    if (items && typeof items === "object") {
      const itemSchemaAt = (index: number) => (Array.isArray(items) ? items[index] : items);
      result = result.map((item, index) => secretRefsAsIds(item, itemSchemaAt(index)));
    }
    return result;
  }

  const properties = node.properties;
  if (result && typeof result === "object" && properties && typeof properties === "object") {
    const record = { ...(result as Record<string, unknown>) };
    for (const [key, propertySchema] of Object.entries(properties as Record<string, unknown>)) {
      if (key in record) record[key] = secretRefsAsIds(record[key], propertySchema);
    }
    result = record;
  }
  return result;
}

/**
 * Validate a config object against a JSON Schema.
 *
 * @param configJson - The configuration values to validate.
 * @param schema - The JSON Schema from the plugin manifest's `instanceConfigSchema`.
 * @returns Validation result with structured field errors on failure.
 */
export function validateInstanceConfig(
  configJson: Record<string, unknown>,
  schema: JsonSchema,
): ConfigValidationResult {
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  const AjvCtor = (Ajv as any).default ?? Ajv;
  const ajv = new AjvCtor({ allErrors: true });
  // ajv-formats v3 default export is a FormatsPlugin object; call it as a plugin.
  const applyFormats = (addFormats as any).default ?? addFormats;
  applyFormats(ajv);
  // Register the secret-ref format used by plugin manifests to mark fields that
  // hold a Paperclip secret UUID rather than a raw value. The format is a UI
  // hint only — UUID validation happens in the secrets handler at resolve time.
  ajv.addFormat("secret-ref", { validate: () => true });
  const validate = ajv.compile(schema);
  const valid = validate(secretRefsAsIds(configJson, schema));

  if (valid) {
    return { valid: true };
  }

  const errors = (validate.errors ?? []).map((err: ErrorObject) => ({
    field: err.instancePath || "/",
    message: err.message ?? "validation failed",
  }));

  return { valid: false, errors };
}