import type { XOTemplate } from '@xo-cash/types';
import { xoTemplateSchema } from './schemas.ts';
import { TemplateInvalidError, buildErrorDescription } from './errors.ts';
import { deserializeTemplate, serializeTemplate } from './serialization.ts';

/**
 * Accepts a template value and returns a validated XOTemplate object. The input may be
 * either an Extended JSON string or a pre-parsed object. Both are validated
 * against the XOTemplate schema.
 *
 * @param inputTemplate - The value to validate. May be an Extended JSON string or a pre-parsed object.
 * @returns The validated template object
 * @throws {TemplateSerializationFailedError} If a pre-parsed object input cannot be serialized to JSON for normalization.
 * @throws {TemplateJsonMalformedError} If the string input is not valid JSON.
 * @throws {TemplateInvalidError} If the value does not conform to the XOTemplate schema.
 */
export const parseTemplate = (inputTemplate: string | XOTemplate): XOTemplate => {
    // Regardless of whether the inputTemplate is a string, an imported template or an in-memory object, serialize and then
    // deserialize it to ensure the output shape is consistent. For example, optional fields explicitly set to 'undefined' would be passed through
    // and then dropped on the string path, resulting in structurally different results for the same template.
    const serializedTemplate = typeof inputTemplate === 'string' ? inputTemplate : serializeTemplate(inputTemplate);
    const templateObject = deserializeTemplate(serializedTemplate);

    // Validate the template against the schema.
    const parseResult = xoTemplateSchema.safeParse(templateObject);

    if (parseResult.success) {
        // Return the validated template object
        return parseResult.data as XOTemplate;
    }

    // Build a human-readable description of every validation failure
    const errorDescription = buildErrorDescription(parseResult.error.issues);

    // Throw a typed error with the description
    throw new TemplateInvalidError(errorDescription);
};