import { ErrorObject } from 'ajv';
import getProp from 'lodash.get';
import { ApiErrorSchema, UnleashError } from './unleash-error';

type ValidationErrorDescription = {
    description: string;
    message: string;
    path?: string;
};
class BadDataError extends UnleashError {
    details: ValidationErrorDescription[];

    constructor(
        message: string,
        errors?: [ValidationErrorDescription, ...ValidationErrorDescription[]],
    ) {
        const topLevelMessage =
            'Request validation failed: your request body contains invalid data' +
            (errors
                ? '. Refer to the `details` list to see what happened.'
                : `: ${message}`);
        super(topLevelMessage);

        this.details = errors ?? [{ message: message, description: message }];
    }

    toJSON(): ApiErrorSchema {
        return {
            ...super.toJSON(),
            details: this.details,
        };
    }
}

export default BadDataError;

const constructPath = (pathToParent: string, propertyName: string) =>
    [pathToParent, propertyName].filter(Boolean).join('.');

const missingRequiredPropertyMessage = (
    pathToParentObject: string,
    missingPropertyName: string,
) => {
    const path = constructPath(pathToParentObject, missingPropertyName);
    const description = `The ${path} property is required. It was not present on the data you sent.`;
    return {
        path,
        description,
        message: description,
    };
};

const additionalPropertiesMessage = (
    pathToParentObject: string,
    additionalPropertyName: string,
) => {
    const path = constructPath(pathToParentObject, additionalPropertyName);
    const description = `The ${
        pathToParentObject ? `\`${pathToParentObject}\`` : 'root'
    } object of the request body does not allow additional properties. Your request included the \`${path}\` property.`;

    return {
        path,
        description,
        message: description,
    };
};

const genericErrorMessage = (
    requestBody: object,
    propertyName: string,
    errorMessage: string = 'is invalid',
) => {
    const input = getProp(requestBody, propertyName);

    const youSent = JSON.stringify(input);
    const description = `The .${propertyName} property ${errorMessage}. You sent ${youSent}.`;
    return {
        description,
        message: description,
        path: propertyName,
    };
};

export const fromOpenApiValidationError =
    (requestBody: object) =>
    (validationError: ErrorObject): ValidationErrorDescription => {
        // @ts-expect-error Unsure why, but the `dataPath` isn't listed on the type definition for error objects. However, it's always there. Suspect this is a bug in the library.
        const dataPath = validationError.dataPath.substring('.body.'.length);

        switch (validationError.keyword) {
            case 'required':
                return missingRequiredPropertyMessage(
                    dataPath,
                    validationError.params.missingProperty,
                );
            case 'additionalProperties':
                return additionalPropertiesMessage(
                    dataPath,
                    validationError.params.additionalProperty,
                );
            default:
                return genericErrorMessage(
                    requestBody,
                    dataPath,
                    validationError.message,
                );
        }
    };

export const fromOpenApiValidationErrors = (
    requestBody: object,
    validationErrors: [ErrorObject, ...ErrorObject[]],
): BadDataError => {
    const [firstDetail, ...remainingDetails] = validationErrors.map(
        fromOpenApiValidationError(requestBody),
    );

    return new BadDataError(
        "Request validation failed: the payload you provided doesn't conform to the schema. Check the `details` property for a list of errors that we found.",
        [firstDetail, ...remainingDetails],
    );
};