import {ValidationResult, ValidatorFunction} from './types'
import {UniversalPath} from '../../util'

/** Requires the given input value to be some form of affirmative boolean. */
function accepted(fieldName: string, inputValue: unknown): ValidationResult {
    if ( ['yes', 'Yes', 'YES', 1, true, 'true', 'True', 'TRUE'].includes(String(inputValue)) ) {
        return { valid: true }
    }

    return {
        valid: false,
        message: 'must be accepted',
    }
}

/** Requires the given input value to be some form of boolean. */
function boolean(fieldName: string, inputValue: unknown): ValidationResult {
    const boolish = ['true', 'True', 'TRUE', '1', 'false', 'False', 'FALSE', '0', true, false, 1, 0]
    if ( boolish.includes(String(inputValue)) ) {
        return { valid: true }
    }

    return {
        valid: false,
        message: 'must be true or false',
    }
}

/** Requires the input value to be of type string. */
function string(fieldName: string, inputValue: unknown): ValidationResult {
    if ( typeof inputValue === 'string' ) {
        return { valid: true }
    }

    return {
        valid: false,
        message: 'must be a string',
    }
}

/** Requires the given input value to be present and non-nullish. */
function required(fieldName: string, inputValue: unknown): ValidationResult {
    if ( typeof inputValue !== 'undefined' && inputValue !== null && inputValue !== '' ) {
        return { valid: true }
    }

    return {
        valid: false,
        message: 'is required',
        stopValidation: true,
    }
}

/** Alias of required(). */
function present(fieldName: string, inputValue: unknown): ValidationResult {
    return required(fieldName, inputValue)
}

/** Alias of required(). */
function filled(fieldName: string, inputValue: unknown): ValidationResult {
    return required(fieldName, inputValue)
}

/** Requires the given input value to be absent or nullish. */
function prohibited(fieldName: string, inputValue: unknown): ValidationResult {
    if ( typeof inputValue === 'undefined' || inputValue === null || inputValue === '' ) {
        return { valid: true }
    }

    return {
        valid: false,
        message: 'is not allowed',
        stopValidation: true,
    }
}

/** Alias of prohibited(). */
function absent(fieldName: string, inputValue: unknown): ValidationResult {
    return prohibited(fieldName, inputValue)
}

/** Alias of prohibited(). */
function empty(fieldName: string, inputValue: unknown): ValidationResult {
    return prohibited(fieldName, inputValue)
}

/**
 * Builds a validator function that requires the given input to be found in an array of values.
 * @param values
 */
function foundIn(values: any[]): ValidatorFunction {
    return (fieldName: string, inputValue: unknown): ValidationResult => {
        if ( values.includes(inputValue) ) {
            return { valid: true }
        }

        return {
            valid: false,
            message: `must be one of: ${values.join(', ')}`,
        }
    }
}

/**
 * Builds a validator function that requires the given input NOT to be found in an array of values.
 * @param values
 */
function notFoundIn(values: any[]): ValidatorFunction {
    return (fieldName: string, inputValue: unknown): ValidationResult => {
        if ( values.includes(inputValue) ) {
            return { valid: true }
        }

        return {
            valid: false,
            message: `must be one of: ${values.join(', ')}`,
        }
    }
}

/** Requires the input value to be number-like. */
function numeric(fieldName: string, inputValue: unknown): ValidationResult {
    if ( !isNaN(parseFloat(String(inputValue))) ) {
        return { valid: true }
    }

    return {
        valid: false,
        message: 'must be numeric',
    }
}

/** Requires the given input value to be integer-like. */
function integer(fieldName: string, inputValue: unknown): ValidationResult {
    if ( !isNaN(parseInt(String(inputValue), 10)) && parseInt(String(inputValue), 10) === parseFloat(String(inputValue)) ) {
        return { valid: true }
    }

    return {
        valid: false,
        message: 'must be an integer',
    }
}

/** Requires the given input value to be a UniversalPath. */
function file(fieldName: string, inputValue: unknown): ValidationResult {
    if ( inputValue instanceof UniversalPath ) {
        return { valid: true }
    }

    return {
        valid: false,
        message: 'must be a file',
    }
}

/**
 * A special validator function that marks a field as optional.
 * If the value of the field is nullish, no further validation rules will be applied.
 * If it is non-nullish, validation will continue.
 * @param fieldName
 * @param inputValue
 */
function optional(fieldName: string, inputValue: unknown): ValidationResult {
    if ( inputValue ?? true ) {
        return {
            valid: true,
            stopValidation: true,
        }
    }

    return { valid: true }
}

export const Is = {
    accepted,
    boolean,
    string,
    required,
    present,
    filled,
    prohibited,
    absent,
    empty,
    foundIn,
    notFoundIn,
    numeric,
    integer,
    file,
    optional,
}