/**
 * Type representing a valid where operator.
 */
type WhereOperator = '&' | '>' | '>=' | '<' | '<=' | '!=' | '<=>' | '%' | '|' | '!' | '~' | '=' | '^'

/**
 * Type associating search items with a key.
 */
type AssociatedSearchItem = { key: any, item: any }

/**
 * Type representing the result of a where.
 */
type WhereResult = any[]

/**
 * Returns true if the given item satisfies the given where clause.
 * @param {AssociatedSearchItem} item
 * @param {WhereOperator} operator
 * @param [operand]
 * @return boolean
 */
const whereMatch = (item: AssociatedSearchItem, operator: WhereOperator, operand?: any): boolean => {
    switch ( operator ) {
        case '&':
            if ( item.key & operand ) return true
            break
        case '>':
            if ( item.key > operand ) return true
            break
        case '>=':
            if ( item.key >= operand ) return true
            break
        case '<':
            if ( item.key < operand ) return true
            break
        case '<=':
            if ( item.key <= operand ) return true
            break
        case '!=':
            if ( item.key !== operand ) return true
            break
        case '<=>':
            if ( item.key === operand && typeof item.key !== 'undefined' && item.key !== null )
                return true
            break
        case '%':
            if ( item.key % operand ) return true
            break
        case '|':
            if ( item.key | operand ) return true
            break
        case '!':
            if ( !item.key ) return true
            break
        case '~':
            if ( ~item.key ) return true
            break
        case '=':
            if ( item.key === operand ) return true
            break
        case '^':
            if ( item.key ^ operand ) return true
            break
    }

    return false
}

/**
 * Apply the given where clause to the items and return those that match.
 * @param {Array<AssociatedSearchItem>} items
 * @param {WhereOperator} operator
 * @param [operand]
 */
const applyWhere = (items: AssociatedSearchItem[], operator: WhereOperator, operand?: any): WhereResult => {
    const matches: WhereResult = []
    for ( const item of items ) {
        if ( whereMatch(item, operator, operand) )
            matches.push(item.item)
    }

    return matches
}

export { WhereOperator, WhereResult, AssociatedSearchItem, applyWhere, whereMatch }