package com.plexworlds.l3


fun String.shouldBeSkippedOnPosition(offset: Int) = checkElementUnderCaret(this, offset) {
    afterSemicolon()
            || afterLBrace()
            || afterRBrace()
            || beforeLParenthesis()
            || afterRParenthesis()
            || insideIdentifier()
            || atTheBoundaryOfStringLiteral()
            || atTheBoundaryOfCharLiteral()
            || atTheEndOfDigitalLiteral()
}


private fun Pair<Char, Char>.afterSemicolon(): Boolean {
    return first == ';'
}


private fun Pair<Char, Char>.afterLBrace(): Boolean {
    return first == '{'
}


private fun Pair<Char, Char>.afterRBrace(): Boolean {
    return first == '}'
}


private fun Pair<Char, Char>.beforeLParenthesis(): Boolean {
    return second == '('
}


private fun Pair<Char, Char>.afterRParenthesis(): Boolean {
    return first == ')'
}


private fun Pair<Char, Char>.insideIdentifier(): Boolean {
    return first.isLetterOrDigit() && second.isLetterOrDigit()
}


private fun Pair<Char, Char>.atTheBoundaryOfStringLiteral(): Boolean {
    return first == '"' || second == '"'
}


private fun Pair<Char, Char>.atTheBoundaryOfCharLiteral(): Boolean {
    return first == '\'' || second == '\''
}


private fun Pair<Char, Char>.atTheEndOfDigitalLiteral(): Boolean {
    fun Char.isArithmeticOperator() = this == '+' || this == '-' || this == '*' || this == '/'
    fun Char.isLogicalOperator() = this == '&' || this == '|' || this == '!' || this == '=' || this == '<' || this == '>'
    return (first.isDigit() || first == 'L' || first == 'f')
            && (second == ';' || second == ' ' || second.isArithmeticOperator() || second.isLogicalOperator())
}


private fun checkElementUnderCaret(
    text: String,
    offset: Int,
    satisfySkippedCriteria: Pair<Char, Char>.() -> Boolean
): Boolean {
    val beforeCaretChar = if (offset in 0..text.lastIndex) text[offset] else '\n'
    val afterCaretChar = if (offset + 1 in 0..text.lastIndex) text[offset + 1] else '\n'
    return (beforeCaretChar to afterCaretChar).satisfySkippedCriteria()
}