@file:JvmName("StringUtils")

package com.keylesspalace.tusky.util

import android.text.Spanned
import java.util.Random

private const val POSSIBLE_CHARS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"

fun randomAlphanumericString(count: Int): String {
    val chars = CharArray(count)
    val random = Random()
    for (i in 0 until count) {
        chars[i] = POSSIBLE_CHARS[random.nextInt(POSSIBLE_CHARS.length)]
    }
    return String(chars)
}

// We sort statuses by ID. Something we need to invent some ID for placeholder.

/**
 * "Increment" string so that during sorting it's bigger than [this]. Inverse operation to [dec].
 */
fun String.inc(): String {
    val builder = this.toCharArray()
    var i = builder.lastIndex

    while (i >= 0) {
        if (builder[i] < 'z') {
            builder[i] = builder[i].inc()
            return String(builder)
        } else {
            builder[i] = '0'
        }
        i--
    }
    return String(
        CharArray(builder.size + 1) { index ->
            if (index == 0) '0' else builder[index - 1]
        }
    )
}

/**
 * "Decrement" string so that during sorting it's smaller than [this]. Inverse operation to [inc].
 */
fun String.dec(): String {
    if (this.isEmpty()) return this

    val builder = this.toCharArray()
    var i = builder.lastIndex
    while (i >= 0) {
        if (builder[i] > '0') {
            builder[i] = builder[i].dec()
            return String(builder)
        } else {
            builder[i] = 'z'
        }
        i--
    }
    return String(builder.copyOfRange(1, builder.size))
}

/**
 * A < B (strictly) by length and then by content.
 * Examples:
 * "abc" < "bcd"
 * "ab"  < "abc"
 * "cb"  < "abc"
 * not: "ab" < "ab"
 * not: "abc" > "cb"
 */
fun String.isLessThan(other: String): Boolean {
    return when {
        this.length < other.length -> true
        this.length > other.length -> false
        else -> this < other
    }
}

fun Spanned.trimTrailingWhitespace(): Spanned {
    var i = length
    do {
        i--
    } while (i >= 0 && get(i).isWhitespace())
    return subSequence(0, i + 1) as Spanned
}

/**
 * BidiFormatter.unicodeWrap is insufficient in some cases (see #1921)
 * So we force isolation manually
 * https://unicode.org/reports/tr9/#Explicit_Directional_Isolates
 */
fun CharSequence.unicodeWrap(): String {
    return "\u2068${this}\u2069"
}