KStarbound/src/main/kotlin/ru/dbotthepony/kstarbound/io/Streams.kt

package ru.dbotthepony.kstarbound.io

import it.unimi.dsi.fastutil.bytes.ByteArrayList
import java.io.IOException
import java.io.InputStream
import java.io.RandomAccessFile

/**
 * Читает Variable Length Integer как Long
 */
fun RandomAccessFile.readVarLong(): Long {
	var result = 0L
	var read = read()

	while (true) {
		result = (result shl 7) or (read.toLong() and 0x7FL)

		if (read and 0x80 == 0) {
			break
		}

		read = read()
	}

	return result
}

data class VarIntReadResult(val value: Int, val cells: Int)

/**
 * Читает Variable Length Integer как Int
 */
fun RandomAccessFile.readVarInt(): Int {
	var result = 0
	var read = read()

	while (true) {
		result = (result shl 7) or (read and 0x7F)

		if (read and 0x80 == 0) {
			break
		}

		read = read()
	}

	return result
}

/**
 * Читает Variable Length Integer как Int
 */
fun RandomAccessFile.readVarIntInfo(): VarIntReadResult {
	var result = 0
	var read = read()
	var i = 1

	while (true) {
		result = (result shl 7) or (read and 0x7F)

		if (read and 0x80 == 0) {
			break
		}

		read = read()
		i++
	}

	return VarIntReadResult(result, i)
}

/**
 * Читает Variable Length Integer как Int
 */
fun InputStream.readVarIntInfo(): VarIntReadResult {
	var result = 0
	var read = read()
	var i = 1

	while (true) {
		result = (result shl 7) or (read and 0x7F)

		if (read and 0x80 == 0) {
			break
		}

		read = read()
		i++
	}

	return VarIntReadResult(result, i)
}

/**
 * Читает Variable Length Integer как Long
 */
fun InputStream.readVarLong(): Long {
	var result = 0L
	var read = read()

	while (true) {
		result = (result shl 7) or (read.toLong() and 0x7FL)

		if (read and 0x80 == 0) {
			break
		}

		read = read()
	}

	return result
}

/**
 * Читает Variable Length Integer как Int
 */
fun InputStream.readVarInt(): Int {
	var result = 0
	var read = read()

	while (true) {
		result = (result shl 7) or (read and 0x7F)

		if (read and 0x80 == 0) {
			break
		}

		read = read()
	}

	return result
}

fun RandomAccessFile.readString(length: Int): String {
	require(length >= 0) { "Invalid length $length" }

	val bytes = ByteArray(length)
	try {
		readFully(bytes)
	} catch(err: Throwable) {
		throw IOException("Tried to read string with length of $length", err)
	}

	return bytes.toString(Charsets.UTF_8)
}

fun InputStream.readString(length: Int, allowSmaller: Boolean = false): String {
	require(length >= 0) { "Invalid length $length" }

	val bytes = ByteArray(length)

	try {
		val read = readNBytes(bytes, 0, length)

		if (!allowSmaller)
			require(read == bytes.size) { "Read $read bytes, expected ${bytes.size}" }
	} catch(err: Throwable) {
		throw IOException("Tried to read string with length of $length", err)
	}

	return bytes.toString(Charsets.UTF_8)
}

fun RandomAccessFile.readCString(): String {
	val bytes = ByteArrayList()
	var read = read()

	while (read != 0) {
		bytes.add(read.toByte())
		read = read()
	}

	return ByteArray(bytes.size).also {
		for (i in it.indices) {
			it[i] = bytes.getByte(i)
		}
	}.toString(Charsets.UTF_8)
}

fun InputStream.readCString(): String {
	val bytes = ByteArrayList()
	var read = read()

	while (read != 0) {
		bytes.add(read.toByte())
		read = read()
	}

	return ByteArray(bytes.size).also {
		for (i in it.indices) {
			it[i] = bytes.getByte(i)
		}
	}.toString(Charsets.UTF_8)
}

fun InputStream.readByteChar(): Char {
	return read().toChar()
}

fun InputStream.readHeader(header: String) {
	for ((i, char) in header.withIndex()) {
		val read = readByteChar()

		if (read != char) {
			throw IllegalArgumentException("Malformed header at byte $i: expected $char (${char.code}) got $read (${char.code})")
		}
	}
}