package binary

/* ---------------------------------------------------------------- *
 * IMPORTS
 * ---------------------------------------------------------------- */

import (
	"fmt"

	"ads/internal/core/logging"
	"ads/internal/core/metrics"
)

/* ---------------------------------------------------------------- *
 * GLOBAL VARIABLES/CONSTANTS
 * ---------------------------------------------------------------- */

//

/* ---------------------------------------------------------------- *
 * ALGORITHM binary search
 * ---------------------------------------------------------------- */

/*
Inputs: L = Liste von Zahlen, x = Zahl.

Annahme: L sei aufsteigend sortiert.

Outputs: Position von x in L, sonst −1 wenn x nicht in L.
*/
func BinarySearch(L []int, x int) int {
	if len(L) == 0 {
		logging.LogDebug(fmt.Sprintf("x nicht in L"))
		return -1
	}
	metrics.AddTimeCost()
	m := int(len(L) / 2)
	if L[m] == x {
		logging.LogDebug(fmt.Sprintf("x in Position m gefunden"))
		return m
	} else if x < L[m] {
		logging.LogDebug(fmt.Sprintf("Suche in linker Hälfte fortsetzen."))
		index := BinarySearch(L[:m], x)
		return index
	} else { // } else if x > L[m] {
		logging.LogDebug(fmt.Sprintf("Suche in rechter Hälfte fortsetzen."))
		index := BinarySearch(L[m+1:], x)
		if index >= 0 {
			index += (m + 1) // NOTE: muss Indexwert kompensieren
		}
		return index
	}
}