package day23

import (
	"log"

	mapset "github.com/deckarep/golang-set/v2"
)

type PathEnd struct {
	end     Coord
	visited mapset.Set[Coord]
}

func ExtendPath(p PathEnd, f Field) (nextPaths []PathEnd) {
	endPointNeighbors := f.NeighborsPart2(p.end)
	for _, potentialNewEnd := range endPointNeighbors {
		if !p.visited.Contains(potentialNewEnd) {
			nextVisited := p.visited.Clone()
			nextVisited.Add(p.end)
			nextPaths = append(nextPaths, PathEnd{
				end:     potentialNewEnd,
				visited: nextVisited,
			})
		}
	}

	return
}

// return paths that end on End
func RunAllScenicPaths(f Field) (result []PathEnd) {
	pathsToFurther := []PathEnd{
		{end: Coord{Row: 0, Col: f.StartCol}, visited: mapset.NewSet[Coord]()},
	}

	theEndCoord := Coord{Row: f.MaxRow, Col: f.EndCol}

	for len(pathsToFurther) > 0 {
		curCheckedPath := pathsToFurther[0]
		pathsToFurther = pathsToFurther[1:]

		if curCheckedPath.end == theEndCoord {
			result = append(result, curCheckedPath)
			log.Printf("found end path of len %d . %+v", curCheckedPath.visited.Cardinality(), curCheckedPath)
			continue
		}

		nextSteps := ExtendPath(curCheckedPath, f)

		// log.Printf("for %+v next steps %+v\n", curCheckedPath, pathsToFurther)
		// log.Printf("remaining paths to check len is %d", len(pathsToFurther))
		// log.Println(pathsToFurther)

		if len(nextSteps) > 0 {
			pathsToFurther = append(pathsToFurther, nextSteps...)
		}
	}

	return
}