package year25

import (
	"fmt"

	"git.bizdoc.ro/gabi-public/Advent-of-Code.git/aoc"
	"git.bizdoc.ro/gabi-public/Advent-of-Code.git/aocutils"
	"git.bizdoc.ro/gabi-public/Advent-of-Code.git/year25/day7_pg"
	"git.bizdoc.ro/private/devkit.git/collections/geometry/v2"
)

func day7ParseInput(c aoc.Context) (g geometry.Grid[byte], start geometry.Point, _ error) {
	g, err := geometry.ReaderToByteGrid(c.Body)
	if err != nil {
		return g, start, fmt.Errorf("day7: failed to read input %w", err)
	}

	findStart := g.Find(func(b byte) bool {
		return b == byte('S')
	})

	for start = range findStart {
		return g, start, nil
	}

	return g, start, fmt.Errorf("day7: failed to find starting point")
}

func Day7Part1(c aoc.Context) (int, error) {
	g, start, err := day7ParseInput(c)
	if err != nil {
		return 0, fmt.Errorf("day7: failed to parse input %w", err)
	}

	var fill func(g geometry.Grid[byte], start geometry.Point) int
	fill = func(g geometry.Grid[byte], start geometry.Point) int {
		if g.ContainsPoint(start) {
			switch g.At(start) {
			case 'S':
				return fill(g, start.MoveDown())
			case '.':
				g.Set(start, '|')
				return fill(g, start.MoveDown())
			case '^':
				return 1 + fill(g, start.MoveLeft()) + fill(g, start.MoveRight())
			}
		}
		return 0
	}
	return fill(g, start), nil
}

func Day7Part2(c aoc.Context) (int, error) {
	g, start, err := day7ParseInput(c)
	if err != nil {
		return 0, fmt.Errorf("day7: failed to parse input %w", err)
	}

	h := geometry.NewGrid[int](g.Rows(), g.Cols())

	var fill func(g geometry.Grid[byte], h geometry.Grid[int], start geometry.Point) int
	fill = func(g geometry.Grid[byte], cache geometry.Grid[int], start geometry.Point) int {
		if g.ContainsPoint(start) {
			switch g.At(start) {
			case 'S':
				return 1 + fill(g, cache, start.MoveDown())
			case '.':
				g.Set(start, '|')
				v := fill(g, cache, start.MoveDown())
				cache.Set(start, v)
				return v
			case '|':
				return cache.At(start) // cached value
			case '^':
				return 1 + fill(g, cache, start.MoveLeft()) + fill(g, cache, start.MoveRight())
			}
		}
		return 0
	}
	return fill(g, h, start), nil
}

func Day7Part1Render(c aoc.Context) (int, error) {
	g, start, err := day7ParseInput(c)
	if err != nil {
		return 0, fmt.Errorf("day7: failed to parse input %w", err)
	}
	var ev day7_pg.Day7Part1RenderEvent
	for ev = range day7_pg.Day7ProgressFillPart1(g, start) {
	}
	return int(ev.TotalProcessed), nil
}