package piscine
import "strings"

func SudokuSolver(lines ...string) string {
    if len(lines) != 9 {
        return "Erreur"
    }
    var sudoku [9][9]rune
    for i, line := range lines {
        line = strings.ReplaceAll(line, " ", "")
        for j, value := range line {
            if value == '.' {
                sudoku[i][j] = '0'
            } else {
                sudoku[i][j] = value
            }
        }
    }
    if resSudoku(&sudoku) {
        return returnPresentation(sudoku)
    }
    return "Erreur"
}

func resSudoku(sudoku *[9][9]rune) bool {
    var rang, col int
    if !caseVide(sudoku, &rang, &col) {
        return true
    }

    for num := '1'; num <= '9'; num++ {
        if caseValide(sudoku, rang, col, num) {
            sudoku[rang][col] = num
            if resSudoku(sudoku) {
                return true
            }
            sudoku[rang][col] = '0'
        }
    }
    return false
}

func caseVide(sudoku *[9][9]rune, rang, col *int) bool {
    for i := 0; i < 9; i++ {
        for j := 0; j < 9; j++ {
            if sudoku[i][j] == '0' {
                *rang, *col = i, j
                return true
            }
        }
    }
    return false
}

func caseValide(sudoku *[9][9]rune, rang, col int, num rune) bool {
    return dansRang(sudoku, rang, num) == false &&
        dansCol(sudoku, col, num) == false &&
        dansBlock(sudoku, rang-rang%3, col-col%3, num) == false
}

func dansRang(sudoku *[9][9]rune, rang int, num rune) bool {
    for col := 0; col < 9; col++ {
        if sudoku[rang][col] == num {
            return true
        }
    }
    return false
}

func dansCol(sudoku *[9][9]rune, col int, num rune) bool {
    for rang := 0; rang < 9; rang++ {
        if sudoku[rang][col] == num {
            return true
        }
    }
    return false
}

func dansBlock(sudoku *[9][9]rune, boxStartrang, boxStartCol int, num rune) bool {
    for rang := 0; rang < 3; rang++ {
        for col := 0; col < 3; col++ {
            if sudoku[rang+boxStartrang][col+boxStartCol] == num {
                return true
            }
        }
    }
    return false
}

func returnPresentation(sudoku [9][9]rune) string {
    result := ""
    for i := 0; i < 9; i++ {
        for j := 0; j < 9; j++ {
            result += string(sudoku[i][j])
            if j < 8 {
                result += " "
            }
        }
        if i < 8 {
            result += "\n"
        }
    }
    return result
}