wgoodall01/shikaku

package shikaku

import "fmt"

// Square represents a Shikaku square, part of a Board.
type Square struct {
    // Area of the rectangle which must enclose the Square.
    // For a given square, Area != 0. For a blank, Area <= 0.
    Area int

    // Final is a blank square's parent rectangle, if it's known for certain
    // If !nil, then Possible should be nil.
    // If set to this square, a Given has been finalized.
    Final Rect

    // For a blank square, possible values for its parent Rects
    Possible []Rect
}

// NewBlank creates a blank Square
func NewBlank() Square {
    return Square{
        Area:     0,
        Possible: make([]Rect, 0, 5),
    }
}

// NewGiven creates a given Square with an area
func NewGiven(area int) Square {
    return Square{
        Area:     area,
        Possible: nil,
    }
}

// String returns a string representation of a Given
func (sq Square) String() string {
    str := ""
    if IsGiven(sq) {
        str += fmt.Sprintf("Given(%d) ", sq.Area)
    }

    if IsFinal(sq) {
        str += fmt.Sprintf("Final(%v) ", sq.Final)
    }

    if len(sq.Possible) > 0 {
        str += fmt.Sprintf("Blank%v ", sq.Possible)
    }

    if str == "" {
        return "?"
    } else {
        return str[:len(str)-1]
    }
}

// AddPossible adds a given Rect to the list of possiblities, ignoring duplicates.
// Returns true when a unique possibility is added.
func (sq *Square) AddPossible(r Rect) bool {
    // See if it's already in the list of possibles
    for _, p := range sq.Possible {
        if p == r {
            return false
        }
    }

    // Add it to the list
    sq.Possible = append(sq.Possible, r)
    return true
}

// IsNotFinal returns !IsFinal(sq)
func IsNotFinal(sq Square) bool {
    return !IsFinal(sq)
}

// IsFinal returns true if a square's value is known, and false if it isn't.
func IsFinal(sq Square) bool {
    return sq.Final != Rect{} || IsGiven(sq)
}

// IsAny returns true.
// (for use as predicate, passed to Board.IterWhere)
func IsAny(sq Square) bool {
    return true
}

// IsGiven returns if a square is Given
func IsGiven(sq Square) bool {
    return sq.Area > 0
}

// IsUnsolvedGiven returns if a square is Given and not finalized
func IsUnsolvedGiven(sq Square) bool {
    return IsGiven(sq) && (sq.Final == Rect{})
}