aoc2025/day12/area.zig

const std = @import("std");

const shapeModule = @import("shape.zig");
const Shape = shapeModule.Shape;
const kShapeSize = shapeModule.kShapeSize;

pub const Area = struct {
    rows: i32 = 0,
    cols: i32 = 0,
    data: []u8 = undefined,
    dataAllocator: std.mem.Allocator,

    pub fn init(allocator: std.mem.Allocator, rows: i32, cols: i32) !Area {
        var area: Area = .{
            .rows = rows,
            .cols = cols,
            .data = try allocator.alloc(u8, @intCast(rows*cols)),
            .dataAllocator = allocator,
        };

        for (0 .. area.data.len) |i| {
            area.data[i] = '.';
        }
        return area;
    }

    pub fn deinit(self: *const Area) void {
        self.dataAllocator.free(self.data);
    }

    pub fn copy(self: *const Area, allocator: std.mem.Allocator) !Area {
        const area: Area = .{
            .rows = self.rows,
            .cols = self.cols,
            .data = try allocator.alloc(u8, @intCast(self.rows*self.cols)),
            .dataAllocator = allocator,
        };
        std.mem.copyForwards(u8, area.data, self.data);
        return area;
    }

    pub fn totalFreeSize(self: *const Area) usize {
        var freeSize:usize = 0;
        for (self.data) |d| {
            if (d == '.') {
                freeSize += 1;
            }
        }
        return freeSize;
    }

    pub fn getCell(self: *const Area, row: i32, col: i32) u8 {
        return self.data[@intCast(row*self.cols + col)];
    }

    pub fn setCell(self: *Area, row: i32, col: i32, cell: u8) void {
        self.data[@intCast(row*self.cols + col)] = cell;
    }

    pub fn print(self: *const Area, allocator: std.mem.Allocator) !void {
        const rows:usize = @intCast(self.rows);
        const cols:usize = @intCast(self.cols);
        for (0..rows) |row| {
            for (0..cols) |col| {
                const cell = self.getCell(@intCast(row), @intCast(col));
                try std.fs.File.stdout().writeAll(
                  try std.fmt.allocPrint(allocator, "{c}", .{cell}));
        
            }
            try std.fs.File.stdout().writeAll("\n");
        }
    }

    pub fn appendShape(self: * const Area, allocator: std.mem.Allocator,
                       shape: *const Shape, row: i32, col: i32, shapeSymbol: u8) !?Area {
        var area = try self.copy(allocator);
        for (0..kShapeSize) |shapeRow| {
            for (0..kShapeSize) |shapeCol| {
                if (shape.getCell(@intCast(shapeRow), @intCast(shapeCol)) == '.') {
                    continue;
                }

                var areaRow:i32 = @intCast(shapeRow);
                areaRow += row;
                if (areaRow >= area.rows) {
                    area.deinit();
                    return null;
                }

                var areaCol:i32 = @intCast(shapeCol);
                areaCol += col;
                if (areaCol >= area.cols) {
                    area.deinit();
                    return null;
                }

                if (area.getCell(areaRow, areaCol) != '.') {
                    area.deinit();
                    return null;
                }

                area.setCell(areaRow, areaCol, shapeSymbol);
            }
        }

        return area;
    }
};