local robot = require('robot')
local sides = require('sides')
local nav = require('nav')
local io = require('io')

local filename, mode = ...

if not filename or not mode then
    print('Usage: build <filename> <corner|center>')
    print('Top of the blueprint file will be where the robot is facing')
    return 1
end


---Read file line by line and split lines to characters and parse numbers
---@param f file*
---@return table grid
local function parse_file(f)
    local grid = {}

    local line = f:read("*l")

    while line do
        local index = 1
        local row = {}
        for c in string.gmatch(line, ".") do
            if c ~= '.' and c ~= ' ' then
                local n = tonumber(c)
                if n then
                    row[index] = n
                else
                    row[index] = 0
                end
            else
                row[index] = 0
            end

            index = index + 1
        end

        grid[#grid + 1] = row

        line = f:read("*l")
    end

    return grid
end

---Move the robot from the center of the grid to the top left corner
---Begins facing "up" and ends facing "up"
---@param grid table 2d array
local function move_to_corner(grid)
    local x = math.floor(#grid / 2)
    nav.forward(x)
    robot.turnLeft()
    local z = math.floor(#(grid[1]) / 2)
    nav.forward(z)
    robot.turnRight()
end

---Move the robot from the bottom left corner of the grid to the center
---Begins facing "up" and ends facing "up"
---@param grid table 2d array
local function move_back_to_center(grid)
    local x = math.floor(#grid / 2)
    nav.forward(x)
    robot.turnRight()
    local z = math.floor(#(grid[1]) / 2)
    nav.forward(z)
    robot.turnLeft()
end

---Move the robot from the bottom left corner of the grid to the center
---Begins facing "up" and ends facing "up"
---@param grid table 2d array
local function move_back_to_top_corner(grid)
    nav.forward(#grid - 1)
end

---Build the blueprint
---Robot begins facing up
---@param grid table 2d array
local function build(grid)
    robot.turnRight()
    for _, row in ipairs(grid) do
        for _, block in ipairs(row) do
            if block ~= 0 then
                robot.select(block)
                robot.placeDown(sides.down)
            end
            nav.forward(1)
        end
        robot.turnRight()
        nav.forward(1)
        robot.turnRight()
        nav.forward(#row)
        robot.turnAround()
    end
    robot.turnLeft()
    nav.forward()
end


local file = io.open(filename, 'r')

if not file then
    print('File not found')
    return 2
end

local grid = parse_file(file)

if mode == 'center' then
    move_to_corner(grid)
end

build(grid)

if mode == 'center' then
    move_back_to_center(grid)
else
    move_back_to_top_corner(grid)
end

file:close()