--- Functions for working with directions and orientations.
-- @module Area.Direction
-- @usage local Direction = require('__stdlib__/stdlib/area/direction')
-- @see defines.direction

local Direction = {
    __class = 'Direction',
    __index = require('__stdlib__/stdlib/core')
}
setmetatable(Direction, Direction)

--- defines.direction.north
Direction.north = defines.direction.north
--- defines.direction.east
Direction.east = defines.direction.east
--- defines.direction.west
Direction.west = defines.direction.west
--- defines.direction.south
Direction.south = defines.direction.south
--- defines.direction.northeast
Direction.northeast = defines.direction.northeast
--- defines.direction.northwest
Direction.northwest = defines.direction.northwest
--- defines.direction.southeast
Direction.southeast = defines.direction.southeast
--- defines.direction.southwest
Direction.southwest = defines.direction.southwest


--- Returns the opposite direction
-- @tparam defines.direction direction the direction
-- @treturn defines.direction the opposite direction
function Direction.opposite(direction)
    return (direction + 4) % 8
end

--- Returns the next direction.
--> For entities that only support two directions, see @{opposite}.
-- @tparam defines.direction direction the starting direction
-- @tparam[opt=false] boolean eight_way true to get the next direction in 8-way (note: not many prototypes support 8-way)
-- @treturn defines.direction the next direction
function Direction.next(direction, eight_way)
    return (direction + (eight_way and 1 or 2)) % 8
end

--- Returns the previous direction.
--> For entities that only support two directions, see @{opposite}.
-- @tparam defines.direction direction the starting direction
-- @tparam[opt=false] boolean eight_way true to get the previous direction in 8-way (note: not many prototypes support 8-way)
-- @treturn defines.direction the next direction
function Direction.previous(direction, eight_way)
    return (direction + (eight_way and -1 or -2)) % 8
end

--- Returns an orientation from a direction.
-- @tparam defines.direction direction
-- @treturn float
function Direction.to_orientation(direction)
    return direction / 8
end

--- Returns a vector from a direction.
-- @tparam defines.direction direction
-- @tparam[opt = 1] number distance
-- @treturn Position
function Direction.to_vector(direction, distance)
    distance = distance or 1
    local x, y = 0, 0
    if direction == Direction.north then
        y = y - distance
    elseif direction == Direction.northeast then
        x, y = x + distance, y - distance
    elseif direction == Direction.east then
        x = x + distance
    elseif direction == Direction.southeast then
        x, y = x + distance, y + distance
    elseif direction == Direction.south then
        y = y + distance
    elseif direction == Direction.southwest then
        x, y = x - distance, y + distance
    elseif direction == Direction.west then
        x = x - distance
    elseif direction == Direction.northwest then
        x, y = x - distance, y - distance
    end
    return { x = x, y = y }
end

-- Deprecated
do
    local Orientation = require('__stdlib__/stdlib/area/orientation')
    Direction.opposite_direction = Direction.opposite
    Direction.direction_to_orientation = Direction.to_orientation

    function Direction.orientation_to_4way(orientation)
        return Orientation.to_direction(orientation)
    end

    function Direction.orientation_to_8way(orientation)
        return Orientation.to_direction(orientation, true)
    end

    function Direction.next_direction(direction, reverse, eight_way)
        return (direction + (eight_way and ((reverse and -1) or 1) or ((reverse and -2) or 2))) % 8
    end
end

return Direction