openspace.autonavigation.documentation = {
    {
        Name = "removeRenderedPath",
        Arguments = "",
        Documentation = "Remove the rendered path, if any."
    },
    {
        Name = "renderPath",
        Arguments = "int, [bool], [bool], [number]",
        Documentation = "Render the currently active path, using linear segments. " .. 
            "The first argurment is the number of samples per path segment. " ..
            "The optional second argument can be used to render the points of " ..
            "the path as spheres, if set to true." ..
            "The optional third argument will visualize camera orientation if set to true." ..
            "The optional fourth input affects the size of the points and orientation lines."
    },
    {
        Name = "removeControlPoints",
        Arguments = "",
        Documentation = "Remove the rendered control points, if any."
    },
    {
        Name = "renderControlPoints",
        Arguments = "[number]",
        Documentation = "Test method for rendering the control points of the camera " .. 
            "path spline. The optional input is used to specify the radius of the points."
    },
}

openspace.autonavigation.removeRenderedPath = function () 
    local path_identifier = "Camera_Path"
    if openspace.hasSceneGraphNode(path_identifier) then
        openspace.removeSceneGraphNode(path_identifier) 
    end
end

openspace.autonavigation.renderPath = function (nrLinesPerSegment, renderPoints, renderOrientations, sphereRadius)
    local path_identifier = "Camera_Path"
    local label_point = "Point"
    local label_line = "Line"
    local lineColor = {1.0, 1.0, 0.0}
    local lineWidth = 4
    local sphereTexture = openspace.absPath("${MODULES}/autonavigation/textures/red.png")
    local sphereSegments = 50
    local label_orientation = "Orientation"
    local orientationLineColor = {1.0, 0.0, 0.0}
    local orientationLineWidth = 2

    if (sphereRadius == nil) then 
        sphereRadius = 2000000 -- TODO: better default
    end 

    local orientationLineLength = 30 * sphereRadius

    if openspace.hasSceneGraphNode(path_identifier) then
        openspace.removeSceneGraphNode(path_identifier) 
    end

    local path = { Identifier = path_identifier }
    openspace.addSceneGraphNode(path)

    local points = openspace.autonavigation.getPathPositions(nrLinesPerSegment)
    local viewDirections = openspace.autonavigation.getPathViewDirections(nrLinesPerSegment)
    local nrPoints = 0
    for _ in pairs(points) do 
        nrPoints = nrPoints + 1 
    end

    -- points
    for key, point in pairs(points) do
        local node = {
            Identifier = label_point .. key,
            Transform = {
                Translation = {
                    Type = "StaticTranslation",
                    Position = point 
                }
            }, 
            Parent = path_identifier
        }

        if renderPoints then 
            node.Renderable = {
                Type = "RenderableSphere",
                Enabled = true,
                Segments = sphereSegments,
                Size = sphereRadius,
                Texture = sphereTexture,
                Opacity = 1
            }
        end

        openspace.addSceneGraphNode(node)
    end

    -- lines between points
    for i = 1,(nrPoints-1) do
        local node = {
            Identifier = label_line .. i,
            Renderable = {
                Enabled = true,
                Type = "RenderableNodeLine",
                StartNode = label_point .. i,
                EndNode = label_point .. (i+1),
                Color = lineColor,
                LineWidth = lineWidth,
                Opacity = 0.5
            }, 
            Parent = path_identifier
        }
        openspace.addSceneGraphNode(node)
    end

    -- lines for view direction
    if renderOrientations then

        for key, point in pairs(points) do
            local viewPos = { 
                tonumber(point[1]) + tonumber(viewDirections[key][1]) * orientationLineLength,
                tonumber(point[2]) + tonumber(viewDirections[key][2]) * orientationLineLength,
                tonumber(point[3]) + tonumber(viewDirections[key][3]) * orientationLineLength
            }

            local node = {
                Identifier = label_orientation .. label_point .. key,
                Transform = {
                    Translation = {
                        Type = "StaticTranslation",
                        Position = viewPos
                    }
                }, 
                Parent = path_identifier
            }
            openspace.addSceneGraphNode(node)
        end

        for i = 1,nrPoints do
            local node = {
                Identifier = label_orientation .. label_line .. i,
                Renderable = {
                    Enabled = true,
                    Type = "RenderableNodeLine",
                    StartNode = label_point .. i,
                    EndNode = label_orientation .. label_point .. i,
                    Color = orientationLineColor,
                    LineWidth = orientationLineWidth,
                    Opacity = 1
                }, 
                Parent = path_identifier
            }
            openspace.addSceneGraphNode(node)
        end                                         
    end

end

openspace.autonavigation.removeControlPoints = function () 
    local base_identifier = "Path_Control_Points"
    if openspace.hasSceneGraphNode(base_identifier) then
        openspace.removeSceneGraphNode(base_identifier) 
    end
end

openspace.autonavigation.renderControlPoints = function (sphereRadius)
    local base_identifier = "Path_Control_Points"
    local label_point = "ControlPoint"
    local sphereTexture = openspace.absPath("${MODULES}/autonavigation/textures/yellow.png") 
    local sphereSegments = 50

    if (sphereRadius == nil) then 
        sphereRadius = 2000000 -- TODO: better default
    end 

    if openspace.hasSceneGraphNode(base_identifier) then
        openspace.removeSceneGraphNode(base_identifier)
    end

    local base = { Identifier = base_identifier}
    openspace.addSceneGraphNode(base)

    local points = openspace.autonavigation.getControlPoints()

    for key, point in pairs(points) do
        local node = {
            Identifier = label_point .. key,
            Transform = {
                Translation = {
                    Type = "StaticTranslation",
                    Position = point 
                }
            }, 
            Renderable = {
                Type = "RenderableSphere",
                Enabled = true,
                Segments = sphereSegments,
                Size = sphereRadius,
                Texture = sphereTexture,
                Opacity = 1
            },
            Parent = base_identifier, 
            GUI = {
                Name = "Control Point" .. key,
                Path = "/Camera Paths Debug/",
            }
        }
        openspace.addSceneGraphNode(node)
    end
end