using Base
import Luxor as L

"""
Colour of a component given its fluctuations
"""
function colour_of_diff(diff::Real)::Tuple{Real,Real,Real}
    if diff > 0
        return (0.5,1,0.5)
    else
        return (1,0.5,0.5)
    end
end

component_text_size = 20

@kwdef struct Component
    pos::Tuple{UInt, UInt}
    size::Tuple{UInt, UInt}
    name::String
    diff::Real
end

sector_title_font_size = 16
sector_title_height = 20

@kwdef struct Sector
    name::String
    pos::Tuple{UInt, UInt}
    size::Tuple{UInt, UInt}
    components::Array{Component}
end

@kwdef struct CompositionDiagram
    sectors::Array{Sector}
end

"""
Draws stock index composition chart
"""
function draw(diagram::CompositionDiagram, size=(800, 600))
    L.Drawing(size[1], size[2], :png)
    L.background("black")
    for sector in diagram.sectors
        L.sethue("gray")
        L.rect(L.Point(sector.pos), sector.size[1], sector.size[2], action = :fillpreserve)
        L.setline(2)
        L.strokepath()
        L.sethue("white")
        L.setfont("Helvetica", sector_title_font_size)
        L.settext(
            sector.name,
            L.Point(sector.pos),
            halign="left",
            valign="top",
        )
        L.setfont("Helvetica", component_text_size)
        for component in sector.components
            pos = sector.pos .+ component.pos
            L.setcolor(colour_of_diff(component.diff))
            L.rect(L.Point(pos), component.size[1], component.size[2], action = :fillpreserve)
            L.sethue("white")
            L.setline(5)
            L.strokepath()
            L.settext(
                component.name,
                L.Point(pos .+ component.size ./ 2),
                halign="center",
                valign="bottom",
            )
            L.settext(
                "$(component.diff)%",
                L.Point(pos .+ component.size ./ 2),
                halign="center",
                valign="top",
            )
        end
    end
    L.finish()
end

diagram = CompositionDiagram(
    sectors=[
        Sector(
            name="technology",
            pos=(0,0),
            size=(200,300),
            components=[
                Component(pos=(0,20), size=(200,200),name="AAPL", diff=0.5),
                Component(pos=(0,200), size=(200,100),name="GOOG", diff=-0.3),
            ],
        ),
        Sector(
            name="resources",
            pos=(200,0),
            size=(200,200),
            components=[
                Component(pos=(0,20), size=(200,150),name="OIL", diff=0.1),
            ],
        ),
    ],
)
draw(diagram)