using Dictionaries: Dictionary

using Graphs: AbstractGraph, nv, vertices

using ITensors: ITensors, Index, siteind

function ITensors.siteind(sitetype::String, v::Tuple; kwargs...)

return addtags(siteind(sitetype; kwargs...), vertex_tag(v))

end

# naming collision of ITensors.addtags and addtags keyword in siteind system

function ITensors.siteind(d::Integer, v; addtags="", kwargs...)

return ITensors.addtags(Index(d; tags="Site, $addtags", kwargs...), vertex_tag(v))

end

to_siteinds_callable(x) = Returns(x)

function to_siteinds_callable(x::AbstractDictionary)

return Base.Fix1(getindex, x) ∘ keytype(x)

end

function siteinds(x, g::AbstractGraph; kwargs...)

return siteinds(to_siteinds_callable(x), g; kwargs...)

end

# Convenient syntax for path graph.

function siteinds(x, nv::Int; kwargs...)

return siteinds(x, path_graph(nv); kwargs...)

end

function to_siteind(x, vertex; kwargs...)

return [siteind(x, vertex_tag(vertex); kwargs...)]

end

to_siteind(x::Index, vertex; kwargs...) = [x]

function siteinds(f::Function, g::AbstractGraph; kwargs...)

is = IndsNetwork(g)

for v in vertices(g)

is[v] = to_siteind(f(v), v; kwargs...)

end

return is

end