defaultlibrary.jl

export DefaultLibrary, DefaultPolyhedron

"""
    DefaultLibrary{T}

Default library for polyhedra of dimension larger than 1 ([`IntervalLibrary`](@ref) is the default for polyhedra of dimension 1).
The library implements the bare minimum and uses the fallback implementation for all operations.
"""
struct DefaultLibrary{T} <: Library
    solver
    function DefaultLibrary{T}(solver=nothing) where T
        new{T}(solver)
    end
end

similar_library(lib::DefaultLibrary, d::FullDim, ::Type{T}) where T = default_library(d, T) # default_library allows to fallback to Interval if d is FullDim{1}

mutable struct DefaultPolyhedron{T, HRepT<:HRepresentation{T}, VRepT<:VRepresentation{T}} <: Polyhedron{T}

    hrep::Union{HRepT, Nothing}
    hred::Redundancy
    vrep::Union{VRepT, Nothing}
    vred::Redundancy
    solver
    function DefaultPolyhedron{T, HRepT, VRepT}(hrep::Union{HRepT, Nothing}, vrep::Union{VRepT, Nothing}, solver) where {T, HRepT<:HRepresentation{T}, VRepT<:VRepresentation{T}}
        new{T, HRepT, VRepT}(hrep, UNKNOWN_REDUNDANCY, vrep, UNKNOWN_REDUNDANCY, solver)
    end
end
function DefaultPolyhedron{T, HRepT, VRepT}(hrep::HRepT, solver) where {T, HRepT<:HRepresentation{T}, VRepT<:VRepresentation{T}}
    DefaultPolyhedron{T, HRepT, VRepT}(hrep, nothing, solver)
end
function DefaultPolyhedron{T, HRepT, VRepT}(vrep::VRepT, solver) where {T, HRepT<:HRepresentation{T}, VRepT<:VRepresentation{T}}
    DefaultPolyhedron{T, HRepT, VRepT}(nothing, vrep, solver)
end
function DefaultPolyhedron{T, HRepT, VRepT}(hrep::HRepresentation, solver) where {T, HRepT<:HRepresentation{T}, VRepT<:VRepresentation{T}}
    DefaultPolyhedron{T, HRepT, VRepT}(convert(HRepT, hrep), solver)
end
function DefaultPolyhedron{T, HRepT, VRepT}(vrep::VRepresentation, solver) where {T, HRepT<:HRepresentation{T}, VRepT<:VRepresentation{T}}
    DefaultPolyhedron{T, HRepT, VRepT}(convert(VRepT, vrep), solver)
end

FullDim(p::DefaultPolyhedron) = FullDim_rep(p.hrep, p.vrep)
library(::Type{<:DefaultPolyhedron{T}}) where {T} = DefaultLibrary{T}()
library(p::DefaultPolyhedron{T}) where {T} = DefaultLibrary{T}(p.solver)
default_solver(p::DefaultPolyhedron; T = nothing) = p.solver
supportssolver(::Type{<:DefaultPolyhedron}) = true

hvectortype(::Type{<:DefaultPolyhedron{T, HRepT}}) where {T, HRepT} = hvectortype(HRepT)
vvectortype(::Type{DefaultPolyhedron{T, HRepT, VRepT}}) where {T, HRepT, VRepT} = vvectortype(VRepT)

similar_type(::Type{<:DefaultPolyhedron{S, HRepT, VRepT}}, d::FullDim, ::Type{T}) where {S, HRepT, VRepT, T} = DefaultPolyhedron{T, similar_type(HRepT, d, T), similar_type(VRepT, d, T)}

function DefaultPolyhedron{T, HRepT, VRepT}(d::FullDim, hits::HIt...; solver=nothing) where {T, HRepT, VRepT}
    DefaultPolyhedron{T, HRepT, VRepT}(HRepT(d, hits...), solver)
end
function DefaultPolyhedron{T, HRepT, VRepT}(d::FullDim, vits::VIt...; solver=nothing) where {T, HRepT, VRepT}
    DefaultPolyhedron{T, HRepT, VRepT}(VRepT(d, vits...), solver)
end

# Need fulltype in case the use does `intersect!` with another element
DefaultPolyhedron{T}(rep::Representation, solver) where {T} = DefaultPolyhedron{T}(change_coefficient_type(rep, T), solver)
function DefaultPolyhedron{T}(rep::HRepresentation{T}, solver) where {T}
    HRepT = fulltype(typeof(rep))
    VRepT = dualtype(HRepT)
    DefaultPolyhedron{T, HRepT, VRepT}(rep, solver)
end
function DefaultPolyhedron{T}(rep::VRepresentation{T}, solver) where {T}
    VRepT = fulltype(typeof(rep))
    HRepT = dualtype(VRepT)
    DefaultPolyhedron{T, HRepT, VRepT}(rep, solver)
end

function polyhedron(rep::Representation, lib::DefaultLibrary{T}) where {T}
    DefaultPolyhedron{polytypefor(T)}(rep, lib.solver)
end

function Base.copy(p::DefaultPolyhedron{T}) where {T}
    if p.hrep !== nothing
        DefaultPolyhedron{T}(p.hrep, p.solver)
    else
        DefaultPolyhedron{T}(p.vrep, p.solver)
    end
end

hredundancy(p::DefaultPolyhedron) = p.hred
vredundancy(p::DefaultPolyhedron) = p.vred

hrepiscomputed(p::DefaultPolyhedron) = p.hrep !== nothing
function computehrep!(p::DefaultPolyhedron)
    # vrep(p) could trigger an infinite loop if both vrep and hrep are null
    p.hrep = doubledescription(p.vrep, p.solver)
    p.hred = NO_REDUNDANCY
end
function hrep(p::DefaultPolyhedron)
    if !hrepiscomputed(p)
        computehrep!(p)
    end
    return p.hrep
end
vrepiscomputed(p::DefaultPolyhedron) = p.vrep !== nothing
function computevrep!(p::DefaultPolyhedron)
    # hrep(p) could trigger an infinite loop if both vrep and hrep are null
    p.vrep = doubledescription(p.hrep, p.solver)
    p.vred = NO_REDUNDANCY
end
function vrep(p::DefaultPolyhedron)
    if !vrepiscomputed(p)
        computevrep!(p)
    end
    return p.vrep
end

# Fallback to avoid breaking library adding this new `red` arg.
# TODO We should remove these fallbacks in the future
sethrep!(p, h, red) = sethrep!(p, h)
setvrep!(p, v, red) = setvrep!(p, v)
resethrep!(p, h, red) = resethrep!(p, h)
resetvrep!(p, v, red) = resetvrep!(p, v)

function sethrep!(p::DefaultPolyhedron, h::HRepresentation, redundancy::Redundancy = UNKNOWN_REDUNDANCY)
    p.hrep = h
    p.hred = redundancy
    return
end
function setvrep!(p::DefaultPolyhedron, v::VRepresentation, redundancy::Redundancy = UNKNOWN_REDUNDANCY)
    p.vrep = v
    p.vred = redundancy
    return
end
function resethrep!(p::DefaultPolyhedron, h::HRepresentation, redundancy::Redundancy = UNKNOWN_REDUNDANCY)
    p.hrep = h
    p.hred = redundancy
    p.vrep = nothing
    return
end
function resetvrep!(p::DefaultPolyhedron, v::VRepresentation, redundancy::Redundancy = UNKNOWN_REDUNDANCY)
    p.vrep = v
    p.vred = redundancy
    p.hrep = nothing
    return
end