data_functions.jl

"""
    constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::EmissionsEnergy)
    constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::EmissionsProcess)
    constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::CaptureEnergyEmissions)
    constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::CaptureProcessEmissions)
    constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::CaptureProcessEnergyEmissions)

Constraints functions for calculating both the emissions and amount of CO₂ captured in the
process. If the data ia a [`CaptureData`](@ref), it provides the constraint for the variable
:flow_out of CO₂.

There exist several configurations:
- **[`EmissionsEnergy`](@ref)** corresponds to only energy usage related emissions.
- **[`EmissionsProcess`](@ref)** corresponds to both process and energy usage related emissions.
- **[`CaptureEnergyEmissions`](@ref)** corresponds to capture of energy usage related emissions,
  can include process emissions.
- **[`CaptureProcessEmissions`](@ref)** corresponds to capture of process emissions while
  energy usage related emissions are not captured.
- **[`CaptureProcessEnergyEmissions`](@ref)** corresponds to capture of both process and energy
   usage related emissions.
"""
function constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::EmissionsEnergy)

    # Declaration of the required subsets.
    𝒫ⁱⁿ = inputs(n)
    CO2 = co2_instance(modeltype)
    𝒫ᵉᵐ = setdiff(filter(is_resource_emit, 𝒫), [CO2])

    # Constraint for the CO2 emissions
    @constraint(m, [t ∈ 𝒯],
        m[:emissions_node][n, t, CO2] == sum(co2_int(p) * m[:flow_in][n, t, p] for p ∈ 𝒫ⁱⁿ)
    )

    # Fix the other emissions to 0 to avoid problems with unconstrained variables
    for t ∈ 𝒯, p_em ∈ 𝒫ᵉᵐ
        fix(m[:emissions_node][n, t, p_em], 0; force = true)
    end
end
function constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::EmissionsProcess)

    # Declaration of the required subsets.
    𝒫ⁱⁿ = inputs(n)
    CO2 = co2_instance(modeltype)
    𝒫ᵉᵐ = setdiff(filter(is_resource_emit, 𝒫), [CO2])

    # Constraint for the CO2 emissions
    @constraint(m, [t ∈ 𝒯],
        m[:emissions_node][n, t, CO2] ==
        m[:cap_use][n, t] * process_emissions(data, CO2, t) +
        sum(co2_int(p) * m[:flow_in][n, t, p] for p ∈ 𝒫ⁱⁿ)
    )

    # Constraint for the other emissions based on the provided process emissions
    @constraint(m, [t ∈ 𝒯, p_em ∈ 𝒫ᵉᵐ],
        m[:emissions_node][n, t, p_em] ==
        m[:cap_use][n, t] * process_emissions(data, p_em, t)
    )
end
function constraints_ext_data(
    m,
    n::Node,
    𝒯,
    𝒫,
    modeltype::EnergyModel,
    data::CaptureEnergyEmissions,
)

    # Declaration of the required subsets.
    𝒫ⁱⁿ = inputs(n)
    CO2 = co2_instance(modeltype)
    𝒫ᵉᵐ = setdiff(filter(is_resource_emit, 𝒫), [CO2])

    # Calculate the total amount of CO2 to be considered for capture
    CO2_tot = @expression(m, [t ∈ 𝒯],
        sum(co2_int(p) * m[:flow_in][n, t, p] for p ∈ 𝒫ⁱⁿ)
    )

    # Constraint for the CO2 emissions
    @constraint(m, [t ∈ 𝒯],
        m[:emissions_node][n, t, CO2] ==
        (1 - co2_capture(data)) * CO2_tot[t] +
        m[:cap_use][n, t] * process_emissions(data, CO2, t)
    )

    # Constraint for the other emissions to avoid problems with unconstrained variables.
    @constraint(m, [t ∈ 𝒯, p_em ∈ 𝒫ᵉᵐ],
        m[:emissions_node][n, t, p_em] ==
        m[:cap_use][n, t] * process_emissions(data, p_em, t)
    )

    # Constraint for the outlet of the CO2
    @constraint(m, [t ∈ 𝒯], m[:flow_out][n, t, CO2] == CO2_tot[t] * co2_capture(data))
end
function constraints_ext_data(
    m,
    n::Node,
    𝒯,
    𝒫,
    modeltype::EnergyModel,
    data::CaptureProcessEmissions,
)

    # Declaration of the required subsets.
    𝒫ⁱⁿ = inputs(n)
    CO2 = co2_instance(modeltype)
    𝒫ᵉᵐ = setdiff(filter(is_resource_emit, 𝒫), [CO2])

    # Calculate the total amount of CO2 to be considered for capture
    CO2_tot = @expression(m, [t ∈ 𝒯],
        m[:cap_use][n, t] * process_emissions(data, CO2, t)
    )

    # Constraint for the CO2 emissions
    @constraint(m, [t ∈ 𝒯],
        m[:emissions_node][n, t, CO2] ==
        (1 - co2_capture(data)) * CO2_tot[t] +
        sum(co2_int(p) * m[:flow_in][n, t, p] for p ∈ 𝒫ⁱⁿ)
    )

    # Constraint for the other emissions to avoid problems with unconstrained variables.
    @constraint(m, [t ∈ 𝒯, p_em ∈ 𝒫ᵉᵐ],
        m[:emissions_node][n, t, p_em] ==
        m[:cap_use][n, t] * process_emissions(data, p_em, t)
    )

    # Constraint for the outlet of the CO2
    @constraint(m, [t ∈ 𝒯], m[:flow_out][n, t, CO2] == CO2_tot[t] * co2_capture(data))
end
function constraints_ext_data(
    m,
    n::Node,
    𝒯,
    𝒫,
    modeltype::EnergyModel,
    data::CaptureProcessEnergyEmissions,
)

    # Declaration of the required subsets
    𝒫ⁱⁿ = inputs(n)
    CO2 = co2_instance(modeltype)
    𝒫ᵉᵐ = setdiff(filter(is_resource_emit, 𝒫), [CO2])

    # Calculate the total amount of CO2 to be considered for capture
    CO2_tot = @expression(m, [t ∈ 𝒯],
        m[:cap_use][n, t] * process_emissions(data, CO2, t) +
        sum(co2_int(p) * m[:flow_in][n, t, p] for p ∈ 𝒫ⁱⁿ)
    )

    # Constraint for the CO2 emissions
    @constraint(m, [t ∈ 𝒯],
        m[:emissions_node][n, t, CO2] == (1 - co2_capture(data)) * CO2_tot[t]
    )

    # Constraint for the other emissions to avoid problems with unconstrained variables.
    @constraint(m, [t ∈ 𝒯, p_em ∈ 𝒫ᵉᵐ],
        m[:emissions_node][n, t, p_em] ==
        m[:cap_use][n, t] * process_emissions(data, p_em, t)
    )

    # Constraint for the outlet of the CO2
    @constraint(m, [t ∈ 𝒯], m[:flow_out][n, t, CO2] == CO2_tot[t] * co2_capture(data))
end

"""
    constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::ExtensionData)

Fallback option when data is specified, but it is not desired to add the constraints through
this function. This is, *e.g.*, the case for `EnergyModelsInvestments` as the capacity
constraint has to be replaced.
"""
constraints_ext_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::ExtensionData) = nothing

"""
    constraints_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::ExtensionData)

Legacy function for calling the new function [`constraints_ext_data`](@ref).
The function will be removed in release 0.10.
"""
function constraints_data(m, n::Node, 𝒯, 𝒫, modeltype::EnergyModel, data::ExtensionData)
    constraints_ext_data(m, n, 𝒯, 𝒫, modeltype, data)
end