require 'spec_helper'

describe Solve::Solver do
  let(:graph) { double(Solve::Graph) }
  let(:demands) { [["mysql"], ["nginx"]] }
  subject(:solver) { described_class.new(graph, demands) }

  it "has a list of demands as ruby literals" do
    solver.demands_array.should == demands
  end

  it "has a list of demands as model objects" do
    expected = [
      Solve::Demand.new(solver, "mysql"),
      Solve::Demand.new(solver, "nginx")
    ]
    solver.demands.should == expected
  end

  it "has a graph" do
    solver.graph.should == graph
  end

  describe "when the constraints are solvable" do
    let(:graph) do
      graph = Solve::Graph.new
      graph.artifact("A", "1.0.0")
      graph.artifact("B", "1.0.0").depends("A")
      graph
    end

    let(:demands) { [["A"], ["B"]] }

    it "gives the solution as a Hash" do
      solver.resolve.should == {"A"=>"1.0.0", "B"=>"1.0.0"}
    end

    it "gives the solution in sorted form" do
      solver.resolve(sorted: true).should == [["A", "1.0.0"], ["B", "1.0.0"]]
    end
  end

  describe "when the constraints are not solvable" do
    let(:error) do
      begin
        solver.resolve
      rescue => e
        e
      else
        raise "Expected resolve to cause an error"
      end
    end

    context "and dep-selector identifies missing artifacts" do
      let(:graph) do
        graph = Solve::Graph.new
        graph.artifact("A", "1.0.0")
        graph
      end

      let(:demands) { [ ["Z"] ] }

      it "raises an error detailing the missing artifacts" do
        error.to_s.should include("Missing artifacts: Z")
      end
    end

    context "and dep-selector identifies constraints that exclude all known versions" do
      let(:graph) do
        graph = Solve::Graph.new
        graph.artifact("A", "1.0.0")
        graph
      end

      let(:demands) { [ ["A", "> 1.0.0"] ] }

      it "raises an error detailing the missing artifacts" do
        error.to_s.should include("Required artifacts do not exist at the desired version")
        error.to_s.should include("Constraints that match no available version: (A > 1.0.0)")
      end
    end

    context "and dep-selector identifies dependency conflicts" do
      let(:graph) do
        graph = Solve::Graph.new
        graph.artifact("A", "1.0.0").depends("B").depends("C")
        graph.artifact("B", "1.0.0").depends("D", "= 1.0.0")
        graph.artifact("C", "1.0.0").depends("D", "= 2.0.0")
        graph.artifact("D", "1.0.0")
        graph.artifact("D", "2.0.0")
        graph
      end

      let(:demands) { [ [ "A" ] ] }

      it "raises an error detailing the missing artifacts" do
        error.to_s.should include("Demand that cannot be met: (A >= 0.0.0)")
        error.to_s.should include("Artifacts for which there are conflicting dependencies: D = 1.0.0 -> []")
      end
    end

    context "and dep-selector times out looking for a solution" do
      let(:selector) { double(DepSelector::Selector) }

      before do
        graph.stub(:artifacts).and_return([])
        DepSelector::Selector.stub(:new).and_return(selector)
        selector.stub(:find_solution).and_raise(DepSelector::Exceptions::TimeBoundExceeded)
      end

      it "raises an error explaining no solution could be found" do
        error.to_s.should include("The dependency constraints could not be solved in the time allotted.")
      end
    end

    context "and dep-selector times out looking for dependency conflicts" do
      let(:selector) { double(DepSelector::Selector) }

      before do
        graph.stub(:artifacts).and_return([])
        DepSelector::Selector.stub(:new).and_return(selector)
        selector.stub(:find_solution).and_raise(DepSelector::Exceptions::TimeBoundExceededNoSolution)
      end

      it "raises a NoSolutionCauseUnknown error to indicate that no debug info was generated" do
        error.should be_a_kind_of(Solve::Errors::NoSolutionCauseUnknown)
      end

      it "raises an error explaining that no solution exists but the cause could not be determined" do
        error.to_s.should include("There is a dependency conflict, but the solver could not determine the precise cause in the time allotted.")
      end
    end
  end

  describe "finding unsatisfiable demands" do
    it "partitions demands into satisfiable and not satisfiable"
  end

  describe "supporting Serializer interface" do
    let(:serializer) { Solve::Solver::Serializer.new }

    before do
      graph.stub(:artifacts).and_return([])
    end

    it "implements the required interface" do
      json_string = serializer.serialize(solver)
      problem_data = JSON.parse(json_string)
      expected_demands = [
        {"name" => "mysql", "constraint" => ">= 0.0.0"},
        {"name" => "nginx", "constraint" => ">= 0.0.0"}
      ]

      problem_data["demands"].should =~ expected_demands
    end
  end
end